Zoonotic infections in military scout and tracker dogs in Vietnam

Significant levels of antibodies indicative of a variety of zoonotic infections were demonstrated in sera collected from 64 U.S. military scout and tracker dogs after service in the Republic of Vietnam (RVN). Scrub typhus antibodies were found in 45% of the specimens, melioidosis in 19%, group B arbovirus in 49%, and leptospirosis in 62%. Only 38% of the seropositive reactions for leptospirosis could be related to overseas infections. Tests were conducted on paired sera obtained from 32 of the dogs before service in RVN. Significant increases in titer were demonstrated with scrub typhus, melioidosis, leptospirosis, plague, group B arbovirus, and Rickettsia canada antigens. After 2 to 6 months of service in RVN, 8 of 19 dogs developed antibody titers to at least one of four zoonotic diseases. Only 3 of 45 dogs with 7 or more months of service failed to develop antibodies to one or more of the agents. The serological findings pose questions on the potential epidemiological importance and veterinary significance of scrub typhus, group B arbovirus, leptospirosis, and melioidosis infections in dogs.