Anthelmintic resistance in nematode parasites of sheep and goats on a government farm in north Malaysia was monitored over a 3-year period (1997-2000). The faecal egg count reduction test (FECRT) was conducted on young sheep at the beginning and end of this period. Changes in management, designed to reduce the selection pressure for the development of anthelmintic resistance, were also implemented during this time. By far the most important parasite problem was Haemonchus contortus. In 1997, this nematode was found to be resistant to levamisole, with suspected resistance to closantel and moxidectin. However, when the FECRT was repeated 3 years later, its resistance status had become much more severe, with resistance to benzimidazole, levamisole and ivermectin, and suspected resistance to moxidectin. This rapid evolution to multiple anthelmintic resistance is a major concern that needs to be arrested. There is an urgent need to evaluate other control strategies that incorporate livestock management, the 'smart' use of drugs and non-chemotherapeutic approaches, such as biological control agents.
The prevalence of drug-resistant parasites in goats in West Malaysia has rarely been reported. Ten commercial goat farms were surveyed for resistance to anthelminthics by measuring the reduction in faecal egg counts (FECs) after treatment with levamisole, pyrantel pamoate and fenbendazole. Resistance to fenbendazole was seen in most farms; there was no evidence of resistance to levamisole but some resistance to pyrantel pamoate was detected on one farm. The significance of the findings are discussed.
Fourteen goat kids of the local indigenous breed naturally infected with Eimeria species were divided into two equal groups. The first group was superinfected with 500,000 Eimeria species oocysts and the second group was treated with amprolium. Sixty days later both groups were infected with 5000 third-stage caprine Haemonchus contortus larvae. The goats experimentally superinfected with eimeria shed more H contortus eggs and gained weight more slowly.
The therapeutic and prophylactic effects of closantel on natural infections with Haemonchus contortus were studied in goats in Peninsular Malaysia. Closantel was highly effective against H. contortus, either at a subcutaneous (s.c.) injection of 5.0 mg kg-1 body weight (100%), or in an oral drench mixture with mebendazole at a dose of 10.0 mg kg-1 (99.2%), as indicated by faecal egg counts. H. contortus larvae were absent from faecal cultures for 5, 6 and 7 weeks following treatment with s.c. injections of closantel at doses of 2.5 mg kg-1, 5.0 mg kg-1 and 10.0 mg kg-1 respectively, and for 6 weeks after treatment with closantel at 10.0 mg kg-1, given orally. Through its sustained activity, closantel not only prevented reinfection with H. contortus but also caused a dramatic reduction in pasture contamination. The potential utility of closantel in the strategic control of haemonchosis in goats, and as an alternative treatment for benzimidazoles and levamisole resistant H. contortus strains, is discussed.
This study investigated dexamethasone-treatment, shedding routes, tissue antigen distribution, and pathology of caprine Brucellosis. Eighteen non-pregnant goats were randomly grouped into A, B, and C. Group A was administered dexamethasone for 7 days at 2 mg/kg before inoculating 0.5 mL B. melitensis at 107 CFU ocularly while group B was inoculated 0.5 mL B. melitensis only, and C as control negative. Blood samples, ocular, nasal, and vaginal swabs were obtained for evaluation. Three goats were sacrificed from each group at days 21 and 42 post-inoculation (pi) and selected tissues collected for PCR, histopathology, and immunohistochemistry. Brucella melitensis was detected in the ocular swabs of group A significantly higher than group B. Shedding was prolonged in group A compared to B. The overall shedding was 22.2% in group A and 9.4% in group B. The uterus of both groups A and B revealed mild inflammation and microgranuloma, extensive necrotic lesions in lymph nodes. Liver showed multifocal necrosis predominantly in group A. Lesion scoring showed significantly higher scores in A compared to B. Strong immunostaining was observed in the liver, lungs, and spleen, predominantly at day 21 pi. This study demonstrated dexamethasone prolonged shedding, tissue antigen distribution, and pathology in dexamethasone-treated goats.
A study was conducted to evaluate the anthelmintic properties of enhanced virgin coconut oil (EVCO) and senduduk (Melastoma malabathricum) plant against strongyle nematodes in goats. Two preparations of 10% EVCO dissolved in 90% virgin coconut oil and 10% EVCO dissolved in 90% palm oil, were given orally to two groups of mixed breeds goats. The efficacy test indicated that EVCO was insufficiently active as an anthelmintic. Four concentrations of senduduk solution (1.25, 2.5, 5.0 and 10 mg ml(-1)) were compared with a control and albendazole in an in vitro test for larvicidal effect. There was no significant larval mortality using senduduk solution. An in vivo test of senduduk was conducted by comparing three groups of goats, namely control, levamisole and treatment groups that were given a daily oral dose of senduduk crude extract with 1g kg(-1) from Day 0 to Day 12 and 2 g kg(-1) from Day 13 to Day 30. This efficacy test with senduduk also gave negative results. The findings obtained indicated that EVCO and senduduk were ineffective as anthelmintics against caprinestrongyle nematodes at the concentrations used.
Haemonchosis is a common problem on goat farms in tropical countries such as Malaysia. Prevention of production losses generally depends on the use of anthelmintic drugs, but is threatened by the emergence of anthelmintic resistance. This study investigates anthelmintic efficacy on small-scale Malaysian goat farms and describes putative risk factors. Adult goats had moderate to high pre-treatment faecal trichostrongyle egg counts, despite being housed on slatted floors and fed on cut-and-carry forage, raising questions about the source of nematode infection. Our results show multiple resistance to benzimidazole and macrocyclic lactone anthelmintic drugs and allow us to discuss the genetic origins of resistance with reference to farm husbandry and management. We conclude that improvement in Malaysian goat production efficiency will require the development of sustainable helminth control strategies, underpinned by a better understanding of the origins and population genetics of anthelmintic resistance.
The faecal egg count reduction test (FECRT) was conducted on 39 sheep farms and 9 goat farms located in Peninsular Malaysia. The anthelmintic groups used in these tests were the benzimidazoles, levamisole, the benzimidazole/levamisole combination, macrocyclic lactones and closantel. Results indicated that the prevalence of resistance to the benzimidazole group was high, with approximately 50% of the sheep farms and 75% of the goat farms having resistant nematode parasite populations present. Resistance to levamisole, closantel and ivermectin was also detected. Differentiation of the infective larvae derived from faecal cultures indicated that by far the most predominant parasite species was Haemonchus contortus.