An entomological investigation of the likely impact of cattle ownership on malaria in an Afghan refugee camp in the North West Frontier Province of Pakistan

Abstract

Field trials were undertaken to determine the effect of close proximity of humans to livestock on the human biting rates exhibited by various anophelines. The results indicate that proximity to cattle and to goats increases the subject's chances of being bitten by anophelines. Man-biting by Anopheles stephensi rose by 38% (8-68% CI) in the presence of a cow, and by 50% (16-84% CI) in the presence of two goats. Other species exhibited similar trends. These findings explain the results of an earlier trial which revealed that malaria prevalence was higher amongst families that kept cattle than those that did not. The findings are discussed in relation to existing information regarding the host preferences of local anophelines and classic theories regarding zooprophylaxis. Our findings suggest that animals are only likely to have a worthwhile prophylactic affect when the vector is zoophilic, and then only when the animals are deployed to form a barrier between that vector and man. In situations where deployment of livestock to form a zoobarrier is impractical, the livestock should be located as far from man as possible.