Status of Forest Onchocerciasis in the Lower Cross River Basin, Nigeria: Entomologic Profile After Five Years of Ivermectin Intervention

Abstract

In the Lower Cross River basin in Nigeria, no pre-control entomologic profile of Onchocerca volvulus infection in the local Simulium damnosum population was available prior to the initiation of an ivermectin control program in 1995. A longitudinal entomologic study was therefore carried out over a 12-month period (January-December 2001) at the Agbokim waterfalls and Afi River, which are breeding sites of S. damnosum in the river basin. A total of 9,287 adult S. damnosum were caught on human bait; 9,048 (97.43%) were dissected, of which 313 (3.46%) were infected. Annual biting rates (ABRs) of 42,419 and 28,346 bites per persons per year were recorded at the Agbokim Waterfalls and Afi River, respectively. The annual transmission potential (ATP) was 419 infective larvae per person per year at the Agbokim Waterfalls and 427 at the Afi River. Monthly biting rate and monthly transmission potential varied significantly (P < 0.05) at the two sites. Transmission was highly seasonal from April to September, corresponding to the peak biting period of the vector. The high ATP and ABR values are a measure of the mesoendemicity of onchocerciasis in the river basin. There was a significant F(0).05 (1, 10) (P < 0.05) variation in the relative fly abundance from both sites. It was observed that human activities such as farming, fishing, timber cutting, and hunting are done in the early morning and late afternoon, which corresponds to the peak diurnal biting period of the vector. Changes in these practices and attitudes may markedly affect the disease intensity and transmission.

Repellency of Hydrogenated Catmint Oil Formulations to Black Flies and Mosquitoes in the Field

“…In the previous studies, Kutin et al (2004), Opara et al (2005) and Usip et al (2006) have found the similar results.…”

Current status of bancroftian filariasis in rural communities of the lower cross river basin, Nigeria: parasitological and clinical aspects

“…Cattle rearing and bee farming are largely practiced. A detailed description of the study site and area is documented elsewhere (Opara et al 2005;Ibanga 2004). …”

Immunomodulating effects and hypersensitivity reactions caused by Northeast Indian black fly salivary gland extract

“…Some Simulium species can transmit Onchocerca volvulus, causative parasites of river blindness (onchocerciasis) in Africa (WHO, 1995). Clinical manifestations of onchocerciasis include itching and disfiguring of skin, nodules on bony areas, serious eye lesions, and blindness; all of these are considered both public health problems and socioeconomic hazards (Opara et al, 2005;Youssefi et al, 2008). In countries like India, even despite evidence of O. volvulus not being reported so far, black flies still bite and crawl on the skin of individuals and livestock (Malhotra et al, 1986).…”