observations of the sheath extension of the third stage, infective larvae of trichostrongylus rugatus.the length of the sheath extension of third stage (l(3)), infective larvae of trichostrongylus rugatus is reported. the total length and length of the sheath extension of l(3) recovered from the faeces of sheep originating from two localities in south australia were measured. the total length of larvae was 615-722 microm and the length of the sheath extension was 46-56 microm (mean 51.5). the larvae of t. rugatus comprised up to 72% of the larvae recovered. worm free sheep were infected with lar ...200415567044
high-level ivermectin resistance in a field isolate of haemonchus contortus associated with a low level of resistance in the larval stage: implications for resistance detection.the ivpro isolate of haemonchus contortus was isolated in 1999 after significant numbers of the parasite survived an ivermectin capsule treatment of grazing sheep acquiring a natural infection at prospect, nsw, australia. the isolate shows high-level resistance to ivermectin (faecal egg count is unaffected by ivermectin oral treatment at 0.2mg kg(-1)). the larval lc(50), as assessed by larval development assays (ldas), is only approximately two-fold higher than several susceptible isolates, maki ...200212237144
the trichostrongyloid parasites of sheep in south australia and their regional distribution.the species of trichostrongyloid nematodes present in 376 sheep from different agricultural regions of the state of south australia were determined. parasites encountered in the abomasum were teladorsagia circumcincta, t. trifurcata, t. davtiani, camelostrongylus mentulatus, haemonchus contortus and trichostrongylus axei. t. circumcincta was the species most commonly encountered, but c. mentulatus was widespread in arid areas. h. contortus was present in a small number of sheep only, mainly in s ...19827168719
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