Evaluation of a laboratory test to detect resistance to closantel in Haemonchus contortus

OBJECTIVE: To evaluate a laboratory test for closantel resistance in Haemonchus contortus. PROCEDURE: Field isolates of H contortus, known to be resistant to closantel, were tested in the assay. In addition, mixtures of closantel-susceptible and closantel-resistant laboratory reference strains were tested to develop a method of predicting the proportion of resistant worms in a sample from the field. RESULTS: The assay correctly identified as resistant all of the closantel-resistant field isolates of H contortus. It also identified one isolate with an in vivo efficacy of 98% as having emerging resistance. Testing of the mixtures of laboratory reference strains revealed that an isolate would be classified as resistant when it consists of about 25% or more resistant worms. Test samples that are not fully susceptible yet contain less than 25% resistant worms may be classified as emerging resistance. CONCLUSION: The in vitro migration assay is a sensitive method of detecting closantel resistance in H contortus.     

The effect of coccidian infection on the gut microflora of Nubian goat kids

Enteric coccidiosis was experimentally induced in Nubian goat kids by the oral inoculation of 1.5 x 10(6) sporulated oocysts of five mixed Eimeria species. Diarrhoea was the major manifestation of the disease, which terminated fatally within 19 to 25 days postinfection. Faecal excretion of oocysts was first detected on day 8 (mean 58 x 10(2)) with a maximum shedding (mean 16.39 x 10(5)) on day 14 post-infection. In addition, noticeable alterations were further observed on the normal constituents of the gut microflora in coccidia-infected kids. These changes were characterized by progressive reduction of the Gram-positive population from 84% pre-infection to 24.3% after the onset of diarrhoea. On the other hand, the Gramnegative population was conversely increased from 16% pre-infection to 75.7% after diarrhoea. At this stage (diarrhoea) E. coli was the most dominant organism amongst the various constituents of the gut microflora.