Experimental studies with Strongyloides papillosus in goats

Unusual clinical and pathological observations in the field in goats and sh eep suffering from Strongyloides papillosus infection prompted experimental work on this parasite. Goats were infected percutaneously with either sing le or multiple, low or high levels of S. papillosus. Young goats up to 12 m onths of age were found to be the most susceptible. Some animals, however, showed substantial resistance to infective doses. Clinical signs included t ransient diarrhoea, misshapen, elongated faecal pellets terminally, dehydra tion, anorexia, cachexia, gnashing of teeth, foaming at the mouth, anaemia and nervous signs such as ataxia, a wide-based stance, stupor and nystagmus . A 'pushing syndrome' was seen in 22 % of the animals. The pathological ch anges are described and included enteritis, status spongiosus in the brain, hepatosis leading to rupture of the liver, nephrosis, pulmonary oedema, in terstitial pneumonia and pneumonia. About 6 % of the goats died acutely fro m fatal hepatic rupture. The development of an acquired immunity was determined. The immunity elicit ed an allergic skin reaction at the application site of larvae or injection sites of larval metabolites. This immunity, however, could be breached by large doses of larvae. The most profound clinicopathological changes induced by the parasites were an anaemia (most pronounced in the young goats) and hypophosphataemia. Trace element analyses provided evidence of Cu, Mn and possibly Se deficien cies in some goats.