Seroprevalence of Toxoplasma gondii and Neospora caninum in feral cats (Felis silvestris catus) in Majorca, Balearic Islands, Spain

Felids are important in the epidemiology of Toxoplasma gondii infection because they are the only hosts that can excrete environmentally resistant oocysts. Antibodies to T. gondii and Neospora caninum were determined in serum samples from 59 feral cats (Felis silvestris catus) captured in baited traps during authorized predator control campaigns in Majorca, Balearic Islands, Spain. Antibodies to T. gondii assayed by the modified agglutination test (MAT) were found in 50 (84.7%) of 59 cats with MAT titers of 1:25 in one cat, 1:200 in four cats, 1:500 in seven cats, 1:1000 in nine cats, and ≥1:2000 in 29 cats. Seroprevalence (MAT, 1:25 or more) was significantly higher in adults (94.6%) than in juveniles (<6 months old; 40.0%). Seroprevalence to N. caninum, assayed by cELISA (VMRD) and confirmed by an indirect fluorescent antibody test, was low (6.8%, 4 of 59). The prevalence of T. gondii observed in wild cats in Majorca is one of the highest reported worldwide in this species and the highest observed in Europe to date. The results suggest that feral cats in Majorca have a high rate of T. gondii infection with important implications for public health on the island since the seropositive cats are likely to have already shed T. gondii oocysts in the environment.