An Assessment of the Effects of Insecticide-Treated Livestock Protective Fences (LPF) for Protecting Humans from Anthropophilic Mosquitoes and Malaria Transmission in a Suburb of Kumasi in the Forest Zone of Ghana

Abstract

Aim: The study investigated whether a 100 cm high livestock protective fence (LPF), effectively protects humans against anthropophilic mosquitoes and hence malaria. Study Design: Four experimental segregated, half-roofed shelters with concrete floors, each measuring 6m x 7m, separated from each other by 500m, fenced by 100cm high chicken wire, one of them enclosed by an LPF, were used. Place and Duration of Study: Work was done on Boadi Cattle Farm by Kumasi Centre for Collaborative Research in Tropical Medicine, Kwame Nkrumah University of Science and Technology, Ghana, for four weeks. Methodology: Human landing catches of mosquitoes were conducted twice a week. Two groups of two mosquito collectors worked at each of the four shelters during the same night; one group collected from 1800h to midnight, the second group from midnight to 0600h. One collector collected inside as the other collected outside at a distance of about 20m. Results: Altogether 6118 mosquitoes were collected, of which 773 Anopheles gambiae, 11 A. funestus, 874 A. ziemanni and 4460 Culicinae. There were insignificant (P = 0.30) and significant (P = 0.0003) decreases in numbers of A. ziemanni and culicines entering the shelters with LPF respectively. However, significantly more A. gambiae entered the LPF fenced shelters than in unfenced shelters (P = 0.0008). A variation of hourly biting activities of A. gambiae with a peak between 0100 and 0400 at Boadi and between 1100 and 0300 at two sites at Anwomaso, was observed. Plasmodium falciparum infections were detected in only 1% of A. gambiae but not in A. ziemanni. All 47 A. gambiae s.l. randomly selected and tested using Polymerase Chain Reaction were identified as A. gambiae s.s. Conclusion: LPF protects humans against some mosquitoes but not the malaria vector, A. gambiae.