Towards malaria control in Nigeria: implications of the malaria parasite rate and spleen rate among children living in a rural community in southwest Nigeria.

Background: The World Health Organization prioritizes malaria surveillance for accurate tracking of progress of intervention programmes. The malaria parasite rate (PR) and spleen rate (SR) are economical surveillance tools. There has been a global decline in the burden of malaria over the last decade, but most African countries, like Nigeria, have a slow rate of decline. There is a need for adequate malaria surveillance to guide malaria control strategies and policymaking.

Methods: A community-based cross-sectional study was conducted among 363 children ages 1-15 y in rural southwest Nigeria. The participants' PR was determined by microscopy and the SR was determined by palpation and ultrasonography. The associations between PR and SR and other covariates were assessed.

Results: The PR was 26.7% and the SR was 12.9%. There was no significant association between PR or SR across age groups, but low social class was significantly associated with PR (55 [33.5%], p=0.004) and SR (29 [17.3%], p=0.013). The odds of having splenomegaly doubled with malaria parasitaemia (odds ratio 2.03 [95% confidence interval 1.06 to 3.88).

Conclusions: The PR and SR suggest that the study area is meso-endemic. The PR in the study area was almost equal across age groups; our findings suggest there may be a need for policy review to plan malaria intervention programmes and include older children, not just children <5 y of age. Routine malaria surveillance using simple tools such as the PR and SR are necessary for reviewing malaria control programmes in the community.