Seroprevalence and correlates of Toxoplasma gondii infection in domestic pigs in Veracruz State, Mexico.

Toxoplasma gondii infection in pigs has epidemiological concern for its contributing role in human infections. We determined seroprevalence of T. gondii infection in 402 domestic pigs raised in backyards in Veracruz State, Mexico using the modified agglutination test (MAT; cut off 1:25); 182 (45.3%) of the 402 pigs were seropositive with MAT titers of 1:25 in 28, 1:50 in 22, 1:100 in 18, 1:200 in 30, 1:400 in 35, 1:800 in 23, 1:1,600 in 11, and 1:3,200 or higher in 15. Seropositive pigs were found in 137 (53.3%) of 257 homes in all 7 municipalities surveyed. Multivariate analysis showed that T. gondii seropositivity in pigs was associated with tropical-humid climate (OR = 4.32; 95% CI 1.47-12.62; P = 0.007) of the raising municipalities, feeding with leftovers (OR = 2.83; 95% CI 1.01-7.91; P = 0.04), storing pig food in the owner's home (OR = 2.39; 95% CI 1.09-5.22; P = 0.02), and free ranging (OR = 3.48; 95% CI 1.49-8.15; P = 0.003). Results indicate that backyard pigs in Veracruz have the highest seroprevalence of T. gondii infection obtained by MAT in pigs studied in Mexico so far. The correlates of T. gondii infection found in the present study may be useful for an optimal planning of preventive measures against T. gondii infection in pigs. Results also remark the risk of T. gondii infection in humans by ingestion of raw or undercook pork in Mexico.