Global Prevalence of Neospora caninum in Domestic Pigs (Sus domesticus) and Wild Boars (Sus scrofa): A Systematic Review and Meta-Analysis

Background: Neospora caninum (Apicomplexa, Sarcocystidae) is a protozoan parasite regarded as a major cause of reproductive failure in cattle. Swine are susceptible to N. caninum infection; however, the role of these animals in the circulation, maintenance, and transmission of N. caninum remains unclear. Therefore, we aimed to estimate the global seroprevalence of N. caninum in domestic pigs (Sus domesticus) and wild boars (Sus scrofa).

Methods: Online databases including PubMed, Web of Science, Scopus, and Google Scholar were systematically searched to identify relevant studies up to 30 April 2024. A random-effects meta-analysis model was used to estimate the overall and subgroup-pooled prevalence of N. caninum across studies. The Cochrane test (Q) and the I² index were employed to heterogeneity. Funnel plots and Egger's regression test were used to evaluate publication bias, year of publication, and sample size.

Results: A total of 11,124 animals from 26 eligible studies were included. The pooled seroprevalence of N. caninum in swine was 17% (95% CI: 7%-26%) with a prevalence of 17% in domestic pigs and 16% in wild boars. In the subgroup analysis, the highest prevalence was observed among female animals, with a pooled seroprevalence of 17% (95% CI: 7%-26%). The pooled seroprevalence of N. caninum was nearly equal in adult and sub-adult swine (18% and 14%, respectively). The overall seroprevalence of N. caninum in swine, based on sample size and year of publication, showed no statistically significant correlations.

Conclusion: The present study showed that domestic swine are suitable intermediate hosts of N. caninum based on serological findings. However, further studies are needed to describe the epidemiology of the N. caninum and to isolate the parasite from swine to confirm this hypothesis.