Preventing the Spread of Malaria in Mali
Condition: Malaria
MeSH terms: Malaria
Study type: Observational

Summary: 
      A vaccine which interrupts malaria transmission is a critical tool to achieve the ultimate
      goal of eradication of this disease. Transmission blocking vaccines work by inducing antibody
      in vaccinated individuals that inhibits the development of malaria parasites in the mosquito,
      thus interrupting the cycle of transmission to the next human host. Efficacy of these
      vaccines may be estimated by in vitro membrane feeding assays using immune sera and
      laboratory strain mosquitoes, but these assays need to be qualified to determine to what
      extent they are predictive of transmission blocking in the field. Clinical trials of
      transmission blocking vaccines are also anticipated and have started in this community. This
      protocol will use a nested casecontrol cohort design to compare results of mosquito feeding
      assays in a malaria exposed population in Bancoumana and surrounding villages in Mali.
      Households will be identified using census data and individuals will be consented for
      participation. Malaria smears will be obtained at monthly visits, and gametocytemic
      individuals will be asked to participate in direct feed experiments using insectary-raised
      mosquitoes. Infectivity in these mosquitoes will be compared against those of mosquitoes fed
      in membrane feeding assays in Mali and the USA. Data will also be obtained on gametocyte and
      parasite carriage rates through the year. A total of 250 volunteers from Bancoumana, ages 3
      months to 50 years, were initially enrolled in 2011. In 2012, an additional 250 adults from
      Bancoumana were enrolled and participants older than 5 years of age who were enrolled in 2011
      and wanted to continue participation were re-enrolled into the study. A transmission blocking
      vaccine trial started in May 2013, and has enrolled participants from this adult cohort in
      that study. Up to 50 new adults from Bancoumana and surrounding villages will be enrolled in
      2014 and those volunteers previously enrolled into the study over theage of 5 years old will
      be offered re-enrollment into the study.
    

Detailed description: 
      A vaccine which interrupts malaria transmission is a critical tool to achieve the ultimate
      goal of eradication of this disease. Transmission blocking vaccines work by inducing antibody
      in vaccinated individuals that inhibits the development of malaria parasites in the mosquito,
      thus interrupting the cycle of transmission to the next human host. Efficacy of these
      vaccines may be estimated by in vitro membrane feeding assays using immune sera and
      laboratory strain mosquitoes, but these assays need to be qualified to determine to what
      extent they are predictive of transmission blocking in the field. Clinical trials of
      transmission blocking vaccines are also anticipated and have started in this community. This
      protocol will use a nested casecontrol cohort design to compare results of mosquito feeding
      assays in a malaria exposed population in Bancoumana and surrounding villages in Mali.
      Households will be identified using census data and individuals will be consented for
      participation. Malaria smears will be obtained at monthly visits, and gametocytemic
      individuals will be asked to participate in direct feed experiments using insectary-raised
      mosquitoes. Infectivity in these mosquitoes will be compared against those of mosquitoes fed
      in membrane feeding assays in Mali and the USA. Data will also be obtained on gametocyte and
      parasite carriage rates through the year. A total of 250 volunteers from Bancoumana, ages 3
      months to 50 years, were initially enrolled in 2011. In 2012, an additional 250 adults from
      Bancoumana were enrolled and participants older than 5 years of age who were enrolled in 2011
      and wanted to continue participation were re-enrolled into the study. A transmission blocking
      vaccine trial started in May 2013, and has enrolled participants from this adult cohort in
      that study. Up to 50 new adults from Bancoumana and surrounding villages will be enrolled in
      2014 and those volunteers previously enrolled into the study over theage of 5 years old will
      be offered re-enrollment into the study.
    

Observational model: Cohort
Time perspective: Prospective
Keywords: Mosquito; Membrane; Feeding; Parasites; Infection; Malaria