Authors: Dawit Hawaria^{1, 4}, Assalif Demissew^{2, 6}, Solomon Kibret³, Ming-Chieh Lee³, Delenasaw Yewhalaw^{4, 5*}, Guiyun Yan³

¹Yirgalem Hospital Medical College, Yirgalem, Ethiopia

²Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Ambo University, Ambo, Ethiopia

³Program in Public Health, University of California at Irvine, Irvine, CA 92697, USA

⁴Department of Medical Laboratory Sciences and Pathology, Institute of Health, Jimma University, Jimma, Ethiopia

⁵Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia

⁶Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia

Abstract

Background: Irrigated agriculture is key to increase agricultural productivity and ensure food security in Africa. However, unintended negative public health impacts (e.g. malaria) of such environmental modification have been a challenge. This study assessed the diversity and distribution of breeding habitats of malaria vector mosquitoes around Arjo-Dedessa irrigation development site in Southwest Ethiopia.

Methods: Anopheline mosquito larvae were surveyed from two agroecosystems, ‘irrigated’ and ‘non-irrigated’ area during the dry (December 2017 – February 2018) and wet (June 2018 – August 2018) seasons. Mosquito habitat diversity and larval abundance were compared between the irrigated and non-irrigated areas.

Results:  Overall, 319 aquatic habitats were surveyed during the study period. Around 60% (n = 152) of the habitats were positive for Anopheline mosquito larvae, of which 63.8% (n = 97) and 36.2% (n = 55) were from irrigated and non-irrigated areas, respectively. Anopheline positive habitats were two-fold higher in irrigated area compared to the non-irrigated area. Anopheline larval abundance in the irrigated area was 16.6 % higher than the non-irrigated area. Pearson’s chi-square analysis showed that season (c² = 63.122, df = 1, P < 0.001), agroecosystem (being irrigated or non-irrigated) (c² = 6.448, df = 1, P = 0.011), and turbidity (c² = 7.296, df = 2, P = 0.025) have a significant association with larval Anopheline occurrence.

Conclusion: The study showed higher Anopheline mosquito aquatic habitat diversity, larval occurrence and abundance in the irrigated than non-irrigated areas in both dry and wet seasons. This indicates that irrigation development activities contribute to more aquatic habitat proliferation suitable for malaria vector mosquito breeding, which could increase the risk of malaria transmission. Thus, incorporating larval source management as a major malaria vector intervention tool into routine malaria control efforts could help reduce mosquito population density and malaria transmission around irrigation development schemes.