community dynamics of malaria transmission and mosquito feeding in bancoumana, mali

Conditions: Malaria

Summary: background: half of the world's population is at risk of malaria. malaria is a disease that affects many people in mali and other parts of africa. it is caused by germs spread by mosquito bites. malaria may be mild. but it can also be serious or can lead to death if it is not diagnosed and treated promptly. researchers want to learn more about the disease so they can develop new approaches to malaria control. objective: to collect data on how mosquitoes spread malaria and how many people get malaria in the community by comparing different areas, seasons, and years. eligibility: residents of a certain area of mali who are of any age design: participants will be screened with a physical exam and medical history. all participants will have at least 1 visit. they will answer questions about their health and malaria. they may have a physical exam. they will have blood collected. some participants will have 1 visit every month for 3 years. they will repeat the procedures above. these participants will have mosquitoes collected in their home monthly. they may be able to catch some of the mosquitoes alive or may need to use a spray to kill the mosquitoes. participants in this part of the study can be up to 65 years old. some participants will also have about 60 mosquitoes directly feed on their arm or leg for 15-20 minutes each month. these participants must be 5-65 years old. ...

a vaccine that interrupts malaria transmission is critical to eradicate the disease, but improved assays are needed to measure the efficacy of vaccines. transmission-blocking vaccines (tbvs) work by inducing antibodies in vaccinees that inhibit parasite development in the mosquito interrupting transmission. efficacy of vaccines may be estimated by in vitro membrane feeding assays using immune sera and laboratory mosquitoes, but qualified assays that measure transmission in the field are needed to assess transmission-blocking interventions in natura. clinical trials of tbv have started in bancoumana and doneguebougou, and we expect to expand tbv studies here and in adjacent areas in the future. this protocol will use a longitudinal cohort to gather information on mosquito feeding and infection patterns in bancoumana, doneguebougou and surrounding villages in mali. individuals actively participating in lmiv vaccine trials will be approached first for participation, including permission to contact their household and neighbors of their compound for participation. households will be identified using census data and individuals will be consented for participation. malaria smears will be obtained at monthly visits, in conjunction with mosquito collections in/around village residences and with direct skin feeds (dsfs) using insectary-raised mosquitoes. parasite transmission to mosquitoes will be assessed longitudinally for differences by season and year, and compared between wild-caught and laboratory-raised mosquitoes. data will also be obtained on gametocyte and parasite carriage rates by season and year. genotyping of individual subjects will be performed to pair with the bloodmeals of wild-caught mosquitoes. a total of 3,200 volunteers from bancoumana, doneguebougou and surrounding areas will be enrolled into three distinct cohorts. the genotype only cohort (n=1000), which will include the vaccine trial participants, will complete a single visit to obtain a blood sample for genotyping with no additional follow up. the dsf cohort (n=1200) will enroll subjects aged 5 to 65 years for monthly blood sampling, dsf, and mosquito collection at their household. the parasite surveillance cohort (n=1000) will enroll subjects under the age of 5 years (as young as 6 months) and subjects of any age who are unwilling to participate in dsf; they will have monthly blood sampling and mosquito collection at their household. enrollment into the genotype and parasite surveillance cohorts will be linked to full enrollment of the dsf cohort. participants in the parasite surveillance and dsf cohorts, will be followed for up to 3 years, to collect data that will guide the design of future community-based trials of tbv.

Eligibility criteria:
* inclusion criteria: * genotype only cohort * any age * known resident of bancoumana or the surrounding villages * acceptance and signature of the written informed consent and the assent for children aged 12-17 years * willingness to allow stored laboratory specimens to be used for future research * parasite surveillance cohort * 6 months to 65 years of age * known resident of bancoumana or the surrounding villages * willingness to allow stored laboratory specimens to be used for future research * acceptance and signature of the written informed consent and the assent for children aged 12-17 years * dsf cohort * aged between 5 and 65 years, inclusive * good general health as determined by review of medical history and/or clinical testing at the time of screening * known resident of bancoumana or the surrounding villages * willingness to allow stored laboratory specimens to be used for future research * willingness to undergo dsf * acceptance and signature of the written informed consent and the assent for children aged 12-17 years exclusion criteria: * genotype only cohort * behavioral, cognitive, or psychiatric disease that in the opinion of the investigator affects the ability of the subject to understand and cooperate with the study protocol * other condition that, in the opinion of the investigator, would jeopardize the safety or rights of a volunteer participating in the trial or would render the subject unable to comply with the protocol * parasite surveillance chort * behavioral, cognitive, or psychiatric disease that in the opinion of the investigator affects the ability of the subject to understand and cooperate with the study protocol * other condition that, in the opinion of the investigator, would jeopardize the safety or rights of a volunteer participating in the trial or would render the subject unable to comply with the protocol * currently enrolled participant in protocol 17-i-n006 or another active lmiv/mrtc vaccine clinical trial * dsf cohort * behavioral, cognitive, or psychiatric disease that in the opinion of the investigator affects the ability of the subject to understand and cooperate with the study protocol * other condition that, in the opinion of the investigator, would jeopardize the safety or rights of a volunteer participating in the trial or would render the subject unable to comply with the protocol * currently enrolled participant in protocol 17-i-n006 or another lmiv/mrtc vaccine clinical trial * history of severe reaction to mosquito bites

Keywords: assays direct skin feeds infection parasite gametocyte natural history