Anthelminthic resistance of small ruminants in the Philippines

Results of initial studies conducted in Region 8 [Eastern Visayas, Philippines] from sheep on a government station and two backyard farms showed efficacies of albendazole of 30%, 91% and 60%, respectively. The predominant species of nematode parasites showing resistance to albendazole was Haemoncus contortus. At the manufacturer's recommended dose rate, efficacies of greater than 99% would be expected if the nematodes were fully susceptible to the action of the BZ [Benzimidazoles] group of anthelmintics. This results suggest that anthelmintic resistance to albendazole is already a problem in both government station and backyard farms. It can be speculated that the possible reason for the incidence of anthelmintic resistance to backyard raisers may be attributed to the dispersal project of the government among the poor farmers in the community. Since government livestock stations are the one responsible for dispersing animals to poor villages, they are somehow spreading out anthelmintic resistant animals at the backyard level. In Region 3 [Central Luzon, Philippines], initial studies were conducted using the conventional method of drenching animals and measuring the reduction in the concentration of worm eggs in faeces after treatment. In a group of Upgraded (Native x Anglo-Nubian) goats in a university station, the efficacy of a commercially available albendazole given at the manufacturer's recommended dose rate was 70% on the pooled fecal samples from native goats, exotic Anglo-Nubian Saanen Boer, upgrade and native sheep examined for LDA [larval development assay], it was shown that the efficacies of BZ were estimated to be 35%, 30%, 52%, 65%, 40% and 40%, respectively. Seventy-seven percent of larvae recovered from culture of the faeces before the assay was conducted were H. contortus, 16% Trichostrongylus and 7% Ostertagia. The population of resistant parasites i.e. those which survived at high concentrations of chemical were 70% Haemonchus, 19% Trichostrongylus and 11% Ostertagia suggesting that resistance is being detected in all three genera of parasite