Helminths of sheep and goats in desert areas of south-west Mauritania (Trarza)

Faecal samples were obtained from sheep and goats before, during and after the rainy season at three locations in south-west Mauritania. Several animals were also necropsied at the same time.Haemonchus contortus was the most prevalent worm. Infection by digestive-tract strongyles andStrongyloides papillosus was always very light (prevalence less than 20%). Sheep were more heavily infected than goats but animals under 1 year of age were not infected by digestive-tract strongyles. It is likely that young small ruminants became infected during the rainy season and that the parasites so acquired are inhibited in their development and/or survive nearly one year as adults.     

Development and survival of Haemonchus contortus larvae on pasture at Vom,Plateau State,Nigeria

The development and survival of the eggs of Haemonchus contortus on pasture at Vom were studied by depositing faecal pellets on grass plots over a period of 12 months. Development and survival to the infective larvae occurred throughout the study except during the dry season months of December to April. More infective larvae were recovered from the herbage in June, July and August than in other months. The survival time of the infective larvae ranged from 2 weeks in October to 10 weeks in June, July and August. Rainfall was the most important epizootiological factor influencing the development and survival of the infective larvae. Temperature was not a limiting factor.     

宁夏羊胃肠道线虫对现行驱虫药的抗药性调查

采用粪便虫卵减少试验对宁夏地区所属灵武、贺兰、盐池、吴忠、中宁、中卫、永宁和银川市郊8个县（市）的12个绵羊场、6个山羊场进行了丙硫苯咪唑和阿维菌素抗药性的随机调查。结果表明：在用丙硫苯咪唑调查的10个绵羊场和6个山羊场中，虫卵减少率在95％以下和95％的置信域下限在90％以下的有山羊场2个、绵羊场2个，证明对丙硫苯咪唑有抗药性；1个绵羊场和1个山羊场的虫卵减少率是96．3％、95．9％，但95％置信域的下限在90％以下，具有抗药性可疑；山羊群中丙硫苯咪唑的抗药性为33．3％，绵羊群为20．0％。用同样的方法调查了1个山羊场和5个绵羊场（其中有4个羊场曾执行了丙硫苯咪唑的试验），查出1个山羊场和1个绵羊场对阿维菌素具有抗药性可疑，其虫卵减少率分别为97．3％和95．5％，置信域下限在90％以下。揭示了宁夏地区羊消化道线虫对现行驱虫药的抗药状态，为今后防治提供了依据。     

Climate and the epidemiology of gastrointestinal nematode infections of sheep in Europe

The free-living stages of gastrointestinal nematode parasites of sheep are strongly affected by climate. Thus, extreme heat and cold are detrimental to development and survival, while, within tolerable limits, increasing temperatures generally accelerate development but increase mortality. Moisture is needed for development and translation of larvae from faeces to pasture, and so rainfall is a limiting factor for transmission. Together, these factors underpin seasonal patterns of infection in sheep, as well as geographic variation in the epidemiology and relative importance of different species within Europe. Local knowledge and experience enable treatment to be targeted appropriately to prevent dangerous levels of infection. This traditional know-how can be supplemented by predictive epidemiological models, built on thorough understanding of the influence of climate on larval availability. However, management also has a dominant role in determining patterns of infection, and is itself influenced by climate. Current geographic variation in nematode epidemiology across Europe, and knowledge of systems from outside Europe, can provide only limited perspectives on the likely effects of climate change on disease in future. This is because disease arises from complex interaction between host and parasite factors, and the implementation of optimal control strategies to meet new challenges will be slowed by the inertia of current systems. Approaches to nematode control must therefore take account not only of parasite biology, but also the forces that shape sheep farming systems and management decisions.     

Development and survival of infective larvae of gastrointestinal nematodes of cattle on pasture in central Kenya

On a series of pasture plots, 2 kg pats of bovine faeces containing known numbers of strongylid (Haemonchus, Cooperia, Oesophagostomum and Trichostrongylus) eggs were deposited at intervals of 4 weeks from July 1995 to June 1996. The plots were sampled every 2 weeks after contamination and infective larvae were identified and counted. Larvae of all the genera developed throughout the year, but the pats exposed during the rainy season yielded more abundant larvae on the herbage. Irrespective of the season of deposition of the pats, larvae were found in larger numbers from 2 to 6 weeks after deposition and generally declined to below detectable levels within 12 to 16 weeks of contamination. The comparatively short survival times noted in this experiment may present opportunities for manipulation of the population dynamics of the gastrointestinal nematodes in the tropical environment of Kenya.     

Resistance of Santa Ines and crossbred ewes to naturally acquired gastrointestinal nematode infections

This trial was carried out in Piracicaba, São Paulo State, Brazil, to comparatively evaluate the degree of resistance to naturally acquired gastrointestinal nematode infections in sheep of the following genetic groups: purebred Santa Ines (SI), SI crossbred with Dorper (DO × SI), Ile de France (IF × SI), Suffolk (SU × SI), and Texel (TE × SI). Fifteen ewes from each group were raised indoors until 12 months of age. At this age, they were moved to pasture that was naturally contaminated by nematode infective larvae and were evaluated from December to May, 2007. Rainfall ranged from 267 mm in January to 37 mm in April. Maximum and minimum mean temperatures ranged from 32.5 °C to 19.0 °C in March and from 25.9 °C to 12.8 °C in May. There was an increase in the mean number of eggs per gram of feces (EPG) after animals were placed on pasture with significant difference between the SI (80 EPG) and IF × SI (347 EPG) groups in January; and the DO × SI (386 EPG) and TE × SI (258 EPG) groups in May. The highest mean fecal egg count (FEC), 2073 EPG, was recorded for the TE × SI group in February. All groups showed a progressive reduction in body weight throughout the experiment of 12.0% (TE × SI) to 15.9% (SU × SI). In general, the animals with the highest FEC presented the lowest packed cell volumes (PCV); the highest correlation coefficient between FEC × PCV occurred in the SU × SI sheep in January (r = −0.70; P < 0.01). Similarly, there was an inverse relationship between FEC and blood eosinophil values, with the highest correlation coefficient in the TE × SI sheep in February (r = −0.64; P < 0.05). Immunoglobulin G (IgG) levels against Haemonchus contortus antigens increased in all groups as a result of the exposure to parasites and remained relatively constant until the end of the study, with the exceptions of SU × SI and TE × SI, which showed a rise in IgG levels during the last sampling that coincided with a reduction in mean FEC. In conclusion, crossbreeding Santa Ines sheep with any of the breeds evaluated can result in a production increase and the maintenance of a satisfactory degree of infection resistance, especially against H. contortus and Trichostrongylus colubriformis, the major nematodes detected in this flock.     

Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia

Sissay, M.M., Uggla, A. and Waller, P.J., XXXX. Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia. Tropical Animal Health and Production, XXXX. A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger, Oesophagostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.     

Toxoplasmosis in sheep,goats and cattle in central Ethiopia

In a seroepidemiological survey using an indirect haemagglutination assay, the prevalence rate of toxoplasmosis in central Ethiopia was 22.9% of 899 sheep, 11.6% of 753 goats and 6.6% of 785 cattle. There were high titres of 1:256 or more which suggest current infections. These results indicate that toxoplasmosis may be an important cause of reproductive wastage in small ruminants. The public health significance of this disease is discussed. Improved hygiene and management could reduce the prevalence of the disease.     

Epidemiological Studies on Gastrointestinal Parasitic Infections of Lambs in the Coastal Savanna Regions of Ghana

The types of gastrointestinal parasites (Eimeria and helminths) encountered by 70 lambs and the seasonal pattern of both Eimeria and strongylate infections in these lambs in the derived Coastal Savanna were followed for three years. Eimeria oocysts and helminth eggs were detected in the faeces of lambs at the same time, indicating the concurrence of both Eimeria and helminth infections. Eimeria oocysts were first seen in the lambs 20 days after birth (DAB) and the level of oocyst output increased by the fourth week. Eimeria species identified in the lambs were E. parva, E. pallida, E. faurei, E. ahsata, E. bakuensis, E. intricata, E. granulosa, E. ovinoidalis and, occasionally, E. marsica. E. ovinoidalis, the most pathogenic species, dominated the oocyst output during the early part of the life of the lambs. Strongyloides papillosus eggs appeared at 46 DAB, preceding strongylate nematode eggs, which were seen at 57 DAB and those of Moniezia at 69 DAB. The pattern of Eimeria oocyst output paralleled that of the worm egg output, and high oocyst and strongylate worm egg counts corresponded with the period of high rainfall during the study period. Although oocyst and worm egg output fluctuated, high Eimeria oocyst counts were seen again in the lambs when they were 1 and 2 years old. Haemonchus species formed 71% of the infective larvae revealed by larval culture.     

Occurrence and antimicrobial resistance of Salmonella serovars in apparently healthy slaughtered sheep and goats of central Ethiopia

The present study was undertaken to determine the occurrence, distribution and antimicrobial resistance pattern of Salmonella serovars in apparently healthy slaughtered sheep and goats in central Ethiopia. A total 1224 samples consisting of faeces, mesenteric lymph nodes, liver, spleen, and abdominal and diaphragmatic muscle samples were collected from 104 sheep and 100 goats. Salmonella was isolated from 12 of 104 (11.5%) sheep and 3 of 100 (3%) goats. Of the total 624 and 600 samples examined from sheep and goats, 18 (2.9%) and 4 (0.7%), respectively, were Salmonella positive. The 22 Salmonella isolates belonged to 9 different serovars. The common serovars isolated were S. typhimurium, followed by S. heidelberg, S. reading, S. give, and S. poona. Seven of the 22 isolates (31.8%) were multidrug-resistant to various antimicrobials.     

Anthelmintic Resistance on an Organized Sheep Farm in India

Monitoring anthelmintic resistance in strongyle nematodes by the faecal egg count reduction test and a commercial larval development assay on an organized sheep farm in the semi-arid area of Rajasthan revealed the emergence of resistance to benzimidazoles and rafoxanide and a potential risk of the development of levamisole/tetramisole resistance. A benzimidazole/levamisole combination, avermectins and closantel were each found to be efficacious.     

Gastrointestinal helminths and lungworms of French dairy goats: Prevalence and geographical distribution in Poitou-Charentes

A study was conducted on 81 dairy-goat farms in western France. Faecal samples were collected once and 31 culled goats were necropsied in order to assess their gastrointestinal and respiratory helminth species, their prevalences and the intensities of infection as well as their geographical distribution in six subregions of the surveyed area. Fifteen species of helminth were recovered. The most frequent wereMuellerius capillaris, Trichostrongylus colubriformis andTeladorsagia circumcincta with a prevalence more than 90%. The two latter species represented respectively 50.9% and 30.2% of the total worm burden of the digestive tract. Other prevalent species wereHaemonchus contortus, Strongyloides papillosus, Trichuris spp.,Moniezia spp. andDicrocoelium lanceolatum. The occurrence ofDicrocoelium lanceolatum was related to the presence of calcareous or alkaline soils and restricted to the south of the surveyed area. No area at particular risk was defined for the other helminth infections, probably because of the relative homogeneity in climatic and topographic conditions of the six agricultural regions.     

Development and survival of Haemonchus contortus infective larvae derived from sheep faeces under sub-tropical conditions in the Potohar region of Pakistan

Assessment on the development and survival of Haemonchus contortus larvae was made to evaluate the influence of microclimatic variables viz., relative humidity (%), temperature (°C), rainfall (mm) and intensity of sunlight (hrs). Pasture plots in a sub-tropical area, Pakistan were contaminated with H. contortus eggs at the start of every month. The plots were sampled on fortnightly basis after contamination for three consecutive months. The overall pattern indicated the most favorable conditions for survival, development and translation to herbage was during the wet season from July to October and the least favorable was during the dry season from April to June. Peak infective larvae (L₃) recovery was during the 15–45 day interval for each plot and the lowest number was during the 75–90 day interval. Herbage was collected in the morning, afternoon and evening and greatest recovery of L₃ was in the morning time and least in the afternoon. The number of L₃ on pasture was directly related to the pattern of rainfall and relative humidity with a significant (P < 0.05) positive correlation and temperature and intensity of sunshine were negatively correlated (P < 0.05). The results suggest that pastures can remain infective for up to 2 months and become relatively clean by 90 days after contamination. Thus, long pasture rest periods, especially during the high risk wet season, may be a helpful strategy to reduce the infection levels.     

动物产品中牛、羊源性成分多重PCR检测方法的建立

以肉骨粉、鱼粉、猪肉干和鱼肉干为研究对象,异硫氰酸胍法提取总DNA,18S rDNA片段的扩增结果表明提取到的DNA中不存在抑制PCR的物质。应用梯度PCR技术对牛、羊源性成分检测的退火温度进行了优化,在单一PCR检测技术的基础上分别进行了18S rDNA片段和牛、羊源性成分的多重PCR分析,得到了预期的结果。试验表明,本文建立的多重PCR方法具有快速、简便、准确等特点,对动物产品牛、羊源性成分检测具有重要意义。     

Prevalence and seasonal incidence of larval and adult cestode infections of sheep and goats in eastern Ethiopia

A study on the prevalence and seasonal incidence of cestode parasite infections of sheep and goats was carried out in eastern Ethiopia for 2 years (May 2003-April 2005). During this period, viscera including liver, lungs, heart, kidneys and the gastro-intestinal tract were collected from 655 sheep and 632 goats slaughtered at four abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga. At the abattoirs the abdominal, thoracic and pelvic cavities as well as the muscle surfaces of all animals were visually examined for the presence of larval (cystic) stages of cestode parasites. The viscera were transported within 24 h to the parasitology laboratory of Haramaya University and were examined for larval and adult cestodes following standard procedures. The most prevalent metacestodes (larval cestodes) were Cysticercus ovis (Taenia ovis), Cysticercus tenuicollis (T. hydatigena) and hydatid cysts (Echinococcus granulosus). In sheep, the overall prevalence was 26% for C. ovis, 79% for C. tenuicollis, and 68% for hydatid cysts. Similarly, for goats, the corresponding prevalence was 22%, 53% and 65%, respectively. The difference between sheep and goats in prevalence of C. tenuicollis was significant. The high prevalence of hydatid cysts in both sheep and goats indicates that cystic echinococcosis/hydatidosis is a public health problem in these regions which requires implementation of control measures, including public health education, strict meat inspection and control of stray dogs. The results of the survey also implies that infections of small ruminants with these metacestodes are responsible for condemnation of substantial quantities of affected organs and muscles and therefore of direct economic importance. Intestinal infections with adult tapeworms of Moniezia expansa, Avitellina centripunctata and Stilesia globipunctata, and bile duct infections with Stilesia hepatica were also common in both sheep and goats. In sheep, the overall prevalence of these tapeworms were 61%, 20%, 24% and 39%, respectively. Similarly, the overall prevalence of these parasites in goats was 53%, 21%, 27% and 36%, respectively.     

A Preliminary Study on the Anthelmintic Activity of Calotropis procera Latex against Haemonchus contortus Infection in Najdi Sheep

The anthelmintic activity of Calotropis procera latex was investigated in sheep that had been infected with single oral doses of 12 000 infective Haemonchus contortus larvae. Inappetence, dullness, erosive abomasitis, decreased haemoglobin concentration and increased eosinophils were the main features of haemonchosis in the sheep. In the sheep treated with single oral doses of 0.01 ml or 0.02 ml/kg body weight of C. procera latex, egg production was significantly reduced, but not completely suppressed, and fewer adult Haemonchus worms were found in the abomasum. Although the appetite improved, the haemoglobin concentration and serum copper, iron and zinc levels were still reduced after therapy with Calotropis latex. Calotropis latex showed a concentration-dependent larvicidal activity in vitro within 20 min of application.     

The Effect of Oral Administration of Polyethylene Glycol on Faecal Helminth Egg Counts in Pregnant Goats Grazed on Browse Containing Condensed Tannins

Thirty yearling F₁ Anglo-Nubian×Mubende goats, averaging 21±0.45 kg, kept on free-range feeding in the Ankole range land, Uganda, were screened for health and nutritional status, effectively treated against helminth parasites, mated, and randomly divided into two equal groups during a 3-month preparatory phase. During the 6 months that followed, the goats in one group received a daily oral dose (50 g/goat) of poly(ethylene glycol) (PEG), while the other group acted as the control (no PEG). The goats were monitored for faecal nematode egg counts and body weight gains, along with the quality of their diet, nematode contamination of the pasture, and the prevailing climatic factors in the area. Goats treated with PEG had significantly (p<0.05) higher faecal helminth egg loads. The mean nematode eggs per gram of faeces (epg) of the PEG group (290 epg) was more than double that of the control group (129 epg). All the PEG-treated goats exhibited moderate to severe infections at the end of the experiment. The gain in body weight during gestation was lower (p<0.05) in the PEG group (70.4 g per goat per day) than in the control group (91.8 g per goat per day). The PEG group lost 2.3 g per goat per day in the fifth month. PEG deactivates condensed tannins, and it was concluded that condensed tannins play a significant role in reducing the negative effects of gastrointestinal helminth burdens in the natural free-range feeding system of the Ankole range land in Uganda. Selective feeding on such range lands might expose goats to optimal concentrations of dietary condensed tannins with resultant beneficial effects.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

PCR detection of lentiviral GAG segment DNA in the white blood cells of sheep and goats

A PCR assay for the detection of small ruminant lentiviral gag DNA (provirus) in the white blood cells of sheep and goats was developed and compared with a serological test (AGIDT). A sample of the DNA prepared from the white blood cells in 3 ml of blood from 208 sheep and goats from 18 different flocks was subjected to PCR assay. One of 85 animals from flocks accredited under the Dutch national MVV/CAEV control programme was positive by PCR while none was positive by AGIDT. In infected flocks, the AGIDT appeared slightly more sensitive, but preliminary results show that the sensitivity of the PCR assay may be further improved by increasing the number of monocytes tested. The PCR assay, however, was clearly more sensitive in detecting animals in the early stages of infection. With the use of a set of mixed primers and probes, the assay was able to detect the variety of CAEV and MVV strains occurring in the field.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.