"It Takes a Village": Understanding Micro-spatial Factors and Biomarkers Associated with Malaria and Malarial Anemia in Western Kenya?

Christina Mair
Bachelors of Science in Environmental Science
May 2003

This thesis addresses two separate questions relating to falciparum malaria in western Kenya. It uses two different approaches to analyze both the spatial distribution of malaria and the biologic mechanisms of malaria-attributable anemia. The first utilizes a micro-spatial statistical technique known as the Equal Population Area (EPA) method to assess clustering of potential disease risk factors in an area smaller than those previously mapped for malaria, a single village with fewer than 2000 residents. Several outcome measures and risk factors associated with malaria were examined: mean parasite density and frequency of positive blood smears of the subjects, hemoglobin levels, and the mosquito count in each household. There was significant microspatial clustering of all the variables. In addition, indoor mosquito exposure was positively associated with proximity to water, and mean parasite density and hemoglobin were negatively associated with proximity to water. Knowledge generated from this type of micro-spatial analysis can lead to better malaria prevention strategies within villages.

The second part of the thesis uses bivariate and multivariate statistical analysis to untangle the mechanisms of malarial anemia, a common and sometimes serious side-effect in people with malaria. Multivariate modeling revealed a statistically significant relationship between pro-inflammatory cytokine levels and malarial anemia even after controlling for covariates such as age, baseline hemoglobin level, mean parasite density, and indoor mosquito exposure. These results implicate a non-parasite direct cause of anemia in infected people, in addition to the more commonly understood parasite cause. It suggests that malarial anemia is not only caused by increased destruction of red blood cells; anemia of inflammation, and the decreased RBC production mediated by it, also plays a role. Iron supplementation is therefore not adequate treatment for malarial anemia. The treatment for anemia of inflammation is to address the underlying malaria infection with effective anti-malarial drugs.