Haematological and immunological response of unrestrained cattle to Psoroptes ovis, the sheep scab mite.
Cows were infected twice with 600 and 500 nymphs and adults of a bovine strain of Psoroptes ovis with a nine-week interval. The haematological response and the non-specific mitogen- and antigen-induced responsiveness of the peripheral blood lymphocytes of the animals was followed. Dermal reactivity to P ovis antigen injection was studied five weeks after reinfection. After the first infection with 600 mites none of the infected animals developed clinical psoroptic mange but a leucocytosis developed, contributed to primarily by an eosinophilia and by a slight lymphocytosis. Antigen-induced lymphocyte blastogenesis was used to measure the antigen-sensitive cell population in peripheral blood and this population showed a maximum increase 10 days after infection; however, antigen-sensitive cells remained above normal levels until reinfection. Upon challenge infection with 500 mites the infected animals showed an immediate hypersensitivity type reaction with a marked pruritus, scratching and exudation. Thereafter the lesions healed rapidly and none of the animals developed clinical mange. This clinical reaction was accompanied by a secondary eosinophilia but no change was apparent in the other blood elements. A marked increase in the blastogenic response of the peripheral blood lymphocytes was also apparent and this peaked three weeks after challenge. Following the intradermal injection of P ovis antigen there was an immediate swelling of the injection site in all infected and control animals and skin thickness was maximal one hour after injection. Thereafter there was a clear distinction in dermal reactions between P ovis infected and control animals; after 48 hours reactions were not seen in the control animals while marked dermal reactions were still present in the P ovis infected group.
Losson
B
B
Faculty of Veterinary Medicine, University of Liège, Brussels, Belgium.
Detry-Pouplard
M
M
Pouplard
L
L
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood* / Q000276:immunology; D004802:Eosinophilia / Q000662:veterinary; D005260:Female; D006969:Hypersensitivity, Immediate / Q000662:veterinary; D007111:Immunity, Cellular; D007958:Leukocyte Count / Q000662:veterinary; D007964:Leukocytosis / Q000662:veterinary; D008213:Lymphocyte Activation; D008924:Mite Infestations / Q000097:blood / Q000276:immunology / Q000662:veterinary*; D008925:Mites; D012882:Skin Tests / Q000662:veterinary