Toxoplasma gondii seroprevalence in dairy and beef cattle: Large-scale epidemiological study in Estonia

- Almost one fifth of cattle tested Toxoplasma gondii seropositive in Estonia.
- The seroprevalence appeared to increase with age until the age of five years.
- Animals of Estonian Red breed had higher odds to test seropositive than Holsteins.
- Serological evidence of exposure to T. gondii was evident on most farms.
- Farms with T. gondii seropositive cattle were detected in all counties.

Toxoplasma gondii is a zoonotic protozoan parasite that thrives in Estonia. In this nationwide cross-sectional study, we tested sera from 3991 cattle, collected from 228 farms in 2012-2013, for anti-T. gondii immunoglobulin G antibodies using a commercial direct agglutination test. Titer of 100 was set as cut-off: samples that tested positive at the dilution 1:100 were defined as positive. The apparent animal-level seroprevalence was 18.62%. At least one seropositive animal was found on 68.86% of the farms, and seropositive cattle were detected in all counties. The seroprevalence appeared to increase with age until five years (60-71 months) of age, but had no obvious pattern in the older animals. Animals of the local Estonian Red breed had higher odds to test seropositive than did animals of the Estonian Holstein breed. Whether the farm focused on dairy or beef cattle was not associated with an animal testing T. gondii seropositive nor with finding at least one T. gondii seropositive animal on the farm. The odds of finding at least one T. gondii seropositive animal on the farm were higher if the herd size was above median (105 in dairy and mixed dairy farms; 35 in beef and mixed beef farms). The results indicate that T. gondii is endemic within the agricultural setting in Estonia and present on the majority of cattle farms.

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