Seroprevalence of and risk factors for Mycoplasma mycoides subspecies capri infection in small ruminants in Northern Jordan

During the period from January 2002 to December 2003, serum samples were collected from 104 small ruminant flocks consisting of 18 sheep flocks, 27 goat flocks, and 59 mixed flocks containing both sheep and goats in northern Jordan. Only female sheep and goats were sampled. At least five females aged over 2 years per flock per species were sampled and examined for Mycoplasma mycoides subspecies capri using the latex agglutination test. To increase the chances of detecting positive flocks, sick or older ewes were sampled. Specific information was obtained using a questionnaire to identify potential risk factors for M. mycoides subsp. capri seropositivity in small ruminants. The true flock-level seroprevalences of M. mycoides subsp. capri were 34%, 32%, and 38% in small ruminants (sheep and goats), sheep, and goats, respectively. Differences between flock-level seroprevalences in sheep and goats were not significant (p = 0.7). Multivariable logistic regression analysis of 21 production and health management practices showed four to be associated with M. mycoides subsp. capri seropositivity including flocks which were grazed and fed concentrate supplement (OR = 4.6), improper cleaning of milking utensils (OR = 4.7), buying new animals to replace culled ones (OR = 0.3), and treating against helminths when clinical signs of helminth infections appear (OR = 0.4).     

Seroprevalence of, and risk factors for, peste des petits ruminants in sheep and goats in Northern Jordan

Peste des petits ruminants (PPR) is an economically important disease that affect sheep and goat industry in Asia and Africa. In this study, we investigated the seroprevalence, and risk factors, of PPR in sheep and goat flocks from five different governorates (Irbid, Jarash, Ajloun, Mafraq and Zarka) located in Northern Jordan. Serum samples from 929 and 400 sheep and goats, respectively, corresponding to 122 sheep flock and 60 goats flock were collected. Seroprevalence was determined using PPR competitive ELISA. Health status and management information were collected using a semi-structured pre-tested questionnaire. The individual true prevalence of PPR in sheep and goats was 29 and 49%, respectively. The flock level true prevalence of PPR was 60 and 74% in sheep and goats, respectively. In both sheep and goat flocks, large flock size, visiting live animals market and inadequate veterinary services were identified as risk factors for PPR seropositivity. Mixed (sheep and goats) raising was identified as a risk factor for PPR seropositivity in sheep flocks only.     

Comparison of infection rates of Oestrus ovis between sheep and goats kept in mixed flocks

Oestrosis is a nasal myiasis of sheep and goats caused by larvae of the fly Oestrus ovis and can lead to severe clinical signs, which together with the disturbance caused by the adult fly may result into serious economic losses. Infection rates and larval burdens are always higher in sheep than in goats after either natural or artificial infestation. The aim of this study was to compare the host preference of the adult fly O. ovis between sheep and goats in mixed flocks, where they are kept together under the same husbandry conditions and hence, are very similarly exposed to the fly preference. Blood sera samples were collected from a total of 397 sheep and 335 goats, from 43 mixed flocks located at different regions of Greece. Antibodies specific to O. ovis IgG were measured by ELISA. A flock was considered positive when at least one individual was positive, i.e. showed a seropositivity of >or=20% in relation to positive control sera. A total of 193 (48.6%) sheep and 58 (17.9%) goats were found to be seropositive against O. ovis. Thirty-eight (88.4%) out of 43 flocks had at least one seropositive animal. The mean seroconversion against O. ovis in animals from the different flocks was 38.6% and 13.6% for sheep and goats, respectively, whereas the variance of infection within each flock was 0-100%. The mean seropositivity between sheep that were found to be positive or negative was 60.6% and 5.4%, respectively, whereas the corresponding values between goats were 35.2% and 5.2%, respectively. No significant difference in the seroconversion values was noted between flocks from the different areas (P=0.817), whereas a very significant difference was observed between animal species (P=0.001). However, there was no significant difference when seroconversion comparisons were made within samples of the same animals species, sheep or goats from different flocks of all the regions included in the study (P=0.695). The results of this study clearly demonstrate that O. ovis has a widespread distribution in Greece, and the seroprevalence is significantly higher in sheep than goats (P=0.001).     

Bluetongue virus seropositivity in sheep flocks in North West Frontier Province, Pakistan

The objectives of this study were to describe the prevalence and distribution of serum antibodies to Bluetongue virus (BTV) in a sample of 38 sheep flocks in northern areas of the North West Frontier Province of Pakistan and to identify demographic and productivity variables that are associated with BTV seropositivity. Blood samples were taken from a random sample of ewes in each flock in April 1995. The owners of the flocks were interviewed regarding some demographic, husbandry and productivity variables of the flocks on the day of blood sampling. A competitive enzyme-linked immunosorbent assay was conducted to test the serum samples for BTV group-specific antibodies. BTV seropositive reactions were obtained in 184 (48.4%) out of 380 tested sera, and in 89.5% (34/38) of the flocks. In the 34 seropositive flocks, the prevalences ranged from 12.5 to 100% (median = 47). A multivariable logistic analysis was carried out to study the influence of demographic and productivity variables on the BTV serological status of the sheep flocks. Abortion risk in the previous lambing season was mildly associated with the serological status of the flock (adjusted odds ratio = 1.16, P = 0.07). For the seropositive flocks, a linear multiple regression showed that distance travelled by the flock during transhumant movement was significantly associated with percent seropositivity (partial regression coefficient (± SE) = − 0.091 ± 0.045).     

Maedi-visna impact on productivity in Quebec sheep flocks (Canada)

An epidemiological study was conducted to determine the impact of maedi-visna (MV) seropositivity on productivity in commercial sheep flocks of the province of Quebec, Canada. A total of 1734 ewes and 220 rams were selected randomly from 29 flocks distributed in the Bas-St-Laurent and Estrie regions. Serostatus was determined with an enzyme-linked immunosorbent assay (ELISA) using recombinant proteins.Flock-specific, animal-level seroprevalence varied from 3 to 70% (median=29%). Seroprevalence increased with age and size of the flock, and was higher in ewes relative to rams (but was not associated with body score). A decrease of 0.94 kg per lamb in weaning weight was seen only for lambs raised by seropositive ewes >/=4 years old, and seropositivity in ewes of any age was associated with an increase in 0-30 days lamb-mortality (OR: 1.65). The impact of MV infection on weaning weight and lamb mortality did not vary between flocks, and seropositivity in ewes was not associated with litter size or lamb's birth weight.     

Seroprevalence of Brucella ovis infection in commercial ram flocks in the Tamworth area

Commercial ram flocks in the Tamworth area of northern New South Wales were surveyed to estimate the proportion of flocks, and rams, infected with Brucella ovis. The flock prevalence (percentage of flocks containing seropositive rams) of 9.1% for Merino flocks was significantly lower than that for British-breed flocks (43.8%, p=0.006) and mixed-breed flocks (46.7%, p=0.017). The mean flock prevalence over all flock types was 32.9%. These estimates were supported by data obtained from diagnostic testing for brucellosis carried out during the previous 6 years. The seroprevalence in rams was 10.8% overall, 2.5% for Merinos, 19% for Border Leicester and 26% for Dorset rams. Within infected flocks, the estimated prevalences were 21%, 65% and 67% for Merinos, Border Leicester and Dorset rams respectively. The seroprevalence in Merino rams was significantly lower than that for both other breeds (p<0.001) for all flocks and in infected flocks. There was no apparent association between age and serological status, or age and the prevalence of epididymitis.     

Prevalence of Bovine viral diarrhoea virus (BVDV) antibodies among sheep and goats in India

The aim of this study was to determine the prevalence of pestivirus antibodies in sheep and goats in India. A total of 2803 serum samples collected between 2004 and 2008 from 1777 sheep in 92 flocks and 1026 goats in 63 flocks belonging to 13 states were tested by competition ELISA for detection of pestivirus antibodies. In sheep, the true prevalence rate was 23.4% (95% confidence interval: 22.9%–27.0%) and in goats it was 16.9% (95% CI: 16.4%–21.3%). The flock level seroprevalence was 66.3% for sheep and 54.0% for goats. Geographical variation in individual and flock prevalence was highly significant. A significant association (p?<?0.05) was found between sheep and goat flocks having cattle contact and the flock level seroprevalence. The seroprevalence was lower in 6 months–1 year age group compared to the 1–2 year and >2 year age groups in both sheep and goats. Cross neutralization studies on 61 seropositive sheep and 34 seropositive goat samples representing all positive flocks, exhibited > four fold higher titre to bovine viral diarrhoea virus type 1 (BVDV-1) in 41 sheep and 23 goat samples and to BVDV-2 in one sheep and goat each. This study for the first time showed serological evidence of wide spread BVDV infections in Indian sheep and goats, with BVDV-1 predominating and BVDV-2 occasionally besides highlighting the potential risk of infection to other species, which needs to be considered whenever BVD control measures are initiated.     

Risk factors for brucellosis seroprevalence of sheep and goat flocks in Spain

Risk factors for ovine and caprine brucellosis in the Ávila region (center of Spain) were evaluated using data from a cross-sectional study of the most important diseases of small ruminants in this Spanish region between 1996 and 1997. Questionnaire data from 56 herds (35 ovine and 21 caprine) were used. Sixteen (29%) flocks (3 caprine and 13 ovine) were brucellosis-seropositive. Overall, 0.7% of sheep and 0.1% of goats were seropositive. Eleven risk factors were studied at the group level by logistic regression using flock brucellosis-status as outcome, and by linear regression using percentage of brucellosis-seropositivity as outcome. Both final models contained the same variables: contact with sheep and grazing in communal pastures as risk factors, and frequency of disinfecting practices as a protective factor.     

Impact of natural sheep-goat transmission on detection and control of small ruminant lentivirus group C infections

Dissemination of small ruminant lentivirus (SRLV) infections in Norway is affected by the different control strategies used for maedi-visna virus (MVV) infections in sheep and caprine arthritis-encephalitis virus (CAEV) infections in goats. Here we investigated SRLV phylogenetic group variants in sheep. CAEV-like isolates, belonging to phylogenetic group C, were found among both seropositive sheep and goats in mixed flocks, in which sheep and goats are kept together. Intra-herd clustering confirmed that mixed flock animals were infected by the same virus variant, suggesting ongoing interspecies transmission. Few sheep flocks were found to be infected with the MVV-like phylogenetic group A. The apparent absence of SRLV group A type in goats is probably due to the MVV control programme and animal management practices. SRLV group C targets lungs and mammary glands in sheep, and induces typical SRLV pathological lesions. SRLV group C isolated from the sheep mammary glands suggested a productive infection and potential for transmission to offspring. SRLV group C was most prevalent among goats. A lower PCR sensitivity in seropositive sheep suggested a lower load of SRLV group C provirus in sheep than in goats. Higher genetic divergence of group C than in other SRLV groups and extensive heterogeneity among group C isolates in the matrix C-terminal region demonstrate the need for identifying conserved target regions when developing PCR protocols for SRLV detection. As sheep and goats may serve as reservoirs for all SRLV genogroup types, successful control programmes require inclusion of both species.     

Seroprevalence of Q fever (coxiellosis) in sheep from the Southern Marmara Region, Turkey

Little information is available in Turkey on Q fever, a zoonose caused by Coxiella burnetii and transmitted from domestic ruminants. This study aimed at investigating the seroprevalence in sheep flocks from three provinces (Bursa, Balikesir and Canakkale). Serosurvey was undertaken on 42 flocks, which were categorised by sizes. Sera were collected randomly from specific age groups within the young population. CHEKIT Q-fever ELISA kit was used to identify the infection in sheep. The results showed that 20% (n=151) of sheep were seropositive. A total of 34 flocks (81%) revealed at least one seropositive animal. Higher seroprevalence was observed in Balikesir region. Larger flocks resulted more infected than medium and small flocks. An association was found between seropositivity and age, when the primiparous ewes (1-year old) had higher antibodies rates than newborn sheep (aged less than 10 months) or biparous ewes (2 years old). These results showed that Q fever infection was common and circulating in the studied region, hence encourage efforts to propose measures that could reduce the spread and the zoonotic risk.     

Identification of Leptospira spp. carriers among seroreactive goats and sheep by polymerase chain reaction

Few studies were conducted on the diagnosis and control of small ruminants’ leptospirosis. Thirteen goat herds and seven sheep flocks located in the state of Rio de Janeiro, Brazil, were screened for leptospirosis. From the three herds and three flocks with greatest seroreactivity by MAT (Microscopic Agglutination Test), 19 and 40 seropositive goats and sheep, respectively, were selected, and urine samples were collected for bacteriology and PCR. For both species of animals, the most prevalent reactions were due to serogroups Sejroe and Shermani. Although leptospires were observed by darkfield microscopy in eight samples, pure isolates were obtained by bacteriological culture from only two samples. However, twelve urine samples (six goats and six sheep) were positive by PCR. Based on these findings, we consider that the combined use of MAT as a screening test followed by urine PCR for the direct detection of Leptospira spp. DNA was adequate for the identification of carrier animals among goats and sheep. These are valuable tools for the control of leptospirosis in small ruminants.     

Prevalence and distribution of Peste des petits ruminants virus antibodies in various districts of Tanzania

Despite the widespread prevalence of infection with Peste des petits ruminants virus (PPRV) in goats and sheep industry in Asia and sub-Saharan Africa, there have been few, if any, structured population-based studies examining the epidemiology of this infection in Tanzania. In this study, we investigated the seroprevalence, and risk factors, of Peste des petitis ruminants(PPR) in sheep and goat flocks from seven different geographical administration authorities (Ngorongoro, Monduli, Longido, Karatu, Mbulu, Siha and Simanjiro) located in Northern Tanzania. Serum samples from 657 and 892 sheep and goats, respectively, corresponding to 91 sheep/goat flocks and 43 villages were collected. Competitive enzyme linked immunosorbent assay (c-ELISA) was used to detect the presence of antibodies in the serum against PPRV. Chi-square analysis and multivariable logistic regression model were used to identify risk factors for PPRV seropositivity. Findings suggested that the sero-positive cases were significantly higher in goats than in sheep (49.5% versus 39.8%; P = 0.002). The overall seroprevalence of PPRV infection in small ruminants was 45.8%. Highest seroprevalence (42.6–88.02%) was observed in Mbulu, Siha, Longido, Ngorongoro districts, while antibodies less than 40% to none were found in serum from Monduli, Karatu and Simanjiro, respectively. These findings confirm natural transmission of PPRV under field condition for the first time in Tanzania. Results may be correlated with variations in the sheep and goat husbandry practices within different geographic localities, the uncontrolled movement of animals, the levels of natural immunity and the sharing of grazing field amongst agro and pastoralists.     

Serological survey and epidemiological investigation of maedi-visna in sheep in Finland

A survey for antibodies to maedi-visna virus (MV) in the Finnish sheep surveillance flocks was conducted in 1994. Examination of a total of 12931 serum samples from animals over 1 year of age from 545 flocks (81% of all flocks) revealed eight seropositive flocks and the subsequent epidemiological investigation yielded one additional seropositive flock, indicating a low prevalence of 1.6%. The infection was very probably imported from Sweden in 1981, but it was not detected until the survey was conducted 13 years later. The entire primary infection flock was slaughtered in 1995. 77% of the sheep were seropositive but the animals were clinically healthy and only one (5%) of the contact flocks of the primary infection flock had contracted the infection. This secondary infection flock, 77% of which was seropositive, was slaughtered in 1994; however, animals in this flock had respiratory problems and the lungs of three sheep showed typical MV lesions. Seven (24%) of its contact flocks had contracted the infection and these each had one or two seropositive animals except for one flock which had seven (18%) seropositive animals. The results show that the initial spread of MV can be insidious and wide before infection is revealed in surveys or any clinical cases are encountered.     

Anthelmintic resistance of nematode parasites of small ruminants in eastern Ethiopia: exploitation of refugia to restore anthelmintic efficacy

Faecal egg count reduction tests (FECRT) were conducted in May 2003 to determine the efficacy of anthelmintics used for treatment against nematode parasites in separately managed sheep and goat flocks at Alemaya University in eastern Ethiopia. These tests revealed high levels of anthelmintic resistance to albendazole, tetramisole, the combination of these two drugs, and to ivermectin in the goat flock (predominantly infected by Haemonchus contortus and Trichostrongylus spp.), whereas all drugs were highly efficacious in the sheep flock. A second FECRT confirmed these observations. Following this, a new management system was implemented on the goat flock for a period of 9 months (January-September 2004) in an attempt to restore the anthelmintic efficacy. This involved a combination of measures: eliminating the existing parasite infections in the goats, exclusion from the traditional goat pastures, and introducing communal grazing of the goats with the university sheep flock and livestock owned by neighbouring small-holder farmers. A second series of FECRTs (Tests 3 and 4) conducted 7 months after this change in management, showed high levels of efficacy to all three drugs (albendazole, tetramisole and ivermectin) in the goat flock. This is the first field study to demonstrate that anthelmintic efficacy in the control of nematode parasites of small ruminants can be restored by exploiting refugia.     

Seroepidemiological survey of sheep flocks from Northern Japan for Mycoplasma ovipneumoniae and Mycoplasma agalactiae

Sheep flocks from Hokkaido, Iwate and Aomori, three northern prefectures of Japan, were screened for antibodies to Mycoplasma ovipneumoniae and Mycoplasma agalactiae by ELISA. Sixty four animals out of 246 (26%) were seropositive to M. ovipneumoniae, with positive results obtained from all three prefectures. None of the sera tested were serologically positive to M. agalactiae.     

A case-control study on scrapie in Norwegian sheep flocks

Scrapie first was detected in indigenous sheep in Norway in 1981, and from 1995 to 1997 an increase in the number of flocks with scrapie cases was recorded. These flocks were mainly in one geographical region. A study to identify risk factors for scrapie was conducted. The study had three frequency-matched controls selected for every case within the same Veterinary District. A questionnaire was submitted to 176 sheep flocks (42 had been scrapie flocks). The data obtained by the questionnaire were linked to data collected from governmental and industry registers. After imputing missing data using single random imputation, the statistical analysis was performed using multivariable conditional logistic regression.

Purchase of female sheep from scrapie flocks, sharing of rams, or sharing of pastures between different flocks were the risk factors associated with the occurrence of scrapie. Of factors potentially sustaining and promoting the infection in the flock, number of winter-fed sheep, number of buildings for housing sheep, rams and ewes shared room during mating period and increase in the flock size were associated with scrapie. We interpret these findings to show that factors involving transfer of sheep between flocks or direct contact between sheep of different flocks are important for the spread of scrapie. Management factors are important for the development of scrapie. However, it was not possible to discriminate between the different management factors in this study at the flock level. Also, factors indicating awareness and interest of the farmer (as well as willingness to contact a veterinarian for diseased sheep) were related to the detection of scrapie in the flock.     

Ovine and caprine toxoplasmosis (Toxoplasma gondii) in aborted animals in Jordanian goat and sheep flocks

Two hundred and fifty-five biological samples (106 aborted foetal tissue samples and 149 blood samples from aborted sheep and goats) were collected from 188 animals during the lambing season from September 2009 to April 2010 from the Mafraq region of Jordan. The sampled animals belonged to 93 goat and sheep flocks that had cases of abortion. A total of 169 (66.3%) biological samples were collected from sheep and 86 (33.7%) from goats. Seventy-six (29.8%) biological samples (45 blood and 31 tissue samples) were positive for Toxoplasma gondii by PCR assay. The positive samples were obtained from 43 sheep and 23 goats. The overall toxoplasma-specific prevalence rate was 35.1% (66/188). Forty flocks (43%) had at least one T. gondii PCR-positive animal. The risk factors related to flock health status and farm management that are hypothesized to be associated with T. gondii PCR positivity were also assessed using multiple logistic regressions. The presence of cats (OR = 4.74), a large flock size (OR = 2.76) and the method of disposing the aborted foetuses (OR = 3.77) were all statistically significant (P < 0.05) risk factors that were positively associated with toxoplasma positivity in goat and sheep flocks.     

Investigation and control of mastitis outbreaks caused by Pseudomonas aeruginosa in a sheep flock and a goat herd

Outbreaks of mastitis in a sheep flock and a goat herd caused by Pseudomonas aeruginosa, and their control are described.The morbidity rates of mastitis in a sheep flock and in a goat herd were 18.7 and 18.2 per cent, respectively. The lethality and involuntary culling rates of the animals with sub-clinical mastitis correspond to the morbidity rate.The highest morbidity rates were noted in yearlings--22.5 and 30 per cent, as well as in animals pre- and post partum (7 and 20 per cent, in sheep and goats, respectively). The morbidity periods in the flock and in the herd were 20 and 27 months, respectively. A strict-hygiene milking programme and maintenance of the milking devices was introduced. In addition, prevention of crowding, provision of dry bedding and thorough cleaning of water troughs have also been instituted. Ruthless culling of all infected and carrier animals was an essential part of the control program against Pseudomonas aeruginosa mastitis.     

Seroprevalence of ovine progressive pneumonia virus in sheep in the United States as assessed by analyses of voluntarily submitted samples.

Ovine progressive pneumonia (OPP) is a lentivirus-induced disease of sheep in the United States that is similar, if not identical, to maedi/visna in many other countries. Prevalence estimates of seropositivity to this virus in sheep in the United States have been confined to limited groups or flocks of sheep and have varied from 1 to 90%. In this study of detection of antibodies against OPP virus, we found a lower general prevalence of antibodies to OPP virus in sheep than was previously reported. Of 16,827 sheep from 29 states in the United States, 26% were seropositive and 48% of 164 flocks that were tested had 1 or more seropositive sheep. Seropositivity to OPP virus for sheep within special categories was determined, although nonrandom samples that were available may have biased the results. Within regions of the United States, prevalence was highest in the Rocky Mountain region at 49% and lowest in the northern Atlantic region at 9%. Seropositive sheep were not evenly distributed among flocks, but were clustered in a few flocks of sheep. A high number of flocks had no or few seropositive sheep. Prevalence increased with age from 4% at less than 1 year to a plateau of 34% at 4 years. Seropositivity was variable among breeds and was not associated with sex, wool class, or place of origin of ancestors.     

Seroprevalence and risk factors associated with Visna/Maedi virus in semi-intensive lamb-producing flocks in northwestern Spain

A cross-sectional study was carried out to determine Visna/Maedi virus (VMV) seroprevalence and risk factors in semi-intensive lamb-producing flocks as a prelude to establishing a monitoring program in northwestern (NW) Spain. A total of 15,155 serum samples were taken from 78 commercial flocks and were submitted to an indirect VMV ELISA. Association between potential risk factors and seroprevalence at the flock level was assessed using a multivariable logistic regression model. A Generalized Estimating Equations (GEE) model and Exhaustive Chi-squared Automatic Interaction Detector (CHAID) were used to determine the seropositivity against VMV at the individual animal level. Individual seropositivity was 24.8% while 52.6% of the flocks examined had a true seroprevalence ≥1%. Flock size and introduction of new animals in the flock were significantly associated with seropositivity at the flock level. Flock size, sheep-goat contact, type of housing of lambs prior to weaning and age were significantly associated with individual VMV seropositivity. Confinement of lambs in preweaning lamb groups and high sheep-goat contact, regardless of the low number of goats per flock, were risk factors associated with individual VMV seropositivity, suggesting that these two factors are crucial for VMV control in semi-intensive lamb-producing flocks. These factors should be considered for developing more efficient strategies that will reduce the rate of VMV transmission.