The Effect of Head of Household Occupation and Activity at Sunrise and Sunset on Malaria Prevalence in Sussundenga, Mozambique

There is evidence that outdoor occupations and being active outdoors at night increase the risk of malaria infection. This study aimed to examine the associations between both head of household occupation and whether an individual was active at sunrise and/or sunset on the outcome of malaria infection separately and to determine if there was an interaction between the two exposures. We used data from a cross-sectional study in Sussundenga, Mozambique of 297 individuals within 84 households. Generalized linear mixed models were used to calculate the associations between each of the exposures and malaria infection as well as their interaction. After adjustment, the difference in predicted malaria prevalence comparing those in which the head of household had an outdoor versus indoor occupation was 0.015 (95% CI: -0.12 to 0.15). The difference in predicted malaria prevalence among those active at sunrise and sunset was 0.10 (95% CI: -0.063 to 0.26) and those active at either time was 0.011 (95% CI: -0.11 to 0.13) compared with those active at neither time. In the interaction model, the difference in malaria prevalence between those with the head of household having an outdoor versus indoor occupation was 0.33 (95% CI: 0.037-0.62) greater in those active at sunrise and sunset compared with those not active at either time. Although the test for additive interaction was not statistically significant or indicative of any clear association, the magnitude may indicate that those with different head of household occupation and outdoor times could have different malaria risk.