Abstract:
Unusual clinical and pathological observations in the field in goats and sheep suffering from Strongyloides
papillosus infection prompted experimental work on this parasite. Goats were infected percutaneously
with either single or multiple, low or high levels of S. papillosus. Young goats up to 12 months
of age were found to be the most susceptible. Some animals, however, showed substantial resistance
to infective doses. Clinical signs included transient diarrhoea, misshapen, elongated faecal pellets
terminally, dehydration, 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 changes are described and included enteritis, status
spongiosus in the brain, hepatosis leading to rupture of the liver, nephrosis, pulmonary oedema,
interstitial pneumonia and pneumonia. About 6 % of the goats died acutely from fatal hepatic rupture.
The development of an acquired immunity was determined. The immunity elicited 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 deficiencies in some goats.