Christel Bruckner

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R.K. Reinecke

American Society of Safety Professionals

I.L. De Villiers

University of Limpopo

De Villiers Il

Reinecke Rk

University of Pretoria

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University of Pretoria

American Society of Safety Professionals

Universidade Federal Rural do Rio de Janeiro

Ordem dos Médicos

Onderstepoort Veterinary Academic Hospital

Brazilian Agricultural Research Corporation

Onderstepoort Veterinary Institute

University of Limpopo

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Studies on haemonchus contortus. VII. The effect of treatment of Trichostrongylus axei prior to challenge with H. contortus.

PubMed (1982)

R.K. Reinecke Christel Bruckner I.L. De Villiers

Four-month-old worm-free Merino lambs were dosed with 20 000 infective larvae of Trichostrongylus axei on Day 0 and again on Day +14. On Day +83 they were treated with mebendazole at 15 mg/kg. All lambs in this group and a further group of 11 worm-free Merino control lambs were challenged with 50 000 infective larvae of Haemonchus contortus dosed from Day +90-Day +92. At necropsy 27 and 28 days later there was no significant difference between the worm burdens of the 2 groups. T. axei must be present in the abomasum to protect sheep from challenge with H. contortus.

Mebendazole

Trichostrongylus

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Studies on Haemonchus contortus. V. Chemoprophylaxis and its effect on worm egg counts and the haematocrit.

PubMed (1981)

R.K. Reinecke I.L. De Villiers Christel Bruckner

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.

Eggs per gram

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Studies on Haemonchus contortus. IV. The effect of Trichostrongylus axei and Ostertagia circumcincta on challenge with H. contortus.

PubMed (1981)

Reinecke Rk Christel Bruckner De Villiers Il

Worm-free Merino yearlings were dosed with either a mixture of infective larvae of Trichostrongylus axei and Ostertagia circumcincta or with O. circumcincta only, and challenged 90-93 days later with infective larvae of Haemonchus contortus. Neither of these methods protected sheep against challenged and slight protection was afforded sheep predosed with T. axei and O. circumcincta and challenged with a trickle dose of H. contortus.

Ostertagia

Trichostrongylus

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Studies on Haemonchus contortus. IX. The effect of Trichostrongylus axei in Merinos on natural pasture.

PubMed (1984)

R.K. Reinecke I.L. De Villiers Christel Bruckner

Four groups of 6-7-month-old Merino lambs were each dosed with 40 000 infective larvae of Trichostrongylus axei on 2 November 1976 and subsequently exposed to challenge with Haemonchus contortus on natural grazing at the University of Pretoria's Experimental Farm in the eastern suburbs of Pretoria. One of these groups and one group of controls were killed every 8 weeks from the end of December 1976-June 1977. Predosing with T. axei was greater than 50% effective against 5th stage and adult H. contortus in greater than 50% of sheep for 164 days (Class C), improving to greater than 60% in greater than 60% of sheep (Class B) 220 days after dosing T. axei. The numbers of retarded 4th stage larvae (L4) of H. contortus in the undosed controls as well as in the sheep predosed with T. axei rose from a low level in summer (December) to a peak in late Autumn (June).

Trichostrongylus

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Studies on Haemonchus contortus. III. Titration of Trichostrongylus axei and explusion of H. contortus.

PubMed (1980)

R.K. Reinecke Christel Bruckner I.L. De Villiers

Groups of Merino weaners were dosed with infective larvae of Trichostrongylus axei in numbers ranging from 20 000-50 000 and challenged 3 months later with 50 000 infective larvae of Haemonchus contortus. When the dose of infective larvae of T. axei was given on Day 0 and the balance on Day + 14, efficacy against H. contortus was > 60% in > 60% of sheep (P < 0, 1). A single dose of 40 000 or 50 000 infective larvae of T. axei was > 80% effective against H. contortus in > 80% of sheep (P < 0, 01). Two doses of 20 000 infective larvae of T. axei followed by a challenge with H. contortus 31-33 days after the initial dose caused a reduction of > 50% in > 50% of sheep (P < 0, 1). This rose to > 60% in > 60% of sheep if the doses of 25 000 infective larvae of T. axei were followed by a challenge with H. contortus 45 days after the initial dose of T. axei. Most of the challenge doses of infective larvae of H. contortus were rejected within 3 days. Surviving worms were retarded in the 4th stage and only a few developed to the 5th or adult stage.

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Studies on Haemonchus contortus. VI. Attempts to stimulate immunity to abomasal trichostrongylids in Merino sheep.

PubMed (1982)

R.K. Reinecke I.L. De Villiers Christel Bruckner

Two doses of infective larvae of 20 000 Trichostrongylus axei, dosed to Merino lambs at an interval of 14 days and subsequently challenged with Ostertagia circumcincta, caused a significant reduction (P less than 0.01) in the establishment of 5th and adult stages of the latter. T. axei was unable to protect Merino sheep against homologous challenge nor was Haemonchus contortus a successful vaccine against challenge with the same species. The vaccinated group showed a reduction (P less than 0,025) only in 5th and adult H. contortus, but not in the total worm burdens.

Ostertagia ostertagi

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A residual anthelmintic 2,6-diiodo-4-nitrophenol (Disophenol). Methods of testing its anthelmintic efficacy.

PubMed (1981)

R.K. Reinecke Christel Bruckner I.L. De Villiers

A subcutaneous injection of 2,6-diiodo-4-nitrophenol (Disophenol) at 10 mg/kg sheep leaves a residue bound to serum albumin which is lethal to Haemonchus contortus for 3 months after treatment. In the larval anthelmintic test, susceptible worm free sheep are dosed so that either third stage larvae (L3), or fourth stage larvae (L4) or 5th and adult stages are present on the day of treatment but slaughter is delayed to allow these larval stages to develop to adults because the larger worms are more easily seen, identified and counted. The larval anthelmintic test in sheep had to be altered and sheep killed within a few days of treatment, because the residues may be more effective against subsequent stages of development. Disophenol was greater than 60% effective against L3 of Oesophagostomum columbianum and L4 of H. contortus in greater than 60% of sheep (Class B). It rose to greater than 80% effective against adult H. contortus in greater than 80% of sheep (Class A). Against H. contortus it maintained Class A for 32 days, fell to Class B from 45--76 days and Class C (greater than 50% effective in greater than 50% of sheep) at 91 days after treatment respectively. In the RSA a treatment in December followed by another in March would protect sheep adequately against H. contortus for the entire season.

Ancylostoma caninum

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Citations (4)