Community Dynamics of Malaria Transmission and Mosquito Feeding in Bancoumana, Mali

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.

• 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