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1.
Objective To observe the effect upon the foetus of experimental infection of pregnant cattle with Leptospira borg-petersenii serovar hardjo .
Design A disease transmission study using pregnant cattle.
Procedure Fourteen heifers serologically negative to L hardjo were artificially inseminated and later challenged with a north-Queensland isolate of L hardjo by conjunctival inoculation. The heifers were serologically monitored and their urine examined for the presence of leptospires using culture and fluorescent-antibody tests at appropriate intervals. Elective caesarean sections were performed on pregnant heifers at 6.5 weeks after the challenge. Foetuses were examined using serological, histopathological, microbiological and fluorescent-antibody tests.
Results Ten of the heifers became pregnant, but three subsequently aborted before challenge. After challenge, all 14 heifers seroconverted and L hardjo was isolated from the urine of 6 of the 7 pregnant heifers. No evidence of foetal L hardjo infection was detected. Two of the foetuses had histopatho-logical lesions consistent with Neospora s p infection.
Conclusion It is likely that the isolate of L hardjo used in this study does not normally infect the foetus. Neospora s p may be a more significant cause of bovine reproductive wastage.  相似文献   

2.
OBJECTIVE: To determine whether a monovalent Leptospira borgpetersenii serovar hardjo (type hardjobovis) vaccine commercially available in Australia, New Zealand, Ireland, and the United Kingdom would protect cattle from renal colonization and urinary shedding when exposed to a US strain of Leptospira borgpetersenii serovar hardjo. ANIMALS: 24 Hereford heifers that lacked detectable antibodies against serovar hardjo. PROCEDURE: Heifers received 2 doses, 4 weeks apart, of the commercial hardjo vaccine (n = 8) or a monovalent US reference hardjo vaccine (8) or were not vaccinated (controls; 8). Heifers were challenged 16 weeks later by intraperitoneal inoculation or conjunctival instillation. Serum antibody titers were measured weekly, and urine samples were examined for leptospires. Heifers were euthanatized 11 to 14 weeks after challenge, and kidney tissue was examined for evidence of colonization. RESULTS: All 8 heifers vaccinated with the reference vaccine were found to be shedding leptospires in their urine and had evidence of renal colonization. All 4 control heifers challenged by conjunctival instillation and 2 of 4 control heifers challenged by intraperitoneal inoculation shed leptospires in their urine, and all 8 had evidence of renal colonization. In contrast, leptospires were not detected in the urine or tissues of any of the 8 heifers that received the commercial hardjo vaccine. Heifers that received the commercial hardjo vaccine had significantly higher antibody titers than did heifers that received the reference vaccine. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cattle that received 2 doses of the commercial hardjo vaccine were protected against renal colonization and urinary shedding when challenged with L borgpetersenii serovar hardjo strain 203 four months after vaccination.  相似文献   

3.
This is a report on the experimental infection of cattle with Leptospira interrogans serotype szwajizak. The principal clinical features in three 4-week-old Holstein-Friesian heifers intravenously inoculated were fever, listlessness, anorexia, weakness, and diarrhea. Szwajizak was isolated from the blood for the first 5 to 8 days after inoculation. Leptospires were recovered from kidneys, but not from liver, spleen, brain, or urine. Two of the 3 calves produced homologous agglutinins, with maximum serum titers of 1:80 and 1:160. The sera of the 2 calves that developed szwajizak agglutinins showed cross reactivity with wolffi and hardjo antigens. There were not significant differences of plasma and urine constituents between the inoculated calves and the control calf. Endocardial hemorrhages and large soft black-red spleen were present in the 2 calves given the greatest numbers of leptospires. Histopathologically, kidney of all infected calves had multiple small foci of lymphoid cells, chiefly pasmacytes, which were present in periglomerular and interstitial areas.  相似文献   

4.
The excretion of Leptospira interrogans serovar hardjo in the urine of cattle was studied in naturally and experimentally infected animals. Five of 15 naturally infected animals with microscopic agglutination test titres of > or = 1:300 shed leptospires for between 28 and 40 weeks. Twenty yearling heifers, experimentally infected by either the supraconjunctival or intrauterine routes, shed leptospires for from eight to 60 weeks; the 10 infected via the uterus shed L interrogans serovar hardjo for a mean of 26 weeks (range eight to 54 weeks) and the 10 infected by the supraconjunctival route shed the organism for a mean of 32 weeks (range 12 to 60 weeks). The results suggest that natural infection results in more prolonged excretion than experimental infection. No intermittent or seasonal excretion of the organism was observed. After the initial experimental infection, large numbers of leptospires were shed in the urine for several weeks, and thereafter there was a progressive decline in the number of organisms shed.  相似文献   

5.
Effectiveness of 2 concentrations of a monovalent vaccine containing Leptospira interrogans serovar hardjo type hardjo-bovis was evaluated for protection of heifers from infection with type hardjo-bovis. Nine heifers were given 2 doses of low-dose vaccine (8.32 x 10(8) cells/dose); 9 heifers were given 2 doses of high-dose vaccine (8.32 x 10(9) cells/dose); and 1 steer and 1 heifer were maintained as nonvaccinated controls. Groups of vaccinated cattle were challenge-exposed with serovar hardjo type hardjo-bovis at 7 (n = 6), 11 (n = 6), or 15 (n = 6) weeks after completion of vaccination. All cattle were challenge-exposed by conjunctival instillation of 1 x 10(5) hardjo-bovis cells on 3 consecutive days. Both control and all vaccinated cattle became infected and shed serovar hardjo type hardjo-bovis in their urine. Leptospires were detected in 15 of 16 (94%) urine samples from control cattle and in 124 of 143 (87%) samples from vaccinated cattle. Leptospires were detected in kidneys of 17 of 18 vaccinated cattle and 2 of 2 control cattle and in the uterus or oviducts of 13 of 18 vaccinates and the 1 control heifer.  相似文献   

6.
Kidneys from 117 cattle from 110 Ontario farms were examined at slaughter for leptospires. Leptospira hardjo (hardjo-bovis A) was isolated from 11 kidneys and L. kennewicki from one. The isolations were all made (12/89, 13.5%) from beef cattle from feedlots, no isolates being obtained from dairy or beef cattle from extensive farms (0/28). Isolations were only made from cattle with antibody titers (greater than or equal to 20) against the serovars recovered. Isolation was more sensitive than immunofluorescence in identifying leptospira, particularly in animals with low antibody titers against L. hardjo. Leptospira were isolated from two kidneys with multiple gross lesions of focal nephritis, but there was no correlation between the presence of scanty kidney lesions and isolations of leptospira. Leptospira hardjo infection appears to be common in Ontario feedlot cattle.  相似文献   

7.
OBJECTIVE: To evaluate antibiotics for treatment of cattle with leptospirosis caused by Leptospira borgpetersenii serovar hardjo. DESIGN: Randomized controlled trial. ANIMALS: 42 healthy mixed-breed cattle. PROCEDURE: Cattle were inoculated via conjunctival instillation with L. borgpetersenii serovar hardjo. After infection and urinary shedding of L. borgpetersenii were confirmed, cattle were treated with various antibiotics. To determine effectiveness of antibiotic treatment, urinary shedding of L. borgpetersenii was monitored for 4 to 6 weeks after administration of antibiotics, using darkfield microscopic examination, microbial culture, immunofluorescence testing, and a polymerase chain reaction assay. RESULTS: All inoculated cattle developed leptospirosis and shed leptospires in their urine. The following antibiotic treatments resulted in elimination of urinary shedding of leptospires: a single injection of oxytetracycline (20 mg/kg 19 mg/lb] of body weight, IM), tilmicosin (10 mg/kg [4.5 mg/lb], SC), or a combination product that contained dihydrostreptomycin-penicillin G (25 mg/kg [11.4 mg/lb], IM) or multiple injections of ceftiofur sodium (2.2 or 5 mg/kg [1 or 2.3 mg/lb], IM, once daily for 5 days, or 20 mg/kg, IM, once daily for 3 days). CONCLUSIONS AND CLINICAL RELEVANCE: Successful resolution of leptospirosis in cattle by administration of dihydrostreptomycin-penicillin G confirms results obtained by other investigators. Three other antibiotics (oxytetracycline, tilmicosin, and ceftiofur) also were effective for resolving leptospirosis and may be useful substitutes for dihydrostreptomycin, an antibiotic that is no longer available for use in food-producing animals in the United States. Cost, safety, and withdrawal times of these various treatment options need to be considered.  相似文献   

8.
Kidneys from cattle at slaughter were examined for the presence of leptospires. Of 218 (8.3%) kidneys leptospires were isolated from 18; all were identified as Leptospira interrogans serovar hardjo. None of the leptospire-infected kidneys had histopathological lesions indicative of leptospirosis and leptospires were demonstrated in only 2 by immunogold silver staining. Leptospires infected kidneys remained viable for at least 21 days when stored at 4 degrees but became non-viable within 14 days when stored frozen at -15 degrees.  相似文献   

9.
A study of "white spotted kidneys" in cattle   总被引：1，自引：0，他引：1  
A study was performed at an abattoir in Australia, in an attempt to correlate focal chronic interstitial nephritis (FCIN) producing the so-called "white spotted kidney", with Leptospira spp. and other pathogens in cattle. Samples of kidneys, urine and blood were collected immediately after slaughter from 46 two-year-old heifers, and 72 cows and bulls with gross lesions consistent with FCIN. The same samples were also collected from nine heifers and 12 cows with no gross kidney lesions. Aqueous humour was also collected from the eye of 17 of the adult animals. The sera were processed by a microscopic agglutination test for leptospira antibodies, while all the other samples were cultured for Leptospira spp. and also processed for routine aerobic and anaerobic culture for other pathogens. Sub-samples from all the kidneys were fixed in 10% buffered formalin and processed histologically. Antibody titers of 1:400 or higher for Lepstospira borgpeterseni serovar hardjo were found in six adult animals with FCIN and in one adult animal with no gross kidney changes, while antibody titers of 1:400 to L. borgpeterseni serovar tarassovi were found in only one animal with FCIN. L. borgpeterseni serovar hardjo was isolated from the urine and kidney of one adult animal and from the urine of another adult animal, both with FCIN. No pathogens were isolated from any of the other samples. The histological lesions were consistent in most cases with FCIN. The results suggest that neither Leptospira spp. nor active infection by other bacteria are associated with the so-called "white spotted kidneys".  相似文献   

10.
The use of the diuretic furosemide made it possible to obtain samples of urine from cattle for leptospiral isolations. The drug was injected IV at a dose level of 0.8 mg/kg for heifers and 0.5 mg/kg for calves. The average time to first voiding in heifers was 19 minutes. The average time from the first to the second voiding was 17 minutes. The average time to the first voiding in four calves was 12 minutes; the average time from the first to the second voiding was 10 minutes. A decrease in urinary osmolarity provoked by furosemide created a more favorable condition for the survival of leptospires. Leptospires were isolated in 24 (72.7%) of 33 weekly cultural attempts with the aid of furosemide in three experimentally infected adult cattle. Serovar hardjo was isolated in 16 (57.1%) of 28 weekly cultural attempts with aid of the diuretic in four experimentally infected calves. The recovery frequency was 28.5% from the first voiding and 50% from the second. Leptospires were not isolated from urine obtained from the calves by manual stimulation. Untoward side effects that might have been attributable to furosemide were not observed. Furosemide appears to be well suited to obtain urine samples from cattle for leptospiral isolation.  相似文献   

11.
This study demonstrated the ability of the antimicrobials tulathromycin (Draxxin) and ceftiofur crystalline free acid sterile suspension (Excede) to clear the spirochete Leptospira borgpetersenii serovar hardjo type hardjo-bovis (L. hardjo-bovis) from experimentally infected cattle. Treatment with tulathromycin resulted in clearance of L. hardjo-bovis organisms from the urine and kidney tissue of all animals (9 of 9), and treatment with ceftiofur crystalline free acid resulted in clearance of the organisms from the urine of 8 of 10 heifers and the kidney tissue of all 10 animals. In contrast, 10 of 10 placebo-treated cattle had L. hardjo-bovis organisms in their urine and 8 of 10 had the organisms in kidney tissue.  相似文献   

12.
OBJECTIVE: To compare sensitivity and specificity of various polymerase chain reaction (PCR) assays for detection of Leptospira borgpetersenii serovar hardjo in bovine urine and to compare results of the optimal PCR assay with results of immunofluorescence, nucleic acid hybridization, and bacteriologic culture. ANIMALS: 6 heifers. PROCEDURE: Heifers were exposed to serovar hardjo type hardjo-bovis by conjunctival instillation of 10(6) leptospires on 3 successive days. Urine samples were collected before and after infection. Sensitivity and specificity of 5 PCR assays were compared, to determine the optimal assay for use with bovine urine samples. The optimal PCR assay was then compared with results of bacteriologic culture, nucleic acid hybridization, and immunofluorescence. RESULTS: A PCR assay with the best combination of specificity (100%) and sensitivity (91%) was selected for comparison with the other diagnostic tests. Sensitivity for nucleic acid hybridization was 55%, whereas sensitivity for bacteriologic culture and immunofluorescence was 89 to 93%. CONCLUSIONS AND CLINICAL RELEVANCE: Bacteriologic culture, PCR, and immunofluorescence were sensitive for detection of L borgpetersenii serovar hardjo type hardjo-bovis in urine specimens of cattle, but a single technique was not the most sensitive for each animal tested. Therefore, the use of 2 techniques in combination is warranted for maximal sensitivity for diagnosis.  相似文献   

13.
Abortion, premature calving, hemolytic anemia and fatal hematuria were associated with high levels (titer > 10(-4)) of antibody to Leptospira interrogans serovar hardjo and with isolation of hardjo in a herd of 265 beef cattle in the Great Clay Belt of northern Ontario. This herd was bred by artificial insemination, after heat detection by vasectomized bulls. The antibody prevalence rate in the herd was 54 to 60% over a five year period. The rate tended to reach 100% by age three years and to be below 5% in yearlings, which were raised in isolation from older cattle. Hardjo was isolated from the urine of a cow that aborted in the eighth month of pregnancy, and from kidneys of yearling steers which had been exposed to an older cow. Maternal antibody levels in calves paralleled those in their dams, protecting calves while they were being naturally exposed to infection, thus contributing to the achievement of balance between host and parasite. A controlled vaccination trial was conducted in 50 initially seronegative yearling steers and heifers. Serological response to vaccine was limited to a maximum agglutinin titer of 10(-2) in 8% of vaccinated cattle. Vaccination reduced the infection rate from 86% in the controls to 46% in the treated group, indirectly reducing the number of calves for which colostral antibody against hardjo would be available. A vaccination program was not implemented in the herd. Hardjo infection appeared to die out over a period of six years following the initial five year study period, with antibody prevalence falling from 60% to 0.7% and reactors persisting only in two eight year old cows. Decline in infection was coincident with changes in management which protected heifers from exposure to infection until their third pregnancy, and which probably lowered the reservoir of infection by increased culling from older age classes.  相似文献   

14.
Nucleic acid hybridization, bacteriologic culture, and a fluorescent antibody test were compared for detection of Leptospira interrogans serovar hardjo type hardjo-bovis in bovine urine. Seventy-five urine samples were collected from pregnant cows challenge exposed with type hardjo-bovis. Twenty samples were collected from steers not exposed to hardjo-bovis. Sediments from each sample were examined, using fluorescent antibodies and a repetitive sequence element nucleic acid probe, to detect the presence of leptospires. Urine samples were processed for bacteriologic culture, using standard techniques. Under laboratory conditions typically used for these techniques, leptospires were detected in 60 of 75 urine samples from challenge exposed cows by nucleic acid hybridization, in 24 samples by fluorescent antibody test, and in 13 samples by bacteriologic culture. Leptospires were not detected in the urine of steers not exposed to hardjo-bovis.  相似文献   

15.
Effectiveness of a pentavalent leptospiral vaccine to protect cattle from infection and reproductive problems caused by Leptospira interrogans serovar hardjo type hardjo-bovis was evaluated. Seven cows were vaccinated once and 8 cows were vaccinated twice with a USDA-licensed pentavalent leptospiral vaccine. Five cows were maintained as nonvaccinated controls. Cows were bred 1 to 2 months after the last vaccination. During the 4th to 6th month of gestation, all cows were challenge exposed on 4 occasions by conjunctival instillation of 10(8) serovar hardjo type hardjo-bovis organisms and on 3 occasions by conjunctival instillation of urine from a cow shedding hardjo-bovis. All control cows and 13 of 15 vaccinated cows became infected and shed leptospires in the urine. Leptospires were detected in fewer urine samples collected from vaccinated cows, compared with those collected from control cows. Four stillborn calves and 3 weak calves were born to control and vaccinated cows. Leptospires were detected in the kidneys of 11 apparently healthy calves born to vaccinated and control cows. Agglutinating antibodies were not detected in the precolostral serum of these calves.  相似文献   

16.
The infectivity and pathogenicity of a strain of Leptospira hardjo isolated from the eastern plains of Colombia were evaluated. Ten pregnant heifers were artificially inoculated and monitored during 10 months. During the trial, isolation of leptospires was attempted and antibodies were detected by the microscopic agglutination test. Leptospires were recovered from the urine of six of the inoculated animals up to 6 months after infection. Eight of ten calves born from the inoculated heifers were born weak, and one of them died 12 h after parturition. Three of the weak calves had generalized jaundice of the internal surfaces. Half of the cows developed metritis and had a retained placenta. Serological reactions were seen against serotypes other than L. hardjo. A chronic infection was apparently established in the inoculated heifers with leptospiruria resulting in reinfection of the animals and a secondary rise in antibody levels.  相似文献   

17.
Cattle were vaccinated against leptospirosis with 3 bacterin preparations: (a) trivalent (serotypes grippotyphosa, pomona, and hardjo) whole cell bacterin; (b) bivalent pomona and hardjo whole cell bacterin; and (c) pentavalent (canicola, grippotyphosa, icterohaemorrhagiae, pomona, and hardjo) cell wall bacterin. Microscopic agglutinating antibody responses in cattle given the last-named bacterin were higher than those in cattle vaccinated with the 2 whole cell bacterins (trivalent and bivalent). However, microscopic agglutinating antibody responses occurred in all vaccinated cattle after they were given a challenge inoculation of serotype hardjo. Leptospires were isolated from 2 of 4 challenge controls (i.e., not given any bacterin), but none of the 15 vaccinated cattle given any one of the bacterins and then challenge inoculated with hardjo became culturally positive. It was concluded that the 3 multivalent bacterins were protective against experimental challenge inoculation of hardjo.  相似文献   

18.
Serum samples were examined for evidence of leptospiral agglutinins from 928 sheep from 45 lines and kidneys from 12 of these lines for evidence of leptospiral infection. All sheep had been submitted for slaughter at meat works in the Manawatu. Serological results were analysed using the results at a minimum serum dilution in the microscopic agglutination test (MAT) of 1:24 and at a minimum dilution of 1:48. It was shown that a minimum dilution of 1:24 resulted in many non-specific or cross-reactions. A minimum dilution of 1:48 was more accurate for detecting the serological prevalence of specific agglutinins to leptospires in ovine sera. Twenty percent of the sheep had titres of 1:48 or greater to hardjo, 3.8% to pomona, 2.6% to tarassovi, 2.3% to copenhageni and 2.7% to ballum. No titres of 1:48 or greater to australis were detected. Serovar hardjo was isolated from the kidneys of three animals in one line. Eighteen months later 291 serum samples and 95 urine samples were collected from live animals on the property from which the three hardjo infected animals originated. No titres to hardjo were detected in the sera of lambs, but a serological prevalence of 44% and 84% to this serovar was demonstrated in the hoggets and ewes respectively. No leptospires were demonstrated in any of the urine samples. These results show that sporadic infection of sheep with hardjo can occur but they also indicate that infection with this serovar is not endemic and that sheep are unlikely to act as maintenance hosts for hardjo in New Zealand.  相似文献   

19.
Ten non-pregnant heifers, experimentally infected with Leptospira interrogans serovar hardjo, were each given an intramuscular injection of dihydrostreptomycin at a dose rate of 25 mg kg-1. In five of these animals this treatment was repeated after 14 days. Treatment failed to remove established genital or renal infection in seven of the 10 heifers, although the number of organisms persisting was apparently reduced in these animals. Serovar hardjo infection persisted for at least 83 days in the oviduct and uterus and these tissues may be as important carrier sites for serovar hardjo as bovine kidney tissue.  相似文献   

20.
Eight-month-old calves, housed under maximum isolation, were exposed to pathogenic Leptospira interrogans serovar hardjo by the conjunctival route or IV. One calf served as an unexposed control. Infection was monitored serologically (microscopic agglutination test and enzyme-linked immunosorbent assay; ELISA) and by leptospiral culture isolation from periodic urine samples and from the kidneys, epididymides, and aqueous humor collected at slaughter. Microscopic agglutination test titers of greater than or equal to 1:40 were detected among all IV exposed calves at postinoculation day (PID) 7 and among conjunctival exposed calves at PID 14. By ELISA, all IV exposed calves were positive by PID 3, whereas conjunctival exposed calves were positive at PID 14. The ELISA was more sensitive for the detection of antibodies against leptospires in cattle. Leptospires were isolated from the urine of 4 calves and from the kidney of 3 calves exposed by the conjunctival route, but not from IV exposed calves. The results indicated that the conjunctival route of exposure was a more natural and successful route for experimental infection of cattle with serovar hardjo.  相似文献   

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