nitrophenols and Trichostrongyloidiasis

Topics: Administration, Oral; Animals; Anthelmintics; Benzimidazoles; Drug Resistance; Feces; Fenbendazole; Haemonchiasis; Haemonchus; Injections, Subcutaneous; Ivermectin; Nitrophenols; Nitroxinil; Parasite Egg Count; Salicylamides; Salicylanilides; Sheep; Sheep Diseases; Time Factors; Trichostrongyloidea; Trichostrongyloidiasis

Topics: Animals; Benzimidazoles; Drug Resistance; Feces; Haemonchiasis; Haemonchus; Nitrophenols; Nitroxinil; Parasite Egg Count; Sheep; Sheep Diseases; Trichostrongyloidiasis

Sheep grazed on natural pastures heavily infested with infective larvae of Haemonchus contortus. Sixty-eight weaned Merinos were divided into 6 groups on Day 0 (23 November 1977), and on Day +14 (7 December) 79 Merinos were divided into 7 groups. There were 2 groups of undosed controls and other groups were either dosed with infective larvae of Trichostrongylus axei (bovine strain) only on Days 0 and +14, or in combination with H. contortus, or with subsequent doses of H. contortus, 28 days later. One group (Group 12) was dosed with T. axei and treated with a subcutaneous injection of di-iodonitrophenol (DNP) on Day +14. With the exception of 2 sheep, the sheep of the first 6 groups survived until slaughter in March and April 1978, while many sheep (43) of the latter 7 groups died or were killed in extremis from March-May. T. axei dosed on 23 November (Day 0) protected Group 2 by greater than 50% in greater than 50% of sheep. In the latter 7 groups the best results were achieved when DNP was combined with predosing with T. axei. The poor results were probably due either to delayed predosing with T. axei or a massive challenge in the wettest summer on record.

Topics: Animals; Cattle; Feces; Haemonchiasis; Haemonchus; Host-Parasite Interactions; Nitrophenols; Parasite Egg Count; Sheep; Sheep Diseases; Trichostrongyloidea; Trichostrongyloidiasis; Trichostrongylosis

Two long-acting anthelmintics, closantel and disophenol, were tested by treatment 90, 60 and 30 days before challenge with a thiabendazole selected laboratory strain of Haemonchus contortus. The sheep were slaughtered 28 days after infection for total worm counts. A significant reduction in the number of adults remaining at autopsy was recorded after treatment with both anthelmintics 30 and 60 days before challenge but there was zero efficacy when the animals were treated 90 days before challenge. No significant difference was exhibited between the two compounds. Variability in response was recorded between animals on the 60 day period of treatment, which for disophenol may be dose related because animals receiving the lower volumes showed higher worm counts. For both anthelmintics a variability in the rate of metabolism may be responsible. The possibility offered by both anthelmintics for treating benzimidazole resistant strains of H contortus is discussed.

Topics: Animals; Anthelmintics; Drug Resistance; Haemonchiasis; Haemonchus; Nitrophenols; Salicylamides; Salicylanilides; Sheep; Sheep Diseases; Thiabendazole; Trichostrongyloidiasis

A group of 12 10-month-old, worm-free Merino lambs were given a single injection of disophenol at 10 mg/kg. This group and another group of 12 worm-free lambs were infested with infective larvae of Haemonchus contortus 1-3 times a week with a maximum dose of 4000/week from 0-91 days. From 95-168 days the dose was increased to a maximum of 6000/week. Every 7 days faeces were examined for worm eggs and blood samples for haematocrit (Ht). Worm egg counts in the controls rose from 21-56 days, fluctuated, and rose to another peak at 84 days, while the Ht fell from 28 days to rise again after 105 days. In the group treated with disophenol egg counts were negative until 161 days and Ht remained at normal values throughout.

Topics: Animals; Anthelmintics; Feces; Haemonchiasis; Hematocrit; Nitrophenols; Parasite Egg Count; Sheep; Sheep Diseases; Time Factors; Trichostrongyloidiasis

Topics: Acute Disease; Animals; Haemonchiasis; Nitrophenols; Parasite Egg Count; Rain; Seasons; Sheep; Sheep Diseases; Trichostrongyloidiasis

The result of a field trial investigating the anthelmintic effect of disophenol against H. contortus in sheep raised under Asian small farming practice is reported. it was clearly shown that a single injection of disophenol suppressed the numbers of H. contortus to very low levels for periods up to 3 months despite the presence of large populations of H. contortus infective larvae available on pasture and herbage grasses.

Topics: Animals; Anthelmintics; Feces; Female; Haemonchiasis; Haemonchus; Indonesia; Male; Nitrophenols; Parasite Egg Count; Sheep; Sheep Diseases; Trichostrongyloidiasis

Disphenol was administered to sheep infected with Haemonchus contortus in order to prevent the development of populations of adult worms, and studies were made of the pathogenicity of the arrested fourth-stage larvae which remained. The treated sheep showed elevated plasma pepsinogen and abomasal pH, predominantly negative dry-matter balance, and evidence of greater fluid loss, including plasma, into the gastro-intestinal tract. It was concluded that arrested larvae may cause damage to the abomasal mucosa.

Topics: Abomasum; Animals; Haemonchiasis; Haemonchus; Larva; Male; Nitrophenols; Pepsinogens; Sheep; Sheep Diseases; Trichostrongyloidea; Trichostrongyloidiasis