Construction of standardized surveillance indicators for bovine cysticercosis.

Bovine cysticercosis is a zoonotic parasitic disease due to Cysticercus bovis. This study aimed to identify factors that could have an impact on the prevalence of cysticercosis and to use them to build standardized indicators of prevalence. Multivariate logistic regression analyses were performed on data from 4,564,065 cattle (91.3% of the cattle population slaughtered in France in 2010) among which 6491 cattle (0.14%) were found to harbor at least one lesion of cysticercosis (including 611 cattle harboring viable cysts, 0.01%). Two multivariate logistic models were fit to the data using as outcome variables either the presence or absence of viable cysts and the presence or absence of cysts whatever their level of development. Age and sex were identified as the main factors influencing bovine cysticercosis prevalence and were used for the construction of standardized prevalence and standardized cysticercosis rate. To illustrate the use of such indicators, they were calculated for the first and second semester of 2010 and for two different areas in France. The differences between raw prevalence and standardized prevalence highlight the use of standardized indicators for comparisons of prevalence between different areas and time periods as the structure of the slaughtered populations differ considerably from one to another.

Prevalence of Taenia saginata cysticercosis in French cattle in 2010.

Bovine cysticercosis is a foodborne disease caused by the cestode Taenia saginata with cattle as the intermediate host and humans as the final host. This disease is responsible for direct financial losses for farmers. It is also economically important because human infestation through raw or undercooked meat consumption can have a negative impact on the confidence the consumer has in the food industry. This study aimed to determine the apparent and true prevalence of bovine cysticercosis in France and describe the locations of identified cysticercosis lesions. The study sample included 4,564,065 cattle slaughtered in 2010 in France, among which 6491 were detected as harbouring cysticercosis lesions using the current EU meat inspection process. The overall apparent prevalence (including both viable and degenerated cysticerci) was estimated at 0.142% [0.142-0.143]. The true overall prevalence defined as the estimation of the prevalence after taking into account the sensitivity of meat inspection (detection fraction) was 1.23% [0.83-1.93]. The true prevalence of cattle with at least one viable cysticercus was 0.113% [0.076-0.189]. Taking into account both our results and those of a previous study on the prevalence of human cysticercosis in France, we estimated that one carcass could infest an average of 8-20 individuals. The spatial distribution of viable cysticerci showed that the highest apparent prevalence was found in eastern France. This study, the largest survey ever conducted on bovine cysticercosis in France, indicated a low but spatially heterogeneous prevalence of the parasite among the cattle population. Considering French eating habits, according to which it is not uncommon to consume undercooked meat, the possibility of humans being infested even though viable cysticerci are not detected during meat inspection is high. Increasing the detection sensitivity of meat inspection through the use of a risk-based meat inspection procedure should improve prevention of human infestation.