Evaluating the efficiency of participatory epidemiology to estimate the incidence and impacts of foot-and-mouth disease among livestock owners in Cambodia.

The economic and social impacts of foot-and-mouth disease (FMD) for livestock owners of developed countries have been extensively documented over the past few years. In developing countries such as Cambodia, this evaluation is often lacking due to the scarcity of accurate data. In the present study, we used a range of participatory tools to infer farmers' knowledge and perception, and the relative incidence of FMD from January 2009 to June 2010 in fifty-one villages of Svay Rieng province, Cambodia. In addition, the detection of non-structural protein at village level was used to cross-validate the results from the participatory epidemiology (PE) study. A quantitative assessment using Bayesian modeling was carried out to assess the ability of PE to retrospectively determine the FMD-infected status of a village in Cambodia. Our study shows that even if FMD is ranked second in the list of priority diseases, livestock owners did not see any benefit in reporting it since the disease entailed low direct losses. The average clinical incidence rates at individual level for cattle-buffaloes and pigs in infected villages were assessed by proportional piling at 18% and 11%, respectively for the year 2009. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of PE study were estimated at 87%, 30%, 51% and 74%, respectively. This approach seems to largely overestimate the presence of the disease but proves useful in evaluating the impact of FMD at household level and in understanding the reasons for not reporting it. This information may be important in establishing well-adapted disease prevention and control strategies in Cambodia.