Risk factors associated with the outbreaks of african swine fever in Lusaka province, Zambia.
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Date
2015
Authors
Siamupa, Cynthia M.
Journal Title
Journal ISSN
Volume Title
Publisher
The University of Zambia
Abstract
African Swine Fever (ASF) is one of the most complex diseases of swine and a worldwide problem with most countries in the sub-Saharan region being endemic. The disease is characterised by widespread hemorrhages and high mortalities and affects trade in pigs and/or pork products both locally and internationally. The aetiological agent for ASF is a DNA virus that does not produce neutralising antibodies in affected animals. Lusaka province of Zambia experienced outbreaks of ASF in 2013. The outbreak was first reported in Lusaka district and later spread to Chilanga and Chongwe districts and a total of 6 471 out of 40 233 pigs were depopulated on 20 farms that were surveyed. The Zambian government incurred a huge cost in terms of loss in trade, cost of control measures and compensation of affected farmers. This study was carried out to identify the risk factors that were associated with these outbreaks in the province. The participants were selected purposively from the four (4) districts of Lusaka province namely; Lusaka, Chilanga, Kafue and Chongwe that had cases of ASF diagnosed by Central Veterinary Research Institute and reported by the Director of Veterinary Services in the 2013-2014 outbreaks. The recruited participants included 3 District Veterinary Officers, 3 Veterinary assistants, 4 police officers and 2 Veterinary staff from veterinary check points, 3 managers from abattoirs and processing plants, 3 meat inspectors from Ministry of Local Government and Housing, 3 market chairpersons, 15 traders and 50 pig farmers. All participants were purposively sampled except for the pig
farmers that were included using respondent-driven technique. Apart from managers at abattoirs and processing plants and pig farmers that used semi-structured questionnaires for data collection, all the participants utilized interviews. Interview data and questionnaire responses from managers at abattoirs and processing plants was analysed using narrations, tables and flow charts. Some key statements or quotations emerging from the interviews were used to illustrate the main ideas. Information from the questionnaire for farmers was coded and entered into Microsoft Excel. The coded data was then transferred to STATA® Version 12 (STATA Corporation, College Station, Texas). The variables that could be associated with spread of ASF such as location, duration of pig keeping, alternative source of income, absence of a boar, type of feed, source of feed/ingredient, ASF screening, market availability, knowledge on ASF transmission, occurrence of ASF outbreak and regulation on pig movement were identified. Univariate analysis using Chi-square to determine the effect of each independent variable on the dependant variable (ASF) and multivariate analysis using logistic regression were performed. A confidence interval of 95% was used to ascertain the effects of the above factors on ASF positivity. The P-value for the test was >0.05 meaning that the logistic model used was an adequate fit for the data. The study revealed that farmers bought breeding stock from fellow farmers and live pig markets such as Chibolya market near the Lusaka Central Business District. The farmers (4/50, 8%) that had no boars took their sows to other farms for servicing. Fifty eight per cent (29/50) of the farmers used disinfectants while traders did not disinfect the modes of transport they used. Only 48% (24/50) and 33.3% (5/15) of farmers and traders respectively had knowledge of ASF transmission. Fifty per cent (25/50) of farmers had their animals screened for ASF before sale. All the markets did not have the pork inspected. Further, farmers and traders used alternative routes to avoid check points. The study revealed that the risk factors that were associated with the spread of ASF in Lusaka province were (1) purchase of pigs for replacement and breeding stock from one another and from markets, (2) poor adherence or absence of biosecurity measures, (3) laxity in enforcing livestock movement control and inadequate police and veterinary staff manning check points, (4)
evading pig checks at check points by traders who use alternative routes, (5) low awareness levels on ASF transmission among pig farmers and traders, (6) lack of enforcement of regulations at pig markets and (7) inadequate of ASF screening. Of these factors, only absence of a boar (P=0.01, 95% C.I:8.22-68.41) and occurrence of ASF outbreaks in the previous year (P=0.08, 95% C.I:0.23-35.54) were significantly associated with the ASF outbreak. Improving biosecurity, sensitizing farmers, traders and all stakeholders in the pig value chain on ASF, reinforcement of staff at check points
and regulation of pig markets are some of the ways in which future outbreaks can be prevented since there is no vaccine or treatment for ASF.
Description
Thesis of Master of Science in One Health Analytical Epidemiology.