Serological detection of anti-Trichinella antibodies in wild foxes and experimentally infected farmed foxes in Norway.
Trichinella surveillance in wildlife has relied on the detection of muscle larvae using digestion techniques. Serology has been proposed as more suitable for large-scale epidemiological studies in wildlife. In this study, 328 individual sera from wild red foxes and 16 sera from experimentally infected farmed foxes were serologically tested with both excretory/secretory antigen (E/S) and the synthetic beta-tyvelose glycan antigen, in indirect ELISA tests. The wild red foxes (Vulpes vulpes) had previously been examined for muscle larvae, using muscle digestion, whilst the experimentally infected farmed foxes were inoculated per os with either a low dose, 500 larvae, or a high dose, 10,000 of Trichinella nativa muscle larvae. Western blot (WB) was carried out on all seropositive samples using crude larval antigen. The present study found both beta-tyvelose and E/S antigen suited for the detection of antibodies to Trichinella spp., and T. nativa in particular, in foxes. Both ELISA antigens performed well, although, the E/S antigen was superior to the beta-tyvelose antigen, with sera that had been stored at -20 degrees C for more than 10 years. Neither antigen, however, detected all of the samples proven seropositive by WB: E/S detected 21 of the 27 wild red fox sera positive by WB; beta-tyvelose detected 22 positive sera; and in total 24 of the 27 positive WB sera were identified using both antigens. Serology alone, without WB or muscle digestion, led to a two- to threefold higher seroprevalence estimate, respectively. The use of E/S antigen in conjunction with the WB was the method of choice for the screening of wild red fox populations for Trichinella. Antibody persistence to T. nativa was short in the low dose group where antibody levels were not different from background by 32 wpi. In total, 7.3% (24/328) of the wild red fox population had antibodies to Trichinella on ELISA and WB. Antibodies were identified in foxes from a further two regions in Norway compared to the original muscle digestion results.
Davidson
Rebecca K
RK
Section for Wildlife Diseases, National Veterinary Institute, P.O. Box 750 Sentrum, NO-0106 Oslo, Norway. rebecca.davidson@vetinst.no
Ørpetveit
Irene
I
Møller
Lone
L
Kapel
Christian M O
CM
D000383:Agriculture; D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005589:Foxes / Q000276:immunology / Q000469:parasitology*; D018482:Muscle, Skeletal / Q000469:parasitology; D009664:Norway; D012698:Serologic Tests / Q000662:veterinary*; D014234:Trichinella / Q000276:immunology*; D014235:Trichinellosis / Q000097:blood / Q000276:immunology / Q000662:veterinary*
D000909:Antibodies, Helminth