Trop Anim Health Prod (2009) 41:655–662 DOI 10.1007/s11250-008-9237-z
ORIGINAL PAPER
Multiple anthelmintic resistance on a goat farm in Hawassa (southern Ethiopia) Bersissa Kumsa & Girma Abebe
Accepted: 28 August 2008 / Published online: 13 September 2008 # Springer Science + Business Media B.V. 2008
Abstract A study was conducted to determine the presence of anthelmintic resistance on Hawassa University goat farm in southern Ethiopia. The 180 goats were stratified by age and sex and randomly assigned to treatment groups (albendazole, tetramisole and ivermectin and untreated control). Each treatment group included 15 goats and treatments were administered according to weight of each goat with 7.5 mg/kg bw albendazole, 22.5 mg/kg bw tetramisole and 0.2 mg/kg bw ivermectin dose rates recommended by scientists. Faecal samples were collected on day 0 before treatment, and again on day 12 post treatment. Efficacy of all the drugs was assessed on day 12 post treatment by faecal egg count reduction test (FECRT). Multiple anthelmintic resistance in Haemonchus spp. against albendazole, tetramisole and ivermectin was recorded in all age categories of the goats. Likewise, Trichostrongylus/Teladorsagia spp. showed resistance against ivermectin. Coprocultures from all pre- and post-treatments revealed the
predominance of Haemonchus spp. Resistance against anthelmintics is attributed to the high frequency of treatment and low dosage of treatment practices on the farm. Large scale studies, however, are needed to assess the current status of anthelmintic resistance against the most commonly used anthelmintics in different agroecology, species of animals and management systems in Ethiopia. Keywords Anthelmintic resistance . Hawassa University goat farm . Nematodes Abbreviations CL confidence limit EPG eggs per gram of faeces FEC faecal egg count FECRT faecal egg count reduction test L3 third stage infective larvae WAAVP World Association for the Advancement of Veterinary Parasitology
Introduction B. Kumsa (*) Department of Parasitology, Faculty of Veterinary Medicine, Addis Ababa University, P.O. Box 34, Debre Zeit, Ethiopia e-mail:
[email protected] G. Abebe Department of Animal and Range Sciences, Hawassa College of Agriculture, Hawassa University, P.O. Box 5, Hawassa, Ethiopia
Ethiopia owns about 23.6 million sheep and 23.3 million goats (CSA 2004) that are mainly kept by smallholder resource poor farmers. The productivity of this huge population, however remains marginal due to prevailing diseases, poor nutrition and husbandry systems and lack of effective veterinary services. Gastrointestinal nematodes are one of the
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major impediments to the economical benefits from small ruminants (Tembely et al. 1997). Several previous studies conducted in different parts of Ethiopia indicate that gastrointestinal nematodes in goats are very common and widespread in all livestock systems in the country (Hussein et al. 1999; Kumsa and Wossene 2006a; Sissay et al. 2006a; Thomas et al. 2007). The most commonly reported adverse effects of gastrointestinal nematodes in goats include: low productivity, decreased weight gain, unthriftness, delay in puberty, anorexia, hypoproteinaemia, loss of meat and wool, impaired digestive efficiency, organ condemnation, poor reproductive performance, and death of severely infected animals (Tembely et al. 1997). Anthelmintics have a pivotal role in minimizing the negative effects of nematodes worldwide. However, indiscriminate and frequent use of these drugs has resulted in the emergence of anthelmintic resistance against most of the major classes of anthelmintics in several countries (Coles et al. 2006; Jabbar et al. 2006; Saeed et al. 2007). Anthelmintic resistance in nematodes of small ruminants has been reported from different parts of the world (Borgsteede et al. 1996; Requejo-Fernandez et al. 1997; Chartier et al. 1998; Chandrawathani et al. 2004; Schnyder et al. 2005; Cringoli et al. 2007; Saeed et al. 2007). Vatta and Lindberg (2006) in their recent review stated that anthelmintic resistance has been reported in goats and/or sheep from at least 14 countries in Africa with most of the reports emanating from South Africa and Kenya and the majority concerning Haemonchus contortus. Mwamachi et al. (1995) from Kenya, Boersema and Pandey (1997) from Zimbabwe, Van Wyk et al. (1999) from South Africa, Atanasio et al. (2002) from Mozambique and Keyyu et al. (2003) from Tanzania are some of the reports on anthelmintic resistance from countries in Africa. Despite the great importance and considerable time of use of anthelmintics in Ethiopia, limited numbers examining the efficacy of these drugs are reported (Hussein et al. 1999; Asmare et al. 2005; Kumsa and Wossene 2006b; Sissay et al. 2006a, b). This implies that the extent, prevalence and economic significance of anthelmintic resistance in the country are not known. In response to the difficulties encountered by the management of Hawassa University goat farm to control gastrointestinal parasites using anthelmin-
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tics, this study was designed to test the efficacy of anthelmintics commonly used on the farm. This paper reports the result of a study on the efficacy of albendazole, tetramisole and ivermectin in three age categories of goats on Hawassa University goat farm in southern Ethiopia.
Materials and methods Study area The study was carried out on Hawassa University goat farm approximately 275 km south of Addis Ababa. Hawassa town is geographically located at 380 29’E and 70 05N. The elevation is about 1790 m above sea level and the respective minimum and maximum average temperature is 12oCand 28oC. The main rainy season in the area is from June to August whereas the dry season is from October to March. During the study months in September 2006, October, November, December, January and February 2007 the amount of rainfall received by Hawassa was 194.9 mm, 56.9 mm, 79.2 mm, 48.3 mm, 14.7 mm and 0 mm, respectively. The area is covered by dry savanna and bush types of vegetation. Farm history and animal management Hawassa College of Agriculture in collaboration with a non governmental organization called FARM AFRICA in 1988 established a dairy goat breeding farm. The main objective of the dairy goat development program was to produce suitable stock for distribution to smallholder farmers of the surrounding areas. The cross breeding program was based on the local Arsi-Blae goats and the Toggenburg exotic breed. The study goats consisted Arsi-Blae, Toggenburg and their crosses. During the study period a total of 400 goats were maintained on the farm. All the goats graze on a permanent natural pasture designated only for this flock. During the night all the goats are housed with free access to water and mineral salt. The main kidding time is from August to September. Due to intensive grazing management on the farm gastrointestinal nematode infection is controlled by treatment of all the animals with anthelmintics four times a year. Additional anthelmintic treatment could
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be given to any individual animal at any other time based on a diagnosis of clinical parasitism. The information obtained from the farm record revealed that anthelmintics mainly albendazole, tetramisole and ivermectin have been used since the establishment of the farm. Decisions on what drug to use were largely determined by price and availability, and alternation of anthelmintics was not deliberately practiced. All treatments prior to the efficacy study were given at the same rate to treat sheep was used for treating the goats on the farm at the dose rates of 3.75 mg/kg body weight (bw) albendazole (Exiptol, ERFAR, Pallini-Attiki, Greece), 15 mg/kg bw tetramisole (tetramisole ERFAR, Pallini-Attiki, Greece) and 0.2 mg/kg bw ivermectin (Norbrook laboratories, Newry/Ireland) as per the recommendations of the manufacturers. The only previous investigation on the efficacy of anthelmintics was conducted in 1997 by Asmare et al. (2005) who reported high efficacy of 99.7% in albendazole, 99.8% in tetramisole and 99.97% in ivermectin administered at the dose rates of 7.5 mg/kg bw, 15 mg/kg bw and 0.2 mg/kg bw, respectively. However, details of the anthelmintics used were not given. On the other hand Ademe (2003) reported strong indication of resistance against albendazole on the farm, but this was based only by observing clinical signs on postmortem examination. Study design and faecal examination In September 2006, prior to the efficacy study 200 faecal samples were collected from the rectum of randomly selected goats for coprological examination and coprocultures. Eggs per gram of faeces (EPG) was determined for each sample using the modified McMaster technique according to MAFF (1977) and Coles et al. (1992) with a sensitivity of 50 eggs per gram of faeces using saturated salt flotation fluid.
Modified sedimentation technique was employed for trematode eggs. Samples were examined for the presence of eggs or oocysts of nematodes, cestodes, protozoa and trematodes within 2 hours of collection at the laboratory of Animal Science of Hawassa University. The degree of infection by strongyle type nematodes in each goat was categorized as light (50– 800), moderate (800–1200) and heavy (>1200) degree of infection based on EPG value of strongyle type nematodes in the pretreatment faecal samples as described by Hansen and Perry (1994). For efficacy study a total of 180 goats were divided into three categories: less than 1 year of age of either sex, adult females of greater than one year of age and adult males of greater than one year of age. Subsequently, sixty goats within age and sex category were stratified by faecal egg count and were blocked in groups of 4 then assigned randomly within a block to one of the drug treatment (albendazole, tetramisole and ivermectin and untreated control). Each treatment group included 15 goats and treatments were administered according to the weight of each goat with the dose rates of 7.5 mg/kg bw albendazole, 22.5 mg/kg bw tetramisole and 0.2 mg/kg bw ivermectin as recommended by Hennesy (1994) and Jabbar et al. (2006). Faecal samples were collected rectally from each goat into pre-labeled universal bottles on day 0 before treatment and again on day 12 post treatments to determine EPG and for coprocultures. The efficacy of each anthelmintic was evaluated in each of the three age categories of goats. Anthelmintics All the evaluated anthelmintics were imported into the country by registered companies that are licensed to distribute veterinary drugs. All the drugs were used within their expiry date and stored as per instructions of the manufacturers. The details of anthelmintics used in the FECRT are given in Table 1.
Table 1 Details of anthelmintic drugs used in the FECRT for efficacy evaluation Trade name
Generic name
Manufacturer
Country of Origin
Dose/kg body weight
Mode of administration
Exiptol Tetramisole Noromectin
albendazole Tetramisole ivermectin
ERFAR ERFAR Norbrook laboratories
Pallini-Attiki /Greece Pallini-Attiki /Greece Newry/Northern Ireland
7.5 mg/kg 22.5 mg/kg 0.2 mg/kg
Oral Oral SC injection
FECRT, faecal egg count reduction test; SC, Subcutanoeus
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Efficacy evaluation Faecal egg count reduction tests (FECRTs) were carried out over a period of 5 months (October 2006 through February 2007) for the three age categories of goats. Efficacy of albendazole, tetramisole and ivermectin for the three age categories of goats was tested and interpreted according to the guidelines provided by WAAVP recommendations for efficacy evaluations of anthelmintics (Coles et al 1992, 2006). Faecal strongyle egg count reduction percentage (FECR%) was determined using the formula: FECR%=100(1Xt/Xc) where Xt and Xc are the arithmetic mean EPG in the treated (t) and untreated control (c) groups respectively, at day 12 post treatment. Anthelmintic resistance is considered to exist if the FECR% is less than 95% and the lower 95% confidence limit for the reductions is less than 90%. Anthelmintic resistance is suspected if either of the two criteria is met. L3 identification Approximately 5 g rectal faecal samples from each goat was pooled for each group and incubated at 27oc for 7 days before and after treatment. The L3 were recovered using Baermann technique. Then L3 were counted and identified according to the morphological keys given by MAFF (1977) and van Wyk et al. (2004). Where possible 100 L3 were identified per group; if less than 100 L3 were available then all were identified. Data analysis Descriptive statistics were used to analyze the mean EPG of the helminth egg count, prevalence, pre and post treatment results using a statistical software package, Intercooled Stata 9.2 for windows, 1984– 2006 (Stata Corporation 2002). Chi-square(X2) was used to measure the association among prevalence of different genera of parasites and degree of EPG of Table 2 Prevalence of gastrointestinal parasites in goats of Hawassa University farm prior to the efficacy study
Epg, eggs per gram of faeces; ND, not determined
strongyle type nematodes of the study goats. P
