Geographical and temporal differences in reducing malaria infection in children under 5 years old across Nigeria – Nigeria
Wellington Oyibo, Godwin Ntadom, Perpetua Uhomoibhi, Olusola Oresanya, Nnenna Ogbulafor, Olufemi Ajumobi, Festus Okoh, Kolawole Maxwell, Sonachi Ezeiru, Ernest Nwokolo, Chioma Amajoh, Nnenna EWEISwe, Mohammed Audu, David Conway.
Global progress in reducing malaria has stalled since 2015. An analysis of the situation is particularly necessary in Nigeria, the country with by far the largest share of the burden, which is estimated to occur around a quarter of all cases worldwide.
We analyzed data from three nationwide surveys (Malaria Indicator Surveys in 2010 and 2015 and National Demographic and Health Survey in 2018), where the prevalence of malaria parasites in children under 5 was determined using samples from all 36 states of Nigeria and a blood test Microscopy performed in the same accredited laboratory for all samples. Changes over time were assessed by calculating prevalence ratio (PR) values with 95% CIs for each state along with Mantel-Haenszel adjusted PRs (PRadj) for each of the country’s six major geopolitical zones.
Between 2010 and 2018, there was a significant decrease in parasite prevalence in 25 countries, but not in the other 11 countries. The prevalence decreased most in the southern zones of the country (South West PRadj = 0.53; South East PRadj = 0.59; South South PRadj = 0.51) and in the North Central Zone (PRadj = 0.36) . The changes in the north were less pronounced but significant and showed an overall reduction of more than 20% (north-west PRadj = 0.74; north-east PRadj = 0.70). The changes in the south mainly occurred between 2010 and 2015, while the changes in the north were more gradual and most continued after 2015. The recent changes did not correlate with the fluctuations in the use of preventive measures reported by the survey.
Most individual states in Nigeria have seen a decrease in malaria infections in children under 5 since 2010. However, significant geographic differences in timing and extent indicate that there are challenges to be overcome in order to reduce malaria worldwide.