Lack of household clustering of malaria in a complex humanitarian emergency: implications for active case detection.

Background: Malaria contributes to elevated morbidity and mortality in populations displaced by conflict in tropical zones. In an attempt to reduce malaria transmission in an internally displaced persons (IDP) camp in eastern Democratic Republic of Congo (DRC), we tested a strategy of active case detection of household contacts of malaria cases.

Methods: Prospective community-based survey.

Results: From a convenience sample of 100 febrile patients under 5 years of age from the IDP camp presenting to a nearby clinic for management of a fever episode, 19 cases of uncomplicated malaria and 81 controls with non-malarial febrile illness (NFMI) were diagnosed. We engaged community health workers in the IDP camp to screen their household contacts for malaria using rapid diagnostic tests. We detected 29 cases of malaria through this active case-finding procedure. Household contacts of children with uncomplicated malaria were no more likely to have positive Plasmodium falciparum antigenemia than controls with NFMI (OR 0.89, 95% CI 0.33 to 2.4, p = 1.0), suggesting that malaria cases did not cluster at the household level. However, household contacts reporting mild symptoms at the time of community survey (headache, myalgia) had a higher odds of malaria than asymptomatic individuals (OR 14 (95% CI 4.2-48), p ≤ 0.001 and 18 (95% CI 5.9-54), p ≤ 0.001, respectively).

Conclusion: Screening household contacts of malaria cases was not an efficient case-finding strategy in a Congolese IDP camp. Symptom-based screening may be a simpler and cost-effective method to identify individuals at increased risk of malaria for targeted screening and treatment in an IDP camp.