Serological survey of Neospora caninum and Leishmania infantum co-infection in dogs

A seroprevalence survey and risk analysis of Neospora caninum and Leishmania infantum was conducted in dogs from an area of the Campania region of southern Italy, in order to investigate the co-infection of these two protozoa. Blood samples were collected from 1058 asymptomatic dogs over a 18 months period. Serum samples were tested for antibodies to N. caninum and to L. infantum using the indirect fluorescent antibody test. Epidemiological data (breed, age, sex, and utilization) were collected and statistically analysed in relation to N. caninum and to L. infantum seropositivity and antibody titres. Out of the 1058 sera samples tested, 68 (6.4%) were found to have antibodies to N. caninum, and 222 (21.0%) to have antibodies to L. infantum. The co-presence of antibodies to N. caninum and to L infantum was found in 46 (4.3%) dogs. Thus, 67.6% of the dogs positive for N. caninum also had antibodies to L. infantum. The major risk factor for N. caninum seropositivity was the presence of antibodies to L. infantum, and the major risk factor for L. infantum seropositivity was the presence of antibodies to N. caninum. In addition, high N. caninum seroprevalence was closely correlated to Boxer breed, and high L. infantum seroprevatence was correlated to masculine gender and Setter and Pit bull breeds. Low L. infantum seroprevalence was closely correlated to Yorkshire breed. The findings of this survey indicate that in the Campania region of southern Italy the co-presence of antibodies to N. caninum and to L infantum is very common in dogs, and that infection by one protozoan seems to enhance the susceptibility to the other one. This is probably due to the immunological status of the tested dogs. (C) 2002 Elsevier Science B.V. All rights reserved.