Potential application of serological tests on fluids from carcasses: detection of antibodies against Toxoplasma gondii and Sarcoptes scabiei in red foxes (Vulpes vulpes)

In 22 (39%) foxes antibodies against Sarcoptes scabiei were detected in both fluid types by ELISA and Western blot. In 46 (82%) foxes, antibodies against Toxoplasma gondii were detected in pleural fluid and in 41 (73%) in lung extract applying a Toxo-screen test (DAT). Antibodies were still detectable in the same fluids kept at room temperature for 28 days, although in fewer foxes (16 and 14 foxes tested for T. gondii in lung extract and pleural fluid respectively; and 1 and 4 tested for S. scabiei in lung extract and pleural fluid respectively.These results indicate the potential utility of using fluids from carcasses for antibody screening of wild animals at the population level.Serological surveys are widely applied to study the presence and distribution of infectious diseases in wild animal populations. They are most often conducted as active surveillance programs on blood samples obtained from hunted animals, which implies restrictions with regards to the animal species, time of the year, age category and geographical distribution that can be tested. Serological testing of diseased wild animals necessitates immobilization or euthanasia. An advantageous alternative is to conduct antibody tests on body fluids obtained from carcasses. Few studies have investigated the presence of antibodies in fluids from carcasses in wild animals in Europe [1-3]. A main limitation of testing fluids from carcasses is its decay. The aim of the present study was to obtain a preliminary indication of the utility of conducting antibody detection tests on 2 types of fluids collected from carcasses of red foxes from which no serum was available, and to obtain an indication of the stability and persistence of antibodies in the fluids subjected to storing at room temperature (RT) for up to 28 days. The study investigated antibodies against two parasites that frequently infect red foxes in Sweden, the mite Sarcoptes scabiei which causes sarcoptic mange and the obligate intracellular protoz