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At least 919 records · Page 51Linked to original sources
PubMed1982

Quantitative studies of ovine haemonchosis. 3. The interpretation and diagnostic significance of the changes in serial egg counts of Haemonchus contortus in a sheep flock.

An examination of the level and distribution of egg counts of H. contortus within an extensively managed flock of Merino sheep in south-east Queensland was carried out on three occasions over a ten week period. During this time the geometric mean egg count increased from 527 to 1331 eggs per gram, and although 26.3% of the flock were responsible for this increase, clinical evidence of haemonchosis was not observed. Examination of the distribution of counts supported the hypothesis that counts followed a negative binomial distribution. The values obtained for "k" (the index of over-dispersion), ranged from 0.5 to 1.4. However, on the two latter examinations, counts showed a divergence from the expected pattern (P = 0.015; P = 0.014). Further examinations of flocks at higher mean levels of count are required to establish if the trend towards a more normal distribution were maintained. The evidence from the present study and from outbreaks previously reported, suggested that in extensively managed sheep, the level of variance remained high as the mean egg count increased. It therefore appeared likely that in outbreaks of acute haemonchosis under grazing conditions, only a small proportion of the flock may become seriously affected.

Animals↗
PubMed1981

Immune response of sheep to Haemonchus contortus: serum antibodies against cross reacting antigens between parasites.

Normal and H. contortus infected sera were studied by ELISA technique against different stages of the parasites. In all cases antibody activity was detected. This activity in serum is partially eliminated after absorption with an adult worm extract of N brasiliensis. N. brasiliensis and H. contortus antigens were analysed by TCIEP with a rabbit anti-N. brasiliensis serum to examine shared antigens of H. contortus. A minimum of seven cross reacting antigens were detected. H. contortus adult worm extract was absorbed by the rabbit anti-N. brasiliensis serum. After absorption all cross reacting antigens were removed but at least one antigen reacting with a rabbit serum anti-H. Contortus is maintained. When this antigen is tested in elisa technique only a weak antibody activity is found in normal serum.

Animals↗
PubMed1981

[Immune response in sheep experimentally infected with Haemonchus contortus, Comparative study in male and female (author's transl)].

Merino breed sheep eight months old at the beginning of the experiment and carriers of hemaglobin A were used. They were infected one or more times with H. contortus larvae and then challenged with 500 or 5000 larvae L3. Self-cure was reproduced and animals were found immune after infectation. Self-cure was more evident in females than in males and immunity was also better and appeared earlier in females than in males.

Animals↗
PubMed1993

Efficacy of moxidectin against a strain of Haemonchus contortus resistant to ivermectin, a benzimidazole and a salicylanilide.

The efficacy of moxidectin at 0.2 mg kg-1 live body mass against the multiple anthelmintic resistant White River Krtz strain of H. contortus was determined and compared to that of ivermectin, a benzimidazole, a salicylanilide and levamisole. Moxidectin and levamisole were effective against this strain of H. contortus and reduced the arithmetic mean burdens of this parasite in the sheep by 99.98% and 99.59%, respectively, while the efficacy of ivermectin, albendazole and closantel was only 29.1%, 33.75% and 78.3%, respectively.

Albendazole↗