Seroprevalence of antibodies against Leishmania spp among dogs in the United States.

Objective: To determine seroprevalence of antibodies against Leishmania spp among dogs other than Foxhounds in the United States.

Design: Cross-sectional study.

Sample Population: 957 serum samples from dogs throughout the United States submitted between January 2000 and August 2001 to the Diagnostic Center for Population and Animal Health at Michigan State University for serologic testing for tick-borne diseases.

Procedure: Samples were tested for antibodies against Leishmania spp with an immunofluorescent antibody (IFA) assay. Samples with positive results were submitted to the Centers for Disease Control and Prevention for confirmatory testing.

Results: Results of the IFA assay were negative for 939 of 957 samples. For 16 samples, titers were from 1:16 to 1:64, and titers in these dogs were considered likely to be a result of cross-reactivity with antibodies directed against other organisms. For the remaining 2 samples, the titers were > or = 1:128. One of these samples was from a blood donor dog that had never had any clinical signs of leishmaniasis. Follow-up samples from both dogs also had Leishmania IFA titers > or = 1:128. Both dogs had antibodies against Trypanosoma cruzi, as determined with a radioimmunoprecipitation assay.

Conclusions And Clinical Relevance: Results suggested that the seroprevalence of antibodies against Leishmania spp in dogs in the United States was low. However, results further suggested that leishmaniasis may not be limited to Foxhounds in the United States.