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The chapter investigats whether a 100 cm high livestock protective fence (LPF), effectively protects humans against anthropophilic mosquitoes (mosquitoes that are attracted to and bite human beings) and hence malaria. In order to do this, four experimental segregated, half-roofed shelters with concrete floors, were constructed. Each shelter measured 6m x 7m and each was separated from the other by 500m. Then, each shelter was fenced by a 100cm high chicken wire. However, only one of them was enclosed by an LPF, on the chicken wire, at a time. This experimental investigation was done on a Cattle Farm called Boadi Cattle Farm by Kumasi Centre for Collaborative Research in Tropical Medicine (KCCR), a research centre in Kwame Nkrumah University of Science and Technology, Ghana. The duration of the experiment was four weeks. Mosquitoes were caught by human landing catches (human beings sitting down as baits to attract and catch mosquitoes) twice a week. Two groups of two mosquito collectors (catchers) worked at each of the four shelters during the same night; one group collected from 18.00 hours to midnight, the second group from midnight to 6.00 hours. One mosquito collector sat and collected inside the shelter as the other sat and collected outside of it at a distance of about 20m. Altogether 6118 mosquitoes were collected, of which 773 Anopheles gambiae, 11 A. funestus, 874 A. ziemanni and 4460 Culicinae. Analysis of the number of mosquitoes caught in the shelters shows that there was no significant decrease (P = 0.30) in the number of A. ziemanni entering the shelters which were enclosed with LPF compared to the number of the same type of mosquito (A. ziemanni) entering shelters that were not enclosed by the LPF. However, there was a significant (P = 0.0003) decrease in the numbers of culicines entering the shelters with LPF compared to the number of the same mosquito type (culicines) entering shelters that were not enclosed by the LPF. However, significantly more A. gambiae, the most efficient malaria vector, rather entered the LPF fenced shelters than in shelters that were not fenced with the LPF (P = 0.0008)! Again, analysis of the hourly biting activities of A. gambiae revealed that at Boadi, most of them come out to bite between 0100 and 0400. However, at two different locations in a town called Anwomaso, 0.7 and 1.3 km northeast of one of the shelters in Boadi, most of the same A. gambiae mosquitoes came out to bite people at 11.00 hours and 0300 respectively! 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 (PCR) were identified as A. gambiae s.s. Therefore, we conclude that the LPF protects human beings against some mosquitoes like the culicines and A. ziemanni but not the malaria vector, A. gambiae. |
