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.