Podcasts about falciparum

On today's episode we'll discuss the findings from a phase 2 study of sorafenib plus intensive chemotherapy in newly diagnosed FLT3-ITD AML, learn more about the inhibition of PLK4 in TP53-mutated AML, and discuss the role of CD44 in Plasmodium falciparum infection.

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.07.03.547458v1?rss=1 Authors: Kweyamba, P., Hofer, L. M., Kibondo, U. A., Mwanga, R. Y., Sayi, R. M., Matwewe, F., Austin, J. W., Stutz, S., Moore, S. J., Müller, P., Tambwe, M. M. Abstract: Pyrethroid resistance in the key malaria vectors threatens the success of pyrethroid-treated nets. To overcome pyrethroid resistance, Interceptor(R) G2 (IG2), a first-in-class dual insecticidal net that combines alpha-cypermethrin with chlorfenapyr was developed. Chlorfenapyr is a pro-insecticide, requiring bio-activation by oxidative metabolism within the insects mitochondria, constituting a mode of action preventing cross-resistance to pyrethroids. Recent epidemiological trials conducted in Benin and Tanzania confirm IG2s public health value in areas with pyrethroid-resistant Anopheles mosquitoes. As chlorfenapyr might also interfere with the metabolic mechanism of the Plasmodium parasite, we hypothesised that chlorfenapyr may provide additional transmission-reducing effects even if a mosquito survives a sub-lethal dose. Therefore, we tested the effect of chlorfenapyr netting to reduce Plasmodium falciparum transmission using a modified WHO tunnel test with a dose yielding sub-lethal effects. Pyrethroid-resistant Anopheles gambiae s.s. with established mixed-function oxidases and Vgsc-L995F knockdown resistance alleles were exposed to untreated netting and netting treated with 200 mg/m3 chlorfenapyr for 8 hours overnight and then fed on gametocytemic blood meals from naturally infected individuals. Prevalence and intensity of oocysts and sporozoites were determined on day 8 and day 16 after feeding. Both prevalence and intensity of P. falciparum infection in the surviving mosquitoes were substantially reduced in the chlorfenapyr-exposed mosquitoes compared to untreated nets. The odds ratios in the prevalence of oocysts and sporozoites were 0.33 (95% confidence interval; 95% CI: 0.23- 0.46) and 0.43 (95% CI: 0.25-0.73), respectively, while only the incidence rate ratio for oocysts was 0.30 (95% CI: 0.22-0.41). We demonstrated that sub-lethal exposure of pyrethroid-resistant mosquitoes to chlorfenapyr substantially reduces the proportion of infected mosquitoes and the intensity of the P. falciparum infection. This will likely also contribute to the reduction of malaria in communities beyond the direct killing of mosquitoes. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.03.22.533773v1?rss=1 Authors: Liffner, B., Cepeda Diaz, A. K., Blauwkamp, J., Anaguano, D., Frolich, S., Muralidharan, V., Wilson, D. W., Dvorin, J., Absalon, S. Abstract: Apicomplexan parasites exhibit tremendous diversity in much of their fundamental cell biology, but study of these organisms using light microscopy is often hindered by their small size. Ultrastructural expansion microscopy (U-ExM) is a microscopy preparation method that physically expands the sample ~4.5x. Here, we apply U-ExM to the human malaria parasite Plasmodium falciparum during the asexual blood stage of its lifecycle to understand how this parasite is organized in three-dimensions. Using a combination of dye-conjugated reagents and immunostaining, we have catalogued 13 different P. falciparum structures or organelles across the intraerythrocytic development of this parasite and made multiple observations about fundamental parasite cell biology. We describe that the microtubule organizing center (MTOC) and its associated proteins anchor the nucleus to the parasite plasma membrane during mitosis. Furthermore, the rhoptries, Golgi, basal complex, and inner membrane complex, which form around this anchoring site while nuclei are still dividing, are concurrently segregated and maintain an association to the MTOC until the start of segmentation. We also show that the mitochondrion and apicoplast undergo sequential fission events while maintaining an MTOC association during cytokinesis. Collectively, this study represents the most detailed ultrastructural analysis of P. falciparum during its intraerythrocytic development to date, and sheds light on multiple poorly understood aspects of its organelle biogenesis and fundamental cell biology. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.03.16.533063v1?rss=1 Authors: Farrukh, A., Musabyimana, J.-P., Distler, U., Tenzer, S., Pradel, G., Julius Ngwa, C. Abstract: Some proteins have acquired both ubiquitin ligase activity and RNA-binding properties and are therefore known as RNA-binding Ubiquitin ligases (RBULs). These proteins provide a link between the RNA metabolism and the ubiquitin proteasome system (UPS). The UPS is a crucial protein surveillance system of eukaryotes primarily involved in the selective proteolysis of proteins which are covalently marked with ubiquitin through a series of steps involving ubiquitin E1 activating, E2 conjugating and E3 ligating enzymes. The UPS also regulates other key cellular processes such as cell cycle, proliferation, cell differentiation, transcription and signal transduction. While RBULs have been characterized in other organisms, little is known about their role in Plasmodium falciparum, the causative agent of the deadliest human malaria, malaria tropica. In this study, we characterized a previously identified putative P. falciparum RING finger E3 ligase PfRNF1. We show that the protein is highly expressed in sexual stage parasites and mainly present in immature male gametocytes. Using proximity interaction studies with parasite lines expressing PfRNF1 tagged with the Biotin ligase BirA, we identified an interaction network of PfRNF1 in both the asexual blood stages and gametocytes composed mainly of ribosomal proteins, RNA-binding proteins including translational repressors such DOZI, CITH, PUF1 and members of the CCR4-NOT complex, as well as proteins of the UPS such as RPN11, RPT1 and RPT6. Our interaction network analysis reveals PfRNF1 as a potential RNA-binding E3 ligase which links RNA dependent processes with protein ubiquitination to regulate gene expression. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.01.11.523595v1?rss=1 Authors: Carrera-Bravo, C., Zhou, T., Hang, J. W., Modh, H., Huang, F., Malleret, B., Wacker, M. G., Wang, J.-W., Renia, L., Tan, K. S. Abstract: Malaria is a vector-borne parasitic disease that affects millions worldwide. In order to reach the objective, set by the World Health Organization to decrease the cases by 2030, antimalarial drugs with novel modes of action are required. Previously, a novel mechanism of action of chloroquine (CQ) was reported involving features of programmed cell death in the parasite, mainly characterized by calcium efflux from the digestive vacuole (DV) permeabilization. Increased intracellular calcium induces the suicidal death of erythrocytes also known as eryptosis. This study aimed to identify the hallmarks of eryptosis due to calcium redistribution and the downstream cellular effects during CQ treatment in iRBCs. Plasmodium falciparum 3D7 at mid-late trophozoites were used for the antimalarial drug treatment. Our results revealed increased phosphatidylserine (PS) exposure, cell shrinkage and membrane blebbing, delineating an eryptotic phenotype in the host RBC. Interestingly, the blebs on the surface of the iRBCs released to the extracellular milieu become extracellular vesicles (EVs) which are essential for intercellular communication due to their cargo of proteins, nucleic acids, lipids and metabolites. The proteomic characterization displayed 2 highly enriched protein clusters in EVs from CQ-treated iRBCs, the proteasome and ribosome. We demonstrated that this unique protein cargo is not associated with the parasite growth rate. Additionally, we found that these particular EVs might activate IFN signaling pathways mediated by IL-6 in THP-1-derived macrophages. Our findings shed new insights into a novel drug-induced cell death mechanism that targets the parasite and specific components of the infected host RBC. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.08.331538v1?rss=1 Authors: Malcolm, T. R., Belousoff, M. J., Venugopal, H., Borg, N. A., Drinkwater, N., Atkinson, S. C., McGowan, S. Abstract: M17 leucyl aminopeptidases are metal-dependent exopeptidases that rely on oligomerization to diversify their functional roles. The M17 aminopeptidases from Plasmodium falciparum (PfA-M17) and Plasmodium vivax (Pv-M17) function as catalytically active hexamers to acquire free amino acids from human hemoglobin and are drug targets for the design of novel anti-malarial agents. In this study, we found that the active site metal ions essential for catalytic activity have a secondary structural role mediating the formation of active hexamers. We found that PfA-M17 and Pv-M17 exist in a metal-dependent dynamic equilibrium between active hexameric species and smaller inactive species, that can be controlled by manipulating the identity and concentration of metal ions available. Mutation of residues involved in metal ion binding impaired catalytic activity and the formation of active hexamers. Structural resolution of the Pv-M17 hexameric species revealed that PfA-M17 and Pv-M17 bind metal ions and substrates in a conserved fashion, although Pv-M17 forms the active hexamer more readily and processes substrates faster than PfA-M17. On the basis of solution studies and structures determined by cryo-electron microscopy, we propose a dynamic equilibrium between monomer dimer tetramer hexamer, which becomes directional towards the large oligomeric states with the addition of metal ions. M17 aminopeptidases can exploit this sophisticated metal-dependent dynamic equilibrium to regulate formation of the catalytically active hexamer and therefore regulate catalysis. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.08.285346v1?rss=1 Authors: Lebel, P. M., Dial, R., Vemuri, V. N. P., Garcia, V. E., DeRisi, J., Gomez-Sjoberg, R. Abstract: Manual microscopic inspection of fixed and stained blood smears has remained the gold standard for Plasmodium parasitemia analysis for over a century. Unfortunately, smear preparation consumes time and reagents, while manual microscopy is skill-dependent and labor-intensive. Here, we demonstrate that label-free microscopy combined with deep learning enables both life stage classification and accurate parasitemia quantification. Using a custom-built microscope, we find that deep-ultraviolet light enhances image contrast and resolution, achieving four-category classification of Plasmodium falciparum blood stages at an overall accuracy greater than 99%. To increase accessibility, we extended our method to a commercial brightfield microscope using near-ultraviolet and visible light. Both systems were tested extrinsically by parasitemia titration, revealing superior performance over manually-scored Giemsa-stained smears, and a limit of detection below 0.1%. Our results suggest that label-free microscopy combined with deep learning could eliminate the need for conventional blood smear analysis. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.21.213488v1?rss=1 Authors: Bhattacharjee, M., Adhikari, N., Sudhakar, R., Rizvi, Z., Das, D., Palanimurugan, R., Sijwali, P. S. Abstract: A variety of post-translational modifications of Plasmodium falciparum proteins, including phosphorylation and ubiquitination, are shown to have key regulatory roles. The neural precursor cell expressed developmentally downregulated protein 8 (NEDD8) is a ubiquitin-like modifier of cullin-RING E3 ubiquitin ligases, which regulate diverse cellular processes, including the cell-cycle. Although neddylation pathway is conserved in eukaryotes, it is yet to be characterized in Plasmodium and related apicomplexan parasites. Towards studying the neddylation pathway in malaria parasites, we characterized P. falciparum NEDD8 (PfNEDD8) and identified cullins as its physiological substrates. PfNEDD8 is a 76 amino acid residue protein without the C-terminal tail, indicating that it can be readily conjugated. The wild type and mutant (Gly75Gly76 mutated to Ala75Ala76) PfNEDD8 were expressed in P. falciparum. Western blot of wild type PfNEDD8-expressing parasites indicated multiple high molecular weight conjugates, which were absent in the parasites expressing the mutant, indicating conjugation of NEDD8 to proteins through Gly76. Immunoprecipitation followed by mass spectrometry of wild type PfNEDD8-expressing parasites identified several proteins, including two putative cullins. Furthermore, we expressed PfNEDD8 in mutant S. cerevisiae strains that lacked endogenous NEDD8 ({Delta}rub1) or NEDD8 conjugating E2 enzyme ({Delta}Ubc12). The western blot of complemented strains and mass spectrometry of PfNEDD8 immunoprecipitate showed conjugation of PfNEDD8 to S. cerevisiae cullin cdc53, demonstrating functional conservation and cullins as the physiological substrates of PfNEDD8. The characterization of PfNEDD8 and identification of cullins as its substrates make ground for investigation of specific roles and drug target potential of neddylation pathway in malaria parasites. Copy rights belong to original authors. Visit the link for more info

The Knights of the TWiP solve the case of the Man Who Lost Weight, and discuss a Plasmodium protein kinase that is a malarial drug target. Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin Subscribe (free): iTunes, Google Podcasts, RSS, email Links for this episode PWB social media: Facebook, Instagram, Twitter Protein kinase as malaria drug target (Science) Hero: Myron Schultz Letters read on TWiP 178 Become a patron of TWiP. Case Study for TWiP 178 Eastern border of Uganda with Kenya, in mountains. Drinking water from nearby stream. Two young boys come to clinic, without parents. Sent in by grandmother because 1 yo brother has been passing worms. Long, white, flat. Shown photos in PD7, pinkish worm, 8 inches long, round. He points to those, what he has been seeing in brother’s stool. 1 year old seems small, protuberant abdomen; brother small for stated age, bit of protuberant belly. Diet: high carbohydrate, flour deep fried; yams; cabbage; some rice; soybeans; pumpkin; bananas. Send your case diagnosis, questions and comments to twip@microbe.tv Music by Ronald Jenkees

Esta semana hablamos de plasmodium vivas: epidemiología, zonas endémicas, tratamiento de la infeccion aguda y tratamiento radical a proposito de artículos de reciente publicación en la revista científica Lancet.    Referencia:  Baird JK y colaboradores. Diagnosis and Treatment of Plasmodium vivax Malaria. Am J Trop Med hyg 2016; 95 (supp 6): 33-51. Battle KE y colaboradores. Mapping the global endemicity and clinical burden of Plasmodium vivax, 2000–17: a spatial and temporal modelling study. Lancet 2019; 6736 (19) 31096-7. Weiss DJ y colaboradores. Mapping the global prevalence, incidence, and mortality of Plasmodium falciparum, 2000-17: a spatial and temporal modelling study. Lancet 2019; S0140-6736 (19) 31097-9. Taylor WRJ y colaboradores. Short-course primaquine for radical cure of plasmodium vivax malaria: a multi center, randomized, placebo-controlled non inferiority trial. Lancet 2019.S0140-6736 (19) 31285-1.   Frase de la Semana: La tomamos del poeta español Antonio Gamoneda quien nació en Oviedo el 30 de mayo de 1931. Habiendo tenido un padre poeta que murió a temprana edad se dice que Antonio Gamoneda aprendió a leer durante la Guerra Civil Española cuando las escuelas estaban cerradas sumergiéndose en los poemas de su padre. Fue galardonado en el 2006 con el Premio Reina Sofía y El Premio Cervantes que son los honores mas alto que se conceden en la literatura española.  La frase dice:  “Estoy desnudo ante el agua inmóvil. He dejado mi ropa en el silencio de las ultimas ramas. Esto era el destino: llegar al borde y tener miedo de la quietud del agua”        

An in depth review of this notorious parasite. Hosts: Brian Gilberti, MD Audrey Bree Tse, MD https://media.blubrry.com/coreem/content.blubrry.com/coreem/Malaria.mp3 Download Leave a Comment Tags: Infectious Diseases Show Notes Background In 2017, there were 219 million cases and 435,000 people deaths from malaria Five species: Falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi. Falciparum, Vivax and Knowlesi can be fatal History of recent travel to Africa (69% of cases in US), particularly to west-Africa should raise suspicion for malaria Clinical Manifestations Average incubation period for Falciparum is 12 days 95% will develop symptoms within 1 month Clinical findings with high likelihood ratios include periodic fevers, jaundice, splenomegaly, pallor. Can also have vomiting, headache, chills, abdominal pain, cough, and diarrhea Severe malaria has a mortality of 5% to 30%, even with therapy Diagnostic criteria for severe malaria:

An in depth review of this notorious parasite. Hosts: Brian Gilberti, MD Audrey Bree Tse, MD https://media.blubrry.com/coreem/content.blubrry.com/coreem/Malaria.mp3 Download Leave a Comment Tags: Infectious Diseases Show Notes Background In 2017, there were 219 million cases and 435,000 people deaths from malaria Five species: Falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi. Falciparum, Vivax and Knowlesi can be fatal History of recent travel to Africa (69% of cases in US), particularly to west-Africa should raise suspicion for malaria Clinical Manifestations Average incubation period for Falciparum is 12 days 95% will develop symptoms within 1 month Clinical findings with high likelihood ratios include periodic fevers, jaundice, splenomegaly, pallor. Can also have vomiting, headache, chills, abdominal pain, cough, and diarrhea Severe malaria has a mortality of 5% to 30%, even with therapy Diagnostic criteria for severe malaria:

Dr Bob Taylor from MORU (Mahidol Oxford Research Unit) in Bangkok, Thailand, tells us about his research on malaria, and how we can use primaquine to treat vivax malaria and prevent the transmission of falciparum malaria Primaquine can be used both to treat vivax malaria and to prevent the transmission of falciparum malaria from human to mosquito. A shorter and age-based primaquine regimen would reduce the burden of vivax malaria. It would also allow primaquine to be used more widely to block the transmission of falciparum malaria.

The Tremendous Trio solve the case of the Woman With Foul Steatorrhea, and reveal breakdown of the glycocalyx associated with severe and fatal malaria. Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin Subscribe (free): iTunes, Google Podcasts, RSS, email Become a patron of TWiP. Links for this episode: Glycocalyx and severe malaria (Clin Inf Dis) Hero: Bridget Ogilvie Letters read on TWiP 167 Case Study for TWiP 167 Woman 30 yo, traveled to DR, went to tourist part. On return for yearly physical, asked about her chronic constipation. She said does not have it any more, has normal bowel habits. A few weeks after her return this occurred. Primary care doc was intrigued, sent off some tests. Found Entamoeba hartmanni. What might the doc have done? What were the consequences of infection? Send your case diagnosis, questions and comments to twip@microbe.tv Music by Ronald Jenkees

In a follow-up to the podcast last week, Malaria: A general introduction and Plasmodium vivax, I continue the series on the malaria species. On today's show, Parasitology teacher and author, Rosemary Drisdelle, joins me to talk about the deadliest species of malaria, Plasmodium falciparum. P. falciparum can cause severe malaria because it multiples rapidly in the blood, and can thus cause severe anemia. In addition, the infected parasites can clog small blood vessels. When this occurs in the brain, cerebral malaria results, a complication that can be fatal.

In a follow-up to the podcast last week, Malaria: A general introduction and Plasmodium vivax, I continue the series on the malaria species. On today’s show, Parasitology teacher and author, Rosemary Drisdelle, joins me to talk about the deadliest species of malaria, Plasmodium falciparum. P. falciparum can cause severe malaria because it multiples rapidly in the blood, and […] The post Plasmodium falciparum, cerebral malaria and blackwater fever appeared first on Outbreak News Today.

The TWiP peeps solve the case of the Panamanian Mother with Steatorrhea, and reveal new monoclonal antibodies that effectively block malarial infection. Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin Become a patron of TWiP. Links for this episode: Plasmodiumimmunity from injected sporozoites(Nature) New monoclonal prevents malaria infection(Nat Med) Parasite Hero: Carlos Chagas Image credit Letters read on TWiP 152 Case Study for TWiP 152 40 yo man in same Panamanian village, diarrhea for several weeks, notices blood mixed in with stool. Works in fields. No weight change, no fever, but tired. Drinking water from rooftop, lives in home with wooden slat floor, no electricity, many animals around, no one else sick in family. Lower belly tenderness, normal rectal exam. Farmer with 3 weeks of bloody diarrhea. Send your case diagnosis, questions and comments to twip@microbe.tv Music by Ronald Jenkees

The Latest Malaria News, in 60 Seconds. Mosquitoes don’t just bite for food, they also bite to quench their thirst during drought, scientists identify core genes which enables P. Falciparum to survive and The Scripps Research Institute receives $12 million from the Gates Foundation. More: www.fightmalaria.uk/MalariaMinute

The Podfessors solve the case of the Itchy Child from Panama, and discuss competition for blood in human malaria-helminth co-infections. Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin Become a patron of TWiP. Links for this episode: Competingfor Blood (Ecol Letters) Parasite Hero: William C. Campbell Image credit Letters read on TWiP 151 Case Study for TWiP 151 Woman in 30s, mother of last two boys we saw, same locale. Concerned about abdominal pain for 3 years. Fullness, bloating of lower abdomen. No blood in stool, but occasionally loose stools, difficult to clean, stick/pasty/greasy stool. Had visited hospital, underwent test, told it is an ovarian cyst and needs surgery. Took omeprazole, allbendazole, azithromycin, none helped. On exam, diffuse abdominal tenderness. Portable ultrasound: small ovarian cyst 1.5 cm, not tender. Send your case diagnosis, questions and comments to twip@microbe.tv Music by Ronald Jenkees

The Latest Malaria News, in 60 Seconds. Mosquitoes don’t just bite for food, they also bite to quench their thirst during drought, scientists identify core genes which enables P. Falciparum to survive and The Scripps Research Institute receives $12 million from the Gates Foundation. More: www.fightmalaria.uk/MalariaMinute

The TWiPians solve the case of the Woman With Anemia, Eosinophila, and a Worm in Her Intestine, and discuss a study on the function and druggability of two malarial aspartate proteases. Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin Become a patron of TWiP. Links for this episode: Malaria plasmepsins involved in invasion and egress (Science) Letters read on TWiP 143 Case Study for TWiP 143 From 1990s seen by a colleague, boy late teens, initially presented to ER in US chief complaint, visual disturbances and itching preventing sleep. Immigrated from Oaxaca, searching for work. Lived in modest dwelling with dirt floors, no running water, got from local river. Reports dogs, farm animals, many insects. On exam: tender nodules on head, skin irritated from scratching, small punctate lesions on right cornea. Is referred to specialists. Ophthalmologist called in, referred for further diagnostics. Send your case diagnosis, questions and comments to twip@microbe.tv Music by Ronald Jenkees

Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin The TWiPonderers solve the case of the Timber Worker with Severe Shaking Chills, and describe an experimental malaria vaccine comprising attenuated sporozoites produced by genetic engineering. Become a patron of TWiP. Links for this episode: Genetically engineered P. falciparum sporozoite vaccine (Sci Transl Med) Parasitology Superhero: Francesco Redi Image credit: Betsy Weissbrod Letters read on TWiP 125 This episode of TWiP is brought to you by Blue Apron. Blue Apron is the #1 fresh ingredient and recipe delivery service in the country. See what’s on the menu this week and get your first 3 meals free - WITH FREE SHIPPING - by going to blueapron.com/twip. Case Study for TWiP 125 Thanks to the Peace Corps - 24 yo female serving in Cameroon, teaching English and science at local school. Been in country 5 months, first 3 lived with host family, now in own home in community with electricity, 12 hr from Yaounde, capital. Reports intermittent diarrhea, loose stools, abdominal discomfort. No prior problems, no problems in family. No meds. No drinking or smoking. Lots of animals present, roam into class. Eating all local fare, cooks some, or buy locally. Eats fish, vegetables, no fish. Sleeps in house with mosquito nets. Not sexually active, AIDS negative. Young kids at school 6-12 yo, 20 in room. Does not eat at school. Not clear if water is treated. Not on antimalarials. Going on for a few a few weeks. No fever, no rash. Send your case diagnosis, questions and comments to twip@microbe.tv

Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin The TWiPanorama solve the case of the Dutch Woman with Wormy Objects in Her Stool, dissect a study on cytoadhesion of malaria infected red blood cells, and introduce Parasitology Superheroes. Become a patron of TWiP. Links for this episode: Myiasis (Wikipedia) Cytoadhesion of Plasmodium in severe malaria (PLoS Path) Image credit Letters read on TWiP 123 This episode is sponsored by CuriosityStream, a subscription streaming service that offers over 1,400 documentaries and non­fiction series from the world's best filmmakers. Get unlimited access starting at just $2.99 a month, and for our audience, the first two months are completely free if you sign up at curiositystream.com/microbe and use the promo code MICROBE. Case Study for TWiP 123 Nurse in early 20s, recent grad, decides to spend year in global health internship in western DR/Haitian border. On her foot has skin issue: told is fungal infection, using antifungal cream, is getting worse. Several days, only on one foot. Healthy, no past med/surg/allergies, no meds, no HIV, lives with local family. Daughter, wife, husband, cat. No toxic habits. Originally from US, swims, walks barefoot to and from, shoes off in house. Easts local food, exposure to dogs, cats, sister. Very itchy, but not open; rash area is raised. Blistery in certain areas, involves different areas in different days, snakelike.  Send your case diagnosis, questions and comments to twip@microbe.tv

Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin The TWiP troika solve the case of the Female from the Bronx, and reveal how feeding on different plants affects mosquito capacity to transmit malaria. Links for this episode: Plant mediated effects on malaria transmission (PLoS Path) Image credit Letters read on TWiP 114 This episode is sponsored by CuriosityStream, a subscription streaming service that offers over 1,400 documentaries and non­fiction series from the world's best filmmakers. Get unlimited access starting at just $2.99 a month, and for our audience, the first two months are completely free if you sign up at curiositystream.com/microbe and use the promo code MICROBE. This episode is also sponsored by Drobo, a family of safe, expandable, yet simple to use storage arrays. Drobos are designed to protect your important data forever. Visit www.drobo.com to learn more. Become a patron of TWiP. Case Study for TWiP 114 12 year old boy brought to hospital ER by parents with severe headache, stiff neck, fever, decreased alertness. No rashes. Has been healthy with no prior medical problems. No one else in family is ill. In summer, boy has been engaged in usual summertime activities: soccer, swimming in warm freshwater, playing outside. Undergoes lumbar puncture for CSF: start on meningitis treatment. No surgeries, no allergies. Not on any meds. Lives with Mom, Dad, few brothers. No substance abuse. Not a geographically limited illness. Has had bug bites - lots of mosquito bites. Dogs around as well. Symptoms began a day or two before hospital visit. Eats whatever family eats, food is cooked. Exam: 39.4C, bp low, heart rate up, resp up, decreased responsiveness, stiff neck, looks ill. WBC elevated, neutrophil predominant, eosinopenia. CSF glucose low, cells increased, no bacteria, fungi, acid fast bacilli on stain. CT scan, diffuse swelling of brain. Doing poorly, not a good outcome. Send your case diagnosis, questions and comments to twip@microbe.tv

Hosts: Vincent Racaniello and Daniel Griffin Guest: Paul Daniel and Vincent solve the case of the Truck Driver from India, discuss why parasites resistant to an antimalarial drug are not transmitted by mosquitoes, and introduce Paul who presents a new case study.   Links for this episode: Atovaquone resistant parasites not transmitted by mosquitoes (Science) Image credit Letters read on TWiP 109 This episode is sponsored by CuriosityStream, a subscription streaming service that offers over 1,400 documentaries and non­fiction series from the world's best filmmakers. Get unlimited access starting at just $2.99 a month, and for our audience, the first two months are completely free if you sign up at curiositystream.com/m​icrobe ​and use the promo code MICROBE​. Send your case diagnosis, questions and comments to twip@microbe.tv

Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin Guest: Michael Libman The TWiP-scholars solve the case of the Housewife from Kolkata, discuss mutations in the IL17 gene associated with cerebral malaria, and hear a case presentation from guest Michael Libman.   Links for this episode: IL-17 mutations and risk of cerebral malaria (Inf and Imm) Echinococcosis (CDC) Echinococcus life cycle (pdf) Letters read on TWiP 103  Case study for TWiP 103 This week's case concerns a 42 yo male, refugee in Canada, from DRC, former Zaire, where there is unending civil war. Upper middle class, professor of French at university. Had been imprisoned, tortured, lived in jungle for a few years, reached refugee camp in Tanzania, moved to Canada. Came to health care system 15 months after arrived. Was sent to psych, unstable emotionally, delusions, hallucinations, depression, post traumatic issues. Was under psych care for ~1 yr, did not improve, became worse. Sent to hospital. History: talked about having minor injury, hurt lower back, pain there bothering him. Some anemia (normochromic), basic hem/chem/urine/liver nothing remarkable. Physical exam, nothing remarkable. HIV negative. Some evidence for chronic inflammatory condition: sed rate 60 (elevated), had diffuse increase in IgG, IgM. Developed some low level autoantibodies; anti-nuclear, p-anka, anti-neutrophil cytoplasmic antibodies. Slightly elevated fever for a few days, then few days or week with no fever. No eosinophilia. Radiology: on CT did have some mediastinal, aortic, axillae, lymphadenopathy. Prob screened in Africa for malaria and treated; prob also got ivermectin. Also got head MRI: not completely normal, classic nonspecific midbrain abnormality. Diffuse mild edema. Weight loss remarkable. No visual problems. Send your diagnosis to twip@microbe.tv Send your questions and comments to twip@microbe.tv

Mon, 1 Feb 2016 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/19111/ https://edoc.ub.uni-muenchen.de/19111/1/Hiekel_Anian.pdf Hiekel, Anian

Hosts: Vincent Racaniello, Dickson Despommier, Alan Dove, Rich Condit, and Kathy Spindler The TWiVniks consider the role of a cell enzyme that removes a protein linked to the 5'-end of the picornavirus genome, and the connection between malaria, Epstein-Barr virus, and endemic Burkitt's lymphoma.   Links for this episode Divergent requirements for removing VPg (mBio) Bond, covalent bond (TWiV 210) Link between malaria and endemic Burkitt's lymphoma (PLoS Path) Multifactorial role of malaria in Burkitt's lymphoma (PLoS Path) Plasmodium infection promotes AID-dependent B cell lymphoma (Cell) Children's cancer dependent on climatic factors (Nature) Denis Burkitt (Wikipedia) Request for PACE trial data (virology blog) Letters read on TWiV 374 This episode is sponsored by 32nd Clinical Virology Symposium and ASM Grant Writing Webinar Weekly Science Picks Alan - Indoor skydivingVincent - Cancer Virus by Crawford, Johannessen, and RickinsonRich - WitKathy - The Only Woman in the Room by Eileen PollackDickson - Show everyone your clinical data Send your virology questions and comments to twiv@microbe.tv

Vincent, Dickson, and Daniel review how Viagra might be used to block transmission of Plasmodium falciparum, and introduce a new case study. Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin Links for this episode: Malaria life cycle (jpg) cAMP regulates gametocyte infected erythrocyte deformability (PLoS Path) P. falciparum in bone marrow (Blood) Image credit Letters read on TWiP 91 Contact Send your questions and comments (email or mp3 file) to twip@twiv.tv Subscribe Subscribe to TWiP (free) in iTunes, by the RSS feed or by email

Vincent, Dickson, and Daniel discuss identification of an erythrocyte protein essential for invasion of Plasmodium falciparum, and introduce a new case study. Hosts: Vincent Racaniello, Dickson Despommier, and Daniel Griffin Links for this episode: Dermatobia hominis (Wikipedia) Plasmodium falciparum erythrocyte invasion (Science) Plasmodium life cycle (TWiP #10) Letters read on TWiP 90 Contact Send your questions and comments (email or mp3 file) to twip@twiv.tv Subscribe Subscribe to TWiP (free) in iTunes, by the RSS feed or by email

Vincent and Dickson review a novel malaria vaccine candidate comprising a parasite protein involved in egress from red blood cells. Hosts: Vincent Racaniello and Dickson Despommier Links for this episode: Egress protein a malaria vaccine candidate (Science) Human proteins (Wikipedia) Plasmodium genomics resource Image: P. falciparum ring forms and gametocytes in blood Letters read on TWiP 74 Contact Send your questions and comments (email or mp3 file) to twip@twiv.tv Subscribe Subscribe to TWiP (free) in iTunes, by the RSS feed or by email

Hosts: Vincent Racaniello and Dickson Despommier Vincent and Dickson discuss an increase in the altitude of malaria distribution in warmer years in the highlands of Colombia and Ethiopia. Links for this episode: Altitudinal changes in malaria incidence (Science) El Niño (Wikipedia) NOAA El Niño page Image credit: Science Letters read on TWiP 69 Contact Send your questions and comments (email or mp3 file) to twip@twiv.tv Subscribe Subscribe to TWiP (free) in iTunes, by the RSS feed or by email

Thu, 25 Apr 2013 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/15697/ https://edoc.ub.uni-muenchen.de/15697/1/Knappik_Michael.pdf Knappik, Michael

Background: For future eradication strategies of malaria it is important to control the transmission of gametocytes from humans to the anopheline vector which causes the spread of the disease. Sensitive, non-invasive methods to detect gametocytes under field conditions can play a role in monitoring transmission potential. Methods: Microscopically Plasmodium falciparum-positive patients from Jimma, Ethiopia donated finger-prick blood, venous blood, saliva, oral mucosa and urine samples that were spotted on filter paper or swabs. All samples were taken and stored under equal, standardized conditions. RNA was extracted from the filter paper and detected by real-time QT-NASBA. Pfs16-mRNA and Pfs25-mRNA were measured with a time to positivity to detect gametocyte specific mRNA in different gametocyte stages. They were compared to 18S-rRNA, which is expressed in all parasite stages. Results were quantified via a known dilution series of artificial RNA copies. Results: Ninety-six samples of 16 uncomplicated malaria patients were investigated. 10 (66.7%) of the slides showed gametocyte densities between 0.3-2.9 gametocytes/mu l. For all RNA-targets, molecular detection in blood samples was most sensitive; finger-prick sampling required significantly smaller amounts of blood than venous blood collection. Detection of asexual 18S-rRNA in saliva and urine showed sensitivities of 80 and 67%, respectively. Non-invasive methods to count gametocytes proved insensitive. Pfs16-mRNA was detectable in 20% of urine samples, sensitivities for other materials were lower. Pfs25-mRNA was not detectable in any sample. Conclusions: The sensitivity of non-invasively collected material such as urine, saliva or mucosa seems unsuitable for the detection of gametocyte-specific mRNA. Sensitivity in asymptomatic carriers might be generally even lower. Finger-prick testing revealed the highest absolute count of RNA copies per mu L, especially for Pfs25-mRNA copies. The method proved to be the most effective and should preferably be applied in future transmission control and eradication plans. A rapid test for gametocyte targets would simplify efforts.

Background: The large polymorphic protein PfEMP1 is encoded by the var gene family. PfEMP1 has been shown to play an important role as cytoadherence ligand on the surface of infected erythrocytes and thereby contributes to the distinct pathogenesis of malaria. The study explored the diversity of the DBL1 alpha and DBL2 beta-C2 domains of the protein from Indonesian Plasmodium falciparum field isolates. Methods: Samples of patients with severe and uncomplicated malaria from two different malaria-endemic areas in Indonesia were collected and DNA directly extracted. Dried blood on filter paper was prepared for RNA extraction. PCR amplicons were either cloned and subsequently sequenced or directly sequenced for analysis on nucleotide and amino acid level. Recently published as well as self-designed primers were used for amplification. Results: Blood from eight patients was finally used for analysis. Seventy-one different sequences out of over 500 DBL1 alpha sequenced clones were observed, resulting in an average of 8.9 different DBL1 alpha sequences per isolate. The average DBL1 alpha sequence similarity within isolates was similar to between isolates. Phylogenetic analysis demonstrated no clustering of sequences regarding strain or geographical origin. The DBL1 alpha sequences were analysed by distribution of semi-conserved features (cysteine/PoLV1-4 grouping) and classified into six sequence groups. The DBL1 alpha cys2 type was observed in all expressed sequences in vivo. Expression of certain DBL sequences implied potential involvement in the pathogenesis. As expected, the DBL2 beta-C2 domains showed high to moderate homology among each other. Conclusion: The DBL1 alpha domains of PfEMP1 from clinical Indonesian isolates showed high divergence among same isolates and some similarities with other Asia-Pacific strains. Further investigations of important var gene domains with a larger sample size are required to confirm with statistical significance observed associations with severe malaria in Indonesian samples.

Hosts: Vincent Racaniello and Dickson Despommier Vincent and Dickson meet with Judith Straimer and Marcus Lee to discuss their method for site-specific genome editing in Plasmodium falciparumusing zinc finger nucleases. Right-click to download TWiP #46 (46 MB .mp3, 64 minutes). Links for this episode: Judith Straimer and Marcus Lee Genome editing in P. falciparum with zinc finger nucleases (Nature Methods) Zinc finger nucleases (Sigma-Aldrich) Gene-editing nucleases (Nature Methods) Illustration by Andrew Lee Contact Send your questions and comments (email or mp3 file) to twip@twiv.tv.

Thu, 13 Sep 2012 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/15559/ https://edoc.ub.uni-muenchen.de/15559/1/Sulistyaningsih_Erma.pdf Sulistyaningsih, Erma

Vincent and Dickson review how sickle cell microRNAs contribute to malaria resistance, and inhibition of innate immune responses by an enzyme from trypanosomes. Links for this episode: microRNAs involved in sickle cell resistance to Plasmodium (Cell Host Microbe) Trypanosome adenylate cyclases modulate innate immune response (Science) Letters read on TWiP 43 Contact Send your questions and comments (email or mp3 file) to twip@twiv.tv.

Team Jellyfish gives out some info on the protist Plasmodium falciparum.

Background: In Jimma Zone, Ethiopia, the first-line treatment of uncomplicated falciparum malaria has been changed from sulphadoxine-pyrimethamine (SP) to artemether-lumefantrine (AL) in 2006. The objective of this study was to assess the effectiveness of AL in Jimma Zone two to three years after its broad introduction. Methods: An open-label, single-arm, 42-day study of AL against falciparum malaria was conducted in four areas with moderate transmission in Jimma Zone between November 2008 and January 2009 and between August and December 2009. Patients (one-81 years) with uncomplicated Plasmodium falciparum mono-infection were consecutively enrolled. Follow-up visits were at day 2, 3, 7, 28 and 42 or any other day if symptoms reoccurred. Primary and secondary endpoints were PCR-corrected and uncorrected cure rates (molecular differentiation between recrudescence and re-infection) on days 28 and 42. Other secondary endpoints were gametocytaemia at day 7 and day 28, parasitaemia at day 2 and 3, and re-infection rates at day 28 and day 42. Results: Of 348 enrolled patients, 313 and 301 completed follow-up at day 28 and at day 42, respectively. No early treatment failure occurred. For per protocol analysis, PCR-uncorrected cure rates at day 28 and 42 were 99.1% (95% CI 98.0-100.0) and 91.1% (95% CI 87.9-94.3), respectively. PCR-corrected cure rates at day 28 and 42 were 99.4% (95% CI 98.5-100.0) and 94.7% (95% CI 92.2-97.2), respectively. PCR-corrected cure rate at day 42 for children

Due to increasing drug resistance, artemisinin-based combination chemotherapy (ACT) has become the first-line treatment of falciparum malaria in many endemic countries. Ethiopia has also adopted artemether/lumefantrine (AL) as first-line treatment in 2004 and its broad introduction was achieved in 2006. However, irreversible ototoxicity associated with AL has been reported and suggested to be a serious limitation in the use of ACT. The aim of this study was to compare ototoxicity, tolerability, and efficacy of ACT with that of quinine and atovaquone/proguanil in the treatment of uncomplicated falciparum malaria. 97 patients in Jimma area, Ethiopia with slide-confirmed malaria were randomly assigned to receive either artemether/lumefantrine or quinine or atovaquone/proguanil and followed-up on days 7, 28, and 90. Comprehensive audio-vestibular testing by pure tone audiometry (PTA), transitory evoked (TE) and distortion product (DP) otoacoustic emissions (OAE) and brain stem evoked response audiometry (BERA) was done before enrolment and on follow-up days. PTA and DP-OAE levels revealed transient significant cochlear hearing loss in patients treated with quinine but not in those treated with artemether/lumefantrine or atovaquone/proguanil. There was no evidence of drug-induced brain stem lesions by BERA measurements. Hence, there was no detrimental effect of a standard oral regimen of artemether/lumefantrine on peripheral hearing or brainstem auditory pathways in patients with uncomplicated falciparum malaria. In contrast, transient hearing loss was evidenced with quinine therapy due to temporary outer hair cell dysfunction. Reinfection and recrudescence were determined by RFLP of msp-1 and msp-2 genes. Mutations associated with drug resistance were characterized in Pfmdr1, Pfdhfr, Pfcytb, and Pfserca genes. Single nucleotide polymorphisms (SNPs) previously reported to be associated with resistance to the study drugs were identified in both recrudescent and treatment sensitive isolates. A total of seven recrudescences were obtained. The Pfmdr1 N86Y mutation was found in 84.5% of isolates. The triple mutation 51I, 59R, 108N of the Pfdhfr gene occurred in high frequency (83.3%) but no Pfcytb mutation was detected. Sequencing showed a variety of previously described and new mutations in the Pfserca gene. The prevalence of high degree of mutations in Pfmdr1 and Pfdhfr is a reminiscent of the impact of previously used drugs in the area, chloroquine and sulfadoxine/pyrimethamine as first-line treatments. The broad introduction of AL and the cessation of the former drug regimens might probably change the current distribution of polymorphisms, possibly leading to decreased sensitivity to AL in the future. Continuous surveillance of molecular patterns in this region is, therefore, recommended.

Thu, 6 Oct 2011 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/13998/ https://edoc.ub.uni-muenchen.de/13998/1/Urscher_Miriam.pdf Urscher, Miriam ddc:570, ddc:500, Fakultät fü

In episode 44 of MicrobeWorld Video filmed at the American Association for the Advancement of Science Meeting in Washington, D.C., Dr. Stan Maloy talks with Beatrice Hahn, Professor of Medicine and Microbiology at the University of Alabama at Birmingham, about her work on the origins of HIV and Malaria, and how these diseases may have spread to humans.Don't miss an episode of MicrobeWorld Video. Subscribe for free using iTunes or help support our work by purchasing the MicrobeWorld podcast application for iPhone and Android devices in the iTunes or Android app stores.

In episode 44 of MicrobeWorld Video filmed at the American Association for the Advancement of Science Meeting in Washington, D.C., Dr. Stan Maloy talks with Beatrice Hahn, Professor of Medicine and Microbiology at the University of Alabama at Birmingham, about her work on the origins of HIV and Malaria, and how these diseases may have spread to humans.Don't miss an episode of MicrobeWorld Video. Subscribe for free using iTunes or help support our work by purchasing the MicrobeWorld podcast application for iPhone and Android devices in the iTunes or Android app stores.

Background: The emergence of drug resistance is a major problem in malaria control. Combination of molecular genotyping and characterization of mutations or single nucleotide polymorphisms ( SNPs) correlated with drug resistance can provide information for subsequent surveillance of existing and developing drug resistance patterns. The introduction of artemether/lumefantrine (AL) as first-line treatment, never used before in Ethiopia, allowed the collection of baseline data of molecular polymorphisms before a selection due to AL could occur. Method: 97 patients with uncomplicated falciparum malaria were recruited from April to June 2006 and treated with either AL, quinine (Q) or atovaquone/proguanil (AP) in Jimma University Hospital, Ethiopia. Mutations or SNPs associated with resistance to these drugs were analysed by RFLP (pfdhfr, pfmdr1) and sequencing of the target genes (pfcytb, pfserca). Results: SNPs previously reported to be associated with resistance to the study drugs were identified in recrudescent and treatment sensitive isolates. A total of seven recrudescences were obtained. The pfmdr1 N86Y mutation was found in 84.5% of isolates. The triple mutation 51I,59R,108N of the pfdhfr gene occured in high frequency (83.3%) but no pfcytb mutation was detected. Sequencing showed a variety of previously described and new mutations in the pfserca gene. Conclusion: The prevalence of mutations was in accordance with the expected patterns considering recent drug regimens. The broad introduction of AL and the cessation of former drug regimens might probably change the current distribution of polymorphisms, possibly leading to decreased sensitivity to AL in future. Continuous surveillance of molecular patterns in this region is, therefore, recommended.

Background: Between 10,000 and 12,000 cases of imported malaria are notified in the European Union each year. Despite an excellent health care system, fatalities do occur. In case of advanced autolysis, the post-mortem diagnostic is impaired. Quicker diagnosis could be achieved by using rapid diagnostic malaria tests. Methods: In order to evaluate different methods for the post-mortem diagnosis of Plasmodium falciparum malaria in non-immunes, a study was performed on the basis of forensic autopsies of corpses examined at variable intervals after death in five cases of fatal malaria (with an interval of four hours to five days), and in 20 cases of deaths unrelated to malaria. Detection of parasite DNA by PCR and an immunochromatographic test (ICT) based upon the detection of P. falciparum histidine-rich protein 2 (PfHRP2) were compared with the results of microscopic examination of smears from cadaveric blood, histopathological findings, and autopsy results. Results: In all cases of fatal malaria, post-mortem findings were unsuspicious for the final diagnosis, and autoptic investigations, including histopathology, were only performed because of additional information by police officers and neighbours. Macroscopic findings during autopsy were unspecific. Histopathology confirmed sequestration of erythrocytes and pigment in macrophages in most organs in four patients (not evaluable in one patient due to autolysis). Microscopy of cadaveric blood smears revealed remnants of intraerythrocytic parasites, and was compromised or impossible due to autolysis in two cases. PCR and ICT performed with cadaveric blood were positive in all malaria patients and negative in all controls. Conclusion: In non-immune fatalities with unclear anamnesis, ICT can be recommended as a sensitive and specific tool for post-mortem malaria diagnosis, which is easier and faster than microscopy, and also applicable when microscopic examination is impossible due to autolysis. PCR is more expensive and time-consuming, but may be used as confirmatory test. In highly endemic areas where asymptomatic parasitaemia is common, confirmation of the diagnosis of malaria as the cause of death has to rely on histopathological findings.

Thu, 19 Jun 2008 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/8667/ https://edoc.ub.uni-muenchen.de/8667/2/Schoenfeld_Mirjam.pdf Schönfeld, Mirjam

Background: Due to increasing drug resistance, artemisinin-based combination chemotherapy (ACT) has become the first-line treatment of falciparum malaria in many endemic countries. However, irreversible ototoxicity associated with artemether/lumefantrine (AL) has been reported recently and suggested to be a serious limitation in the use of ACT. The aim of the study was to compare ototoxicity, tolerability, and efficacy of ACT with that of quinine and atovaquone/proguanil in the treatment of uncomplicated falciparum malaria. Methods: Ninety-seven patients in south-west Ethiopia with slide-confirmed malaria were randomly assigned to receive either artemether/lumefantrine or quinine or atovaquone/proguanil and followed-up for 90 days. Comprehensive audiovestibular testing by pure tone audiometry (PTA), transitory evoked (TE) and distortion product (DP) otoacoustic emissions (OAE) and brain stem evoked response audiometry (BERA) was done before enrolment and after seven, 28 and 90 days. Results: PTA and DP-OAE levels revealed transient significant cochlear hearing loss in patients treated with quinine but not in those treated with artemether/lumefantrine or atovaquone/proguanil. TE-OAE could be elicited in all examinations, except for three patients in the Q group on day 7, who suffered a transient hearing loss greater than 30 dB. There was no evidence of drug-induced brain stem lesions by BERA measurements. Conclusion: There was no detrimental effect of a standard oral regimen of artemether/lumefantrine on peripheral hearing or brainstem auditory pathways in patients with uncomplicated falciparum malaria. In contrast, transient hearing loss is common after quinine therapy and due to temporary outer hair cell dysfunction.

Besides existing artemisinin-based combination therapies, alternative safe, effective and affordable drug combinations against falciparum malaria are needed. Methylene blue (MB) was the first synthetic antimalarial drug ever used, and recent studies have been promising with regard to its revival in malaria therapy. The objective of this study was to assess the safety and efficacy of two MB-based malaria combination therapies, MB-artesunate (AS) and MB-amodiaquine (AQ), compared to the local standard of care, AS-AQ, in Burkina Faso. Open-label randomised controlled phase II study in 180 children aged 6-10 years with uncomplicated falciparum malaria in Nouna, north-western Burkina Faso. Follow-up was for 28 days and analysis by intention-to-treat. The treatment groups were similar in baseline characteristics and there was only one loss to follow-up. No drug-related serious adverse events and no deaths occurred. MB-containing regimens were associated with mild vomiting and dysuria. No early treatment failures were observed. Parasite clearance time differed significantly among groups and was the shortest with MB-AS. By day 14, the rates of adequate clinical and parasitological response after PCR-based correction for recrudescence were 87% for MB-AS, 100% for MB-AQ (p = 0.004), and 100% for AS-AQ (p = 0.003). By day 28, the respective figure was lowest for MB-AS (62%), intermediate for the standard treatment AS-AQ (82%; p = 0.015), and highest for MB-AQ (95%; p

Background: In Tanzania, drug-resistant malaria parasites are an increasing public health concern. Because of widespread chloroquine (CQ) resistance Tanzania changed its first line treatment recommendations for uncomplicated malaria from CQ to sulfadoxine-pyrimethamine (SP) in 2001. Loss of SP sensitivity is progressing rapidly. SP resistance is associated with mutations in the dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes. Methods: In samples from 86 patients with uncomplicated Plasmodium falciparum malaria from Mbeya and Matema, Mbeya region, south-western Tanzania, the occurrence of mutations was investigated in the pfcrt and pfmdrl genes which are associated with CQ resistance and in pfdhfr and pfdhps, conferring SP resistance, as well in cytb which is linked to resistance to atovaquone. Results: Pfcrt T76 occurs in 50% and pfmdrl Y86 in 51.7%. Pfdhfr triple mutations coexisting with pfdhps double mutations were detected in 64.3% of the P. falciparum isolates. This quintuple mutation is seen as a possible predictive molecular marker for SP treatment failure. Mutations of the cytb gene were not detected. Conclusion: These findings of a high prevalence of mutations conferring SP resistance correspond to data of in vivo SP efficacy studies in other regions of Tanzania and underline the recommendation of changing first-line treatment to artemisinin-based combination therapy.

Background: In Ethiopia, malaria is caused by both Plasmodium falciparum and Plasmodium vivax. Drug resistance of P. falciparum to sulfadoxine-pyrimethamine (SP) and chloroquine (CQ) is frequent and intense in some areas. Methods: In 100 patients with uncomplicated malaria from Dilla, southern Ethiopia, P. falciparum dhfr and dhps mutations as well as P. vivax dhfr polymorphisms associated with resistance to SP and P. falciparum pfcrt and pfmdr1 mutations conferring CQ resistance were assessed. Results: P. falciparum and P. vivax were observed in 69% and 31% of the patients, respectively. Pfdhfr triple mutations and pfdhfr/pfdhps quintuple mutations occurred in 87% and 86% of P. falciparum isolates, respectively. Pfcrt T76 was seen in all and pfmdr1 Y86 in 81% of P. falciparum. The P. vivax dhfr core mutations N117 and R58 were present in 94% and 74%, respectively. Conclusion: These data point to an extraordinarily high frequency of drug-resistance mutations in both P. falciparum and P. vivax in southern Ethiopia, and strongly support that both SP and CQ are inadequate drugs for this region.

Levels of drug resistance of Plasmodium falciparum strains against antimalarials have increased in Laos. In several studies, chloroquine (CQ) resistance has been associated with point mutations in the Pfcrt and pfmdr genes, and sulphadoxine/pyrimethamine (S/P) resistance with point mutations in the genes of dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS). We combined a study of these molecular markers with an in vivo antimalarial drug sensitivity study in Attapeu province in the south of Lao PDR. We treated 100 patients with either CQ, S/P or a combination of both. In the CQ group, Pfcrt mutations showed a very high sensitivity (100%) but a low specificity (12.5%) to predict resistance. The combination of mutations in the Pfcrt and pfmdr genes was highly specific and had a positive predictive value of 100%. Mutations in the DHPS gene showed a high correlation with the development of resistance. The prevalence of mutations in the DHFR gene, especially codon 108 Asn, was predictive with high sensitivity (100%) but low specificity. Isolates derived from patients treated with a combination of both drugs showed a high correlation between the mutation in codon 437 of DHPS gene and in vivo-resistance (odds ratio 16.00, CI). The study provides evidence for the existence of antimalarial drug resistance in the south of Lao PDR, and offers a molecular method to predict resistance.

Background: Safe, effective and affordable drug combinations against falciparum malaria are urgently needed for the poor populations in malaria endemic countries. Methylene blue (MB) combined with chloroquine (CQ) has been considered as one promising new regimen. Objectives: The primary objective of this study was to evaluate the safety of CQ-MB in African children with uncomplicated falciparum malaria. Secondary objectives were to assess the efficacy and the acceptance of CQ-MB in a rural population of West Africa. Methods: In this hospital-based randomized controlled trial, 226 children ( 6 - 59 months) with uncomplicated falciparum malaria were treated in Burkina Faso. The children were 4: 1 randomized to CQ-MB (n = 181; 25 mg/kg CQ and 12 mg/kg MB over three days) or CQ ( n = 45; 25 mg/kg over three days) respectively. The primary outcome was the incidence of severe haemolysis or other serious adverse events (SAEs). Efficacy outcomes were defined according to the WHO 2003 classification system. Patients were hospitalized for four days and followed up until day 14. Results: No differences in the incidence of SAEs and other adverse events were observed between children treated with CQ-MB ( including 24 cases of G6PD deficiency) compared to children treated with CQ. There was no case of severe haemolysis and also no significant difference in mean haemoglobin between study groups. Treatment failure rates were 53.7% (95% CI [37.4%; 69.3%]) in the CQ group compared to 44.0% ( 95% CI [36.3%; 51.9%]) in the CQ-MB group. Conclusion: MB is safe for the treatment of uncomplicated falciparum malaria, even in G6PD deficient African children. However, the efficacy of the CQ-MB combination has not been sufficient at the MB dose used in this study. Future studies need to assess the efficacy of MB at higher doses and in combination with appropriate partner drugs.

Die Malaria bleibt auf Grund ihrer geographischen Verbreitung und durch schätzungsweise 500 Millionen Neuerkrankungen pro Jahr eine der häufigsten Infektionskrankheiten. Sie gehört global gesehen zu den Krankheiten, die u.a. am stärksten die Gesundheitssysteme, die Wirtschaft und nicht zuletzt den betroffenen Patienten selbst beeinflussen. In Hochendemiegebieten verursacht die Malaria jährlich einen enormen Verlust an Wirtschaftskraft und fordert eine große Anzahl an Menschenleben. Die häufigste und oftmals potentiell lebensbedrohlich verlaufende Malaria tropica, verursacht durch Plasmodium falciparum, ist in vielen Ländern der Tropen, nicht zuletzt auf Grund des wachsenden Resistenzpotentials der Erreger zu einer großen und zunehmend schwer kontrollierbaren Bedrohung geworden. Auch durch nach Europa importierte Fälle, kommt es immer wieder zu diagnostischen und therapeutischen Problemen. Bedingt durch den wachsenden Tourismus ist die Zahl der nach Deutschland und andere europäische Länder eingeschleppten Malariainfektionen in den letzten Jahrzehnten erheblich angestiegen. Bei der Auswertung der vorliegenden Daten und Blutproben von 574 Patienten wurden die afrikanischen Länder südlich der Sahara als Hauptinfektionsgebiete identifiziert. In 92,2% der Fälle konnte eine Infektion mit einem Plasmodium falciparum Stamm, einem Land in Zentralafrika, Ostafrika, Südafrika oder Westafrika zugeordnet werden. Weitere Ziele der Arbeit waren die Verteilung und Prävalenz unterschiedlicher, pathogenetisch und immunologisch bedeutsamer Plasmodium falciparum Proteine an Hand von importierten Infektionen nach Europa zu bestimmen. Ebenso sollte die Verbreitung und Prävalenz von diversen mit Medikamentenresistenz assoziierten Punktmutationen auf unterschiedlichen Plasmodium Genen bestimmt werden. Zunächst wurden hierzu verschiedene Methoden entwickelt, um mit Hilfe der PCR- und der Restriktionsenzymverdau- Technik ein schnelles und zuverlässiges Verfahren zu etablieren und zu evaluieren, welche die Punktmutationen in verschieden Genabschnitten der Erreger DNA detektiert. Um ggf. Aussagen über den klinischen Verlauf der Malaria oder Zusammenhänge zwischen Patientengruppen und einigen molekularen Markern machen zu können wurden diese untereinander korreliert. Die Ergebnisse sprechen für Virulenzunterschiede verschiedener P. falciparum-Stämme. Mutationen in bestimmten Genabschnitten von P. falciparum können dazu führen, daß sich enzymatisch- biochemische Zielstrukturen verändern und somit eine Medikamentenresistenz gegen Antimalariamedikamente induziert werden kann. So beruht die Resistenz gegen Sulfonamid/Pyrimethamin (SP)-Kombinationen, wie das in Afrika häufig als „first-line-drug“ eingesetzte Fansidar, auf bestimmten Mutationen der für die Dihydrofolatreduktase (DHFR) und die Dihydropteroatsynthetase (DHPS) codierenden Gene. Die Ergebnisse der Studie zeigen, daß in der Verteilung der Polymorphismen auf dem afrikanischen Kontinent sowohl Gemeinsamkeiten, als auch signifikante Unterschiede zwischen den einzelnen Regionen bestehen. Die erzielten Ergebnisse machen deutlich, daß zahlreiche mit Resistenz gegen SP assoziierte Mutationen auf den untersuchten Genen vorliegen. Die gewonnenen Daten dienen der Früherkennung sich ausbildender Resistenzen und als Grundlage für Malaria-Kontrollprogramme. Zudem ergibt die Verteilung der EBA-175 Fragmente Hinweise für die Zusammensetzung möglicher Impfstoffkandidaten.

Tue, 27 Jan 2004 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/1808/ https://edoc.ub.uni-muenchen.de/1808/1/Schwoebel_Babett.pdf Schwöbel, Babett

Background: The erythrocyte binding antigen 175 (EBA-175) is a 175 kDa antigen of Plasmodium falciparum and plays a major role in erythrocyte recognition by the parasite. The antigen is also supposed to be partly responsible for the invasion of erythrocytes by merozoites. EBA-175 has been sequenced from the FCR-3 and CAMP strains of P. falciparum. The sequences were identical in most parts of the gene. Differences were apparent in a 423 bp segment in the FCR-3 strain, the F-Fragment, that is not found in the CAMP-strain and a 342 bp segment, the C-Fragment, which is present in the CAMP-strain but not in the FCR-3-strain. The aim of this study was to assess the distribution of the two EBA-175-alleles in the Lao PDR. Materials & Methods: Altogether, 240 blood-samples were collected in two areas of the country: Attapeu in the south and Lung Namtha in the north. Subsequently, the material was scanned for the F- and C-fragments. Results: In the whole study population, 52% carried the F- fragment, and 41% the C-fragment while seven percent of the patients were infected with at least two parasite strains and showed both alleles. Conclusion: Distribution of the alleles showed significant differences between the north and the south province. Reasons for this include possible importation of different parasite strains from neighbouring countries.

Background: Malaria parasites that carry the DHFR-mutation I164L are not only highly resistant to sulfadoxine-pyrimethamine but also to the new antimalarial drug chlorproguanil-dapsone. The spread of this mutation in Africa would result in a public health disaster since there is a lack of effective alternatives that are both affordable and safe. Up to now, this mutation has only been described in Asian and Latin-American countries. The objective of this study was to assess the prevalence of this mutation in African isolates of Plasmodium falciparum that have been imported into Europe through travellers. Methods: TropNetEurop is a network for the surveillance of travel-associated diseases and seems to cover approximately 12% of all malaria cases imported into Europe. Within this network we screened 277 imported African isolates of P. falciparum with the help of PCR- and enzyme-digestion-methods for the antifolate-resistant mutation I164L. Results: The I164L mutation was not detected in any of the isolates tested. Discussion: Continuous molecular surveillance of mutations in P. falciparum, as it is practised within TropNetEurop, is an essential tool for the understanding and early detection of the spread of antimalarial drug resistance in Africa.

Background: Resistance of Plasmodium falciparum to atovaquone in vitro and in vivo has been associated to mutations in the parasite cytochrome b gene. Methods: Cultures were sequentially subjected to increasing doses of atovaquone alone or in combination with cycloguanil and the cytochrome b gene was sequenced. Additionally, we investigated the parasite cytochrome b gene of a patient returning from Mali with Malarone(R) treatment failure in vivo. Results: All strains that survived atovaquone concentrations in vitro of 2 x 10(-8) to 2 x 10(7) M showed the M1331 mutation and one strain with the highest atovaquone concentration the additional mutation L171F. Sequencing of the in vivo treatment failure revealed a point mutation at codon 268 resulting in an amino acid change from tyrosine to serine. Based on the repeated emergence of mutations at codon 268, but no detection of alterations at codon 133 in vivo, we developed a detection method for the diagnostic of codon 268 polymorphisms as a potential atovaquone/proguanil resistance marker. A nested PCR with 3 different pairs of primers for the second round was designed. Each product was digested with restriction enzymes, capable to distinguish the wild type from the two reported mutations at codon 268. Conclusion: Mutations at codon 268 of the parasite cytochrome bc(1) gene are associated with atovaquone/proguanil treatment failure in vivo and can be used as potential resistance marker This method provides a novel and robust tool to investigate the relevance of codon 268 polymorphisms as resistance marker and to monitor the further emergence of atovaquone/proguanil resistance.

Die Malaria tropica ist zu Beginn des 21.Jahrhunderts in den tropischen Ländern wegen hoher Inzidenz und Letalität v.a. unter Kindern und Schwangeren nach wie vor ein sehr ernst zu nehmendes Problem. Frühere Hoffnungen auf die komplette Eradikation der Malaria erwiesen sich in großen Teilen Afrikas, Asiens und Südamerikas als haltlos. Gerade die Effektivität von Chloroquin, das wegen guter Wirksamkeit, großer Sicherheit, geringer Nebenwirkungen und niedriger Kosten bei der Prophylaxe und Behandlung der unkomplizierten Malaria jahrelang favorisiert worden war, wird durch zunehmende Resistenz des Erregers Plasmodium falciparum beeinträchtigt [Ridley 1998, Wellems & Plowe 2001]. Studien über die Wirkungsweise Chloroquins – und umso mehr über die gegen das Mittel gerichtete Resistenz- lieferten widersprüchliche Ergebnisse. Weit gehende Einigkeit herrscht im Grundsatz darüber, dass Chloroquin den Abbau des Wirt-Hämoglobins als primäre Nahrungsquelle des Parasiten in der Verdauungsvakuole beeinträchtigt. Ebenso ist gezeigt worden, dass resistente Parasiten Chloroquin in geringerem Maße anreichern. Studien brachten dies mit der pH-Regulation oder einer aktiven Chloroquin-Effluxpumpe an der Nahrungsvakuole in Verbindung, ähnlich dem Resistenzmechanismus von Tumorzellen im Rahmen der so genannten „multiple drug resistance“. Das Auftreten von bestimmten Punktmutationen im sog. Plasmodium falciparum multiple drug resistance Gen 1 (Pfmdr1 auf Chromosom 5), das für das Efflux-Protein kodieren könnte, ist mit Chloroquinresistenz assoziiert worden [Foote et al. 1989, 1990]. In dieser Studie wurden an Plasmodium falciparum-Isolaten mittels PCR und anschließender Restriktionsenzymanalyse Mutationen an den Codons 86, 1042, 1246 und 182 des pmfdr1-Gens und deren Korrelation zu in vivo-Daten von Patienten untersucht, die in Uganda wegen Malaria tropica mit Chloroquin behandelt worden waren. Das Ziel der Studie war, die Punktmutationen als mögliche Ursachen für die Chloroquinresistenz zu bewerten und sie als Kriterien für die Therapiewahl und die Einschätzung des klinischen Verlaufs zu evaluieren. Dabei erwies sich die Prävalenz der Chloroquinresistenz in Uganda bei 40 resistenten unter 57 untersuchten Proben als recht hoch (79%), v.a. im Vergleich zu früheren Publikationen (4- 26%). Assoziationen zwischen in vivo-Resistenz gegen Chloroquin und den Pfmdr1- Polymorphismen ließen sich in dieser Studie zwar belegen: Bei der Auswertung aller PCRErgebnisse zeigte sich, dass Resistenzen durchgehend häufiger auftraten, wenn Mutationen an einem der drei untersuchten Codons vorhanden waren (86%-100%, bei Wildtyp nur 55-64%). In 90% aller resistenten Proben war mindestens ein Pfmdr1-Polymorphismus nachweisbar. Dennoch ist die Einschätzung des klinischen Verlaufs anhand der Pfmdr1-Polymorphismen nicht verlässlich: bei Individuen müssen z.B. auch Faktoren wie Immunität berücksichtigt werden. Im Gegensatz zu einer einfachen Verknüpfung mit der CQR muss ein Zusammenspiel der untersuchten Mutationen mit weiteren genetischen Veränderungen angenommen werden. Dass es sich hierbei um das von Su et al. [1990] identifizierte Cg2-Gen auf Chromosom 7 handelt, wurde in den letzten Jahren propagiert, ist aber mittlerweile unwahrscheinlich geworden. Vielmehr könnte dem in der Nähe gelegenen Pfcrt [Fidock et al. 2000] eine Schlüsselrolle zukommen. Ob dieses oder noch andere Kofaktoren eine Rolle spielen, müssen allerdings weitere Untersuchungen ergeben.