VeterinaryResearch Communications, 16 (1992) 195-198 Copyright ~) KluwerAcademicPublishersby - Printed in the Netherlands
Short Communication MULTIPLE ANTHELMINTIC RESISTANCE IN A FIELD STRAIN OF H A E M O N C H U S CONTORTUS IN GOATS R.P. UPPAL 1, C.L. YADAV 2, P. GODARA 3 AND Z.S. RANA 3 Departments of 1Veterinary Pharmacology, 2Veterinary Parasitology and 3Animal Breeding, CCS Haryana Agricultural University, Hisar, India 125004
Uppal, R.P., Yadav, C.L., Godara, P. and Rana, Z.S., 1992. Multiple anthelmintic resistance in a field strain of Haernonchuscontortus in goats. VeterinaryResearch Communications, 16 (3), 195-198 Keywords: anthelmintic resistance, benzimidazole,goats, India, levamisole
INTRODUCTION Ovine strains of Ostertagia and Trichostron~lus showing multiple resistance to anthelmintics were first reported in Australia (Sangster et al., 1979). In a recent report from South Africa, Haemonchus contortus has been reported to have developed resistance to a number of anthelmintics, including ivermectin (Van Wyk and Malan, 1988). Strains of H. contortus resistant to benzimidazoles in sheep (Yadav, 1990) and to levamisole in goats (Yadav and Uppal, 1992) have been detected in India. A caprine strain showing multiple resistance is now reported.
MATERIALS AND METHODS History. The strain of H. contottus was obtained from a goat farm on which levamisole-resistant H. contortus had been detected. The animals grazed on
permanent pastures and were dosed 3-4 times a year. Levamisole and fenbendazole had been used for 4-5 years. Morantel was also used but was considered ineffective by the local veterinarian. When treatment with fenbendazole failed to alleviate scouring in a flock of 500 goats, a study was undertaken to determine the efficacies of various anthelmintics against the strain of Haemonchus in the animals. Experimental design. Eighty-one naturally infected goats (Beetal, Black Bengal and
Beetal x Black Bengal) aged 9-12 months were divided into seven treatment groups and one untreated control group of 9-12 animals each on the basis of body weights and faecal egg counts. Faecal egg counts were carried out prior to and 8-10 days after treatment. In a second experiment, 12 naturally infected goats, aged 1.5 to 2 years, were maintained indoors for 21 days. Five groups of two goats each were then dosed with anthelmintics while a sixth group served as an infected untreated control. The anthelmintics used, the dosage and the route of administration are given in Table I. All the animals were slaughtered 10 days after treatment.
196
Parasitological techniques. The modified McMaster technique was used for faecal egg counts. Faecal cultures, larval identification and total worm counts were carried out by standard procedures (MAFF, 1977).
Anthelrnintic efficacy. The geometric means of the faecal egg counts and worm counts were calculated after logarithmic transformation of the values (count + 1). The percentage faecal egg count reduction (FECR) was then calculated (Presidente, 1985). The efficacies of the drugs were assessed on the bases of FECR and worm count reduction in the treated and untreated groups.
RESULTS The data on faecal egg count are given in Table I and those on the number of worms in Table II. Larval differentiation and identification of the adult worms showed that the parasite involved was H. contortus.
TABLE I Faecal egg counts (geometric mean) from goats following treatment with different anthelmintics
Treatment (mg/kg)
Faecal egg counts FECR% Pre-treatment
Untreated control Levamisole (7.5) Morantel (10) Fenbendazole (5) Mebendazole (5) Thiophanate (75) Ivermectin (0.2) a Closantel (10)
1083 1170 726 1070 2108 1023 732 1018
Post-treatment
1075 556 550 550 1477 789 2 0
aDrug administered subcutaneously; all other drugs given orally
52.13 23.68 48.22 29.42 22.30 99.72 100.00
197 TABLE II Worm counts (geometric mean) from goats naturally infected with H. contortus and treated with different anthelmintics
Treatment (mg/kg)
Infected untreated control Levamisole (7.5) Morantel (10) Fenbendazole (5) Thiophanate (75) Ivermectin (0.2) a
Worm count
636 224 285 215 271 0
Reduction in worm count (%)
64.73 55.28 66.24 57.37 100.00
aDrug administered subcutaneously; all other drugs given orally
DISCUSSION The results confirm our earlier findings of resistance in caprine H. contortus to levamisole (Yadav and Uppal, 1992). It appears that continuous indiscriminate use of levamisole had selected for a resistant strain. Fenbendazole was used as an alternate drug but, once resistance is present, counterselection with an alternative drug may not re-establish susceptibility to the original drug (Martin et al., 1988). If reversion to susceptibility does occur, it may take several years to do so (Miller and Baker, 1980). The strain resistant to levamisole was also found to be resistant to morantel, fenbendazole, mebendazole and thiophanate but not to ivermectin'or closantel. Levamisole-resistant strains are usually resistant to morantel (Le Jambre and Martin, 1979) because the two drugs have a similar mode of action (Prichard et al., 1980). The strong resistance to mebendazole and thiophanate may be attributed to sideresistance. Thiophanate, a probenzimidazole compound, is converted to a benzimidazole derivative and its anthelmintic activity is dependent upon such a conversion (Douch, 1974). Thus, the site and the mode of action of thiophanate are similar to those of the benzimidazole drugs, including fenbendazole. Closantel and ivermectin proved to be very effective against this strain of H. contortus, as was reported earlier (Hall et al., 1981; Santiago et al., 1986). Since these drugs had not been used on the farm, resistance against them was not expected.
ACKNOWLEDGEMENT The authors are grateful to Dr Arun Atrey, Marketing Manager, Cadila Veterinary, Ahmedabad, for the gift of mebendazole and closantel.
198 REFERENCES Douch, P.G.C., 1974. The metabolism of some thioureidobenzene fungicides in mice and sheep. Xenobiotica, 4, 457-475 Hall, C.A., Ritchie, L. and McDoneU, P.A., 1981. Investigation for anthelmintic resistance in gastrointestinal nematodes from goats. Research in Veterinary Science, 31, 116-119 LeJambre, L.F. and Martin, P.J., 1979. Effectiveness of morantel tartrate and naphthaiophos against levamisole-resistant Ostertag/a in sheep. Veterinary Research Communications, 3, 153-158 MAFF, 1977. Manual of Veterinary Parasitological Techniques, (Technical Bulletin No. 18, Ministry of Agriculture, Fisheries and Food, HMSO, London) Martin, P.I., Anderson, N., Brown, T.H. and Miller, D.K., 1988. Changes in resistance of Ostertagia spp. to thiabendazole following natural selection or treatment with levamisole. International 7ournal for Parasitology, 18, 333-340 Miller, J.E. and Baker, N.F., 1980. Thiabendazole resistant strains ofHaemonc/ms contortus and Ostertagia in California lambs. American Journal of Veterinary Researck, 41, 1674-1676 Presidente, P.LA., 1985. Methods for detection of resistance to anthelmintics. In: N. Anderson and P.J. Waller (eds), Res/stance in Nematodes to AnOtelmintic Drugs, (CSIRO, Melbourne) Prichard, R.IC, Hall, C.A., Kelly, J.D., Martin, I.C.A. and Donald, A.D., 1980. The problem of anthelmintic resistance in nematodes. Australian Veterinary Journal, 56, 239-250 Sangster, N.C., Whitlock, H.V., Russ, I.G., Gunawan, M., Griffin, D.L. and Kelly, J.D., 1979. Trichoswongylus colubriformis and Ostertagia circumcincta resistant to levamisole, morantel tartrate and thiabendazole-occurrence of field strains. Research in Veterinary Science, 27, 106-110 Santiago, M.A.M., Dacosta, U.C., Benevenga, S.F., Bordin, E.L. and Guerrero, J., 1986. Efficacy of ivermectin and anthelmintic resistant isolates of sheep nematode parasites. Veterinary Record, 119, 43-44 Van Wyk, J.A. and Malan, F.S., 1988. Resistance of field strains of Haemonchus contortus to ivermectin, closantel, rafoxanide and thiabendazoles in South Africa. Veterinary Record, 123, 226-228 Yadav, C.L., 1990. Fenbendazole resistance in Haemonchus contonus of sheep. Veterinary Record, 126, 586 Yadav, C.L. and Uppal, R.P., 1992. Levamisole resistant Haemonchus contortus in goats. Veterinary Record, 130, 228 (Accepted: 26 May 1992)
Short Communication MULTIPLE ANTHELMINTIC RESISTANCE IN A FIELD STRAIN OF H A E M O N C H U S CONTORTUS IN GOATS R.P. UPPAL 1, C.L. YADAV 2, P. GODARA 3 AND Z.S. RANA 3 Departments of 1Veterinary Pharmacology, 2Veterinary Parasitology and 3Animal Breeding, CCS Haryana Agricultural University, Hisar, India 125004
Uppal, R.P., Yadav, C.L., Godara, P. and Rana, Z.S., 1992. Multiple anthelmintic resistance in a field strain of Haernonchuscontortus in goats. VeterinaryResearch Communications, 16 (3), 195-198 Keywords: anthelmintic resistance, benzimidazole,goats, India, levamisole
INTRODUCTION Ovine strains of Ostertagia and Trichostron~lus showing multiple resistance to anthelmintics were first reported in Australia (Sangster et al., 1979). In a recent report from South Africa, Haemonchus contortus has been reported to have developed resistance to a number of anthelmintics, including ivermectin (Van Wyk and Malan, 1988). Strains of H. contortus resistant to benzimidazoles in sheep (Yadav, 1990) and to levamisole in goats (Yadav and Uppal, 1992) have been detected in India. A caprine strain showing multiple resistance is now reported.
MATERIALS AND METHODS History. The strain of H. contottus was obtained from a goat farm on which levamisole-resistant H. contortus had been detected. The animals grazed on
permanent pastures and were dosed 3-4 times a year. Levamisole and fenbendazole had been used for 4-5 years. Morantel was also used but was considered ineffective by the local veterinarian. When treatment with fenbendazole failed to alleviate scouring in a flock of 500 goats, a study was undertaken to determine the efficacies of various anthelmintics against the strain of Haemonchus in the animals. Experimental design. Eighty-one naturally infected goats (Beetal, Black Bengal and
Beetal x Black Bengal) aged 9-12 months were divided into seven treatment groups and one untreated control group of 9-12 animals each on the basis of body weights and faecal egg counts. Faecal egg counts were carried out prior to and 8-10 days after treatment. In a second experiment, 12 naturally infected goats, aged 1.5 to 2 years, were maintained indoors for 21 days. Five groups of two goats each were then dosed with anthelmintics while a sixth group served as an infected untreated control. The anthelmintics used, the dosage and the route of administration are given in Table I. All the animals were slaughtered 10 days after treatment.
196
Parasitological techniques. The modified McMaster technique was used for faecal egg counts. Faecal cultures, larval identification and total worm counts were carried out by standard procedures (MAFF, 1977).
Anthelrnintic efficacy. The geometric means of the faecal egg counts and worm counts were calculated after logarithmic transformation of the values (count + 1). The percentage faecal egg count reduction (FECR) was then calculated (Presidente, 1985). The efficacies of the drugs were assessed on the bases of FECR and worm count reduction in the treated and untreated groups.
RESULTS The data on faecal egg count are given in Table I and those on the number of worms in Table II. Larval differentiation and identification of the adult worms showed that the parasite involved was H. contortus.
TABLE I Faecal egg counts (geometric mean) from goats following treatment with different anthelmintics
Treatment (mg/kg)
Faecal egg counts FECR% Pre-treatment
Untreated control Levamisole (7.5) Morantel (10) Fenbendazole (5) Mebendazole (5) Thiophanate (75) Ivermectin (0.2) a Closantel (10)
1083 1170 726 1070 2108 1023 732 1018
Post-treatment
1075 556 550 550 1477 789 2 0
aDrug administered subcutaneously; all other drugs given orally
52.13 23.68 48.22 29.42 22.30 99.72 100.00
197 TABLE II Worm counts (geometric mean) from goats naturally infected with H. contortus and treated with different anthelmintics
Treatment (mg/kg)
Infected untreated control Levamisole (7.5) Morantel (10) Fenbendazole (5) Thiophanate (75) Ivermectin (0.2) a
Worm count
636 224 285 215 271 0
Reduction in worm count (%)
64.73 55.28 66.24 57.37 100.00
aDrug administered subcutaneously; all other drugs given orally
DISCUSSION The results confirm our earlier findings of resistance in caprine H. contortus to levamisole (Yadav and Uppal, 1992). It appears that continuous indiscriminate use of levamisole had selected for a resistant strain. Fenbendazole was used as an alternate drug but, once resistance is present, counterselection with an alternative drug may not re-establish susceptibility to the original drug (Martin et al., 1988). If reversion to susceptibility does occur, it may take several years to do so (Miller and Baker, 1980). The strain resistant to levamisole was also found to be resistant to morantel, fenbendazole, mebendazole and thiophanate but not to ivermectin'or closantel. Levamisole-resistant strains are usually resistant to morantel (Le Jambre and Martin, 1979) because the two drugs have a similar mode of action (Prichard et al., 1980). The strong resistance to mebendazole and thiophanate may be attributed to sideresistance. Thiophanate, a probenzimidazole compound, is converted to a benzimidazole derivative and its anthelmintic activity is dependent upon such a conversion (Douch, 1974). Thus, the site and the mode of action of thiophanate are similar to those of the benzimidazole drugs, including fenbendazole. Closantel and ivermectin proved to be very effective against this strain of H. contortus, as was reported earlier (Hall et al., 1981; Santiago et al., 1986). Since these drugs had not been used on the farm, resistance against them was not expected.
ACKNOWLEDGEMENT The authors are grateful to Dr Arun Atrey, Marketing Manager, Cadila Veterinary, Ahmedabad, for the gift of mebendazole and closantel.
198 REFERENCES Douch, P.G.C., 1974. The metabolism of some thioureidobenzene fungicides in mice and sheep. Xenobiotica, 4, 457-475 Hall, C.A., Ritchie, L. and McDoneU, P.A., 1981. Investigation for anthelmintic resistance in gastrointestinal nematodes from goats. Research in Veterinary Science, 31, 116-119 LeJambre, L.F. and Martin, P.J., 1979. Effectiveness of morantel tartrate and naphthaiophos against levamisole-resistant Ostertag/a in sheep. Veterinary Research Communications, 3, 153-158 MAFF, 1977. Manual of Veterinary Parasitological Techniques, (Technical Bulletin No. 18, Ministry of Agriculture, Fisheries and Food, HMSO, London) Martin, P.I., Anderson, N., Brown, T.H. and Miller, D.K., 1988. Changes in resistance of Ostertagia spp. to thiabendazole following natural selection or treatment with levamisole. International 7ournal for Parasitology, 18, 333-340 Miller, J.E. and Baker, N.F., 1980. Thiabendazole resistant strains ofHaemonc/ms contortus and Ostertagia in California lambs. American Journal of Veterinary Researck, 41, 1674-1676 Presidente, P.LA., 1985. Methods for detection of resistance to anthelmintics. In: N. Anderson and P.J. Waller (eds), Res/stance in Nematodes to AnOtelmintic Drugs, (CSIRO, Melbourne) Prichard, R.IC, Hall, C.A., Kelly, J.D., Martin, I.C.A. and Donald, A.D., 1980. The problem of anthelmintic resistance in nematodes. Australian Veterinary Journal, 56, 239-250 Sangster, N.C., Whitlock, H.V., Russ, I.G., Gunawan, M., Griffin, D.L. and Kelly, J.D., 1979. Trichoswongylus colubriformis and Ostertagia circumcincta resistant to levamisole, morantel tartrate and thiabendazole-occurrence of field strains. Research in Veterinary Science, 27, 106-110 Santiago, M.A.M., Dacosta, U.C., Benevenga, S.F., Bordin, E.L. and Guerrero, J., 1986. Efficacy of ivermectin and anthelmintic resistant isolates of sheep nematode parasites. Veterinary Record, 119, 43-44 Van Wyk, J.A. and Malan, F.S., 1988. Resistance of field strains of Haemonchus contortus to ivermectin, closantel, rafoxanide and thiabendazoles in South Africa. Veterinary Record, 123, 226-228 Yadav, C.L., 1990. Fenbendazole resistance in Haemonchus contonus of sheep. Veterinary Record, 126, 586 Yadav, C.L. and Uppal, R.P., 1992. Levamisole resistant Haemonchus contortus in goats. Veterinary Record, 130, 228 (Accepted: 26 May 1992)
