keywords: Akwanga LGA, Keffi LGA, vector competence, predominantly savannah, Ochocerciasis
A vectorial study was conducted at Akwanga and Keffi Local Government Areas of Nasarawa State to assess the vector competence and transmission rates of onchocerciasis. Monthly blackfly catching was carried out over a period of 12 months from January to December, 2011. A total number of 1,108 blackflies were caught for the period of study at the study sites. Akwanga LGA recorded 1025 blackflies while Keffi LGA recorded 83. The blackflies caught were identified as forest and savannah types based on their morphological profile. Dissections of blackflies were carried out to determine parous rate; infection and infectivity rates. The result indicated a seasonal (wet season) biting activity with a peak in the month of September at both LGAs. The blackflies identified were predominantly the savannah species. Parous flies caught at Akwanga LGA were 382(39.0%) were parous flies for Akwanga LGA while 25 (32.5%) parous flies were recorded at Keffi LGA. At Akwanga LGA 234 were infected with Onchocerca volvulus L3 larvae, while Keffi LGA recorded 04(5.2%) L3 larvae. The maximum monthly biting rate (MBR) and monthly transmission potential (MTP) for Akwanga LGA recorded 2685* in the month of September and 420.3, respectively. Annual biting rate (ABR) and annual biting potential (ATP) for Akwanga LGA were 7845 and 1210, while Keffi LGA recorded 247.5 and 34, respectively. Maximum monthly biting rate (MBR) in month of september and 16.8 for monthly transmission potential (MTP). The annual biting rate (ABR) and annual transmission potential (ATP) for Keffi LGA were 663 and 34, respectively. L3/1000 parous flies for Akwanga LGA and Keffi LGA recorded 3390 and 522, respectively. The results were statistically analysed using one- way analysis of variance (ANOVA). Transmission rates were significantly differed in relation to study areas (p<0.05). The findings recorded low onchocerciasis transmission in Akwanga LGA and no transmission in Keffi LGA in the current study.
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