Epidemiology and economic impact of cystic echinococcosis in livestock among the pastoral and agro-pastoral communities in Uganda

Abstract

A cross-sectional study was carried out in pastoral and agro-pastoral (PAP) areas to study epidemiology and economic impact of Cystic Echinococcosis (CE) in livestock in Uganda in the districts of Moroto representing pastoral areas in the Karamoja region, Kumi in the Teso region, and Luwero and Nakasongola in the Buganda region representing the agro-pastoral areas. No such studies were done before. Both qualitative and quantitative techniques were employed to gather data. Focus group discussions, key informant interviewers, structured questionnaire survey and postmortem examination of carcasses of cattle, goats and sheep in slaughter abattoirs were done. Descriptive statistics were used to summarise data into means and proportions at 95% confidence interval. Univariate logistic regression analysis was done to determine the significant factors responsible for occurrence of CE in livestock at p<0.05. Selected significant variables were used for developing a final multiple logistic regression prediction model. It was shown that farmers over the age of 36 (p<0.001) were more aware of CE in livestock, while the uneducated (p<0.0001) and being agro-pastoralist (p<0.01) were less knowledgeable. Overall, only 17.8% of respondents had knowledge about CE in livestock. While 83.2% of farmers owned roaming dogs that were never dewormed (92.1%) and shared water with livestock and humans. A total of 14,937 livestock (5,873 goats, 1,377 sheep, 3,726 zebu cattle, and 3,054 Ankole cattle) were examined in slaughter abattoirs. The overall livestock CE prevalence was found to be 21.9% in sheep, 15.2% in Zebu cattle, 5.5% in goats and 2.1% in Ankole cattle. Moroto district had a higher CE prevalence of 31.3% in Zebu cattle, 28% in sheep and 29.1% in goats. The lung was the most organ affected in all livestock species. The prevalence of CE by organ infected among livestock species in each district showed that in Moroto, lungs of: goats (27.7%), sheep (24%) and zebu cattle (20.3%) had cysts significantly higher than lungs of goats (0.6%), sheep (2.1%) and zebu cattle (0.8%) in Kumi; lungs of goats (0.5%), zebu cattle (0.9%), Ankole cattle (1.1%) in Luwero district and, lungs of Ankole cattle (1.6%) and of goats (0.2%) in Nakasongola district. Cyst infection in the livers was not reported in goats, sheep and zebu cattle in Nakasongola district. In Moroto district, the livers of zebu cattle (12.8%), sheep (5.3%) and goats (3.6%) were more infected than those of the same animals in Kumi and Luwero districts, and none in goats, sheep and zebu cattle in Nakasongola district and in sheep in Luwero district. Ankole cattle had almost similar prevalence in lungs in Luwero (1.1%) and Nakasongola (1.6%) compared to 0.8 and 1.6% in the liver respectively, and no cysts were recovered from Ankole cattle in Kumi and Moroto districts. Considering cyst fertility, 33.9, 1.7 and 6.4% of Ankole cattle, sheep and zebu cattle respectively had fertile cysts in the liver while 4.5% of goats and 4% Ankole cattle had fertile cysts in the lungs. Tethering and origin of animals in goats in agropastoral areas, communal grazing in cattle and keeping large herds of sheep were the key risk factors towards CE persistence in livestock. The total economic cost of CE was USD 21,353.2 (1USD=3,809.3 UGX) among livestock slaughtered annually of which 88.3% were indirect economic losses associated with production losses caused by weight loss. Only 11.7 % were losses due to condemnation of offal organs. More significant CE mean economic cost due to CE per livestock species slaughtered and examined occurred in Moroto district among Zebu cattle (US 8.4), goats (US 1.4) and sheep (US 1.4). There was an urgent need to sensitise and educate the communities about public health and economic negative effects of CE, how it was maintained and transmitted by dogs to livestock and humans. Communities should be taught not to feed CE livestock infected organs, rejected offals and trimmed cysts to dogs. All dogs in PAP areas should be treated with anti-helminthics. The population of stray dogs should also be controlled. The findings of the economic losses caused by CE in this study using slaughter abattoirs, need to be extrapolated to the livestock populations of each district and regions based on slaughterable age to determine the real economic cost of CE in these places