Seroprevalence of Toxoplasma gondii and associated demographic factors in privately-owned dogs, cats, and community cats in Hong Kong.

BACKGROUND

Toxoplasma gondii (T. gondii) is a zoonotic protozoan parasite of humans and animals, with cats as the definitive host. This study investigated the seroprevalence of T. gondii antibodies and associated demographic factors in 1,110 dogs and cats in Hong Kong including 425 owned dogs, 425 owned cats, and 260 free-roaming "community" cats.

METHODS

Serum samples were tested using an indirect ELISA, and signalment data, including age, breed, sex, neutering status, and health status, were recorded. Fisher's exact test and correspondence analysis were used to evaluate the associations between seropositivity and demographic factors.

RESULTS

The overall apparent seroprevalence was 4.7% (95% confidence interval (CI): 3.5-6.1%), and was more than three times higher in community cats (11.2%; 95% CI: 7.6-15.6%) compared with privately-owned dogs (3.1%; 95% CI: 1.6-5.2%) and privately-owned cats (2.4%; 95% CI: 1.1-4.3%). Correspondence analysis revealed that being seronegative among privately-owned dogs was associated with older, male neutered, purebred dogs, while seronegative among privately-owned cats was associated with purebred neutered male cats aged 5-10 years. In community cats, being seronegative was associated with healthy females.

CONCLUSION

The findings highlight the low overall T. gondii seroprevalence in cats from Hong Kong. In addition, the very low seroprevalence in privately-owned animals compared to free-roaming community cats is likely due to controlled living conditions that preclude or limit outdoor access, and ingestion of prey or raw-meat diets. The results of this study underscore the need for targeted public health interventions, such as trap-neuter-return programs to mitigate T. gondii transmission risks to humans and animals. Further research is essential to identify contributing factors and develop effective control strategies for T. gondii in urban environments.