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1.
In vitro isolation and characterization of bovine Neospora caninum in Korea   总被引：5，自引：0，他引：5  
The brains of nine aborted bovine fetuses and two newborn calves born from dams suspected to be infected with Neospora caninum were homogenized and inoculated into Vero cells. All fetuses and calves were from cows determined as seropositive to N. caninum by an IFA test. Sera and thoracic fluids of all fetuses and calves also revealed high antibody titer to N. caninum by IFAT ranging from 1:800 to 1:3200. N. caninum was isolated from the brains of one aborted fetus and one newborn calf when the brain homogenates were grown continuously in Vero cell culture. N. caninum tachyzoites, giemsa-positive, were first observed on Days 45 and 56 postinoculation in the newborn calf and the aborted fetus, respectively. The isolates (KBA-1 and KBA-2) were morphologically and ultrastructurally similar to previously published Neospora isolates. The isolated parasites were confirmed as N. caninum by means of the antigenic reactivities, immunostaining, PCR and southern blotting, and electron microscopy.  相似文献   

2.
The protozoa Neospora caninum is an important cause of bovine abortion world-wide. The objective of this survey was to determine the distribution pattern of infectious abortion in Southern Brazil with special reference to N. caninum infection. A total of 161 bovine aborted fetuses from 149 farms were analysed during a 1.5 year period. The cause of abortion was identified in 51.5% of cases. Overall, 23% (37/161) of the fetuses were considered to be infected with N. caninum. Bacterial infection accounted for 17.4% (28/161) of cases, fungal infection for 3.1% (5/161) of cases and viral aetiology for 1.8% (3/161). Six fetuses had concurrent infection with N. caninum and Leptospira spp. Data from 111 fetuses and the respective aborted cows were analysed to investigate the association between previous abortion and current N. caninum infection. The prevalence of N. caninum-infected fetuses from cows with and without a history of previous abortion was 44% (11/25) and 24.4% (21/86), respectively. Cows aborting a N. caninum-infected fetuses were 2.4 times more likely to have aborted previously than cows aborting for other reasons (95% CI of odds ratio=0.9-6.8, P=0.06).  相似文献   

3.
A dairy herd experienced an abortion epidemic during which 43 per cent of the cows at risk aborted. Neospora caninum infection was demonstrated in four of six fetuses suitable for examination and the group of at-risk cows that aborted had significantly higher N. caninum antibody concentrations than the at-risk cows that delivered a live calf at term (P<0.001). The antibody concentrations in the cow herd were significantly higher than in the youngstock (P<0.001), and the concentrations in the youngstock increased significantly (P<0.001) with age. When seven months to a year old, the calves born at term to the at-risk cows had significantly higher (P=0.007) antibody concentrations than age-matched calves born before the epidemic. At the time of the epidemic, there was a significant increase in the antibody levels of the herd that was not consistent with vertical infection alone, indicating that there appeared to have been a sudden large increase in the incidence of horizontal postnatal transmission of N. caninum to the cow herd, or to the surviving offspring of the at-risk cows, or to both of these groups.  相似文献   

4.
Seven pregnant cows (gestation durations, 42 days to 7 months) were identified as culture-positive for Tritrichomonas foetus. For 6 of these pregnancies, 2 of the youngest fetuses were aborted, and calves were delivered by the other 4 cows. Two cows became carriers, maintaining trichomonad infections for 6 and 9 weeks after parturition. Carrier cows may be a source of reinfection for their herd mates. Hence, strategies for controlling trichomoniasis might include delaying the time of first breeding and aggressive culling of infected cows.  相似文献   

5.
Two groups of 10 pregnant cows were inoculated with bluetongue virus type 11 at either 40 or 60 days of gestation. All the cows became infected as judged by the detection of viraemia and seroconversion but they showed no clinical signs. Seventeen of the cows produced live calves none of which showed any evidence of prenatal infection. After challenge with the same virus all the calves became viraemic and seroconverted. The response to challenge of the two groups did not differ from that of a control group challenged at the same time. It was concluded that the infection of pregnant cows in early gestation with this virus did not result in the transplacental infection of the fetuses and did not produce immunotolerant, latently infected calves.  相似文献   

6.
Fifteen pregnant, bovine virus diarrhoea-mucosal disease (BVD-MD) antibody-free Jersey heifers were infected experimentally with a mixture of 10 cytopathic strains of BVD-MD virus isolated from cattle in Britain. Each cow was inoculated intramuscularly on gestation day 100 with a high or a low dose of virus grown in primary calf testis tissue cultures. None of the cows showed clinical signs of illness following exposure, but all had seroconverted within six weeks. Six fetuses, including one set of twins, died in utero following infection. Of these five were aborted between days 136 and 154; the sixth one was mummified and still retained at day 300. The remaining 10 fetuses survived to term, but all showed evidence of intrauterine growth retardation with or without gross malformation and/or dysmyelination of the central nervous system. Three were clinically affected with congenital nervous disease. Of the 10 liveborn fetuses, two had specific serum antibodies to BVD-MD. Non-cytopathic BVD-MD virus was recovered from all of the remaining eight. When non-immune cows become infected with BVD-MD virus in mid gestation: transplacental infection of the fetus will probably result; apart from the risk of fetal death, with or without abortion, there is a high probability of fetal mal-development which may not always be clinically obvious; the immunological competence of the fetus may be impaired; congenital infection is likely in a substantial proportion of liveborn calves. About one in 16 bovine fetuses in British herds are estimated to be at risk from BVD-MD virus infection.  相似文献   

7.
Nine cows which were naturally and persistently infected with Neospora caninum were housed and observed intensively throughout pregnancy. No recrudescence of a latent infection was detected by PCR tests on maternal blood but fetal infection, implying a recrudescence of maternal parasitosis, was associated with a marked increase in maternal antibody. The increase occurred in the second half of pregnancy in five cows which infected their calves, and before mid-pregnancy in one cow which aborted. There was no change in the avidity of the antibody, which remained high and characteristic of long-term infection. In three infected cows that gave birth to uninfected calves there was no marked increase in maternal antibody. Antigen-specific interferon gamma responses of peripheral blood mononuclear cells were observed in all the infected cattle but they did not vary significantly either during pregnancy, or whether the cows did or did not infect their calves, although the responses were consistently higher in the latter. There was no change in the plasma concentrations of cortisol or acute phase proteins associated with the recrudescence of the parasite. Three uninfected cows housed with the infected cows remained uninfected throughout the experiment. No immunosuppressive event was detected which might have provoked parasite recrudescence but the acute antibody rise associated with transplacental infection provides a valuable, non-invasive marker for further studies to investigate the cause and consequences of parasite recrudescence in N caninum infection in cattle.  相似文献   

8.
As a result of a BVDV infection in a herd consisting of 95 adult cattle 17 cows aborted their calves within a period of 3.5 months, one third got severe diarrhoea, 3 cows died and an increased percentage of the cattle got lochiometra after calving or abortion. The disease was diagnosed by paired serological testing of cattle with diarrhoea or abortion and post mortem examination of several aborted calves. From one foetus BVDV virus was isolated and subsequently subtyped by sequencing. Of aborting cattle, the testing results were influenced by the interval between infection and abortion. These results indicate that a primary infection with BVDV subtype 1b can cause severe clinical symptoms in a dairy herd.  相似文献   

9.
Mycobacterium avium subsp. paratuberculosis (Mptb) causes Johne's disease in ruminants. Disease control programmes aim to break the faecal-oral cow-calf transmission cycle through hygienic calf rearing and removal of affected cows from the herd, but these programmes do not take account of the potential for congenital infection. The aims of this study were to critically review research on in utero infection, determine the prevalence of fetal infection in cattle through meta-analysis and estimate the incidence of calves infected via the in utero route. About 9% (95% confidence limits 6-14%) of fetuses from subclinically infected cows and 39% (20-60%) from clinically affected cows were infected with Mptb (P<0.001). These are underestimates for methodological reasons. The estimated incidence of calf infection derived via the in utero route depends on within-herd prevalence and the ratio of sub-clinical to clinical cases among infected cows. Assuming 80:20 for the latter, estimates of incidence were in the range 0.44-1.2 infected calves per 100 cows per annum in herds with within-herd prevalence of 5%, and 3.5-9.3 calves in herds with 40% prevalence. These estimates were not markedly sensitive to the value chosen for the proportion of clinical cases. In utero transmission of Mptb could retard the success of disease control programmes if the opportunities for post natal transmission via colostrum/milk and environmental contamination were able to be controlled. The consequences of fetal infection for the calves so infected are discussed in the context of diagnosis and vaccination together with recommendations for future research.  相似文献   

10.
OBJECTIVE: To evaluate the efficacy of a commercially available killed bovine viral diarrhea virus (BVDV) vaccine to protect against fetal infection in pregnant cattle continually exposed to cattle persistently infected with the BVDV. ANIMALS: 60 crossbred beef heifers and 4 cows persistently infected with BVDV. PROCEDURES: Beef heifers were allocated to 2 groups. One group was vaccinated twice (21-day interval between the initial and booster vaccinations) with a commercially available vaccine against BVDV, and the other group served as nonvaccinated control cattle. Estrus was induced, and the heifers were bred. Pregnancy was confirmed by transrectal palpation. Four cows persistently infected with BVDV were housed with 30 pregnant heifers (15 each from the vaccinated and nonvaccinated groups) from day 52 to 150 of gestation. Fetuses were then harvested by cesarean section and tested for evidence of BVDV infection. RESULTS: 1 control heifer aborted after introduction of the persistently infected cows. Bovine viral diarrhea virus was isolated from 14 of 14 fetuses obtained via cesarean section from control heifers but from only 4 of 15 fetuses obtained via cesarean section from vaccinated heifers; these proportions differed significantly. CONCLUSIONS AND CLINICAL RELEVANCE: A commercially available multivalent vaccine containing an inactivated BVDV fraction significantly reduced the risk of fetal infection with BVDV in heifers continually exposed to cattle persistently infected with BVDV. However, not all vaccinated cattle were protected, which emphasizes the need for biosecurity measures and elimination of cattle persistently infected with BVDV in addition to vaccination within a herd.  相似文献   

11.
Histopathologic findings in Brucella abortus-infected, pregnant goats   总被引：1，自引：0，他引：1  
Twenty-eight pregnant goats in midgestation were exposed to a bovine pathogenic strain of Brucella abortus to determine the histologic changes associated with infection. Does were necropsied 0 to 7 days or 4 to 6 weeks after delivery of aborted, stillborn, or live, full-term fetuses. Aborted and stillborn fetuses were necropsied within 16 hours of delivery. Selected, paired tissue specimens were collected for histologic and bacteriologic examination. An avidin-biotin-peroxidase complex immunostaining procedure was used to detect Brucella antigen in tissue section. Histologic changes were evident in specimens from infected does and aborted fetuses. Postpartum does had endometritis, lymphoid hyperplasia in lymph nodes and spleen, and lymphocytic mastitis. The most prominent finding in aborted fetuses was an interstitial pneumonia. Lesions in does and fetuses were similar to those described in Brucella-infected cows and fetuses; however, lesions were less consistently observed in goat fetuses than has been observed in bovine fetuses. Brucella antigen was detected by immunoperoxidase staining within the cytoplasm of placental chorioallantoic trophoblastic cells, macrophages, neutrophils, and uterine epithelial cells. Also, stained brucellae were free in placental and fetal vascular lumens and in the interstitium of autolyzed fetal tissues.  相似文献   

12.
Efficacy and safety of components of an IM-administered vaccine for prevention of infectious bovine rhinotracheitis virus (IBRV), parainfluenza type-3 (PI-3) virus, bovine viral diarrhea virus (BVDV), and respiratory syncytial virus (RSV) infections and campylobacteriosis and leptospirosis were evaluated in cattle, including calves and pregnant cows. Challenge of immunity tests were conducted in calves for IBRV, PI-3 virus, or BVDV vaccinal components. All inoculated calves developed serum-neutralizing antibodies and had substantially greater protection (as measured by clinical rating systems) than did controls after challenge exposure to virulent strains of IBRV, PI-3 virus, BVDV, or RSV. In in utero tests, IBRV or bovine RSV vaccinal strains were inoculated into fetuses of pregnant cows. Histologic changes or abortions did not occur after fetal inoculation of the RSV vaccinal strain, and 10 of 14 fetuses responded serologically. Of 9 fetuses, one responded serologically to the IBRV vaccinal strain after in utero inoculation and was aborted 3 weeks later. In an immunologic interference test, 10 calves vaccinated with 2 doses of the multivalent vaccine, containing the 4 viral components and a Campylobacter-Leptospira bacterin, developed serum-neutralizing antibodies to IBRV, PI-3 virus, BVDV, and RSV without evidence of serologic interference. Under field conditions, 10,771 cattle, including 4,543 pregnant cows, were vaccinated. Vaccine-related abortions did not occur.  相似文献   

13.
HERD HISTORY: A cluster of 19 abortions occurred in April and May 1994 on a seasonal dairy farm of 277 cows in Taranaki. Lesions consistent with neosporosis were seen in several foetuses. The age of the aborting cows ranged from 2 to 12 years. Pregnant rising 2-year-old heifers had been grazed off the main farm on a run-off' until returning in May, when they were replaced on the run-off by the rising l-year-old calves. None of these pregnant heifers aborted. METHODS: Sera were obtained from all calves (n = 32), 32 of 33 pregnant heifers, 59 of 60 3-4 year-old cows and 101 of 150 older cows, plus all cows that had aborted. Sera were tested using an indirect fluorescent antibody assay. Non-aborting cattle sera were screened at 1:400, and further dilutions were tested from 15 aborted cows. RESULTS: The percentages of seropositive cattle were: 32% of the calves, 3% of the heifers, 31% of the younger cows and 27% of the older cows. The proportion of seropositive heifers was significantly lower (p< 0.01) than in the other age classes. There was no significant difference in the proportion of seropositive animals between these other age classes (p >0.05). Of the 15 cows that aborted, and for which further dilutions were tested, nine had titres of 1: 12,800, four had titres of 1:6400, one had a titre of 1: 1600 and one had a titre of 1:400. Twenty cows were the dams of pregnant heifers. Six of these cows were seropositive but all their offspring were seronegative. Fifteen aborting cows were held over to the following year when 13 became pregnant and calved normally. There were only two to three abortions in the whole herd in this following year. CONCLUSION: These results suggest that either a point-infection occurred sometime in early 1994 with an infective period short enough so that the heifers did not get infected when they returned to the main farm, or some factor precipitated a recrudescence of latent infection with a subsequent rise in titres in about 29% of the animals on. the main farm only. Although neither hypothesis can be proven or disproven in this observational study, the former hypothesis seems more likely.  相似文献   

14.
Sequential serum samples from 11 cows experimentally inoculated with different abortigenic strains of Chlamydia psittaci were tested by a modified complement-fixation (MoCF) test, an indirect inclusion fluorescence antibody (IIFA) test, and an enzyme-linked immunosorbent assay (ELISA). One of these cows was not pregnant, another gave birth at term to a healthy calf, and all the others prematurely delivered infected dead calves or weak live calves. The results achieved with these tests on sera of 3 of the cows were compared with those from the previously used standard complement-fixation (CF) test. Six of 11 cows had detectable preinoculation titers between 1:8 and 1:16 when tested by the MoCF test, yet preinoculation titers were not detected by CF. In contrast, 9 of 11 and 10 of 11 preinoculation samples had detectable chlamydia-specific antibodies when examined by the IIFA test and the ELISA, respectively. The preinoculation IIFA titers ranged from 1:8 to 1:64, and the ELISA optical density values varied from 0.150 to 0.450. All cows responded with significant increases in antibody levels detected by the MoCF test, the IIFA test, and ELISA after they were experimentally inoculated and after they aborted or delivered infected calves. Overall, the dynamics of the antibody responses were found to be similar with the 3 different serologic techniques. When cows aborted later than 36 days after they were inoculated, the antibody response was biphasic, whereby the more pronounced responses occurred after the abortion occurred. The nonpregnant cow and the cow that delivered a healthy calf at term had only one phase of increasing and decreasing titers directly after they were inoculated.  相似文献   

15.
An outbreak of Neospora caninum-associated abortion occurred in a South Carolina dairy wherein greater than 10% of the herd aborted over a 4-month period. Of the total number of cows at mid-late gestation, nearly 40% (28/71) aborted while the remaining 60% (43/71) gave birth to normal calves. Immunohistochemical examination of brain tissue from a subset of aborted fetuses confirmed N. caninum as the causative agent of abortion in these animals. A variety of serological assays, including indirect fluorescence antibody test (IFAT), recombinant enzyme-linked immunosorbent assay (rELISA), ISCOM-ELISA, avidity ELISA, and Neospora agglutination test (NAT), were used to evaluate sera collected during the outbreak from 240 cows for antibodies to N. caninum. IFAT and ISCOM-ELISA testing showed that nearly 80% of the dairy cows had antibodies to N. caninum. NAT and rELISA had similar levels of seropositivity relative to IFAT and ISCOM-ELISA, but the percentage of positive sera was dependent on the cut-off value chosen. As indicated by kappa coefficient statistical analysis, ISCOM-ELISA and IFAT exhibited the highest level of agreement in identifying N. caninum-positive and -negative cows. A decrease in the percentage of seropositive cows as determined by ISCOM-ELISA and IFAT with increasing cow age was noted. However, no significant difference was observed between cow age and abortion status. In addition to these tests, an avidity ELISA was performed on all sera with high (> or =0.4) ISCOM-ELISA readings. Avidity index (AI) increased with time post-abortion suggesting that most abortions were due to recent N. caninum infection. Of the cows at risk for abortion, the mean serological AI of aborting cows was significantly lower (P<0.05) than mean serological AI of non-aborting cows.  相似文献   

16.
A seroepidemiological survey of Neospora caninum was done in a dairy farm in Uruguay employing indirect fluorescent antibody test (IFAT). Sera from 217 cattle (155 cows, 31 heifers and 31 calves) were tested for N. caninum antibodies in July 2000 and it was found that abortions were significantly associated with the seropositivity of the cows by chi(2)-test (P = 0.025). The cows with an IFAT titre of 1:3200 were at a significantly higher risk of abortion than seronegative cows (P = 0.0013). Neospora organisms were detected in the brains of two aborted foetuses by immunohistochemical examination. The infection of N. caninum was considered postnatal because of the even distribution of seropositive cows (60%), low seroprevalence (20%) in calves and no significant correlation in the serostatus between calves and their dams (P = 0.43). A fitted binomial generalised linear model revealed that there was an increasing risk of abortion with increasing IFAT titre and increasing age between 2 and 6 years.  相似文献   

17.
Twenty-six calves, born from 25 Anaplasma-infected, intact and splenectomized cows, from a herd kept under strict tick-free laboratory conditions, were monitored for the presence of Anaplasma antibodies, using the rapid card agglutination test. Serum was collected at birth, weekly for 12 weeks, and then monthly for approximately 6 months. Specific antibodies passively acquired could be detected in calf sera for an average period of 8 weeks after birth. Calves that remained positive for longer than 12 weeks were suspected of having contracted in utero infections. Infection of the calves was confirmed by splenectomy. It was concluded that 4 calves in Group I contracted in utero infections. Two of the dams were chronically infected, whilst the other 2 underwent acute primary reactions during the 1st and 2nd trimesters of gestation, respectively. Subsequently all calves born from infected cows in this tick-free herd were serologically screened before being splenectomized at an average age of 8 months. Out of 50 cows, 8 in utero infected calves were identified serologically and this finding was confirmed through splenectomy or subinoculation of blood. Both Anaplasma centrale and Anaplasma marginale were carried transplacentally. Splenectomized and intact cows, chronically infected or undergoing primary reactions during the 1st, 2nd or 3rd trimester of gestation, produced infected calves. A 15,6% incidence of in utero transmitted infections were observed amongst 77 calves under these conditions. None of the 13 splenectomized cows, undergoing primary A. centrale infections during gestation, aborted. Clinical signs of disease were not observed in any of the 12 in utero infected calves prior to splenectomy. The implications of these findings are discussed.  相似文献   

18.
Sixteen pregnant cows were challenged with infectious bovine rhinotracheitis virus intranasally. One had a mummified fetus, four aborted, one calf was stillborn, two live fetuses were taken at the abattoir and eight calves were born alive. Of the eight born alive, five were dead by 12 days of age. Four of these had the usual lesions of infectious bovine rhinotracheitis as well as lesions in the intestine and peritoneum and two of the four had a fibrinous pneumonia thought to be caused by aspiration of milk. The lesions, results of virus isolation and fluorescent antibody testing are recorded in these four calves. Attention is drawn to the intestinal lesions, the peritonitis and fibrinous pneumonia and the ease with which the underlying infectious bovine rhinotracheitis infection may be overlooked.  相似文献   

19.
Coxiella burnetii infections are mostly subclinical in cattle, but can occasionally be associated with abortion. In the present study, 100 aborted fetuses or stillborn calves that were submitted for postmortem examination between September 2007 and March 2008 were examined for infection with C burnetii. Samples of both pooled fetal tissues and placental cotyledon were tested using a real-time PCR assay. In addition, the sections of placental cotyledon were examined using immunohistochemistry (IHC). The IHC of four placentas was positive. The PCR results of the IHC-positive placentas were high positive (HP); the PCR results of the organs of these four fetuses and calves varied from low positive (LP) to HP. The four IHC-positive fetuses had a gestation length of seven to nine months. All four placentas had histological signs of inflammation, but only one of four placentas had gross pathological signs of inflammation possibly due to a concomitant infection with Bacillus licheniformis. Five other IHC-negative placentas had (high) positive PCR results; the PCR results of the organs of these fetuses were LP or negative. The present study indicates that C burnetii infections are detected in a limited percentage of aborted fetuses and stillborn calves by IHC. To assess the importance of placentas with PCR-positive and IHC-negative test results, more research is needed.  相似文献   

20.
OBJECTIVE: To evaluate efficacy of embryo transfer into seronegative recipients, using the procedure proposed by the International Embryo Transfer Society (IETS), for preventing vertical transmission of Neospora caninum in cattle. DESIGN: Prospective clinical trial. ANIMALS: 87 recipient cows and heifers and their embryo transfer calves from 22 donors originating from 9 dairy herds. PROCEDURE: Neospora caninum serologic status of donors and recipients was determined before collection and transfer of embryos. Viable embryos were washed and treated with trypsin. Recipients in experimental groups A (n = 50) and B (29) were seronegative and received embryos from seropositive and seronegative donors, respectively. Recipients in group C (n = 8) were seropositive and received embryos from seronegative or seropositive donors. Antibody titers against N caninum were determined monthly during pregnancy in recipients and in calf blood samples collected at birth. Tissues collected from stillborn calves and aborted fetuses were analyzed histologically and by immunohistochemical (IHC) methods. RESULTS: 76 calves and 11 fetuses and stillborn calves were examined. All calves from groups A and B were seronegative (n = 70) or lacked evidence of infection by use of tissue analysis (9). In group C, 5 of 6 calves were seropositive at birth, and IHC results were positive for 1 of 2 calves. Vertical transmission rate was significantly lower in groups A and B (0%) than in group C (75%). CONCLUSION AND CLINICAL RELEVANCE: Embryo transfer into seronegative recipients, using the procedure proposed by IETS, is an effective way to prevent vertical transmission of N caninum. Results provide support for pretransfer testing of all embryo transfer recipients.  相似文献   

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