Studies on the reactions of animals to infestation with ticks. II. Tick toxins

Abstract

Toxin has been shown to be present in the eggs of 17 species of ixodid ticks, and is probably present in the eggs of all species of this family. It was associated with the globulin fraction of the egg extract, and was thermolabile. Similar toxin was also present in the larvae of the only four species of ixodid ticks of which larvae were tested. The toxin was not present in the eggs of the five species of argasid ticks used in this study. Clinical syndrome and the pathological changes in the tissues of laboratory animals following injection of egg extracts were indicative of toxaemia. At a dose rate of 0.3 g/kg body weight, there was a rapid initial rise in rectal temperature, followed by subnormal temperature and death. At lower dose rates, there was loss of hair a t the site of injection, and usually the development of an indurated, sterile ulcer. The toxin appeared to be quite distinct from the one that causes tick paralysis, which, in Australia, results from infestation with Ixodes holocyclus Neumann.