Biotin-avidin amplified ELISA for detection of antibodies to Sarcoptes scabiei in chamois (Rupicapra spp.)

Scabies is a major threat to the well being of mountain-dwelling Bovid hosts, Rupicapra rupicapra and Rupicapra pyrenaica. Severe outbreaks are in progress over a significant part of their distribution area and resource managers demand improved methods to monitor, analyse and possibly forecast the spread and effects of scabies at the population level. An amplified capture enzyme-linked immunosorbent assay was developed to detect antibodies to Sarcoptes scabiei in chamois (Rupicapra spp.) serum. The method used the biotin-avidin amplification system and was validated on a panel of 144 serum samples, of which 40 were obtained from scabietic and 104 from healthy unexposed individuals originating from a scabies-free area. The antigen, a whole body extract of the various developmental stages of S. scabiei, was prepared from mites actively leaving the skin lesions of naturally infested red foxes (Vulpes vulpes). The resulting LAB-ELISA was characterised by 93% sensitivity, 97% specificity and a high degree of repeatibility. A single seroreactor was found amongst 32 chamois affected with skin pathologies other than scabies, including infestations by other Acarina (Trombicula spp. and Ixodid ticks). Antibodies to S. scabiei were present in 26 out of 169 sera (15.4%) obtained by clinically healthy chamois within a scabies outbreak area, indicating that asymptomatic infestations by S. scabiei can be revealed by serological methods in the studied Caprinae hosts.