Rev. sci. tech. Off. int. Epiz., 16 (1), 215-225 Disease risks to animal health from artificial insemination with bovine semen M.D. Eaglesome & M.M. Garcia Agriculture and Agri-Food Canada, Animal Diseases Research Institute, 3851 Fallowfield Road, P.O. Box 11300, Station H, Nepean, Ontario K2H 8P9, Canada Summary Two of the major goals of artificial insemination of domesticated animals are to achieve continuous genetic improvement and to prevent or eliminate venereal disease. In comparison with natural service, fewer males are needed to artificially inseminate the same number of females and to produce the same number of offspring. However, there are risks associated with artificial insemination, which has the potential to disseminate genetic defects and also to spread infectious disease nationally and internationally. This paper focuses on the risks of six specific diseases which are transmitted in bull semen and outlines the appropriate measures to prevent these risks. Keywords Animal diseases - Artificial insemination - Bovines - Genital disease - Risk - Semen. Introduction The regular testing of semen donors under official veterinary supervision has been adopted by governments world-wide as a means of avoiding the spread of pathogens and reducing excessive contamination of semen by ubiquitous bacteria. National standards for semen production and distribution are usually based on regulatory programmes to ensure that diseases of importance are identified and appropriate tests are applied to all sires entering and residing in artificial insemination (AI) centres. These programmes take into account the national health status as well as the health status of the herds and flocks of the semen donors. In interpreting health status, prime considerations include the sensitivity and specificity of tests, particularly when they are applied to individual animals, and the risk of latent infections. Testing programmes need to be continually improved and updated as new information on the epidemiology, pathogenesis and control of traditional diseases becomes available. As hew' infectious diseases emerge, these additional challenges and risks must also be met ( 9 2 ) . At the international level, guidelines are published by the Office International des Epizooties (OIE) to enable the health of animals in AI centres to be maintained and to facilitate the global distribution of semen which is free of specific pathogenic organisms (62). The aims of this paper are as follows: a) to provide information on some infectious agents known to be transmitted in bull semen b) to discuss risk management methods which will help to control or prevent disease transmission through semen. Infectious bovine rhinotracheitis/infectious pustular vulvovaginitis Bovine herpesvirus-1 (BHV-1), also called infectious bovine rhinotracheitis/infectious pustular vulvovaginitis virus, is a member of the subfamily Alphaherpesvirinae and is one of the most common viral pathogens found in bovine semen. Reproductive disorders caused by BHV-1 include infectious pustular vulvovaginitis, endometritis, salpingitis, shortened oestrus cycles and abortions in susceptible female cattle and balanoposthitis in susceptible bulls. In BHV-1 infection of the genital tract of the bull, the virus replicates in the mucosae of the prepuce, penis and distal part of the urethra, and semen is most likely to be contaminated during ejaculation by virus shedding from infected mucosae. Disease risk Infections with BHV-1 strains, including attenuated live vaccine strains, have the ability to remain latent in clinically normal animals ( 6 5 ) . Following reactivation, the virus is excreted in respiratory and ocular secretions, or in semen, and 216 in the latter case excretion can be with or without a serum antibody response ( 9 5 ) . BHV-1 causes economically important genital, respiratory and neurological diseases in cattle populations world-wide. Infected animals may be immunosuppressed and thus be more susceptible to secondary bacterial infections. BHV-1 infection of the male genital tract can result in mild or severe clinical signs of balanoposthitis or can be clinically inapparent (1). Bulls play an important role in the dissemination of the disease because the virus is excreted in semen both during the acute phase of infection and also following the establishment of latent infection (94). When assessing the risk of semen containing BHV-1, it is important to recognise that clinical signs of the disease may not always be observed in outbreaks of BHV-1 infection in bulls ( 9 5 ) , and that neither the presence of serum neutralising (SN) antibodies nor vaccination may completely prevent shedding of virus in semen. BHV-1 has been detected in semen from infected AI bulls which showed no signs of balanoposthitis, rhinotracheitis or generalised disease (28). In some instances, semen may b e contaminated by a primary local infection of the prepuce before production of neutralising antibodies has occurred (103). Moreover, animals latently infected with BHV-1 may have very low antibody titres or be seronegative, especially if they have not been stressed and virus reactivation has not taken place for a long period of time ( 2 9 ) . In addition, primary genital tract infection may induce very low antibody responses or even none at all (94). Studies in North America have shown that semen from BHV-1 seropositive bulls can be free of virus for periods of several years when bulls are appropriately managed in a low-stress environment (57). Diagnosis and control Methods of BHV-1 detection currently used by diagnostic veterinary laboratories include virus isolation, examination of tissues by the fluorescent antibody (FA) technique and serological testing (SN test or enzyme-linked immunosorbent assay [ELISA]). Another method is the 'Cornell semen test', in which pooled samples of semen are inoculated into susceptible calves or sheep which are then monitored for neutralising antibodies to BHV-1 (76). The traditional method for detection of BHV-1 in bovine semen is virus isolation and identification in cultures of cells of bovine origin ( 8 6 ) . Dilution of the semen (1:20 to 1:128), prior to its inoculation onto cell culture, decreases its cytotoxicity (17, 100, 1 0 4 ) . Molecular-based techniques are also being developed and used to detect the virus (97, 103). For example, polymerase chain reaction (PCR) assays can identify BHV-1 contaminated semen within one day (103). However, PCR is not yet applied routinely, even in well-equipped laboratories. It is preferable to use only seronegative bulls in AI centres and bulls should be bled for further serological testing 21 days after the semen has been collected, as recommended by the OIE ( 6 2 ) . To limit the risks of disease transmission when Rev. sci tech. Off. int. Epiz., 16(1) semen is collected from bulls of unknown or positive serological status, at least two straws per semen batch should be assayed for virus ( 9 4 ) , because semen is diluted before being frozen and not all straws will necessarily contain virus. Assay of blood for gamma-interferon, a measure of cellular immunity, can be used to discriminate between BHV-1 non-infected (or vaccinated) and infected animals, as well as to distinguish serologically positive infected bulls from those with maternal antibodies ( 4 2 ) . Vaccination can be used to control BHV-1 infection in bulls in AI centres, but is not generally used at present (95). Bovine virus diarrhoea Bovine virus diarrhoea (BVD) virus, a ribonucleic acid (RNA) virus, has two main types characterised by non-cytopathic (NCP) or cytopathic (CP) effects on cultured cells. They are indistinguishable serologically. The NCP biotype may infect the foetus and establish a persistent infection (PI) which continues into post-natal life. A high proportion of adult cattle world-wide have antibody to BVD virus (BVDV), although most infections in adults are subclinical. Disease risk Infection with NCP biotypes causes congenital and enteric diseases as well as predisposing infections with other pathogens (e.g. BHV-1, Pasteurella or Salmonella spp.). In the latter instance, there may be increased disease severity compared to the disease caused by either agent alone, and this has been attributed to the immunosuppressive effect of BVDV. Some NCP biotypes of BVDV have caused haemorrhagic disease in cattle with a high mortality rate (11) and, in North America, virulent NCP strains have caused severe diarrhoea and death in adult cattle and veal calves with clinical signs similar to those of mucosal disease ( 3 0 ) . The CP biotypes cause mucosal disease, which occurs only in PI animals. The CP virus appears to arise by mutation from the NCP virus within PI animals (59). BVDV is excreted in bull semen during acute, transient infection and is also present in the semen of PI bulls ( 5 1 , 52, 66). The virus is transmitted in the semen of such bulls during natural or artificial breeding ( 5 6 ) , and causes reproductive losses in females (55, 9 9 ) . Diagnosis and control Antibodies to BVDV may be detected by complement fixation (CF), indirect FA and SN tests (71). In addition, a number of ELISAs of high serological sensitivity and group specificity have been described ( 1 , 2 2 ) . Tests to detect BVDV include virus isolation (1), antigen capture ELISAs (79), and reverse transcription-PCR assays (68). It is important that PI bulls are prevented from entering AI centres. The best method for identifying PI bulls is by virological examination of two blood samples collected four 217 Rev. sci tech. Off. int. Epiz.,16(1) weeks apart. As homologous maternal antibody may interfere with detection of the virus ( 7 1 ) , calves aged less than six months should be treated as if of unknown status and kept separate from others. It should be noted that PI bulls can seroconvert following superinfection or after vaccination with a virus antigenically dissimilar to the persistent virus ( 3 0 ) . Although there is some concern that live attenuated vaccines may be immunosuppressive and potentiate the effect of other pathogens (1), the emergence of virulent NCP strains, and the severe losses that they can cause, make it a prudent strategy to vaccinate bulls (30). Bovine brucellosis Bovine brucellosis is a bacterial disease caused mainly by Brucella abortus. In cattle, the disease is characterised by abortion and is often associated with retained placenta, metritis and a subsequent period of infertility. Brucellosis affects approximately 5% of livestock world-wide and continues to increase. It is also an important zoonosis. Disease risk Brucella abortus infection in bulls may involve the testis and epididymis, and also the seminal vesicle and ampulla. Infected bulls may be serologically positive or negative ( 7 0 ) . The shedding of B. abortus in the semen of bulls has been reported and this may pose a risk of disease transmission by AI (8). In a recent study, following the experimental inoculation of mature bulls, B. abortus strain 19 was constantly present in semen, and this was accompanied by a specific antibody response ( 2 0 ) . However, there was no overt increase in seminal immunoglobulin (Ig) concentration and no definite conclusions could be made concerning the protective role of seminal antibodies in limiting spread of infection at service. Diagnosis and control Serological tests are applied routinely to monitor for brucellosis. A major breakthrough was the elucidation of the structure of the O-chain of the smooth lipopolysaccharide (LPS) of B. abortus ( 2 1 ) . Indirect and competitive ELISA formats have been developed and evaluated in several countries. The ELISA based on use of the O-LPS has been shown to be capable of discriminating between vaccinated animals and non-vaccinated, infected animals (61). Laboratory tests include isolation or demonstration of the organism in tissues or fluids, and serological tests and agglutination tests on milk or seminal plasma, as described in a World Health Organisation (WHO) monograph ( 4 ) . A colony blot ELISA exploits the use of monoclonal antibodies to smooth Brucella O-chain to detect Brucella colonies on agar media even in the presence of contaminants. A specific and sensitive PCR assay has also been developed ( 3 7 ) . Deoxyribonucleic acid (DNA) amplification using six B. abortus gene sequences was found to be highly specific and sensitive but did not differentiate between the different Brucella species (27). Some authorities in Brucella-face countries consider that the serum agglutination test is sufficiently sensitive for health certification of Al bulls ( 6 9 ) , although more sensitive tests are available ( 3 8 , 9 3 ) . Reports of bulls shedding B. abortus in semen while their serum agglutination titres were low or negative (6) indicate the benefits of testing semen for the presence of the organism, or testing seminal plasma for agglutinins, particularly in areas of high risk. Live strain 19 vaccine and the killed 4 5 / 2 0 vaccine have both played an important role in the control of brucellosis. However, strain 19 may produce permanent infections in bulls similar to those of natural disease (60). New vaccines such as RB51, which is an avirulent rough mutant lacking an O-chain, can induce a protective cell-mediated immune response without an accompanying seroconversion ( 7 7 ) , but the value of these vaccines in the field remains to be tested. Leptospirosis Leptospirosis, an important zoonotic disease caused by parasitic spirochaetes, is endemic in animal populations world-wide (5). Genetic studies have revealed heterogeneity among leptospires, and L. interrogans (i.e. the parasitic form) is now subdivided into seven genospecies (72). There are also approximately 2 0 0 serovars of parasitic leptospires (102). Serovar hardjo, the predominant serovar in most cattle populations ( 1 0 ) , has been divided into two genotypes: hardjo-prajitno and hardjo-bovis ( 8 9 ) . Disease risk Clinically, bovine leptospirosis can be acute (septicaemia, hepatitis, nephritis), subacute (nephritis, agalactia), chronic (abortion, stillbirth, infertility) or, in its most common form, asymptomatic. Serovar hardjo has been recovered from the kidney, seminal vesicle, epididymis and testis of naturally infected bulls (36). Leptospira spp. have also been recovered from the semen of naturally ( 4 8 ) and experimentally ( 8 4 ) infected bulls, and seminal transmission has been reported (83). Diagnosis and control The reference laboratory test for serological diagnosis of leptospirosis in cattle is the microscopic agglutination (MA) test (25). There are also immunoenzyme assays for detection of leptospiral antibodies and antigens ( 8 8 ) but these, like the MA test, cannot distinguish between titres resulting from natural infection and those from vaccinal titres ( 9 1 ) . Difficulties have been reported in isolating leptospires from experimentally infected semen, even when antibiotics were absent from the semen diluent ( 6 9 ) , However, molecular 218 Rev. sci tech. Off. int. Epiz., 16 (1) probes for leptospira detection and identification have been described ( 3 1 , 8 5 ) and one PCR used for L. serjoe in non-sterile urine detected as few as 5-10 leptospires per ml (41 ). Leptospires survive in extended unfrozen bovine semen, either with or without antibiotics ( 1 8 ) , and also in frozen semen without antibiotics ( 7 4 ) . Treatment of bulls with 25 mg of dihydrostreptomycin (DHS) per k g body weight has been approved intemationally (62) to stabilise low antibody titres and to prevent shedding of leptospira, but the efficacy of such treatment is questionable ( 3 5 ) . DHS has, furthermore, been withdrawn in some countries which means that other antibiotic treatments (3) will require certification. As the currently available serological tests cannot differentiate vaccinal from infectious litres, vaccination of bulls in AI centres is not usually appropriate. - 1 Bovine genital campylobacteriosis Venereal campylobacteriosis, a widespread bacterial disease associated with both bovine infertility and abortion, is caused by Campylobacter (Vibrio) fetus, particularly the subspecies venerealis. C. fetus infection in cattle has decreased in regions where AI and vaccination are practised, yet the disease continues to be an important pathogen causing reproductive problems in many countries (2, 9 8 ) . Disease risk In bulls, infection is not accompanied by either pathological lesions or modifications in the characteristics of the semen (23). The incidence of infection is higher among bulls over five years of age, and this may be attributed to the deeper epithelial crypts in the prepuce and penis of older bulls which allow the pathogen to survive and grow more readily. C. fetus is transmitted to female cattle at natural or artificial service and causes vaginitis, cervicitis, endometritis and salpingitis. Infertility can last at least ten months. Persistence of C. fetus infection in the bovine genital tract may be due to successive (or intermittent) changes in superficial antigens of the organism (26). Occurrence of these antigenic shifts in vivo is associated with genomic rearrangement of the sapA gene homologs (40). Diagnosis Preputial scrapings and semen from bulls are the usual specimens taken for laboratory tests. Infected bulls produce IgA in their preputial secretions but the titres tend to be so low that they are indistinguishable from those present before infection (101). Recovery of C. fetus from field cases can be difficult, which may be due to the microaerobic requirements of the organisms. Special transport media have been developed to maintain these specific requirements during transit to the laboratory for subsequent culture (24, 3 9 , 53, 54). PCR assays have also been developed (7, 9, 3 4 ) which can detect as few as three C. fetus subsp. venerealis cells per ml in experimentally infected raw and diluted bull semen (34). Since Campylobacters have few unique biochemical features (63), (more discriminating) techniques such as lipopolysacchari.de profiles and pulsed field gel electrophoresis can assist in differentiating the venereal subspecies of C. fetus from others (16, 7 5 ) . Bulls are usually tested in quarantine by culture of preputial samples on three occasions to ensure that they are free of C. fetus before entering AI centres. Thereafter, their disease-free status is confirmed by semi-annual testing. Infected bulls may be treated by simultaneous preputial infusion of an aqueous solution of DHS and subcutaneous injections of the same antibiotic ( 7 8 ) . However, streptomycin-resistant strains of C. fetus have been reported (47), and as DHS has been withdrawn from some markets, alternative treatments will be required in the future. Vaccination is another possible approach which will not only prevent infection in bulls ( 1 5 ) but is also claimed to be curative, although failure to eliminate infection by vaccination alone has been reported (46, 9 6 ) . Various combinations of antibiotics have been used to control C. fetus in liquid or frozen bovine semen ( 3 3 , 8 1 ) . One of these, a combination of gentamycin, lincospectin and tylosin, has been recommended ( 8 0 ) and adopted for commercial application. However, it has been reported that C. fetus could be re-isolated after processing and freezing of experimentally inoculated semen in the presence of these three antibiotics (32). Trichomonosis Trichomonosis is a venereal disease of cattle caused by the protozoan parasite Tritrichomonas foetus. In the female, it is characterised by infertility, early abortion and pyometra but in the infected bull, a symptomless carrier state occurs with T. foetus being found on the penis and preputial membranes. This does not interfere with spermatogenic function or the ability to copulate ( 3 1 ) . Trichomonosis occurs world-wide, particularly among range cattle (44, 6 7 ) . A high herd prevalence has been reported in areas of North America where natural breeding is practised ( 1 3 , 7 3 ) . Control can be achieved through a policy of testing breeding animals and the widespread use of AI (87). Disease risk Although the parasite can survive in diluted semen and through the freezing process, the probability of transmitting infection through AI is not known. If transmitted to cows or 219 Rev. sci tech. Off. int Epiz., 16 (1) heifers at breeding, the infection invades the vagina, uterus and oviducts, causing embryonic death and infertility which may last for several months (12). Diagnosis and control The testing of bulls entering AI should be mandatory, and definitive diagnosis depends on the demonstration of the living motile organisms in preputial washings or scrapings (87). Since these organisms tend to be present only in small numbers, a vigorous scraping of the preputial epithelium is recommended. A diagnostic kit has been developed which consists of a clear plastic pouch with two chambers of selective medium. This is inoculated on-site with the sample and is then used for both transport and culture (90). This kit is an improvement compared to the traditional nutrient medium for recovering T. foetus (14). The inoculated culture media are examined microscopically for motile trichomonads for up to seven to ten days (49). The probability of obtaining a positive culture from a known positive bull has been calculated to be between 8 1 . 6 % and 9 0 % based on three successive weekly cultures (50, 8 2 ) . Studies with an ELISA have shown it was sufficiently sensitive to detect antibody in both seminal plasma and preputial washings of bulls after vaccination and challenge with T. foetus (19). A specific DNA probe and PCR amplification system (45) have also been used to detect ten T. foetus parasites in samples containing bovine preputial smegma. Furthermore, a multiple target PCR technique enabled T. foetus to be distinguished from a variety of other protozoa. This might be a useful adjunct to culture in the primary diagnosis of T. foetus infection (73). Bulls selected for entry into AI should preferably be from disease-free herds and be tested in quarantine by the direct microscopic and culture tests on three occasions to ensure freedom from infection with T. foetus. These health certification requirements are similar to those for genital campylobacteriosis. Continued freedom from infection should then be confirmed by semi-annual tests. The J. foetus protozoan is unaffected by antibiotics in semen extenders so if an AI bull is found to be infected, the entire stock of frozen semen or, at least, the semen collected from the date of the last negative test should be destroyed (64). Information of value in assessing the risk of T. foetus being present in imported semen includes the country of origin of the semen, the history and breed of the bull, and the testing programme applied by the AI centre, with particular reference to the number of pre-entry and annual tests for the organism. categorisation of diseases according to the likelihood of transmission through AI as shown in Table I. It should be noted that the suggestions of the authors in regard to Categories 1, 2 and 3 are based on current knowledge and may change as new information becomes available. For some diseases, there is ample evidence that transmission to the female can occur through AI (Category 1, Table I), whereas for others the available evidence suggests that the risk of transmission through AI is low (Category 2, Table I). A third category of disease agents includes those for which information on transmission is limited, but based on the reports which are available the authors propose that these agents be subdivided into those likely to be transmitted in semen (Category 3a, Table I) and those unlikely to be transmitted (Category 3b, Table I). To illustrate the concept, bluetongue virus (BTV) is listed in Category 2 (Table I). This is because the presence of the virus in bull semen tends to be associated with virus-infected blood cells entering the male reproductive tract during the viraemic phase of infection ( 6 9 ) . There is no evidence that bulb develop persistent congenital infection or immunotolerance to the virus, as is the case with BVDV. Thus, in areas free of BTV, semen from seronegative bulls should pose a very low risk, while the performance of tests to demonstrate the absence of BTV in the blood of any bulls with circulating BTV antibodies should provide a sufficient guarantee for the semen of those bulls to be approved for export. In areas where the disease is endemic, semen collected from bulls with or without circulating antibodies, could also qualify for export provided that blood tests confirmed that the bulls were free of BTV at the time of collection. The schedule and frequency of tests would be determined as part of any risk assessment procedure. Several excellent models are available for assessing the risk of introducing disease into disease-free areas (58). Based on such models, practical risk assessment protocols can be developed. The quantitative assessment of risk of importation of disease by bull semen should be based on several factors, including the following: - the country of origin and the incidence of the specific diseases of concern to the importing country - knowledge of epidemiology of these specific diseases - standards of health certification for AI bulls and integrity and technical competence with which certification is performed - standards of hygiene applied to collecting, processing and storing semen - antibiotic treatment of semen and extenders Conclusions - season of the year when semen is collected (relevant to vector-bome diseases). In addition to the six examples considered in detail above, a wide variety of other disease agents may be excreted in bull semen ( 1 , 3 1 , 3 3 , 4 3 , 6 9 ) . The authors propose a Decisions on risk should be based on scientific knowledge of the diseases of concern and on whether international standards are applied for diagnosis and control. 220 Rev. sci tech. Off. int. Epiz., 16(1) Table I Risk of transmission of infectious bovine diseases through artificial insemination Category Diseases 1 Diseases with evidence that risk of transmission is moderate to high Foot and mouth disease Vesicular stomatitis Rinderpest Infectious bovine rhinotracheitis Bovine virus diarrhoea Bovine tuberculosis Bovine genital campylobacteriosis Bovine brucellosis Trichomonosis Mycoplasmosis Haemophilus somnus Ubiquitous bacteria (e.g. Pseudomonas aeruginosa, Escherichia coli) Diseases with some evidence that risk of transmission is low Bluetongue Enzootic bovine leukosis Bovine ephemeral fever Akabane virus Leptospirosis Diseases with little or no information on risk of transmission a ) Transmission of Category 3 diseases through artificial insemination likely Epizootic haemorrhagic disease Bovine immunodeficiency-like virus Bovine paratuberculosis Contagious bovine pleuropneumonia b) Transmission of Category 3 diseases through artificial insemination unlikely Lumpy skin disease Rift Valley fever Q fever Rabies Haemorrhagic septicaemia Bovine malignant catarrhal fever Bovine spongiform encephalopathy Listeriosis Anaplasmosls Babesiosis Chlamydia Fungi, yeasts 2 3 +: Presence of disease agent in bull semen demonstrated Presence of disease agent OIE Disease List + A A A B NR + + + + + + + + + + - + + A B NR - + + B B B B B + + + + - + A A B NR + B A NR NR NR NR B B B + - NR NR B B + + - NR: Not reported Consideration should also be given to the likely impact the more virulent, strains of indigenous disease agents, which disease would have on animal and human health in the event may become established and cause major economic losses. that the disease enters the country and becomes established. It should be realised that there is a risk of introducing new, • 221 Rev. sci tech. Off. int. Epiz., 16 (1) Risques pour la santé animale associés à l'insémination artificielle de bovins M.D. Eaglesome & M.M. Garcia Résumé Deux des principaux objectifs de l'insémination artificielle des animaux domestiques sont l'amélioration génétique permanente des cheptels et la prévention ou l'élimination de maladies vénériennes. L'insémination artificielle offre l'avantage de féconder autant de femelles et de produire autant de descendants qu'en saillie, mais à partir d'un nombre limité de mâles. Toutefois, l'insémination artificielle n'est pas exempte de risques ; elle peut, en effet, être à l'origine de la dissémination de tares génétiques et propager des maladies infectieuses à l'échelle nationale et internationale. Les auteurs examinent les risques de transmission de six maladies spécifiques par la semence de taureau, et décrivent les mesures appropriées pour prévenir ces risques. Mots-clés Bovins - Insémination artificielle - Maladies animales - Maladies génitales - Risque Semence. Riesgos zoosanitarios asociados a la inseminación artificial de bovino M.D. Eaglesome & M.M. Garcia Resumen Alcanzar una continua mejora genética y prevenir o eliminar las enfermedades venéreas son dos de los grandes objetivos de la inseminación artificial de animales de granja. Comparada con la monta natural, la inseminación artificial exige el concurso de menos machos para fecundar a un mismo número de hembras y producir un mismo número de descendientes. Sin embargo, la inseminación artificial no está exenta de riesgos, pues puede convertirse en vía de diseminación de taras genéticas o en fuente de propagación de enfermedades infecciosas a nivel tanto nacional como internacional. Los autores describen los riesgos asociados a seis enfermedades específicas que se transmiten a través del semen de toro, y presentan las medidas adecuadas para prevenir dichos riesgos. Palabras clave Bovinos - Enfermedades genéticas - Enfermedades animales - Inseminación artificial Riesgo-Semen. 222 Rev. sci tech. Off. int. Epiz., 16(1) References 1. Afshar A. & Eaglesome M.D. (1990). - Viruses associated with bovine semen. Vet. Bull, 60 (2), 93-109. 2. Akhtar S., Riemann H.P., Thurmond M.C., Farver T.B. & Franti C.E. (1990). - Multivariate logistic analysis of repeated cross-sectional surveys of Campylobacter fetus in dairy cattle. Prev. vet. Med., 10, 15-24. 3. Alt D.P. & Bolin C.A. (1996). - Preliminary evaluation of antimicrobial agents for treatment of Leptospira interrogans serovar pomona infection in hamsters and swine. Am. J. vet. Res., 57 (1), 59-62. 4. Alton G.G.; Jones L.M. & Pietz D.E. (1975). - Laboratory techniques in brucellosis, 2nd Ed. World Health Organisation (WHO), Geneva, 163 pp. 5. Amatredjo A. & Campbell R.S.F. leptospirosis. Vet. Bull, 43, 875-891. (1975). - Bovine 16. Brooks B.W., Garcia M.M., Robertson R.H. & Lior H. (1996). - Electrophoretic and immunoblot analysis of Campylobacter fetus lipopolysaccharides. Vet. Microbiol, 5 1 , 105-114. 17. Brunner D., Engels M., Schwyzer M. & Wyler R. (1988). - A comparison of three techniques for detecting bovine herpesvirus type 1 in naturally and experimentally contaminated bovine semen. Zuchthygiene, 23, 1-9. 18. Bryan N.S. & Boley L.E. (1955). - Studies on leptospirosis in domestic animals. IV. Survival of Leptospira pomona in bovine semen extender. Mich. St. Univ. Vet., 16, 27-29, 55. 19. Campero C.M., Hirst R.G., Ladds P.W., Vaughan J.A., Emery D.L. & Watson D.L. (1990). - Measurement of antibody in serum and genital fluids of bulls by ELISA after vaccination and challenge with Tritrichomonas foetus. Aust. vet.J., 67, 175-178. 6. Bartlett D.E. (1981). — Bull semen: specific microorganisms. In FAO, disease control in semen and embryos. FAO Animal Production and Health Paper No. 23, 29-48. 20. Campero C.M., Ladds P.W., Hoffmann D., Duffield B., Watson D. & Fordyce G. (1990). - Immunopathology of experimental Brucella abortus strain 19 infection of the genitalia of bulls. Vet. Immunol. Immunopathol, 24, 235-246. 7. Bastyns K., Chaelle S., VanDamme P., Goosens M. & De Wächter R. (1994). - Species-specific detection of Campylobacters important in veterinary medicine by PCR amplification of 23S rDNA areas. Sys. appl. Microbiol, 17 (4), 563-568. 21. Caroff M., Bundle D.R., Perry M.B., Cherwonogrodzky J.W. & Duncan J.R. (1984). - Antigenic S-type lipopolysaccharide of Brucella abortus 1119-3. Infect. & Immunity, 4 6 , 384-388. 8. Bendixen H.C & Blom E. (1947). - The occurrence of brucellosis in bulls and the importance of artificial insemination. Maanedsskr. Dyrlaag, 59, 61-140. 9. Blom K., Patton C.M., Nicholson M.A.. & Swanminathan B. (1995). - Identification of Campylobacter fetus by PCR-DNA probe method J . clin. Microbiol, 33 (4), 1360-1362. 10. Bokhout B.A., Peterse D.J., Koger P.L. & Terpstra W.J. (1989). - Preliminary serological survey for hardjo-positive cows in the northern Netherlands. Tijdschr. Diergeneesk., 114, 123-130. 11. Bolin S.R. & Ridpath J.F. (1992). - Differences in virulence between two noncytopathic bovine viral diarrhea viruses in calves. Am. J. vet. Res., 53 (11), 2157-2163. 12. BonDurant R.H. (1985). - Diagnosis, treatment, and control of bovine trichomoniasis. Compend. cont. Educ. pract. Vet, 7, S179-S188. 13. BonDurant R.H., Anderson M.L., Blanchard P., Hird D., Danaye-Elmi C , Palmer C , Sischo W.M., Suther D., UtterbackW. & Weigler B.J. (1990). - Prevalence of trichomoniasis among California beef herds. J. Am. vet. med. Assoc., 196, 1590-1593. 14. Borchardt K.A., Norman B.N., Thomas M.W. & Harmon W.M. (1992). - Evaluation of a new culture method for diagnosing Tritrichomonas foerus. Vet. Med., 87, 104-112. 15. Bouters R., Keyser J. de, Vandeplassche M., Aert A. van, Brone E. & Bonte P. (1973). - Vibrio fetus infection in bulls: curative and preventive vaccination. Br. vet.]., 129, 52-57. 22. Cho H.J., Masri S.A., Deregt T.D., Yeo S.-G. & Thomas E.J.G. (1991). - Sensitivity and specificity of an enzyme-linked immunosorbent assay for the detection of bovine viral diarrhea virus antibody in cattle. Can. J. vet. Res., 55, 56-59. 23. Clark B.L. (1971). - Review of bovine vibriosis. Aust. vet. J., 47, 103-107. 24. Clark B.L. & Dufty J.H. (1978). - Isolation of Campylobacter fetus from bulls. Aust. vet. J., 54, 262-263. 25. Cole J.R., Sulzer CR. & Pursell A.R. (1973). - Improved microtechnique for the leptospiral microscopic agglutination test. Appl. Microbiol, 25, 976-980. 26. Corbeil L.B., Schurig G.G.D., Bier P.J. & Winter A.J. (1975). - Bovine venereal vibriosis: antigenic variation of the bacterium during infection. Infect. & Immunity, 11, 240-244. 27. DaCosta M., Guillou J.-P., Garin-Bastuji B., Thiebaud M. & Dubray G. (1996). - Specificity of six gene sequences for the detection of the genus Brucella by DNA amplification. J. appl. Bacteriol, 8 1 , 267-275. 28. Dennet D.P., Barasa J.O. &Johnson R.H. (1976). - Infectious bovine rhinotracheitis virus: studies on the venereal carrier state in range cattle. Res. vet. Sci., 20, 77-83. 29. Deregt D., Cho H.J. & Kozub G.C. (1993). - A comparative evaluation of two sensitive serum neutralization tests for bovine herpesvirus-1 antibodies. Can. J. vet. Res., 57 (1), 56-59. 30. Deregt D. & Loewen K G . (1995). - Bovine viral diarrhea virus: biotypes and disease. Can. vet.J., 36, 371-378. Rev. sci tech. Off. int. Epiz., 16 (1) 31. Eaglesome M.D. & Garcia M.M. (1992). - Microbial agents associated with bovine genital tract infections and semen. Part I. Brucella abortus, Leptospira, Campylobacter fetus and Tritrichomonasfoetus. Vet. Bull, 62 (8), 743-775. 32. Eaglesome M.D. & Garcia M.M. (1992). - Survival of Campylobacter fetus subsp. venerealis in antibiotic-treated processed bovine semen. In Proc. 12th International Conference on Animal Reproduction (ICAR), Vol. III. The Hague, 23-27 August. ICAR Free Communication No. 457, The Hague, 1542-1543. 33. Eaglesome M.D., Garcia M.M. & Stewart R.B. (1992). Microbial agents associated with bovine genital tract infections. Part II. Haemophilus somnus, Mycoplasma spp. and Ureaplasma spp., Chlamydia; pathogens and semen contaminants; treatment of bull semen with antimicrobial agents. Vet. Bull, 62 (9), 887-910. 34. Eaglesome M.D., Sampath M.I. & Garcia M.M. (1995). - A detection assay for Campylobacter fetus in bovine semen by restriction analysis of PCR amplified DNA. Vet Res. Comm., 19, 253-263. 35. Ellis W.A. & Montgomery J.A. (1985). - Dihydrostreptomycin in treatment of bovine carriers of Leptospira interrogans serovar hardjo. Res. vet. Sci., 39, 292-295. 223 44. Herr S., Ribeiro L.M.M., Claassen E. & Myburgh J.G. (1991). - A reduction in the duration of infection with Tritrichomonas foetus following vaccination in heifers and the failure to demonstrate a curative effect in infected bulls. Onderstepoort J. vet. Res., 58, 41-45. 45. Ho M.S.Y., Conrad P.A., Conrad P.J., LeFebvre R.B., Perez E. & BonDurant R.H. (1994). - Detection of bovine trichomoniasis with a specific DNA probe and PCR amplification system. J. clin. Microbiol, 3 2 (1), 98-104. 46. Hum S., Brunner J. & Gardiner B. (1993). - Failure of therapeutic vaccination of a bull infected with Campylobacter fetus. Aust. vet.J., 70 (10), 386-387. . 47. Jones R.L., Davis M.A. & Vonbyem H. (1985). - Cultural procedures for the isolation of Campylobacter fetus subspecies venerealis from preputial secretions and occurrence of antimicrobial resistance. In Proc. Annual Meeting of the American Association of Veterinary Laboratory Diagnosticians, 27-29 October. American Association of Veterinary Laboratory Diagnosticians, Brookings, South Dakota, 28, 225-238. 48. Kiktenko V.S., Balashov N.G. & Rodina V.N. (1976). Leptospirosis infection through insemination of animals. J. Hyg. Epidemiol. Microbiol. and Immunol, 20, 207-213. 36. Ellis W.A., Cassells J.A. & Doyle J . (1986). - Genital leptospirosis in bulls. Vet. Rec., 118, 333. 49. Kimsey P.B. (1986). - Bovine trichomoniasis. In Current therapy in theriogenology, Part II (D.A. Morrow, ed.). W.B. Saunders & Co., Philadelphia, 275-279. 37. Fekete A., Bantle J.A. & Hailing S.M. (1992). - Detection of Brucella by polymerase chain reaction in bovine fetal and maternal tissues. J. vet. Diagn. Invest., 4, 79-83. 50. Kimsey P.B., Darien B.J., Kendrick J.W. & Franti C.E. (1980). - Bovine trichomoniasis: diagnosis and treatment. J. Am. vet. med. Assoc., 177, 616-619. 38. Gall D. & Nielsen K. (1994). - Improvements to the competitive ELISA for detection of antibodies to Brucella abortus in cattle sera. J. Immunoassay, 15 (3), 277-291. 51. Kirkland P.D., Richards S.G., Rothwell J.T. & Stanley D.F. (1991). - Replication of bovine viral diarrhoea virus in the bovine reproductive tract and excretion of virus in semen during acute and chronic infections. Vet. Rec., 128, 587-590. 39. Garcia M.M., Stewart R.B. & Ruckerbauer G.M. (1984). Quantitative evaluation of a transport enrichment medium for Campylobacter fetus. Vet. Rec., 115, 434-436. 52. Kommisrud E., Vatn T., Lang-Ree J.R. & Loken T. (1996). Bovine virus diarrhoea virus in semen from acutely infected bulls. Acta. vet. Scand., 37, 41-47. 40. Garcia M.M., Lutze-Wallace C.L., Denes A.S., Eaglesome M.D., Holst E. & Blaser M.J. (1995). - Protein shift and antigenic variation in the S-layer of Campylobacter fetus subsp. venerealis during bovine infection accompanied by genomic rearrangement of sap A homologs. J. Bacterial., 177 (8), 1976-1980. 53. Lander K.P. (1990). - The development of a transport and enrichment medium for Campylobacter fetus. Br. vet. J., 146, 327-333. 41. Gerritsen M.J., Olyhoek T., Smits M.A. & Bokhout B.A. (1991). - Sample preparation method for polymerase chain reaction-based semiquantitative detection of Leptospira interrogans serovar hardjo subtype hardjobovis in bovine urine. J. clin. Microbiol, 2 9 , 2805-2808. 55. McGowan M.R., Kirkland P.D., Richards S.G. & Littlejohns I.R. (1993). - Increased reproductive losses in cattle infected with bovine pestivirus around the time of insemination. Vet. Rec., 133, 39-43. 42. Godfroid J . , Vanopdenbosch E., Wellemans G. & Letesson J.J. (1994). - Bovine herpesvirus 1 diagnosis based on an in vitro antigenic-specific IFN-y production. In Proc. Third Congress of the European Society of Veterinary Virology. Interlaken, Switzerland, 2, 11. 43. Hare W.C.D. (1985). - Diseases transmissible by semen and embryo transfer techniques. Technical Series No. 4. Office International des Epizooties, Paris, 117 pp. 54. Lander K.P. (1990). - The application of a transport and enrichment medium to the diagnosis of Campylobacter fetus infections in bulls. Br. vet.J., 146, 334-340. 56. Meyling A. & Jensen A.M. (1988). - Transmission of bovine virus diarrhoea virus (BVDV) by artificial insemination (AI) with semen from a persistently-infected bull. Vet. Microbiol., 17, 97-105. 57. Monke D.R. & Howard T.H. (1992). - IBR research update and commentary. In Proc. 14th Technical Conference on artificial insemination and reproduction, 24-25 April. National Association of Animal Breeders, Milwaukee, Wisconsin, 14, 26-29. 224 Rev. sCi tech. Off. int. Epiz., 16 (1) 58. Morley R.S. (ed.) (1993). - Risk analysis, animal health and trade. Rev. sCi. tech. Off. int. Epiz., 12 (4), 448 pp. 59. Nettleton P.F. & Entrican G. (1995). pestiviruses. Br. vet.J., 151, 615-642. - Ruminant 60. Nicoletti P. (1986). - Effects of brucellosis on bovine reproductive efficiency. In Current therapy in theriogenology, Part II (D.A. Morrow, ed.). W.B. Saunders & Co., Philadelphia, 271-274. 61. Nielsen K., Cherwonogrodzky J.W., Duncan J.R. & Bundle D.R (1989). - Enzyme-linked immunosorbent assay for differentiation of the antibody response of cattle naturally infected with Brucella abortus or vaccinated with strain 19. Am.J, vet. Res., 50, 5-9. 62. Office International des Epizooties (OIE) (1992, updated 1996). - International Animal Health Code, 6th Ed. OIE, Paris, 550 pp. 63. On S.L.W. & Holmes B. (1991). - Reproducibility of tolerance tests that are useful in the identification of Campylobacter. J. clin. Microbiol, 29, 1785-1788. 64. Parez M. (1984). - The most important genital diseases of cattle (control, treatment and the hygiene of semen collection), In Proc. 11th Conference of the OIE Regional Commission for Europe, Vienna, 25-28 September. OIE, Paris, 175-203. 65. Pastoret P.-P., Babiuk L.A., Misra V. & Briebel P. (1984). Reactivation of temperature sensitive and non-temperature sensitive infectious bovine rhinotracheitis vaccine virus with dexamethasome. Infect. & Immunity, 29, 493-497. 66. Paton D.J., Goodey R., Brockman S. & Wood L. (1989). Evaluation of the quality and virological status of semen from bulls acutely infected with BVDV. Vet. Rec.., 124, 63-64. 67. Pefanis S.M., Herr S., Venter C.G., Kruger L.P., Queiroga C.C. & Amaral L. (1988). - Trichomoniasis and campylobacteriosis in bulls in the Republic of Transkei. J. S. Afr. vet. Assoc., 59,139-140. 73. Riley D.E., Wagner B., Polley L. & Krieger J.N. (1995). PCR-based study of conserved and variable DNA sequences of Tritrichomonas foetus isolates from Saskatchewan, Canada. J. clin. Microbiol, 33 (5), 1308-1313. 74. Rodina V.N. & Balashov N.G. (1971). - Leptospiral infection of animals transmitted through insemination. In Proc. 19th World Veterinary Congress, Mexico City, Vol. 2. World Veterinary Congress, Mexico City, 708-709. 75. Salama S.M., Garcia M.M. & Taylor D.E. (1992). Differentiation of the subspecies of Campylobacter fetus by genome sizing. Int. J. Syst. Bact., 42, 446-450. 76. Schultz R.D., Adams L.S., Letchworth G., Sheffy B.E., Manning T. & Bean B. (1982). - A method to test large numbers of bovine semen samples for viral contamination and results of a study using this method. Theriogenology, 17, 115-123. 77. Schurig G., Boyle S. & Sriranganathan N.S. (1996). - Brucella abortus vaccine strain RB51: a brief review. Arch. Med. Vet, X X V I I (special issue), 19-22. 78. Seger C.L., Lank R.B. & Levy H.E. (1966). - Dihydrostreptomycin for treatment of genital vibriosis in the bull. J. Am. vet. med. Assoc., 149, 1634-1639. 79. Shannon A.D., Mackintosh S.G. & Kirkland P.D. (1992). Identification of pestivirus carrier calves by an antigencapture ELISA. Aust. vet.J., 70 (2), 74-76. 80. Shin S.J., Lein D.H., Patten V.H. & Runnke H.L. (1988). - A new antibiotic combination for frozen bovine semen. 1. Control of mycoplasmas, Ureaplasmas, Campylobacter fetus subsp. venerealis and Haemophilus somnus. Theriogenology, 29 (3), 577-591. 81. Shisong C , Redwood D.W. & Ellis B. (1990). - Control of Campylobacter fetus in artificially contaminated bovine semen by incubation with antibiotics before freezing. Br. vet. J., 146, 68-74. 82. Skirrow S., BonDurant R., Farley J . & Correa J . (1985). Efficacy of ipronidazole against trichomoniasis in beef bulls. J. Am. vet. med. Assoc., 187, 405-407. 68. Pfeffer M., Wiedmann M. & Batt C.A. (1995). - Applications of DNA amplification techniques in veterinary diagnosis. Vet. Res. Comm., 19, 375-407. 83. Sleight S.D. (1965). - The role of penicillin and streptomycin in the prevention of transmission of bovine leptospirosis by artificial insemination. Am.J. vet. Res., 26, 365-368. 69. Phillpot M. (1993). - The dangers of disease transmission by artificial insemination and embryo transfer. Br. vet. J., 149, 339-369. 84. Sleight S.D., Atollah O.A. & Steinbauer D.J. (1964). Experimental leptospiral pomona infection in bulls. Am. J. vet. Res., 25, 1663-1668. 70. Plant J.W., Claxton P.D., Jakovlyevic D. & De Saram W. (1976). - Brucella abortus infection in the bull. Aust. vet. J., 52, 17-20. 85. Smith C.R., Ketterer P.J., McGowan M.R. & Corney B.G. (1994). - A review of laboratory techniques and their use in the diagnosis of Leptospira interrogans serovar hardjo infection in cattle. Aust. vet.J., 71 (9), 290-294. 71. Radostits O.M. & Litdejohns I.R. (1988). - New concepts in the pathogenesis, diagnosis and control of diseases caused by the bovine viral diarrhea virus. Can. vet.J., 29, 513-525. 72. Ramadass P., Jarvis B.D.W., Corner R.J., Penny D. & Marshall R.B. (1992). - Genetic characterization of pathogenic Leptospira species by DNA hybridisation. Int. J. Syst. Bact., 42 (2), 215-219. 86. Straub O.C (1990). - Infectious bovine rhinotracheitis. In Virus infections of ruminants (Z. Dinter & B. Morein, eds). Elsevier Science Publishers, Amsterdam, 71-108. 87. Taylor M.A., Marshall R.N. & Stack M. (1994). Morphological differentiation of Tritrichomonas foetus from other protozoa of the bovine reproductive tract. Br. vet. J., 150, 73-80. Rev. sci tech. Off. int. Epiz., 16(1) 88. Terpstra W.J. (1989). - Enzymatic detection systems for leptospiral antibodies. antigen, and nucleic acids, In Proc. Canadian Society of Microbiologists Symposium on Leptospires, Vol. 1 (Part 3). Canadian Society of Microbiologists, Laval, Quebec, 14 June, 1-24. 89. Thiermann A.B. & Ellis W.A. (1986). - Identification of leptospires of veterinary importance by restriction endonuclease analysis. In The present state of leptospirosis diagnosis and control (W.A. Ellis & W.A. Little, eds). Martinus Nijhoff Publishers, Dordrecht, 91-104. 225 campylobacteriosis (vibriosis): vaccination of experimentally infected bulls. Am. J. vet. Res., 4 4 (8), 1553-1557. 97. Vilcek S., Nettieton P.F., Herring J.A. & Herring A.J. (1994). - Rapid detection of bovine herpes virus 1 (BHV-1) using the polymerase chain reaction. Vet. Microbiol, 42, 56-64. 98. Villar J.A. & Spina E.M. (1982). - Campilobacteriosis (vibriosis) bovina. Una recopilación de datos sobre su incidencia en el periodo 1966-1981. Gac. Vet, 4 4 , 647-658. 90. Thomas M.W., Harmon W.M. & White C. (1990). - An improved method for the detection of Tritrichomonas foetus infection by culture in bulls. Agri-Practice, 11, 13-17. 99. Virakul P., Fahning M.L., Joo H.S. & Zemjanis R. (1988). Fertility of cows challenged with bovine viral diarrhea virus during an outbreak of spontaneous infection with a noncytopathic strain. Theriogenology, 29 (2), 441-449. 91. Trueba G.A., Bolin C.A. & Thoen C O . (1990). - Evaluation of an enzyme immunoassay for diagnosis of bovine leptospirosis caused by Leptospira interrogans serovar hardjo type hardjo-bovis. J. vet. Diagn. Invest., 2, 323-329. 100. Weiblen R., Kreutz L.C., Canabarro T.F., Schuch L.F. & Rebelatto M.C (1992). - Isolation of bovine herpesvirus 1 from preputial swabs and semen of bulls with balanoposthitis. J. vet. Diagn. Invest., 4, 341-343. 92. Truyen U., Parrish C.R., Harder T.C. & Kaaden O.-R. (1995). - There is nothing permanent except change. The emergence of new virus diseases. Vet. Microbiol, 43, 103-122. 101. Winter A.J. (1982). - Microbial immunity in the reproductive tract. J. Am. vet. med. Assoc., 181 (10), 1969-1073. 93. Van Aert A., Brioen P., Dekeyser P., Uytterhaegen L., Sijens R.J. & Boeye A. (1984). - A comparative study of ELISA and other methods for the detection of Brucella antibodies in bovine sera. Vet. Microbiol, 10, 3-21. 102. World Health Organisation (WHO) (1967). - Current problems in leptospirosis research. Technical Report Series No. 380. WHO, Geneva, 32 pp. 94. Van der Oirschot J.T. (1995). - Bovine herpes virus 1 in semen of bulls and the risk of transmission: a brief review. Vet. Q., 17 (1), 29-33. 95. Van der Oirschot J.T., Straver P.J., van Lieshout J.A.H., Quak J . , Westenbrink F. & van Exsel A.C.A. (1993). A subclinical infection of bulls with bovine herpesvirus type 1 at an artificial insemination centre. Vet. Rec., 132, 32-35. 96. Vasquez L.A., Ball L., Bennett B.W., Rupp G.P., Ellis R., Olson J.D. & Huffman M.H. (1983). - Bovine genital 103. Xia J.Q., Lofstedt R.M., Yason C.V. & Kibenge F.S.B. (1995). - Detection of bovine herpes virus-1 in the semen of experimentally infected bulls by dot-blot hybridisation, polymerase chain reaction and virus isolation. Res. vet. Sci., 59, 183-185. 104. Xia J.Q., Yason C.V. & Kibenge F.S.B. (1995). - Comparison of dot-blot hybridisation, polymerase chain reaction and virus isolation for detection of bovine herpes virus-1 (BHV-1) in artificially infected bovine semen. Can. J. vet. Res., 59, 102-109.