Community Dynamics of Malaria Transmission and Mosquito Feeding in Bancoumana, Mali
Condition: Malaria
MeSH terms: Malaria
Study type: Observational

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.
    

Detailed description: 
      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.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Known resident of Bancoumana, Doneguebougou or the surrounding villages; and Willingness to
        allow stored laboratory specimens to be used for future research@@@@@@
      
Keywords: Assays; Direct Skin Feeds; Infection; Parasite; Gametocyte; Natural History