Seroprevalence of Neospora caninum in Camelids: A Global Systematic Review and Meta-Analysis

Neospora caninum is an apicomplexan parasite that causes significant reproductive losses in livestock, particularly cattle, yet its epidemiological impact on camelids remains poorly understood. This systematic review and meta-analysis aimed to estimate the pooled seroprevalence of N. caninum in camelids worldwide and to compare seroprevalence between Old World camels (OWCs) and New World camelids (NWCs).

A systematic literature search was performed in various international databases from January 1, 2000 to December 20, 2025. Eligible studies reported serological detection of N. caninum antibodies in camelid species with extractable seroprevalence data. Pooled seroprevalence and 95% confidence intervals (CIs) were calculated using a random-effects model in Comprehensive Meta-Analysis (CMA) software. Heterogeneity was assessed by the I² statistic, and subgroup, meta-regression, sensitivity, and publication bias analyses were performed.

Thirty-four studies encompassing 48 datasets met the inclusion criteria, representing 13,784 camelids from 15 countries across five continents. The total dataset included 4,463 OWCs and 9,321 NWCs. The overall pooled seroprevalence of N. caninum in camelids was 9.4% (95% CI: 7.2-12.2%), with substantial heterogeneity among studies (I² = 93.5%, p < 0.001). The pooled seroprevalence was 14.5% (95% CI: 9.7-21%) for OWCs and 5.8% (95% CI: 4-8.5%) for NWCs. Subgroup analysis demonstrated higher seroprevalence estimates in studies published after 2014, in studies with smaller sample sizes (≤ 100 animals), among camelids older than five years, in female animals, in studies conducted in Europe and Asia, and in studies using the Neospora agglutination test (NAT) as the serological diagnostic method. Sensitivity analysis showed stable pooled seroprevalence estimates, while meta-regression indicated that neither publication year nor sample size significantly contributed to between-study heterogeneity or variability in the pooled estimates. Egger's regression test (p = 0.08) and symmetrical funnel plot inspection indicated no substantial publication bias.

This study provides the first global quantitative synthesis of N. caninum seroprevalence in camelids, demonstrating moderate serological exposure based on currently available evidence. However, the findings should be interpreted cautiously because of substantial heterogeneity among studies, unequal subgroup representation, and the use of different serological assays and cut-off values. Moreover, the present study assessed serological exposure rather than clinical disease; therefore, no direct association with reproductive disorders can be inferred. Further standardized longitudinal and molecular studies are needed to better clarify the epidemiological and reproductive significance of N. caninum infection in camelids.