A systematic review on the global occurrence of Taenia hydatigena in pigs and cattle.

Taenia hydatigena, a non-zoonotic tapeworm species shares the same intermediate hosts with other Taenia zoonotic species, such as Taenia solium in pigs and Taenia saginata in cattle. The occurrence of T. hydatigena in pigs and cattle may cause cross-reactions in immunodiagnostic tests and therefore, complicate the diagnosis of the zoonotic species. This study was conducted to systematically review the data on the prevalence of T. hydatigena in pigs and cattle, with the aim to assess the potential interference in serological diagnosis of zoonotic Taenia spp. due to T. hydatigena infection. We searched PubMed, Web of Science, Africa Journal Online, website http://www.google.com and article reference lists in English, French and Vietnamese with no restriction on research time and publication status. Eligible studies included observational studies that showed the occurrence of T. hydatigena. Twenty-six studies, divided into two animal groups, i.e. pigs and cattle, met the eligibility criteria for qualitative synthesis and 17 studies were included for the meta-analysis in three continents. T. hydatigena was found by necropsy in all included studies, which mostly were abattoir surveys. Overall, results showed the worldwide occurrence of T. hydatigena cysticercosis in pigs and cattle. In pigs, there was a marked higher prevalence in Asia and South America that was 17.2% (95% CI: 10.6-26.8%) and 27.5% (CI: 20.8-35.3%), respectively, compared to a low prevalence of 3.9% (95% CI: 1.9-7.9%) in Africa. Overall, the prevalence of T. hydatigena in cattle was low with a mean of 1.1% (95% CI: 0.2-5.2%). These results show that interpretation of results of sero-diagnostic tests for zoonotic Taenia species in pigs and cattle has to take into account the prevalence of T. hydatigena infections in different settings.