Longitudinal household surveillance for malaria in Rakai, Uganda

Background: HIV and malaria exert co-pathogenic effects. Malaria surveillance data are necessary for public health strategies to reduce the burden of disease in high HIV prevalence settings. Methods: This was a longitudinal cohort study to assess the burden of malaria in rural Rakai, Uganda. Households were visited monthly for 1 year to identify confirmed clinical malaria (CCM), or parasitaemia with temperature > 37.5 degrees C, and asymptomatic parasitaemia (AP). Interviews of the adult or child's caregiver and clinical and laboratory assessments were conducted. Rapid diagnostic testing for malaria and anaemia was performed if participants were febrile and anti-malarial treatment given per Uganda Ministry of Health 2010 guidelines. Blood was drawn at every household visit to assess for parasitaemia, and blood smears were assessed at the Rakai Health Science Programme laboratory. Results: A total of 1640 participants were enrolled, including 975 children aged 6 months up to 10 years, 393 adult caregivers, and 272 adolescent/adult household members from 393 randomly selected households in two representative communities. 1459 (89 %) participants completed all study visits. CCM was identified in 304 (19 %) participants, with the highest incidence rate for CCM of 0.38 per person-year (ppy) identified in children < 5 years, and rates decreased with age; the rates were 0.27, 0.16, and 0.09 ppy for ages 5-<10 years, 10-<18 years, and adults 18+ years, respectively. AP was identified in 943 (57 %) participants; the incidence rate was 1.99 ppy for < 5 years, 2.72 ppy for 5-<10 years, 2.55 ppy for 10-<18 years, and 0.86 ppy among adults, with 92 % of cases being attributed to Plasmodium falciparum by smear. 994 (61 %) individuals had at least one positive smear; 342 (21 %) had one positive result, 203 (12 %) had two, 115 (7 %) had three, and 334 (21 %) had > 3 positive smears during follow-up. Seasonal rates generally followed the rains and peaked during July, then decreased through November before increasing again. Conclusions: Plasmodium falciparum infection remains high in rural Uganda. Increased malaria control interventions should be prioritized.