Parasitological and clinico-epidemiological features of onchocerciasis in West Wellega, Ethiopia

Abstract

Onchocerciasis is a disease of public health and socio-economic importance in Ethiopia. The aim of this study was to assess parasitological and clinico-epidemiological features of onchocerciasis in the Anfilo District, West Wellega, prior to implementation of Community Directed Treatment with Ivermectin (CDTI) to generate epidemiological and parasitological data for use in control program of the disease and subsequent evaluation of CDTI. A cross-sectional study was conducted in Anfilo District of West Wellega zone during a period of 1 month: from midAugust to mid-September 2006. Data on socio-demographic characteristics were collected using a standardized questionnaire prepared for this purpose. All persons were examined clinically for skin signs and symptoms of onchocerciasis. Two skin snips, one from each side of the gluteal fold were taken using blood lancet and sterilized razor blade and examined for microfilaria. All data were categorized, coded, entered in a data base and analyzed using SPSS version 15.0. for windows. A total of 1114 individuals C15 years were examined for microfilariae (mf) of Onchocerca volvulus and onchocercal skin disease (OSD). The prevalence of onchocercal (mf) carrier was 74.8% (833/1114). In both genders, the prevalence of onchocerciasis showed direct correlations with the age of individuals (R 2 = 0.79, P \ 0.05). The infection rate varied with the occupation of the study subjects, with preponderance among farmers. Among the subjects with onchocerciasis, the mf density ranged from 1.0 to 711.0 per mg of skin snip with a mean density (SD) and median values of 32.1 (61.5) and 10.4 respectively. The overall community microfilariae load (CMFL), the most sensitive parasitological indicator of onchocerciasis was 19.6. The pervasiveness of OSD among the study subjects was 26.4%. OSD was more frequent in males (32.4%) than their female counterparts (20.8%, P \ 0.05). The overall prevalence of onchocercal nodule carrier, the symptom opted for determining the community-wide prevalence of onchocerciasis was 12.1%. Leopard skin, the proxy of longstanding infection of onchocerciasis in the community, was also relatively high (19.1%). The abundance of mf in skin would definitely lead to high transmission potential in the Anfilo District. The situation in the Anfilo District should call for continued CDTI, owing to success of similar recommendations for such programmes in other parts of the country and elsewhere.

Prevalence of Onchocerciasis and Associated Factors among Adults Aged ≥ 15 Years in Semen Bench District, Bench Maji Zone, Southwest Ethiopia: Community Based Cross-Sectional Study

“…Similarly, individuals whose age was 45 years and above were nearly ten times more likely to develop the infection as compared to individuals in the age group of 15-24 years. The finding was in agreement with findings of studies conducted in Jimma zone, West Welega zone, Nigeria, Equatorial Guinea, and Senegal where age was independently associated with onchocerciasis infection [9,13,[15][16][17][18]. This might be due to the fact that adults are most of the time engaged in outdoor activities where they can be bitten by black fly.…”

“…The finding was consistent with the findings of studies conducted in southwest Ethiopia, Cameroon, Senegal, and Equatorial Guinea [10,[12][13][14][15][16]. The study was not consistent with the studies done at Jimma zone and West Welega zone which showed the prevalence of 22.5% and 74.8%, respectively [9,17]. This difference might be attributed to difference in coverage of community directed ivermectin treatment.…”

A community-based cross-sectional study of the epidemiology of onchocerciasis in unmapped villages for community directed treatment with ivermectin in Jimma Zone, southwestern Ethiopia

“…In the current study, the overall prevalence rate of O. volvulus infection was 22.5 %. This finding was lower compared to the results of other studies conducted in Teppi [ 4 , 14 ] southwestern Ethiopia, around Blue Nile River [ 15 ] and West Wellega [ 16 ].The difference might be due to long time endemicity of the parasite in the mentioned study area and the higher abundance of vectors in those areas compared to the new emerging foci in the current study. Moreover, Teppi area is known for its large coffee farm and there are many daily laborers who came from different parts of the country and are engaged in outdoor activities and are at the same time exposed to simulium bite.…”

Impact of Six Years Community Directed Treatment with Ivermectin in the Control of Onchocerciasis, Western Ethiopia

“…In a previous study conducted in four different villages of Anfilo District, Kelem Wollega Zone, Western Ethiopia or the current study area, the average prevalence of Onchocerciasis was 74.8%. Among the villages 87.6% was recorded in Yeli, which is the highest ever recorded in Ethiopia [ 6 ].…”