Seroprevalence of Toxoplasma gondii in Poultry from Backyard and Intensive Production Systems in Romania

Toxoplasma gondii is a cosmopolitan zoonotic parasite for which free-range poultry can act as sentinels of oocyst contamination. Romanian avian data on toxoplasmosis are limited to extensive systems and wildlife, while poultry seropositivity in intensive systems has not been previously characterized. In this study, 1940 domestic birds from intensive and extensive production systems were tested for T. gondii IgG antibodies by the Modified Agglutination Test (MAT). The descriptive dataset included data on 813 intensive broiler chickens and 1127 backyard birds. Backyard chickens had roughly twice the MAT seroprevalence of intensive broilers (31.2% vs. 14.1%, p < 0.001), rising to more than a tenfold difference at ≥1:48 (18.7% vs. 1.7%, p < 0.001). Seroprevalence varied among counties and farms, but intensive broilers were sampled in a very delimited area, so geographic and production-system patterns partly overlapped and should not be interpreted independently. In models adjusting for county and age, intensive production remained associated with lower odds of infection. These findings establish the first Romanian seroprevalence baseline for intensive poultry and support risk-based surveillance focused on backyard flocks and counties with high extensive-system prevalence.