Seroepidemiological study of canine Leishmania infantum and Toxoplasma gondii infections in Shanghai, China, and analysis of risk factors

The aim of this study was to determine the seroprevalence of Leishmania infantum and Toxoplasma gondii among household dogs in Shanghai (the most important industrial and commercial city in China), and to assess the possible risk factors associated with the infection. During 2014–2015, a total of 408 sera were collected from healthy household dogs and tested for L. infantum and T. gondii infection using commercial ELISA kits. The endemic characteristics according to gender, age group and breed were revealed by statistical descriptions and inference. The positive rates of L. infantum infection (24/408, 5.9%) were lower than those of T. gondii infection (37/408, 9.1%), and co-infection with both parasites was detected in seven dogs (7/408, 1.7%). Seropositivity for either parasite was more likely associated with age: the seroprevalence of T. gondii infection ranged from 1.3% (dogs≤1 year) – 18.7% (dogs>6 years), whereas that of L. infantum ranged from 1.3% (dogs≤1 year) – 9.9 % (dogs>6 years). Interestingly, the rates of exposure to both L. infantum and T. gondii were higher in males than in females. Relatively higher exposure rates for L. infantum and T. gondii were also observed in crossbred dogs compared with purebred dogs. However, neither gender nor breed is likely a determining factor for infection with these two parasites (P > 0.05). Identification of the risk factors that underlie these differences may help in the prevention of L. infantum and T. gondii infection in household dogs. To the best of our knowledge, this is the first report of L. infantum and T. gondii infection in household dogs in Shanghai, which shows that these two important parasites are still prevalent in this region. Therefore, it is necessary to take integrated strategies for prevention and control of infection in animals, which could help to reduce human infection in the region.