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1.
A province-wide, cross-sectional seroprevalence and agroecological risk factor study of Mycobacterium avium subspecies paratuberculosis (MAP), Neospora caninum (NC), Bovine leukemia virus (BLV), and Bovine viral diarrhea virus (BVDv) genotypes 1 and 2 (BVDv1 and BVDv2) infection in dairy cattle herds in Alberta was conducted. Among adults, the seroprevalence of MAP, NC, and BLV was 9.1%, 18.5%, and 26.9%, respectively. For MAP, based on a herd test cutpoint of 2 or more seropositive cows, 58.8% of herds were infected. Herd-level seroprevalence for NC and BLV was 98.7% and 86.7%, respectively, based on a herd-test cutpoint of 1 seropositive cow. Among unvaccinated dairy heifers, the seroprevalence for BVDv1 and BVDv2 infection was 28.4% and 8.9%, respectively, while herd-level infection was 53.4% and 19.7%. Seroprevalence for MAP varied moderately by agroecological region, whereas that for NC, BLV, and BVDv1 and BVDv2 did not. For MAP, aridity and soil pH (correlated features of the region) were also important.  相似文献   

2.
OBJECTIVE: To estimate seroprevalence of antibodies against the serogroup of epizootic hemorrhagic disease viruses (EHDVs) and describe spatial distribution of antibodies against EHDV among cattle herds in Illinois and western Indiana. SAMPLE POPULATION: 9,414 serum samples collected from cattle in 60 herds over 3 transmission seasons. PROCEDURES: Serum samples were tested for antibodies against EHDV by use of an ELISA. Seroprevalence for 4 zones covering the length of Illinois and parts of Indiana were estimated. A multivariable mixed-effects logistic regression model with a random effect for herd was used to estimate seropositive risk for zone (1 through 4), age (yearling, adult), herd type (beef, dairy), transmission season (2000 to 2002), and zone by year interaction. Isopleth maps of seroprevalence at the herd level were produced. RESULTS: Antibodies against EHDV were detected in 1,110 (11.8%) samples. Estimated seroprevalence in 2000, 2001, and 2002 was 15.3%, 13.4%, and 5.2%, respectively. Seroprevalence was highest in the southernmost zone and lowest in the northernmost zone, but risk of seropositivity for EHDV among and within zones varied by year. Clusters of high seroprevalence in the south, low seroprevalence in the north, and outliers of high and low seroprevalence were detected. Risk mapping revealed areas of higher seroprevalence extending northward along the western and eastern ends of the study region. CONCLUSIONS: Seroprevalence of antibodies against EHDV in cattle was higher in the south than north; however, local complexities existed that were not observed in a serosurvey of antibodies against bluetongue virus from the same cattle population.  相似文献   

3.
OBJECTIVE: To estimate seroprevalence of Mycobacterium avium subsp paratuberculosis (MAP) infection among adult dairy cows in Colorado and determine herd-level factors associated with the risk that individual cows would be seropositive. DESIGN: Cross-sectional observational study. ANIMALS: 10,280 adult (> or = 2 years old) dairy cows in 15 herds in Colorado. PROCEDURE: Serum samples were tested with a commercial ELISA. A herd was considered to be infected with MAP if results of mycobacterial culture of > or = 1 individual cow fecal sample were positive or if > or = 1 culled cow had histologic evidence of MAP infection. RESULTS: 424 of the 10,280 (4.12%) cows were seropositive. Within-herd prevalence of seropositive cows ranged from 0% to 7.82% (mean, 2.6%). Infection was confirmed in 11 dairies. Cows in herds that had imported > or = 8% of their current herd size annually during the preceding 5 years were 3.28 times as likely to be seropositive as were cows in herds that imported < 8%. Cows in herds with > or = 600 lactating cows were 3.12 times as likely to be seropositive as were cows in herds with < 600 lactating cows. Cows in herds with a history of clinical signs of MAP infection were 2.27 times as likely to be seropositive as were cows in herds without clinical signs. CONCLUSIONS AND CLINICAL RELEVANCE: Annual importation rate, herd size, and whether cows in the herd had clinical signs typical of MAP infection were associated with the risk that individual cows would be seropositive for MAP infection.  相似文献   

4.
Mycobacterium avium subsp. paratuberculosis (MAP) and Neospora caninum (NC) are two pathogens causing important production limiting diseases in the cattle industry. Significant impacts of MAP and NC have been reported on dairy cattle herds, but little is known about the importance, risk factors and transmission patterns in western Canadian cow-calf herds. In this cross-sectional study, the prevalence of MAP and NC infection in southwest Alberta cow-calf herds was estimated, risk factors for NC were identified, and the reproductive impacts of the two pathogens were assessed.  相似文献   

5.
OBJECTIVE: To estimate seroprevalence of bluetongue virus (BTV) and the geographic distribution of seropositive cattle herds in Illinois and western Indiana. SAMPLE POPULATION: 10,585 serum samples obtained from cattle in 60 herds during 3 transmission seasons (2000 through 2002). PROCEDURES: In a longitudinal study, serum samples were tested for BTV antibodies by use of a competitive ELISA. Four geographic zones were created by use of mean minimum January temperature. A multivariable mixed-effects logistic regression model with a random effect for herd was used to estimate seropositive risk for zone, age of cattle, herd type, and transmission season. RESULTS: Overall, BTV antibodies were detected in 156 (1.5%) samples. Estimated seroprevalence in 2000, 2001, and 2002 was 1.49%, 0.97%, and 2.18%, respectively. Risk of being seropositive for BTV was associated with geographic zone and age. Seroprevalence increased progressively from northern to southern zones, with no evidence of BTV infection in the northernmost zone. In the southernmost zone, annual seroprevalence ranged from 8.65% to 11.00%. Adult cattle were 2.35 times as likely as juvenile cattle to be seropositive. CONCLUSIONS AND CLINICAL RELEVANCE: Overall seroprevalence was lower than has been reported for Illinois cattle. Bluetongue virus antibodies were distributed heterogeneously in this region. Only in the southernmost zone was seroprevalence consistently > 2%. Regionalization of BTV risk based on state borders does not account for such variability. Serologic data could be combined with landscape, climate, and vector data to develop predictive models of BTV risk within transitional regions of the United States.  相似文献   

6.
OBJECTIVE: To investigate herd characteristics and management practices associated with a high seroprevalence of Mycobacterium avium subsp paratuberculosis (MAP) in dairy herds in central California. SAMPLE POPULATION: 60 randomly selected cows from each of 21 dairy herds. PROCEDURES: Sera of selected cows were tested for antibodies against MAP by use of an ELISA test kit. Cows with a test sample-to-positive control sample (S:P) ratio of > or = 0.25 were considered seropositive, and herds with > or = 4% seropositive cows were considered high-seroprevalence herds. Data on herd characteristics and management practices were collected via interviews with owners. Bayesian logistic regression was used to model the predictive probability of a herd having a high seroprevalence on the basis of various herd characteristics and management practices. RESULTS: 9 of 21 (43%) herds were classified as high-seroprevalence herds. Five variables (history of previous signs of paratuberculosis in the herd, herd size, exposing cattle to water from manure storage lagoons, feeding unsalable milk to calves, and exposing heifers < or = 6 months old to manure of adult cows) were included in the predictive model on the basis of statistical and biological considerations. In large herds, the predictive probability of a high seroprevalence of MAP infection decreased from 0.74 to 0.39 when management changed from poor to good practices. In small herds, a similar decrease from 0.64 to 0.29 was predicted. CONCLUSIONS AND CLINICAL RELEVANCE: The seroprevalence of MAP infection in California dairies may be reduced by improvements in herd management practices.  相似文献   

7.
Sera were collected using a systematic random sampling from 348 cattle herds in Ontario, in proportion to the cattle population in different areas. One cow in five from 296 dairy herds and one in three from 52 beef herds were sampled. The sera were analyzed for prevalence of antibodies to Leptospira interrogans serovar grippotyphosa, hardjo, icterohaemorhagiae and pomona using the microscopic agglutination test. Herd seroprevalence (one or more animals with titer greater than or equal to 80) in beef and dairy herds combined was grippotyphosa 2%, hardjo 13.8%, icterohaemorrhagiae 10.1% and pomona 25.8%; 39% of all herds showed evidence of leptospiral infection with one or more serovars; 44.2% of 52 beef herds had serological evidence of infection with serovar hardjo compared to 8.4% of 296 dairy herds (P less than 0.0001). Seroprevalence of other serovars was not significantly different between beef and dairy herds. The proportion of beef animals seropositive for hardjo and for pomona increased with age, particularly for hardjo; 26.5% of beef animals aged nine years or over were seropositive for hardjo. Dairy animals showed a significant rise of hardjo but not pomona titers with age. The seroprevalence of pomona infection was significantly higher in dairy cattle in eastern Ontario than in other regions. Thirty-four (6.1%) of 553 aborted bovine fetuses had leptospires detected by immunofluorescence techniques. Sixty-five percent of these fetuses were from submissions made between November and January. Leptospires were identified as serovar hardjo by specific immunofluorescence. There appeared, however, to be a paradoxical serological response in that eight aborting cows had antibody titers to pomona rather than hardjo.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

8.
OBJECTIVE: To evaluate the seroprevalence of paratuberculosis by use of 2 commercial ELISAs in association with prevalence of fecal shedding of mycobacteria within beef cattle herds. DESIGN: Cross-sectional field study. ANIMALS: Six beef herds (affected herds; 522 cattle) with and 3 geographically matched herds (181 cattle) without high seroprevalence of paratuberculosis. PROCEDURES: Blood and fecal samples were collected from adult cattle and assessed for serum anti-Mycobacterium avium subsp paratuberculosis (MAP) antibodies with 2 commercial ELISA kits and submitted for bacterial culture for MAP and environmental bacteria (termed environmental mycobacteria) via a radiometric method, respectively. Species of mycobacterial isolates were identified, and sensitivities and specificities of the 2 ELISAs were compared. RESULTS: Compared with comparison cattle, cattle from affected herds were 9.4 times as likely to have environmental mycobacteria isolated from feces. Among the 6 affected and 3 comparison herds, the proportions of cattle shedding environmental mycobacteria were 0.225 (range, 0.1 to 0.72) and 0.04 (range, 0 to 0.06), respectively. Although relative MAP- detection specificities (compared with bacterial culture of feces) were different between the 2 ELISAs, sensitivities were not. Nine environmental mycobacterial species were identified from participating herds. All affected herds apparently had > or = 1 bovid infected with MAP, although MAP was not isolated from any cattle in comparison herds. CONCLUSIONS AND CLINICAL RELEVANCE: In beef herds with persistently high rates of false- positive ELISA results, which may be associated with recovery of environmental myco- bacteria from feces, organism detection via bacterial culture of feces or PCR assay should direct paratuberculosis control measures.  相似文献   

9.
We estimated spatial hierarchal variances and age-group covariances for seroprevalence to Leptospira interrogans serovar hardjo (LeptoH), bovine viral-diarrhea virus (BVDV) and bovine herpesvirus type 1 (BoHV-1) among 2343 cattle from 72 properties sampled in the State of Paraíba, Brazil in 2000. From each property, eight animals in each of the four age categories were evaluated. The age categories studied were: pre-weaned (0–6 months), young (7–18 months), replacement (19–30 months) and mature (>30 months). Overall seroprevalence to LeptoH was 16.0% and showed clustering at all levels of the spatial hierarchy and had a high posterior probability of being negatively correlated between replacement and mature groups within herds. Seroprevalence to BoHV-1 was 46.6% and demonstrated very little clustering among levels of the spatial hierarchy and was positively correlated between young and replacement groups within herds. Seroprevalence to BVD was 22.2% and was strongly clustered within herds and was positively correlated between young and replacement age groups within herds.  相似文献   

10.
Serum samples collected in a cross-sectional survey of grazing cattle on Manyara Ranch, Monduli district, Tanzania, were tested by indirect major antigenic protein 1 fragment B (MAP 1-B) ELISA to determine the seroprevalence of Ehrlichia ruminantium and to assess ranch-level risk factors for heartwater. Heartwater-exposed cattle were widespread on the ranch and overall seroprevalence was 50.3% (95% CI, 44.9-55.6), enough to indicate an endemically unstable situation. Multivariate logistic regression modelling was used to identify risk factors associated with seropositivity. Two factors appeared to increase the herd's risk for contracting heartwater. Seroprevalence increased significantly with age (beta = 0.19 per year of age, P < 0.001) and animals carrying ticks of any species were associated with an increased risk of infection with E. ruminantium (Odds ratio, OR = 3.3, P < 0.001). The force of infection based on the age seroprevalence profile was estimated at 18 per 100 cattle year-risk. The current tick control measures on the ranch were associated with a decreased risk of infection with E. ruminantium (OR = 0.25 for no dipping and OR = 0.31 for low dipping, P < 0.001). Six tick species were identified; in order of frequency these were: Ambylomma variegatum 59.9%, Rhipicephalus evertsi evertsi 13.9%, Rhipicephalus pulchellus 12.5%, Hyalomma truncatum 7.03% and Rhipicephalus appendiculatus 6.07%. The least encountered tick was Rhipicephalus simus, which accounted for 0.38%. The cattle seemed well adapted to their environment and capable of resisting the tick burden under this extensive wildlife/livestock grazing and interaction system.  相似文献   

11.
The seroprevalence, in dairy cattle, of antibodies to Neospora caninum, the relationship between seropositivity and age (heifer versus cow), the relationship of herd infection with herd size and the relationship of herd infection with the presence of dogs on the farm were studied. The study involved 549 cows and 82 dogs in 59 dairy herds in Nakhon Pathom, Thailand. A competitive enzyme-linked immunosorbent assay (cELISA) with NC-specific monoclonal antibody was used to detect the NC antibodies in the sera. Individual and herd seroprevalence of NC were 5.5% (30/549) and 34% (20/59), respectively. No significant relationships between NC seropositivity with the age of the cows (heifer versus cow; P > 0.05) and between herd infection and the presence of dogs on the farm (P > 0.05) were found. Herd size significantly affected herd infection (P < 0.05) with higher infection in large than small herds (> or = 21 versus < or = 20 cows). Of 12 cows with a history of abortion, one was seropositive to NC. The seroprevalence of NC antibodies in dogs was 1.2% (1/82). This is the first NC seroprevalence study in dogs in Thailand. It was concluded that Neospora infection was more common at the herd level rather than the individual level in Thailand and the presence of dogs on the farm was not related to the level of herd infection. Caution should be taken in the interpretation of serological tests from the farm dogs.  相似文献   

12.
OBJECTIVE: To describe the distribution and prevalence of cattle herds with detectable antibody to bovine pestivirus in Queensland in 1994/95. MATERIALS AND METHODS: The study used 7,838 serum samples collected from 250 herds in Queensland, as part of a structured animal health surveillance program conducted in 1994 and 1995. Samples were collected from female cattle bred on the property. In each herd, 10 to 20 heifers less than two years of age and 10 to 15 older cows were sampled giving a 95% probability of detecting one or more seropositive animals if the seroprevalence was approximately 10% or greater. Sera were analysed for antibodies to bovine pestivirus using a virus neutralisation test. RESULTS: Total cattle numbers in sampled herds varied from 62 to 24,600 head, while total area of properties sampled varied from 50 to 395,400 hectares. Eleven percent of herds contained no seropositive animals among those sampled, and in 38% of herds, all sampled cattle aged one to two years of age were seronegative. There was a trend for larger herds to have one or more animals seropositive for bovine pestivirus (chi-squared for Linear trend = 3.656, p = 0.056). Herds with more than 500 head of cattle were significantly more likely than herds with less than 500 head to contain one or more seropositive animals in any age group (prevalence ratio = 1.12; 95% confidence interval 1.01 - 1.23; p = 0.026). Age specific seroprevalence increased from around 10% in heifers, to between 75% and 85% in cows aged 10 years. The average annual incidence risk for bovine pestivirus infection varied from 0.12 to 0.24 seroconversions per cattle year at risk, and did not vary with age. The overall crude seroprevalence adjusted for herd size was 45%. There was a wide range of seroprevalence recorded for each level of stocking intensity. CONCLUSIONS: This survey provides valuable baseline data on bovine pestivirus infection in Queensland cattle herds.  相似文献   

13.
This work was conducted to estimate the seroprevalence, to identify potential factors that influence seroprevalence of bovine viral diarrhea virus (BVDV), and to investigate the association between BVDV serostatus and occurrence of reproductive disorders in dairy cattle in three milksheds in Ethiopia. A total of 1379 serum samples were obtained from cattle randomly selected from 149 herds from three milksheds representing central, southern, and western Ethiopia. Sera samples were examined for bovine viral diarrhea virus (BVDV) antibodies using commercial competitive enzyme-linked immunosorbent assay (ELISA) kit. Logistic regression analysis was employed to investigate associations between risk factors and the risk of BVDV seroprevalence, and BVDV serostatus and reproductive disorders. Seroreaction to BVDV antigens was detected in 32.6% of the 1379 cattle and 69.8% of the 149 herds sampled. Factors associated with BVDV seroplevalence were age, breed, and herd size (P?<?0.05). Adult cattle ≥?18 months old had 2.1 (95% CI 1.5, 3.1) times the odds of BVDV seroreaction than younger cattle. Holstein-Friesian (HF) local crosses (OR?=?2.1, 95% CI 1.3, 3.4) and HFs (OR?=?1.3, 95% CI 0.9, 1.9) were more likely to be seropositive than Jersey and the odds of seropositivity in cattle in large herds with 11 or more animals were higher (OR?=?1.8, 95% CI 1.3, 2.5) than the odds of BVDV seropositivity in smaller herds. Seroprevalence was not associated with geographical region (P?>?0.05). Risk of reproductive disorders was not affected by BVDV serostatus, except for repeat breeding (P?>?0.05). The present study demonstrated that BVDV has wide distribution in the country being detected in all the 15 conurbations and 69.8% of herds involved in the study.  相似文献   

14.
A seroprevalence study of bovine neosporosis was conducted among 1,927 dairy cattle and 341 water buffaloes from Karnataka and Andhra Pradesh states in plateau of southern peninsular India by employing competitive enzyme-linked immunosorbent assay. Overall, 12.61 and 9.97 % sera samples were found positive for the presence of Neospora caninum antibody, respectively, among cattle and water buffaloes. Out of 1,927 sera samples from cattle, 912 and 1,015 samples were collected from unorganized and organized herds, respectively. The cattle screened were of upgraded Holstein–Friesian and water buffaloes were of graded Surti breed. Significantly (p?<?0.05) higher prevalence was found in the cattle in unorganized herds (16.66 %) in comparison to organized herds (8.96 %). The highest seroprevalence was recorded in the age group of 4 years and above in both type of cattle herds and water buffaloes. There was a significant variation of seroprevalence (p?<?0.05) observed between different age groups of cattle. The rate of seroprevalence increased with the increment in the age of the animals suggesting a possibility of horizontal mode of transmission of the infection from the environment. The percentage of abortion history was more in seropositive group (51.65 %) in comparison to the seronegative group (5.84 %) and the seropositive cattle were 8.84 times more likely to experience abortion than the seronegative cattle. The occurrence of abortion among different age groups varied significantly (p?<?0.05). The findings revealed the presence of neosporosis in the southern peninsular India among cattle and water buffaloes and a strong association between the seroprevalence and abortion.  相似文献   

15.
A cross-sectional study was performed in the livestock–wildlife interface areas of Lochinvar and Blue Lagoon National Parks and the non-interface area of Kazungula to determine the prevalence of antibodies to Brucella spp. in domestic ruminants and identify individual animal risk factors of infection. A total of 1245 cattle from 124 herds and 280 goats and sheep from 29 flocks were tested sequentially for Brucella antibodies using the Rose Bengal test (RBT) and competitive ELISA. In cattle, individual seroprevalence ranged from 14.1% to 28.1%, while herd sero–prevalence ranged from 46.2% to 74.0% in the three study areas. No goat or sheep tested positive for Brucella antibodies. Three types of cattle grazing strategies were encountered: locally grazed herds (LGH), transhumantly grazed herds (TGH) and river flood plain grazed herds (FGH). Brucella seroprevalence was seen to vary according to area and grazing strategy: Lochinvar and transhumant grazed herds recorded the highest figures, respectively. Age, sex and history of abortion were found to have independent effects on individual seroprevalence. This study establishes that brucellosis is endemic in domestic animals in the livestock–wildlife interface areas of Blue Lagoon and Lochinvar national parks and the disease is also present in Kazungula. We observed that type of grazing strategy had significant impact on cattle Brucella seroprevalence and that transhumant herds were at high risk of being infected.  相似文献   

16.
A study to evaluate BVDV-prevalence, recent -contact and -vaccine use in dairy herds in the "Entre Douro e Minho" (EDM) region in North Portugal was carried out in 124 dairy herds in 2003. Herds were visited to ascertain BVDV-vaccine use and to collect a bulk tank milk (BTM) sample and serum from 1268 cattle to analyse BVDV-antibodies using an NS2-3 ELISA. Fifty-three percent of farmers used inactivated BVDV-vaccines whilst the remaining farmers were not presently using BVDV-vaccines. BMT-antibody results included 35% positives, 25% negative and 39% inconclusive, and were similar in vaccinated and non-vaccinated herds (p>0.05) and allowed estimating a 10% BVDV herd-prevalence from prior knowledge of the relationship between BMT-antibody results and probability of PI cattle in the herd. Overall individual seroprevalence was 27% and was 23% in non-vaccinated and 36% in vaccinated cattle (p<0.05). Contact of the herd with BVDV was assessed according to seroprevalence in young and adult cattle in the herd and it was estimated that 35% of herds were infected or had recent contact with BVDV, 40% were not infected and did not have recent contact with BVDV and the BVDV-infection and -contact status of remaining herds was undetermined. The results from this study indicate BVDV is endemic and BVDV-vaccines are widespread in the dairy-cattle population in EDM region in Portugal.  相似文献   

17.
Our objective was to determine the risk factors associated with the seroprevalence of Mycobacterium avium subspecies paratuberculosis (MAP) in a large number of randomly selected Canadian dairy herds, controlling for important confounding variables and co-infections with bovine leukemia virus (BLV), bovine viral diarrhea virus (BVDV) and Neospora caninum (NC). Serum samples from 30 randomly selected cows, where available, in 315 herds from seven provinces were tested for antibodies against BLV, MAP and NC using commercially available enzyme-linked immunosorbant assay (ELISA) test kits, while five unvaccinated cattle >6 months old from each herd were tested for antibodies to BVDV. We used a zero-inflated negative-binomial (ZINB) multivariable model to determine simultaneously the risk factors associated with the count of MAP-seropositive cows in a herd, and the odds of herds having no MAP-seropositive cows as compared to having one or more MAP seropositive cows in a herd. The following factors were significantly positively associated with the count of MAP-seropositive cows: "more than one cow in the maternity pen", "group-housing for pre-weaned calves in winter", "open heifers purchased during the last 12 months", "beef cattle direct (nose-to-nose) contact", "BVDV-seropositive herds (> or = 1 animal with > or = 1:64 titer)" and "BVD vaccination not done properly in calves" (i.e. after 6 months old, animals were not boostered 2-4 weeks after their first killed vaccine, or not given modified live vaccine), with count ratios of 1.7, 2.0, 2.3, 1.9, 1.4 and 1.8, respectively. The variable "BVDV vaccination (modified live) done properly in calves" (i.e. received another modified live vaccination after 6 months as well) was associated with 0.4 times fewer MAP-seropositive cows.  相似文献   

18.
In November 2011, the new orthobunyavirus Schmallenberg virus (SBV) was identified in dairy cows that had induced fever, drop in milk production and diarrhoea in the Netherlands (Muskens et al., 2012. Tijdschrift voor Diergeneeskunde 137, 112–115) and a drop in milk production in cows in Northwestern Germany (Hoffmann et al., 2012. Emerging Infectious Diseases 18 (3), 469–472), in August/September 2011. This study aimed at quantifying risk factors for high within-herd prevalence of SBV and SBV-induced malformations in newborn calves in dairy herds in the Netherlands. Additionally, the within-herd impact of SBV infection on mortality rates and milk production was estimated.A case-control design was used, including 75 clinically affected case herds and 74 control herds. Control herds were selected based on absence of malformations in newborn calves and anomalies in reproductive performance. SBV-specific within-herd seroprevalences were estimated. Risk factors for high within-herd SBV seroprevalence (>50%) and the probability of malformed newborn calves in a herd were quantified. In addition, within-herd impact of SBV with regard to milk production and mortality was estimated.Animal-level seroprevalence was 84.4% (95% confidence interval (CI): 70.8–92.3) in case herds and 75.8% (95% CI: 67.5–82.5) in control herds. Control herds that were completely free from SBV were not present in the study. Herds that were grazed in 2011 had an increased odds (OR 9.9; 95% CI: 2.4–41.2)) of a high seroprevalence (>50%) compared to herds that were kept indoors. Also, when grazing was applied in 2011, the odds of malformations in newborn calves tended to be 2.6 times higher compared to herds in which cattle were kept indoors. Incidence of malformations in newborn calves at herd level was associated with both within-herd seroprevalence and clinical expression of the disease in adult cattle.The rate of vertical transmission of SBV to the fetus once a dam gets infected seemed low. A total of 146 stillborn or malformed calves were submitted by 65 farmers during the study period, of which 19 were diagnosed as SBV-positive based on pathological investigation and/or RT-qPCR testing of brain tissue. Based on these results combined with calving data from these herds we roughly estimated that at least 0.5% of the calves born between February and September 2012 have been infected by SBV.A drop in milk production was observed between the end of August 2011 and the first half of September (week 35–36), indicating the acute phase of the epidemic. During a 4-week period in which SBV infection was expected to have occurred, the total loss in milk production in affected dairy herds was around 30–51 kg per cow. SBV had no or limited impact on mortality rates which was as expected given the relatively mild expression of SBV in adult cows and the low incidence of malformations in newborn calves.  相似文献   

19.
Leptospirosis is a zoonotic disease with worldwide distribution. The disease affects dairy and beef cattle, causing infertility, abortion, and reduced milk yield. A cross-sectional study was conducted to determine the seroprevalence of leptospirosis in cattle and the associated risk factors in the province of Manabí, Ecuador. Serum samples from 749 animals from 55 cattle herds were analyzed using the microscopic agglutination test (MAT). Animals were considered positive when titers were ≥ 1:100. The association between the potential risk factors and the positive Leptospira result was modeled at both animal and herd level using a generalized linear model with a binomial distribution and logarithmic link. The seroprevalence was 56.21% at the individual level and 98.18% at the herd level. The most prevalent serovars were Pomona (28.57%) and Icterohaemorragiae (22.30%). At the animal level, only the age was associated with leptospirosis seropositivity. Seroprevalence in animals over three years of age was 1.197 (95% confidence intervals (CI), 1.032 – 1.390), higher compared to animals up to three years old. The seroprevalence of Leptospira spp. was higher in farms with no veterinary assistance (PR = 1.209; 95%CI 1.053 – 1.388) and without a vaccination program against Leptospira (PR = 1.399; 95%CI 1.09 - 1.794). In addition, herds from Junín canton had a significantly higher seroprevalence of Leptospira spp (PR = 1.548; 95%CI 1.213 - 1.977) compared to the Bolívar canton, which had the lowest seroprevalence. In conclusion, more than half of the animals were positive to Leptospiraspp, and almost all herds had at least one positive animal. Furthermore, veterinary assistance and vaccination of cattle must be considered as essential aspects of the disease control program.  相似文献   

20.
The seroprevalence of Neospora caninum infection was estimated from a sample of 813 cattle from 20 dairy herds in five regions in Mexico. The true prevalence of infection was estimated to be 42% (95% CI: 39, 46). Seropositivity was associated with abortion (odds ratio (OR)=2.0) and was higher among cows raised on-farm (41%), than among replacement cattle purchased outside the farm (28%). The ORs relating abortion to seropositivity in individual herds ranged from 1.3 to 10. Overall, 26% of the abortions were attributed to N. caninum.  相似文献   

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