Mosquito dynamics and malaria in Alulu-Nike Commnuity, Enugu East Local Government Area, Enugu State, Nigeria

Abstract

Malaria is endemic and stable, being a major cause of morbidity and mortality in Nigeria. Malaria prevalence and mosquito dynamics were studied in the rural villages of Alulu-Nike Community, Enugu East Local Government Area of Enugu State for a period of 12 months. Malaria was diagnosed with microscopy method. Mosquito collection was done using pyrethroid knockdown collection method for indoor biting and resting adult mosquitoes; human bait method for outdoor adult mosquito and larval collection from different breeding sites. Mosquito identification was done using morphological characteristics and PCR. A total of 1,440 people were screened for malaria and 476(32.4%) were infected. The overall mean malaria intensity was 545 parasites per microlitre of blood (p/μl). Nnegbune Village had the highest malaria prevalence 86 (41.5%) which was significant (p<0.05) and the highest mean malaria intensity 741 p/μl. Age 0-10 years had the highest malaria prevalence 229(44.7) and mean intensity 991 p/μl. The age specific malaria prevalence was statistically significant (p<0.05). Malaria intensity was not significant in all categories. Malaria prevalence and intensity were not dependent on sex and occupation of the participants (p>0.05). The primary education group 204(38.6) and the nonformal education group 63(34.2) were mostly infected while the tertiary education group were the least infected 68(26.6) which was significant (p<0.05). PCR characterization of the 990 indoor biting and resting adult mosquitoes revealed Anopheles gambiae ss and A. arabiensis as the sibling species of A. gambiae sl. A. gambiae ss, A. arabiensis and A. funestus (malaria vectors) constituted 764 (77.1%) while the Culicines accounted for 226(22.8%) of the total indoor collection. The highest malaria vectors as well as the highest mosquitoes were collected from Nnegbune village. Of the 694 outdoor biting adult mosquitoes collected. A. gambiae sl 7(1.0%) was the only malaria vector collected while other species of culicine mosquitoes accounted for 687(98.99%) of the outdoor collections. A total of 1,162 mosquito larvae were collected from different villages of Alulu-Nike Community out of which A. gambiae yielded 45(3.9%) while culicine mosquitoes yielded 1,117(96.1%) of the total larval sampling. The highest collection of larvae was from used and discarded tyres 822 (70.7%). Mosquitoes were more abundant in wet months than in dry months. The distribution of indoor and outdoor mosquitoes and larvae in different villages and in different months showed significant results (p<0.05). Entomological study of mosquitoes is important for planning and optimizing malaria control in both time and space.

Keywords: Malaria; Anopheles mosquitoes; culicines