Toxoplasmosis in naturally infected rodents in Belgrade, Serbia.

To assess the role of synanthropic rodents in the epidemiology of urban toxoplasmosis, Toxoplasma gondii infection was examined in 144 rats (Rattus norvegicus) and 12 mice (Mus musculus) captured using live animal traps in three locations in Belgrade city characterized by poor housing and degraded environment. In rats, specific IgG antibodies were detected by modified agglutination test in 22 (27.5%) of the 80 blood samples available. Toxoplasma brain cysts were microscopically detected in 11 (7.6%), and Toxoplasma DNA by real-time polymerase chain reaction was demonstrated in 15 (10.4%) animals. Of these, both cysts and Toxoplasma DNA were detected in five (3.5%) rats. In mice, cysts were observed in 3 (25%), but Toxoplasma DNA was detected in even 10 (83.3%) animals, including all 3 with morphologically recognized cysts. Being a link in the chain of Toxoplasma infection, the existence of urban rodent reservoirs of infection represents a public health risk.