A field trial of production and financial consequences of helminthosis control in sheep production in Ethiopia

We used a partial-budget analysis to evaluate profitability of different management strategies of three genotypes of sheep in a 2 x 2 x 3 factorial experiment conducted at Debre Berhan research station in the central highlands of Ethiopia. This involved two anthelmintic-treatment levels (treated vs. non-treated), two supplementary nutrition levels (protein-energy supplementation yes/no) and three genotypes: indigenous Menz (n=40), 50% Awassi x 50% Menz crosses (n=38) and 75% Awassi x 25% Menz crosses (n=31). All sheep were exposed to natural sub-clinical helminthosis challenge. Supplemented sheep were offered a concentrate mix daily on an individual basis. Anthelmintic-treated sheep were drenched with fenbendazole against nematodes and with triclabendazole against trematodes. Data were collected during the experimental period (for 10 months from approximately 1 year of age) on feed intake, live weight, eggs per gram (EPG) of faeces, packed-cell volume (PCV), wool weight, and adult-worm burden. Actual market input and output prices were recorded. Supplemented sheep had significantly higher marginal profit (MP) per sheep than non-supplemented sheep (ETB 33 vs. 4). Likewise, anthelmintic treated sheep performed significantly better than their non-treated contemporaries (MP=ETB 28 vs. 8). The 75% Awassi crosses were least profitable.     

Studies on fascioliasis in four selected sites in Ethiopia

The incidence of fascioliasis was studied in Asela, Awasa, Debre Zeit and Debre Berhan by using 153 experimental sheep divided up into 4 groups designated tracer sheep, Controls I, II and III. Fasciola hepatica was encountered in Debre Berhan, Asela and Awasa, but it was not detected at Debre Zeit. In all areas, it was most frequently recovered after heavy rains. Altitude, soil type, salt content and local crowding of animals in watering sites appear to have influenced the varying degrees of incidence and intensity of infection.     

Prevalence of Taenia multiceps in sheep in northern Jordan

From March 1996 to February 1997, slaughtered-sheeps' heads were examined for the metacestode of Taenia multiceps. Out of 451 sheep heads, only 12 (3%) were infested. All cysts but one were in the age group 0.5-2.5 years old, with prevalence of 10% (11 of 108). Eleven of 12 infested heads were found during the spring and autumn seasons. Out of 95 flocks involved in questionnaire survey unrelated to the abattoir survey, all the farmers reported the existence of the clinical signs known for coenurosis and described it in locally known names and diseases. Twenty-five of them had recent cases that were diagnosed by the veterinarian as coenurosis cases. Each flock reported one or two cases at the time of survey. A variety of clinical signs were reported from these cases (n = 42). These included circling (86%), head pressing (52%), blindness (29%) and paresis (40%). Coenurosis is a sheep-health problem and an important cause of sheep culling in Jordan.     

Community-based alternative breeding plans for indigenous sheep breeds in four agro-ecological zones of Ethiopia

Based on the results of participatory approaches to define traits in the breeding objectives, four scenarios of ram selection and ram use were compared via deterministic modelling of breeding plans for community-based sheep breeding programmes in four diverse agro-ecological regions of Ethiopia. The regions (and production systems) were Afar (pastoral/agro-pastoral), Bonga and Horro (both mixed crop-livestock) and Menz (sheep-barley). The schemes or scenarios differed in terms of selection intensity and duration of ram use. The predicted genetic gains per year in yearling weight (kilograms) were comparable across the schemes but differed among the breeds and ranged from 0.399 to 0.440 in Afar, 0.813 to 0.894 in Bonga, 0.850 to 0.940 in Horro, and 0.616 to 0.699 in Menz. The genetic gains per year in number of lambs born per ewe bred ranged from 0.009 to 0.010 in both Bonga and Horro. The predicted genetic gain in the proportion of lambs weaned per ewe joined was nearly comparable in all breeds ranging from 0.008 to 0.011. The genetic gain per year in milk yield of Afar breed was in the order of 0.018 to 0.020 kg, while the genetic gain per generation for greasy fleece weight (kg) ranged from 0.016 to 0.024 in Menz. Generally, strong selection and shorter duration of ram use for breeding were the preferred options. The expected genetic gains are satisfactory but largely rely on accurate and continuous pedigree and performance recording.     

Risk factors for mortality associated with respiratory disease among Menz and Horro sheep in Ethiopia

A retrospective case-control study was conducted on 6718 sheep of two breeds (2772 Horro and 3946 Menz) on risk factors for mortality associated with respiratory disease (MARD) in Ethiopia, based on data collected between October 1993 and December 1997. Potential risk factors examined were breed, gender, age, month, and air temperatures.Fifty-four per cent of total deaths in the flock could be attributed to respiratory disease and the annual MARD rate ranged between 6.3 and 19.0%. There was significant breed (P<0.0001) and gender (P<0.0001) difference in MARD. The Horro breed had a higher (P<0.0001) annual MARD than the Menz breed (16.5+/-0.18 vs. 12.4+/-0.15%). A higher (P<0.0001) proportion of males suffered than females (15.1+/-0.23% vs. 13.8+/-0.13%). Age was also an important risk factor for MARD: there was a strong polynomial relationship (R(2)=0.91, P<0.0001) between MARD and age; the risk of being young if a sheep was a MARD case was high. MARD was high between October and March but relatively low between the months of April and September. There was a significant (P<0.05) negative cubic relationship (R(2)=0.49) between monthly MARD and monthly average minimum air temperatures. There was also a significant (P<0.01) positive exponential relationship (R(2)=0.61) between monthly MARD and average monthly daily deviation between maximum and minimum air temperatures.Timely health and management interventions focusing on these factors are necessary to alleviate losses from MARD. Understanding variations in MARD risk within a population can enhance early response to potential outbreaks, reducing losses.     

Cloning and Prokaryotic Expression of Protein Kinase A Catalytic Subunit Gene from Taenia multiceps

To study the potential of protein kinase A catalytic subunit of Taenia multiceps (TmPKA-C) gene as a diagnostic antigen, the TmPKA-C gene was amplified by RT-PCR from the total RNA of Taenia multiceps. The TmPKA-C gene fragment was ligated into prokaryotic expression vector pET-30a and transformed into Escherichia coli Transetta (DE3) strain, then the reactonogenicity of recombinant TmPKA-C protein was analyzed by Western blotting and indirect ELISA. The open reading frame of TmPKA-C gene was 1 032 bp, encoding 343 amino acids. The expression product of TmPKA-C gene mainly existed in the form of inclusion body, and the molecular weight of recombinant protein was about 42 ku. Western blotting analysis showed that the recombinant protein could react specifically with the sera from naturally infected sheep with coenurosis, and it could also have specific reaction with the sera of artificial infected sheep with coenurosis. The indirect ELISA analysis showed that the sera from the coenurosis of sheep could react specifically with the recombinant protein. These results proved that the recombinant protein had good reactionogenicity. This study laid a foundation for the search of new diagnostic antigens for coenurosis of sheep.     

多头带绦虫蛋白激酶A催化亚基基因的克隆及原核表达

为鉴定多头带绦虫蛋白激酶A催化亚基（TmPKA-C）基因作为诊断抗原的潜能,本试验以多头带绦虫成虫RNA为模板,利用RT-PCR扩增TmPKA-C基因。将TmPKA-C基因片段连接至pET-30a原核表达载体进行原核表达,然后利用Western blotting和间接ELISA分析该蛋白的反应原性。结果表明,TmPKA-C基因开放阅读框的长度为1 032 bp,可编码343个氨基酸。TmPKA-C基因的表达产物主要以包涵体的形式存在,重组蛋白的分子质量大小约42 ku。Western blotting结果表明,该重组蛋白既能与自然感染脑多头蚴的绵羊血清发生特异性反应,又能与人工感染脑多头蚴不同时间段的绵羊血清发生特异性反应,表明该重组蛋白具有良好的反应原性。间接ELISA分析结果表明,脑多头蚴绵羊血清能与重组蛋白发生特异性反应,进一步证明该重组蛋白的反应原性良好。本研究为筛选脑多头蚴病诊断新抗原奠定了基础。     

A survey of Taenia multiceps coenurosis in Sardinian sheep

A survey was carried out to assess the occurrence of Coenurus cerebralis infection in Sardinian sheep. A prevalence of 0.35% was observed when 566 regularly slaughtered sheep were examined. However, in 120 sheep with suspected symptoms of coenurosis examined from November 2001 to October 2002, a total of 299 cerebral coenurosis lesions were observed with an incidence of 1% per year. Lesions were classified as migratory, cystic and secondary. Most migratory lesions were found in sheep aged 3-6 months. Cavitary lesions containing cysts in different developing stages were found with high incidence per year in sheep aged 7-12 months. Secondary lesions due to the development of Coenurus were most frequent in sheep aged 19-36 months. Most sheep were found infected in spring and in early summer, between March and June. Most lesions were located in the cortex. The mean number of protoscolices per cyst was 149 (range 10-370).     

羊场暴发脑包虫病的诊治与防控

绵羊脑包虫病是由多头带绦虫（Taenia multiceps）的中绦期幼虫——脑多头蚴（Coenurus cerebralis）引起的一种严重危害羔羊的寄生虫病。脑多头蚴主要寄生于牛羊等反刍动物的脑和脊髓中,病畜出现一系列神经症状,最终导致死亡。介绍绵羊脑包虫病的病例情况、临床症状、病理剖解变化、诊断、手术治疗,分析发病原因,提出了针对脑包虫病的综合防控措施。     

Effects of non-genetic factors on responses to gastro-intestinal nematode infections in Ethiopian sheep

The effects of non-genetic factors on responses to gastrointestinal nematode infections were examined in artificially infected indigenous Horro and Menz lambs in the central highlands of Ethiopia. The experiment involved lambs of two sexes, infection and monitoring regimens (3 levels), dam parity (4 levels) and birth types (2 levels). A total of 152 weaner lambs (103 Menz and 49 Horro) were used. Endoparasite challenge involved three infection periods (primary, secondary and tertiary) each separated by an anthelmintic treatment. Data were collected on faecal egg counts (FEC), packed cell volume (PCV), worm count, and weight gain. Female lambs were found to harbor lower numbers of T. colubriformis counts and had lower (p < 0.01) FEC in tertiary infection compared to males. Younger animals were more susceptible to the nematode infections than older animals as measured by all the parameters studied (p < 0.01). Twins had higher FEC in both secondary and tertiary infections compared to singles. Lambs born to dams of first parity had higher PCV and lower FEC values during the tertiary infection compared to other parities. These results would be used as basic information in designing a more rational control strategy and should also help to advise on better management care for less resistant sheep.     

Fat deposition in tropical sheep as adaptive attribute to periodic feed fluctuation

Ruminants adapt to periodic fluctuation in feed resources by accumulating fat stores during favourable periods. Thus, genetic variations, among ruminant genotypes, in the capacity to deposit fat could be exploited through breeding to improve animal productivity in traditional tropical production systems. Based on this premise, breed differences among weights of principal adipose depots and total body fat were estimated in Menz (n = 303) and Horro (n = 151) sheep of Ethiopia. Animals were kept on supplemental feeding, for about 3.5 months, until slaughter at about 17 months of age and pre‐slaughter live weight of 25 kg. Except the combined weight of tail and rump fat (TRF) which was similar (p > 0.05) in the two breeds, weights of subcutaneous and intermuscular fat (SIF), internal fat (IF) as well as total dissected body fat (TotDF), total ether‐extracted body fat (TotEE) and TotFAT (TotDF plus ‘residual’ fat, fat recovered by ether‐extraction from non‐adipose tissues) were significantly (p < 0.01) higher in the Menz. TotDF, TotEE and TotFAT were 1.91 ± 0.04, 2.05 ± 0.06 and 2.64 ± 0.06 kg, respectively, in the Menz and 1.50 ± 0.05, 1.44 ± 0.06 and 2.02 ± 0.07 kg, respectively, in the Horro. Implications of breed differences in fat distribution among depots, and possible consequences of genetic improvement of some of the depots on adaptation to climatic and nutritional stresses as well as some production objectives are discussed.     

Diversity of bacterial species in the nasal cavity of sheep in the highlands of Ethiopia and first report of Histophilus somni in the country

A study was conducted to isolate bacterial species/pathogens from the nasal cavity of apparently healthy and pneumonic sheep. Nasal swabs were collected aseptically, transported in tryptose soya broth and incubated for 24 h. Then, each swab was streaked onto chocolate and blood agar for culture. Bacterial species were identified following standard bacteriological procedures. Accordingly, a total of 1,556 bacteria were isolated from 960 nasal swabs collected from three different highland areas of Ethiopia, namely Debre Berhan, Asella, and Gimba. In Debre Berhan, 140 Mannheimia haemolytica, 81 Histophilus somni, 57 Staphylococcus species, and 52 Bibersteinia trehalosi were isolated. While from Gimba M. haemolytica, Staphylococcus, Streptococcus, and H. somni were isolated at rates of 25.2, 15.9, 11.4, and 5.9 %, respectively, of the total 647 bacterial species. In Asella from 352 bacterial species isolated, 93 (26.4 %) were M. haemolytica, 48 (13.6 %) were Staphylococcus species, 26 (7.4 %) were B. trehalosi, and 17 (4.8 %) H. somni were recognized. Further identification and characterization using BIOLOG identification system Enterococcus avium and Sphingomonas sanguinis were identified at 100 % probability, while, H. somni and Actinobacillus lignerisii were suggested by the system. The study showed that a variety of bacterial species colonize the nasal cavity of the Ethiopian highland sheep with variable proportion between healthy and pneumonic ones. To our knowledge, this is the first report on isolation of H. somni, an important pathogen in cattle, from the respiratory tract of a ruminant species in the country.     

Ovine progressive pneumonia (Maedi-Visna): an emerging respiratory disease of sheep in Ethiopia

A serological study was done to assess the role of Maedi-Visna (MV) infection in sheep from flocks with high respiratory tract disease morbidity in Ethiopia. Of 105 sheep examined from central Ethiopia 78 (74%) were positive for MV-infection. However, antibodies to the virus were not detected in 48 sheep and 70 goats from elsewhere in Ethiopia. The infection was detected in all breeds of sheep examined (Awassi, Hampshire, Corriedale, indigenous Menz breeds and their crosses) but with a significant breed difference (chi 2 = 20, p < 0.001) varying from 48% in imported Awassi sheep to 92% in the indigenous Menz sheep. This suggests that Menz sheep are more susceptible to infection, which may support the observation of a higher incidence of clinical disease in these sheep compared to exotic breeds and their crosses. It also supports recent studies indicating that MV is becoming one of the most important respiratory tract diseases in sheep in central Ethiopia. Our findings indicate that MV was introduced into Ethiopia via sheep imported into the central highlands and that it now constitutes an important emerging disease is discussed. Measures to control the disease are suggested.     

脑多头蚴病研究进展

脑多头蚴病是由多头带绦虫的中绦期幼虫脑多头蚴寄生于绵羊、山羊、黄牛、牦牛等有蹄动物的脑及脊髓中引起的一种人兽共患寄生虫病,人可因误食虫卵而感染此病。该病在宿主出现典型临床症状后如果得不到治疗,多以死亡为转归,给畜牧业生产造成了巨大的经济损失。论文就脑多头蚴病的病原学、生活史、流行病学、临床症状、诊断、治疗及免疫预防等方面的研究进展进行了综述。     

Parasites of sheep at the international Livestock Centre for Africa Debre Berhan station, Ethiopia

Prevalence of gastrointestinal parasites was investigated using monthly faecal samples and necropsy data in sheep treated regularly and irregularly at the International Livestock Centre for Africa research station at Debre Berhan. Maximum infection rates with nematodes, Fasciola and coccidia in the irregularly treated sheep were 18%, 10% and 37%, respectively, compared with 5%, 3% and 41% for the host treated regularly. Strongylosis was diagnosed mainly in July–November (wet-early dry) season, fasciolosis in January–June (late dry-early wet) season and coccidiosis all the year round. Signs of helminthiasis occured in August–November, primarily in the irregularly treated flock. A single deworming of the latter flock with fenbendazole (November) resulted in low worm-egg output and the absence of clinical helminthiasis as in the regularly dewormed flock. The management of the supplementary feeding of the untreated flock resulted in weight gains superior to the treated group during the entire 1987 period. Haemonchus contortus, Trichostrongylus colubriformis, T. axei, Ostertagia spp., Trichuris ovis, Chabertia ovina and Fasciola hepatica were helminths encountered at necropsy. Free-living stages of H. contortus and Trichostrongylus spp. may appear on pastures in May–July and July–September, respectively. Two broad-spectrum anthelmintics given at the start of the long and short rains should suffice to control the endoparasitism.     

Diagnosis and treatment of coenurosis in sheep

Coenurosis is a disease of the central nervous system in sheep, caused by Coenurus cerebralis, the larval stage of Taenia multiceps, a tapeworm, which infests the small intestine of carnivores. In 80-90% of cases, the cyst is located in one cerebral hemisphere, whilst in 5-10% of cases, it is localised in the cerebellum; rarely it involves two sites in the brain of the affected animal. Listeriosis, louping-ill, sarcocystosis and polioencephalomalacia and brain abscessation should be considered when formulating a diagnosis of acute coenurosis. In all cases, it is essential to carefully examine the animal and not simply rely on results of ancillary tests (mainly of cerebrospinal fluid examination), as disorders other than coenurosis can be responsible for changes in the results of these tests. Treatment is based on surgical removal of the coenurus cyst after general anaesthesia of the animal; the approach has a very good success rate, especially after accurate localisation of the lesion. Despite that, many farmers may choose to slaughter those sheep fit for marketing for economic reasons and euthanise those in poor condition.     

Imported coenurosis in sheep

Thirteen sheep from a milk producing farm in the Canton of Grisons that presented chronic coenurosis were examined and subjected to treatment trials at the veterinary hospital in Zurich. Symptoms were first observed around two months after the import of two dogs from Italy (Abruzza) of which one was infected with Taenia multiceps and Echinococcus granulosus. The most frequently observed clinical symptoms of the sheep were reduced general condition, circling, reduced menace reflex, apathy, unsteady gait and head tilt. Analyses of cerebrospinal fluid revealed an increased leucocyte count in 3 sheep and eosinophilia in 4 sheep. In 4 animals that underwent computertomography, one or more hypodense, definable lesions were found in the brain. In 2 sheep surgical treatment and in 10 animals medical treatment with either Praziquantel (n=8) or Oxfendazol (n=2) was attempted. Only one animal treated with Praziquantel needed not to be euthanized. At necropsy, one or two coenurus cysts could be found either in a side ventricle (n=2), in the cerebellum (n=3) or in the cerebrum (n=7). The locations corresponded with the clinical findings. Despite Praziquantel or Oxfendazol treatment, living protoscoleces could be found in the parasite cysts.     

Sheep oestrosis (Oestrus ovis Linné 1761, Diptera: Oestridae) in Sardinia, Italy.

Oestrosis, the nasal myiasis of sheep and goats, is caused by the larvae of Oestrus ovis L. 1758 (Diptera, Oestridae) that develop from the first to the third stage larva in the nasal cavities and frontal sinuses of affected animals. The authors report the results of an epidemiological study of oestrosis of sheep in Sardinia, Italy. Heads of 6-month to 10-year-old Sardinian sheep (n=566) from 124 free-ranging flocks were examined for the presence and location O. ovis larvae from December 1996 to November 1997. Larvae were collected, counted, and larval stages were identified. O. ovis larvae were found in 100% of examined flocks and in 91% (514/566) of examined sheep. The monthly prevalence ranged from 69% in May to 100% in July. First stage larvae were found in 82% (463) of all heads examined, second stage larvae in 65% (367) and third stage larvae in 10% (56). The majority of sheep harboured first stage larvae, with prevalences of over 80% throughout most of the study period. The prevalence of O. ovis found in this study of Sardinian sheep is the highest reported in the Mediterranean area. The high percentage of first stage larvae found throughout the entire study period may be due to a brief period of decreased rate of larval maturation, in particular in December 1996 (96%) and January-October 1997 (94%). Third stage larvae were consistently present, often however, with extremely low prevalences compared to total larval burden.     

Acute coenurosis of dairy sheep from 11 flocks in Greece

Abstract

CASE HISTORY: A syndrome of acute neurological dysfunction with increased mortality was observed in lambs of 10 dairy sheep flocks and adult animals in one flock in Central and Northern Greece. Each farmer completed a questionnaire regarding the management and feeding of their flocks. In seven of the 11 flocks the affected animals were grazing pasture, while in the remaining four flocks (5, 8, 9, 10) the animals were fed alfalfa hay (Medicago sativa) and concentrates indoors. A follow-up study of the affected flocks was conducted during the next 12 months.

CLINICAL FINDINGS: Of 42 sheep with acute coenurosis that were examined, the most prominent neurological abnormalities were ataxia, depression, blindness, scoliosis, coma and dysmetria. Except for the four sheep that were comatose, all other animals had normal body temperatures and their appetites remained normal or were slightly decreased. Haematological findings of 15 examined sheep were within normal limits. The affected sheep were subject to euthanasia. A histopathological examination was performed in 13 cases. Faecal samples from dogs associated with these flocks were negative for taeniid infections. During the following 12 months cases of chronic coenurosis in these flocks were observed.

PATHOLOGICAL FINDINGS: In the 42 animals that were necropsied, the main gross findings were cystic formations between 0.5–1 cm in diameter with translucent walls that were seen lying free on the leptomeninges or partly penetrating the brain tissue, sterile microabscecess and brain necrosis. Histopathological evaluation of tissue sections of 13 brains showed multifocal purulent or pyogranulomatous meningoencephalitis, accompanied by eosinophilic infiltrations. No bacteria were isolated following bacterial culture of brain tissue Parasitological examination of the cysts from five cases revealed whitish specks on the transparent cyst wall and germination membrane representing the scolices.

DIAGNOSIS: Acute coenurosis was diagnosed in all cases studied.

CLINICAL RELEVANCE: Acute coenurosis can be one of the causes of acute encephalopathy mainly in lambs, but also in adult sheep. This condition is incurable, but can be controlled by changing the feeding regime. Cases of chronic coenurosis may be seen a few months later in the same flock.     

羊脑多头蚴病ELISA试验用抗原制备的初步研究

用羊脑多头蚴包囊头节、犬多头多头线虫节片经超速离心制备的抗原以及多头蚴包囊液抗原,分别对32头份羊脑多头蚴病阳性血清和63头份阴性血清进行EISA检测。头节抗原、节片抗原和囊液抗原的阳性率分别为81.25％、78.12％和53.12％,前两者阳性率均高于后者;其阴性率分别为82.54％、79.36％和80.95％。进而以头节抗原对32头份羊脑多头蚴病血清、25头份羊细颈囊尾蚴病血清、12头份羊棘球蚴病血清和7头份羊肝片吸虫病血清以及31头份羊肝片吸虫病阴性血清进行ELISA试验。结果,分别有26头份、9头份、4头份、1头份和1头份为阳性反应。经Dancan’s检验,多头蚴病血清S/N平均值明显地高于多头蚴病阴性血清。从而初步证明头节抗原用于诊断羊脑多头蚴病具有较高的敏感性和特异性。