FIELD STUDIES OF SELECTED PLANT ESSENTIAL OILS FOR ONCHOCERCIASIS CONTROL AND ELIMINATION
NJE Vol. 41(2): 92-107, 2025
DOI.10.36108/NJE/5202/14.0270
1Chikezie Friday Maduka*, 1Opara Kenneth Nnamdi, 1Ubulom Peace Mayen Edwin , 1Yaro Clement Ameh, 1Akpan Akaniyene Udoh, 1Udoidung Nsima Ibanga, 2Chikezie Chinasa Peace, 3Ezihe Ebuka Kingsley, 4Udoh Dora Imefon
1Department of Animal and Environmental Biology, University of Uyo, Akwa Ibom State, Nigeria.
2Department of Internal Medicine, University of Nigeria Teaching Hospital, Ituku Ozala, Enugu, Enugu State, Nigeria.
3Department of Entomology, Malaria Consortium, Abuja, Nigeria.
4Department of Microbiology, University of Uyo, Akwa Ibom State, Nigeria
Abstract
Black flies of the Simulium damnosum complex transmit both animal and human onchocerciasis (River blindness), a neglected tropical disease (NTD) of public health importance in Nigeria. Efforts have been made for decades to control and eliminate onchocerciasis, mostly focusing on the use of ivermectin chemotherapy targeted on the Onchocerca parasite in infected humans. However, studies have shown that vector control can help fast-track onchocerciasis elimination. The present study investigated the repellent potentials of essential oil extracts of Eryngium foetidum and Eugenia uniflora against black flies in the field using topical application on study volunteers in a repeated-measures experimental design. The chemical composition of these oils extracted by hydro-distillation were determined using GC-MS analysis. Essential oils of E. foetidum and E. uniflora showed 73.0% and 84.3% average repellency at 20% concentration respectively, after 5 hours of exposure. Repellence activities decreased with increase in time of exposure. The two plant oil extracts were more effective repellents when compared with a commercial product, N,N-Diethylbenzamide, which served as a positive control. The average repellence of the positive control was 61.5 % (P<0.05). The characterization of E. foetidum essential oil indicated an abundance of monoterpenes (29.2%), sesquiterpenes (25.0%) and triterpenes (4.2%), while E. uniflora was principally composed of sesquiterpenes (91.0%). The two plant oil extracts proved to be more effective repellents when compared with the positive control. These plants could be exploited in the development of plant-based, natural repellents against black flies. A synergy between Mass Drug Administration (MDA) with ivermectin and vector control using plant-based natural repellents from E. foetidum and E. uniflora would help realize onchocerciasis elimination targets faster than with MDA alone.
Keywords: repellence, black flies, essential oils, onchocerciasis, Simulium damnosum.