Individual and household level factors associated with malaria incidence in a highland region of Ethiopia: a multilevel analysis.

Multilevel analysis was used to identify individual and household level factors associated with malaria risk in 1,367 individuals in a peri-urban area of highland Ethiopia. Living within 450 m of a major vector-breeding site accounted for 38.78% and 78.49% of between-household variance in malaria incidence in adults and children, respectively. In adults, other individual level factors associated with malaria risk were regular or recent travel to rural areas (incidence rate ratio [IRR] = 12.96; 95% confidence interval [CI] = 4.05, 41.48) and having an indoor job (IRR = 0.37; 95% CI = 0.16, 0.87). Household level factors associated with adult malaria risk were low vegetation level in compound (IRR = 0.27; 95% CI = 0.10, 0.78), tidy compound (IRR = 0.29; 95% CI = 0.12, 0.71), household use of preventive measures (IRR = 0.31; 95% CI = 0.13, 0.74), and the number of 5- to 9-year-old children in the household (IRR = 1.66; 95% CI = 1.08, 2.53). Aside from distance to the vector-breeding site, few other malaria risk factors were identified in children. Malaria interventions in highland African communities should address household level factors associated with malaria clustering.