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PubMed2026

A systematic review and meta-analysis to estimate the global prevalence of leptospirosis in sheep.

Leptospirosis in sheep is a zoonotic concern considering sheep may act as potential reservoirs for Leptospira spp. infection to humans. This study aimed to estimate the pooled prevalence of leptospirosis in sheep worldwide. A comprehensive literature search was conducted across databases following PRISMA guidelines. Meta-analyses were performed using a random effect model in R software (version 4.3.1) to calculate pooled prevalence with 95% confidence intervals (CI). Subgroup analyses were performed based on prevalence types, diagnostic methods and continental regions to explore sources of heterogeneity. A total of 138 studies comprising 54,174 samples and 10,299 positive detections were included in this study. The global pooled prevalence of leptospirosis in sheep was 15.69% (95% CI: 12.69-19.25) with overall heterogeneity (I2) 98%. The prediction interval ranged from 1.09% to 75.91%, indicating wide inter-study variability. The seroprevalence was 16.16% (95% CI: 12.91-20.04) and infection prevalence was 12.98% (95% CI: 8.07-20.22), showing no significant difference (P = 0.40). In addition, the prevalence of leptospirosis in sheep differed significantly across diagnostic methods and continents (P < 0.01), indicating substantial variation influenced by both methodological and geographical factors. The funnel plot revealed marked asymmetry, suggesting potential publication bias which was confirmed by Egger's regression test (P < 0.01). In conclusion, leptospirosis is widely prevalent in sheep globally, with marked geographical and methodological heterogeneity. These findings highlight the epidemiological importance of sheep in leptospirosis transmission and underscore the need for improved surveillance, standardized diagnostic approaches, and targeted control strategies within a One Health framework.

Animals↗

PubMed2005

Acute intoxication by Crotalaria retusa in sheep.

Acute intoxication by seeding Crotalaria retusa occurred during the dry season, in a flock of 80 sheep, in the semi-arid region of the state of Paraiba, northeastern Brazil. Anorexia, severe depression, mild jaundice, incoordination and recumbence were observed in 16 sheep that died within 12 h. At necropsy the liver had a nutmeg appearance. Seeds of C. retusa were found in large amounts in the rumen of the dead animals. Histologic lesions of the liver were characterized by centrilobular necrosis. Seeds of C. retusa were given to six sheep at doses of 2.5 (two sheep), 5, 10, 20 and 40 g/kg bw (one sheep for each dose). Sheep ingesting 5-40 g/kg bw were killed when moribund, 38-120 h after the start of the administration. Clinical signs and gross and histologic lesions were similar to those observed in field outbreak. The seeds used in the experiment contained 1.4% of monocrotaline. It is concluded that hungry sheep can be affected spontaneously by acute monocrotaline intoxication when they ingest large amounts of C. retusa seeds in a short period of time.

Animals↗

PubMed2006

Expression of tumor necrosis factor-alpha in IgM+ B-cells from bovine leukemia virus-infected lymphocytotic sheep.

Tumor necrosis factor (TNF)-alpha is thought to be one of the cytokines that account for bovine leukemia virus (BLV)-induced B-cell lymphoproliferative disorder, however, information on TNF-alpha expression in B-cells is limited. In this study, the expression of TNF-alpha in IgM(+) B-cells from BLV-infected sheep with or without lymphocytosis was determined. Freshly isolated IgM(+) B-cells from three sheep with lymphocytosis constitutively transcribed TNF-alpha mRNA. Although TNF-alpha mRNA expression in IgM(+) B-cells was transiently up-regulated after cell culture, TNF-alpha mRNA expression was markedly higher in lymphocytotic sheep when compared to that of non-lymphocytotic sheep or uninfected sheep. Expression of membrane-bound TNF-alpha on IgM(+) B-cells was also augmented in lymphocytotic sheep. TNF-alpha expression in lymphocytotic sheep may support the proliferation of B-cells.

Animals↗

PubMed2004

Validation of the FAMACHA eye color chart for detecting clinical anemia in sheep and goats on farms in the southern United States.

Recent studies on sheep and goat farms in the southern United States indicate that multiple-anthelmintic resistance in Haemonchus contortus is becoming a severe problem. Though many factors are involved in the evolution of resistance, the proportion of the parasite population under drug selection is believed to be the single most important factor influencing how rapidly resistance develops. Therefore, where prevention of resistance is an important parallel goal of worm control, it is recommended to leave a portion of the animals untreated. Recently, a novel system called FAMACHA was developed in South Africa, which enables clinical identification of anemic sheep and goats. When H. contortus is the primary parasitic pathogen, this system can be applied on the farm level to reduce the number of treatments administered, thereby increasing the proportion of the worm population in refugia. Since most studies validating the FAMACHA method have been performed in South Africa, it is important that the method be tested in other regions before its use is broadly recommended. We performed a validation study of FAMACHA by testing the system in sheep (n = 847) and goats (n = 537) of various breeds and ages from 39 farms located in Arkansas, Georgia, Louisiana, Florida, and the US Virgin Islands. The color of the ocular conjunctiva of all animals were scored on a 1-5 scale using the FAMACHA card, and blood samples were collected from each animal for determination of packed cell volume (PCV). Fecal samples were also collected from a majority of the animals tested for performance of fecal egg counts (FEC). Correlations between PCV and eye scores, PCV and FEC, and FEC and eye scores were all highly significant for both sheep and goats (P < 0.001). Data for both FAMACHA scores and PCV were evaluated using two separate criteria for anemia: eye score values of 3, 4 and 5 or 4 and 5, and PCV values of < or =19 or < or =15 were considered anemic. Specificity was maximized when eye score values of 4 and 5 were considered anemic and PCV cut off for anemia was < or =19, but sensitivity was low. In contrast, sensitivity was 100% for both sheep and goats when eye score values of 3, 4 and 5 were considered anemic and PCV cut off was < or =15, but specificity was low. In both sheep and goats, predictive value of a negative was greater than 92% for all anemia and eye score categories, and was greater than 99% for both eye score categories when an anemia cutoff of < or =15 was used. Predictive value of a positive test was low under all criteria indicating that many non-anemic animals would be treated using this system. However, compared to conventional dosing practices where all animals are treated, a large proportion of animals would still be left untreated. These data indicate that the FAMACHA method is an extremely useful tool for identifying anemic sheep and goats in the southern US and US Virgin Islands. However, further studies are required to determine optimal strategies for incorporating FAMACHA-based selective treatment protocols into integrated nematode control programs.

Anemia↗

PubMed2004

Testing for direct anthelmintic effects of bioactive forages against Trichostrongylus colubriformis in grazing sheep.

The aim of the present study was to investigate potential direct anthelmintic effects of forages that contain plant secondary metabolites (PSM) towards the intestinal nematode Trichostrongylus colubriformis. For this purpose, we introduced an experimental design, which enabled us to investigate the direct anthelmintic effects of PSM-rich forages, without significant interference of possible indirect immunological effects of PSM. Sixty parasite naive sheep were infected with 8000 T. colubriformis L(3) on day 1 of the experiment. On day 28, sheep entered one of the experimental plots, which consisted of four PSM-rich forages and one control: Lotus pedunculatus (lotus), Hedysarium coronarium (sulla), Onobrychis viciifolia (sainfoin), Cichorium intybus (chicory) and Lolium perenne/Trifolium repens (grass/clover). On day 35 of the experiment, all sheep were re-infected with 8000 T. colubriformis L(3) and were killed on day 42. By day 42, all parasites of the primary infection would have been recovered as adults, whereas those of the secondary challenge would have only developed to the fourth stage larvae within a week (i.e. days 35-42). The first batch of larvae would enable us to investigate possible direct anthelmintic effects of PSM-rich forages against adult T. colubriformis, whereas the second one whether grazing on the PSM-rich forages could affect the establishment of the incoming infective larvae. Sheep grazing on lotus tended to have a lower FEC compared to sheep grazing on grass/clover (P = 0.06), whereas daily faecal output was higher in sheep grazing lotus compared to those grazing on the other forages (P < 0.05). As a consequence, daily egg output was similar in all sheep. Grazing on the PSM-rich forages for a period of 2 weeks did not affect the immature and adult parasite populations. Although the present experimental design enabled us to test the experimental hypothesis, the lack of evidence on a direct anthelmintic effect of PSM-rich forages can not be considered conclusive, as the composition of PSM-rich forages is variable within and across grazing seasons.

Animal Feed↗

PubMed2005

A method for sheep scab control by applying selective treatment based on flock serology.

Sheep scab, caused by Psoroptes ovis, is a severe and debilitating disease that can be treated and controlled by the use of acaricidal dips or the use of broad-spectrum avermectins. In Switzerland, control measures are state regulated. In particular, sheep should be routinely treated with ectocide dips or avermectin injections before they are moved onto common alpine pasture in late spring. However, a substantial part of the sheep population remains untreated and represents a potential reservoir for the mite population. Untreated sheep that are not moved to alpine pasture may infest treated sheep when flocks are reassembled in autumn. In an attempt to identify infested sheep, all flocks in the Canton of Schwyz (Switzerland) were serologically tested in 2001 and in 2002 (587 and 565 flocks, respectively). In 2003, a representative number (182 of the 531 flocks) was again investigated. Seropositive flocks were treated with doramectin (0.3 mg kg(-1) body weight, intramuscularly) from 2001 to 2003. In spring 2002, no chemo-methaphylaxis was given to seronegative flocks before movement onto common alpine pastures. Of the 587 flocks surveyed in spring 2001, 34 were seropositive (5.8%). These consisted of 21 infested with P. ovis, 1 with P. cuniculi, 4 with Chorioptes spp. and 8 of seropositivity of unknown origin; there was a decrease of seropositive flocks in spring 2002 (4.4%) with 15, 0, 2 and 8, respectively. Of the 182 flocks surveyed in spring 2003, just 4 flocks (2.2%) were seropositive. All the seropositive reactions in these flocks were the result of Chorioptes spp. infestations. There was a corresponding decrease in the proportion of seropositive animals from 6.3% in spring 2001 to 2.1% in spring 2003. These results corroborate the concept that it may be possible to target chemo-metaphylaxis and hence decrease the use of endectocides as well as of ectocides to control sheep scab. This would be of great benefit in reducing the likelihood of development of anthelmintic resistance against avermectins, decreasing the extent of environmental and human contamination with potentially toxic products and diminishing potential drug residues in meat and milk.

Animals↗

PubMed2006

Survey of helminths in adult sheep in Heilongjiang Province, People's Republic of China.

The prevalence of helminths in adult sheep was investigated in Heilongjiang Province, People's Republic of China between January 1999 and September 2003. A total of 326 adult sheep representing local breeds (Xingjiang Fine Wool Sheep, Dongbei Fine Wool Sheep) as well as introduced breeds (Merino and Charollais) from representative geographical locations in Heilongjiang Province were slaughtered and examined for the presence of helminths. The worms were examined, counted and identified to species according to existing keys and descriptions. A total of 26 helminth species were found representing 2 phyla, 3 classes, 13 families and 20 genera. All sheep were infected by more than one helminth species. Oesophagostomum columbianum, Haemonchus contortus and Trichostrongylus colubriformis were the most common nematode species, and Paramphistomum cervi, Orientobilharzia turkestanica and Fasciola hepatica were the most common trematode species, whereas the infection of adult sheep with cestodes was uncommon. The results of the present investigation provide relevant "base-line" data for Heilongjiang Province, China, for assessing the effectiveness of future control strategies against helminth infections in sheep.

Animals↗

PubMed2006

Detection of specific hydatid antigens and antibodies in serum and urine of experimentally infected sheep.

Immunodiagnostic confirmation of cystic human hydatidosis is frequently required before surgical intervention or of chemotherapy. However, it remains inadequate to detect specific antibodies or antigens in some confirmed cases of echinococcosis. This study was carried out to investigate the accuracy of three different immunodiagnostic tests for detection of specific circulating antigens or antibodies in the serum and urine of 13 experimentally infected sheep. For this purpose, Echinococcus granulosus were collected from small intestine of experimentally infected dogs, and 2000 taenid eggs were orally administered to each of the 13 sheep. There were six other sheep, which were kept as the control group. Biweekly serum and urine samples were collected from all the sheep for 4 months after infection. The sera were subjected to indirect hemagglutination test and the concentrated urine samples were subjected to coagglutination and counter immunoelectrophoresis tests. The results revealed that the sensitivity of these tests in detecting the hydatid antigens in the urine or antihydatid antibodies in the serum of the infected sheep reached their maximum in 12th and 13th week after infection; then it decreased in the following weeks. Examination of the non-infected sheep samples throughout the experiment showed that the aforesaid findings were specific only to the infected sheep. It seems that the appearance of specific hydatid antigen in urine and its antibodies in the serum were simultaneous. Although these tests are highly specific, false negative outcomes were encountered in their detection of cystic echinococcosis. In general, it seems rational to establish some series of diagnostic procedures in order to reveal antibodies and antigen of metacestode in serum and urine of the patients.

Animals↗

PubMed2006

The effect of mixed or sequential grazing of cattle and sheep on the faecal egg counts and growth rates of weaned lambs when treated with anthelmintics.

An experiment was conducted over two successive years (2002 and 2003) to investigate the effects of grazing improved permanent pasture (mainly perennial ryegrass/white clover) by cattle or sheep, either sequentially or mixed, on the faecal egg counts and growth rates of weaned lambs when treated with anthelmintics. The grazing season was divided into two parts, May-July then July-October, relating to the pre- and post-weaning of the lambs. Four grazing regimes, replicated three times, were compared: (1) sheep only from May to October (SS); (2) cattle May to July followed by lambs until October (C/S); (3) cattle and sheep May to July followed by lambs until October (C+S/S); and (4) cattle and sheep May to July followed by cattle and lambs until October (C+S/C+S). Sward height was maintained at 6 cm using a "put and take" stocking system. At weaning, lambs were weighed and treated with an anthelmintic (0.08% ivermectin drench, Oramec) before being allocated to plots. They were then weighed and drenched every 28 days until the end of the experiment (Day 84). Faecal egg counts (FEC) were measured in all lambs immediately prior to each anthelmintic treatment. In 2002 and 2003, there were differences between the groups in FEC, with the SS lambs having the highest values and C/S lambs the lowest (P<0.01). There were also differences in the rate of liveweight gain of the lambs in each of the study years: for this parameter SS lambs had the lowest growth rate but the fastest growth was in C+S/C+S lambs not C/S lambs (P<0.01), indicating that these differences were due to factors other than parasite infection. Overall, sequential grazing of pastures with cattle then sheep reduced the faecal egg counts in lambs regularly treated with anthelmintics when compared with lambs grazing in mixed systems with cattle and sheep or with sheep only systems, however, the highest growth rates were observed in lambs in the mixed cattle/sheep grazing system throughout.

Animal Husbandry↗

PubMed2006

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).

Abattoirs↗

PubMedDate not supplied

The immunogenetics of resistance to Trichostrongylus colubriformis and Haemonchus contortus parasites in sheep.

Three possible immunogenetic markers for resistance to intestinal parasites in sheep have been studied. Allotypes of the major histocompatibility complex (MHC) of the sheep have been investigated as markers, using serological typing or gene probes, for associations between allotypes and resistance to parasites in selected high responder and low responder lines of sheep. Only the serologically-determined class I ovine leucocyte antigen (OLA) types SY 1a and SY 1b have been found to be consistently associated with increased resistance to Trichostrongylus colubriformis, but this association has not extended to the immunologically distinct Haemonchus contortus parasite. Gene probes of the sheep DRB, DQB and DQA MHC class II loci have detected animals with increased susceptibility to T. colubriformis. Eosinophilia was investigated as a marker and found to be associated with increased resistance to parasites in lines of Australian Merinos and New Zealand Romneys selected for resistance on the basis of low faecal egg count. Blood eosinophilia was distinct from eosinophil infiltration of the gut which was poorly associated with resistance. The mechanism of parasite resistance appeared to involve the release of vasoactive amines and leukotrienes into intestinal mucus, since the selected high responder sheep to T. colubriformis and H. contortus had significantly increased amounts of these agents in their gut mucus, compared with selected low responder or random-bred sheep. Antibodies to T. colubriformis and H. contortus have also been used as markers to select high responder sire groups of lambs in contact with the parasites, for the first time, at weaning. This assay had the advantage of detecting distinct antigens for the two parasites, which would allow resistance to the species of parasite to be selected in the lambs. Vaccines have been developed against H. contortus using 'novel' gut antigens from the parasite, but variable responsiveness of the host sheep seemed to result in varying degrees of protection which were stimulated by these vaccines.

Animals↗

PubMed1999

The pathogenesis and control of diarrhoea and breech soiling in adult Merino sheep.

Diarrhoea and soiling of the breech with faeces ('winter scours') is a serious problem in adult Merino sheep grazing improved pastures in south-eastern Australia during winter and spring. This occurs even on farms where gastro-intestinal nematodes are effectively controlled. It was shown that winter scours was associated with the ingestion of trichostrongylid larvae, and that host factors were important in determining susceptibility to this syndrome. No differences were detected in the protective immune response of affected and unaffected sheep to gut nematodes. However, affected sheep had a hypersensitive inflammatory reaction in the pylorus and upper jejunum, characterised by the infiltration of significantly more eosinophils and changed lymphocyte populations. The changes in the lymphocyte populations included a reduced number of CD8+ cells, increased CD4+:CD8+ T-cell ratio, and significantly reduced numbers of cells reacting to interferon-gamma. High doses of infective larvae (20,000/week of Ostertagia circumcincta and Trichostrongylus vitrinus) did not induce diarrhoea in sheep not susceptible to winter scours. In contrast, only low doses (2000/week) initiated scouring in sheep selected as being susceptible to winter scours. Therefore, even considerably improved worm control programmes, including the selection of sheep with increased resistance to gut nematodes, will not prevent winter scours. Rather, phenotypic culling and genetic selection, to remove sheep susceptible to the hypersensitivity inflammatory response, is proposed as the most suitable long-term control strategy.

Animal Husbandry↗

PubMed1996

Description and classification of different types of lesion associated with natural paratuberculosis infection in sheep.

Paratuberculosis lesions in naturally infected sheep were classified histologically. Adult sheep (n = 166) culled for various reasons, from four flocks in which clinical cases of the disease had occurred, were studied. Eight-two sheep (49.4%) showed lesions that could be divided into three main categories. Type 1 lesions, found in 24.1% of these animals, consisted of small granulomata formed by macrophages and were located exclusively in the ileocaecal Peyer's patch. In type 2 lesions, found in 4.8% of the sheep, granulomata were also observed in the mucosa associated with Peyer's patches. Type 3 lesions were characterized by granulomata in areas of the mucosa associated with, and also distinct from, the Peyer's patches. Three subtypes of type 3 lesions were recognized. In subtype 3a, found in 4.2% of the sheep, multifocal granulomata appeared in different areas of the lamina propria; they were not apparently associated with lymphoid tissue, and neither did they modify the morphology of the affected areas. Subtype 3b, found in 13.9% of animals, consisted of large numbers of macrophages, widespread in the lamina propria; in subtype 3c (2.4% of sheep) lymphocytes were the main inflammatory cell, with some macrophages scattered amongst them. In subtypes 3a and b, villi were distended and the mucosa appeared thickened. Mycobacteria could be demonstrated in tissue sections from all the samples with subtype 3b lesions and in almost all of those with type 2 and 3a lesions; these organisms were absent or sparse, however, in type 1 and 3c lesions. Macroscopical lesions were clearly visible only in sheep with type 3b and 3c lesions. Mycobacterium paratuberculosis was cultured from all the animals with type 3 lesions, from 87.5% of those with type 2 lesions, and from 47.5% of those with type 1. Type 3b lesions resembled the "borderline-lepromatous" form of mycobacterial lesions, whereas type 3c lesions resembled the "borderline-tuberculoid" form. The relationship between intestinal lymphoid tissue and paratuberculosis lesions is discussed, and the diagnostic importance of histological examination of the ileocaecal valve emphasized.

Animals↗

PubMed2001

A single-chain variable region immunoglobulin library from the abomasal lymph node of sheep infected with the gastrointestinal nematode parasite Haemonchus contortus.

Sheep immunoglobulin (Ig) heavy-chain (V(H)DJ(H)) and lambda light-chain variable region (V(lambda)J(lambda)) nucleotide coding sequence was isolated by reverse transcriptase-polymerase chain reaction (RT-PCR) from abomasal lymph node (ALN) B cells of immune sheep challenged with the gastrointestinal nematode parasite Haemonchus contortus. Single-chain antibodies (scFv) were then constructed with the purified V(H)DJ(H) and V(lambda)J(lambda) Ig gene region DNA using oligonucleotides to PCR and join the variable regions to a central [Gly(4)Ser](3)-linker. In a similar fashion 5'-SfiI and 3'-NotI restriction endonuclease sites were added for cloning into a phagemid expression vector. Expression of sheep scFv from pHFA phagemid in an amber-suppresser strain of Escherichia coli, after infection with filamentous phage, resulted in 10(9) sheep scFv antibodies displayed as a library on phagemid particles. Western blot analysis demonstrated sheep scFv gene expression in E. coli cell lysate and on purified library phage. In addition, four rounds of scFv-library selection against H. contortus surface antigen resulted in a 300-fold increase in the elution titre of phage recovered from parasite surface antigen. Nearly 1000 of the selected and eluted scFvs were expressed in an attempt to identify monoclonal sheep scFv against parasite antigen. Only low affinity clones were isolated during screening of this sheep scFv-library, suggesting different strategies will be needed for isolation of specific high affinity recombinant antibody in future studies.

Amino Acid Sequence↗

PubMed2000

Uptake of albendazole and albendazole sulphoxide by Haemonchus contortus and Fasciola hepatica in sheep.

The pattern of in vivo uptake of albendazole (ABZ) and its major metabolite, ABZ-sulphoxide (ABZSO), by Haemonchus contortus and Fasciola hepatica recovered from ABZ-treated sheep, was investigated. Concentration profiles of both compounds were simultaneously measured in target tissues/fluids from the same infected sheep. In addition, the proportion of the (+) and (-) ABZSO enantiomers was determined in plasma, bile and F. hepatica recovered from treated sheep. Sheep naturally infected with H. contortus were intraruminally (i.r.) treated with ABZ (micronized suspension, 7. 5mg/kg) and the plasma concentrations of ABZSO and ABZ-sulphone (ABZSO(2)) determined in addition to the concentration of ABZ and ABZSO in H. contortus, abomasal mucosa and fluid content samples. In addition, F. hepatica artificially infected sheep were treated i.r. with the same ABZ suspension (7.5mg/kg), and samples of blood, bile, liver tissue and adult flukes were collected and analysed by HPLC to determine the concentrations of ABZ and both enantiomers of ABZSO. ABZSO and ABZSO(2) were the analytes recovered in plasma with ABZ and ABZSO present in H. contortus. ABZ was the analyte recovered at the highest concentration in H. contortus and abomasal mucosa, whereas higher concentrations of ABZSO were measured in abomasal fluid content. Only low concentrations of ABZ were detected in F. hepatica and bile, but markedly higher concentrations of ABZ were measured in liver tissue. ABZSO was the main molecule recovered in F. hepatica, plasma and bile samples collected from ABZ-treated sheep. The (+) enantiomer of ABZSO was recovered at a higher proportion in plasma (75%), bile (78%) and F. hepatica (74%) after ABZ administration to infected sheep.

Abomasum↗

PubMed2001

Diagnosis of psoroptic sheep scab with an improved enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of specific antibodies against crude Psoroptes antigen. The diagnostic sensitivity was 93.7% in 191 sheep with clinical signs associated with mange. These animals originated from 29 flocks in which psoroptic mites were detected. All of 59 sheep infested with Psoroptes ovis were seropositive. Additionally, in 49% of 70 clinically unaffected sheep originating from P. ovis-infested flocks, specific antibodies could be detected, suggesting that asymptomatic infestations can be diagnosed by serology. The specificity of the ELISA was 96.5% as determined with 254 sheep originating from 44 flocks without clinical mange. Cross-reactivity in a low range was detected with selected sera of sheep with clinical chorioptic or forage mite infestations. Four sheep seroconverted 2 weeks after experimental P. ovis infestation, i.e. 2 weeks before clinical signs became obvious. After successful doramectin treatment of 14 sheep with naturally acquired P. ovis infestation, the ELISA values declined slowly but remained positive in seven cases beyond 17 weeks.

Animals↗

PubMed2001

Evaluation of cercarial antigen for the serodiagnosis of fasciolosis in experimentally and naturally infected sheep.

The value of cercarial antigen for diagnosis of experimental and natural sheep fasciolosis was studied by enzyme linked immunosorbent assay (ELISA) and enzyme linked immunotransfer blot (EITB). In ELISA, the antibody levels of experimentally infected sheep with Fasciola gigantica appeared at 2 weeks post infection (PI), gradually increased till 7 weeks PI and nearly remained at the same level from 7 to 13 weeks PI (the end of experiment). Also, the sensitivity and specificity of cercarial antigen for diagnosis of naturally sheep fasciolosis were 100 and 90%, respectively. In EITB, in the sheep experimentally infected with F. gigantica, the band of 32.5kDa molecular weight polypeptide appeared at 2 weeks PI and continued till the end of experiment. Also, the cercarial antigen recognized 32.5kDa molecular weight band with all sera from naturally infected sheep with fasciolosis (n = 25). This band did not cross-react when tested with sera from infected sheep with Cysticercus tenuicollus (n = 20). This study suggests that, the 32.5kDa molecular weight polypeptide could be used as sensitive and specific epitope for the serodiagnosis of sheep fasciolosis.

Animals↗

PubMed2002

Estimating genetic differences in natural resistance in Rhön and Merinoland sheep following experimental Haemonchus contortus infection.

Genetic parameters of natural resistance were estimated in Rhön and Merinoland (German Merino) sheep following experimental infection with Haemonchus contortus. A total of 133 Rhön and 244 Merinoland lambs descending from 5 and 6 rams, respectively, were evaluated. Each helminth-naive lamb was orally infected with 5000 infective third-stage larvae (L(3)) of the nematode H. contortus at 12 weeks of age. Faecal egg counts (FEC) and haematocrit values were measured in all lambs at 16 and 20 weeks of age. Seventy-nine Merinoland and 29 Rhön male lambs were slaughtered immediately after the second sampling and worms were collected. Mean worm burden was calculated and the length of adults worms from an aliquot was measured.FEC of Rhön sheep was higher compared with Merinoland sheep (P<0.01). H. contortus L(3)-larvae specific antibody (IgL) level was higher in Rhön sheep (P<0.05). However, no differences in haematocrit, worm burden and IgG antibody values could be found between the breeds. Heritabilities for log FEC (+/-S.E.) were 0.0 and 0.07 (+/-0.07) for the first sample in Rhön and Merinoland sheep, respectively. Values for the second sample were higher in both breeds (Rhön 0.35+/-0.14, P<0.05; Merinoland 0.17+/-0.07, P<0.05). Corresponding heritabilities for haematocrit were higher in Merinoland (0.56+/-0.20 and 0.51+/-0.27) compared with Rhön (0.29+/-0.12 and 0.08+/-0.13). Heritabilities for worm burden were high in Rhön (0.54+/-0.2) and low in Merinoland (0.06+/-0.14 and 0.11+/-0.15). Estimated values for IgL were between 0.13 (+/-0.11) for the first sample in both breeds and 0.30 (+/-0.18) for the second sample in Rhön sheep. Corresponding heritabilities for IgG were not different from 0.0 in both breeds (P>0.05). Positive phenotypic correlations were estimated for IgG and IgL values in both breeds (P<0.01). IgG was significantly (P<0.05) and positively correlated with worm burden in male Merinoland and IgL with worm burden in male Rhön sheep.

Animals↗