Prevalence of Malaria Parasite Infection and Vector Species Abundance in Huye District, Southern Rwanda

Abstract

Background: Malaria is a leading cause of mortality and morbidity in sub-Saharan Africa including Rwanda. Effective control of malaria requires knowledge of vector species but information on species distribution in Rwanda is limited. Objectives: The main objective of this study was to determine the prevalence of malaria parasites in children under five and vector species abundance in Rukira cell, Huye district, Rwanda. Methodology: A total of 222 children under five years randomly selected from 13 villages were examined. Data on malaria vectors and risk factors were collected. Adult mosquitoes were collected indoors by light traps and Pyrethrum Spray Catch, and outdoors by light traps. Female Anopheles mosquitoes were identified to species level by morphological characteristics. Screening for Plasmodium falciparum circumsporozoite protein and for host blood meal sources was achieved by Enzyme-linked Immunosorbent Assays. Anopheles larvae were sampled using dippers and raised into adult stages which were identified morphologically. Data were analyzed by IBM SPSS software version 22. In all tests, a p-value below 0.05 was regarded as statistically significant. Results: Two hundred and twenty-two children were included in the study. Nearly a third (28.8%) of the children were within the age of 25-36 months. The majority (54%) of the children were female. Most of the parents/guardians were married (95.9%), nearly all (99.5%) had attended primary school and most (97.3%) were farmers. The overall Plasmodium falciparum prevalence in children under five was 12.2%. Children aged 1 to 12 months were 3.5 times more likely to have malaria parasites than children aged 13 to 59 months [AOR=3.56; 95%CI=1.18-10.71; p=0.024]. Children who were not sleeping under insecticide treated nets (ITNs) were 15 times more likely to be infected with malaria parasites compared to those who were sleeping under one [AOR=15.27; 95%CI=4.42-52.82; p<0.001]. An. gambiae s.l was the most dominant malaria vector 69.7% of the 567 collected Anopheles. Others were An. funestus 4.1%, An. squamosus 16.6%, An. maculipalpis 6.5%, An. ziemanni 1.8% and An.coustani 0.2%. The overall human biting index was 0.509 while Sporozoite rate was 1.9%. A total of, 661 anopheline larvae from 22 larval habitas were collected. They comprised of 2 species: An. gambiae s.l (89%) and An. ziemanni (11%). The absolute breeding index was 86.4%. The most common larval habitats were in full sunlight with still water such as rice paddies and bodies of stagnant water. The larval density was significantly associated with still water current (p=0.038). Conclusion: P. falciparum infection is seen in one out of 8 children under five years of age. There is need to protect children from mosquito bites by ensuring that they sleep under ITNs. The primary potential malaria vector was An.gambiae s.l but secondary vectors like An. ziemanni, An. squamosus and An. maculipalpis may play an important role as well. The findings provide useful baseline information on malaria vectors composition that would guide integrated vector management strategies in the locality