Strongyloides papillosus occurs in the small intestine of cattle, sheep, goats and other ruminants all over the world. Threadworms of a different species occur in other animals and man. Each species is host-specific i.e. it only develops in its preferred host.
Infection is most often associated with young animals managed at high stocking rates under moist unhygienic conditions in warm climates. Calves as young as 3-5 months of age are affected and a strong host resistance develops by about 8 months of age. Young dairy calves in coastal eastern Australia, and buffalo in the Northern Territory are commonly infected but numbers of invading parasites are usually low.
Figure 1. Eggs of the threadworm, Strongyloides papillosus. Image courtesy of Dr Mani Lejeune, Cornell University Animal Health Diagnostic Centre.
The adult worms are thin and thread-like, 3.5–6 mm long. Only parthenogenetic female worms are present in cattle.
Further ecological information on worms and their control:
Location in cattle
Threadworm inhabits the small intestine of young cattle.
Infection is common in very young animals. Disease is only seen in very heavy infestations. Depression, weight-loss, harsh coat, diarrhoea, and inflammation between the toes are typical. Repeated skin penetration can result in oedema, serum exudation and scab formation at the site of entry. Death can occur in calves shortly after skin penetration.
The characteristic eggs are found on a worm egg count (WEC) when analysing dung samples for other roundworm eggs.
Broad-spectrum anthelmintics give good control of this worm.