International Journal of Biochemistry Research & Review

Transmission of human African trypanosomiasis is caused by the bites of the tsetse fly (Genus: Glossina) infected with microscopic parasites of the species Trypanosoma brucei in sub-Saharan Africa. The tsetse fly constitutes a major threat, and the disease, African trypanosomiasis poses a big socio-economic burden in sub-Saharan African countries. Two different subspecies of pathogens cause two forms of the disease: Trypanosoma brucei gambiense causes a slowly progressing human African trypanosomiasis in western and central Africa, and Trypanosoma brucei rhodesiense causes a more acute human African trypanosomiasis in eastern and southern Africa. The presence of the tsetse fly is one of the major root causes of hunger and poverty in sub-Saharan Africa; the tsetse fly prevents crop farming and livestock rearing leading to inadequate milk and meat production for nourishment, making productive livestock absent in the vast fertile tsetse infested area. This study aimed at comparing the repellent activities of the oil extracts of fresh garlic bulbs, and fresh onion bulbs against Glossina palpalis gambiensis. The oils were extracted using cold maceration with n-hexane. The repellent activities of garlic oil extract, and onion oil extract against laboratory-reared teneral Glossina palpalis gambiensis, were evaluated on the fore-arm skin of five human subjects under laboratory conditions.  Data generated were subjected to statistical analysis using One-way Analysis of Variance.  All graded concentrations of garlic oil extract (50%, 75%, 87.5% and 100%), and onion oil extract (50%, 75%, 87.5% and 100%), showed significant difference (p ˂ 0.01) in their mean values in preventing tsetse flies from landing, and probing on human skin. However, onion oil extract at 100% concentration post-application on skin exhibited more repellent activity (0.0+0.00) against Glossina palpalis gambiensis landing behavior than garlic oil extract at 100% concentration (2.7+0.33) post-application on skin, while garlic oil extract and onion oil extract both at 100% concentrations post-application on skin exhibited equal repellent efficacy (0.0+0.00) against the probing behavior of Glossina palpalis gambiensis on skin. The high repellent effects of 100% concentration of garlic oil extract, and 100% concentration of onion oil extract, against Glossina palpalis gambiensis make them possible tools in the control of tsetse flies, as they prevented human skin contact with the tsetse flies, therefore eliciting their potential to reduce fly-human contact and thus reduce trypanosomiasis transmission and disease burden. Garlic oil extract applied at a concentration of 100% on skin, and onion oil extract applied at a concentration of 100% on skin may protect humans and livestock from the bites of tsetse flies, and so curb trypanosomiasis disease transmission and prevalence.