Prevalence and risk factors for Trichomonas foetus infection in cattle in northeastern Costa Rica

Survey of beef bulls in Brazil to assess their role as source of infectious agents related to cow infertility

Poor reproductive performance in beef cattle caused by infectious agents results in major financial losses as a result of reduced pregnancy rates and extended calving intervals. Bulls can be subclinical chronic carriers of bacterial and protozoal agents involved in cow infertility, such as Campylobacter fetus subsp. venerealis, Ureaplasma diversum, Mycoplasma bovigenitalium, Mycoplasma bovis, and Tritrichomonas foetus. Bulls harbor these microorganisms in their preputial crypts and transmit the agents to cows during natural mating. To obtain an overview of the etiologic agents in the preputial mucus of bulls, we aimed to identify, by PCR assay, C. fetus subsp. venerealis, M. bovis, U. diversum, M. bovigenitalium, and T. foetus in Brazilian bulls from farms with high infertility rates. We collected preputial mucus from 210 bulls on 18 beef cattle farms in Brazil between 2019 and 2020. We found at least one of the infectious agents that we were studying in bulls on 16 of the 18 beef cattle farms tested. We detected at least one infectious agent from 159 of 210 (76%) bulls tested, namely C. fetus subsp. venerealis, M. bovis, U. diversum, M. bovigenitalium, and T. foetus in 87 (55%), 84 (53%), 45 (28%), 28 (18%), and 1 (0.6%) animal, respectively. We found 95 bulls (60%) positive for only 1 etiologic agent (single infection) and 64 bulls (40%) carried multiple agents. Our results demonstrate the occurrence of bacterial and protozoal infectious agents that may be related to infertility in Brazilian beef cattle herds.

Tritrichomonas Foetus as a Causative Agent of Tritrichomonosis in Different Animal Hosts

Tritrichomonas foetus is a protozoan parasite that has been traditionally identified as a cause of reproductive tract disease in cattle and gastrointestinal tract infection in cats. Moreover, T. foetus is also well known as a commensal of the nasal cavity, intestines, and stomach in swine. In this review we describe T. foetus as a pathogen dangerous to more than one animal host, diagnostic and taxonomic aspects of this infection, and the extent to which isolates from different hosts share genetic identity.

Prevalence of bovine trichomonosis and associated risk factors in bulls from Spanish beef herds

Bovine trichomonosis is a sexually transmitted disease considered as an important cause of early reproductive failure in beef cattle. To investigate the occurrence of the infection in different Spanish beef cattle-producing areas, retrospective data from the SALUVET veterinary diagnostic laboratory (Veterinary Faculty, Madrid, Spain) derived from the analysis of samples from beef bulls that were routinely tested for Tritrichomonas foetus infection, were compiled from 2011 to 2015. In addition, a number of potential risk factors were assessed. T. foetus was detected in 12.7% (385/3016; 95% CI: 11.5%-13.9%) of samples from bulls and in 20.7% (195/941; 95% CI: 18.1%-23.3%) of the herds tested. "Bull age" and "reproductive disorders in the herd" were the risk factors identified in the multivariable analysis. Bulls older than 3 years (19.7%) were more likely to be infected than young bulls (8.2%) and T. foetus was more often detected in herds with reproductive problems (27.9%) than in those without reproductive disorders (9.4%). The prevalence in bulls originating in mountain systems (13.9%, 267/1922) was significantly higher than that in "dehesa" (Mediterranean holm-oak pasture) areas (10.8%; 118/1094) (P ˂ 0.05), which might be attributable to the use of communal pastures and specific management practices in mountain systems. The results reported here indicate that T. foetus infection is substantially spread among beef cattle herds, suggesting that BT could be having a significant negative impact on the reproduction and productivity of Spanish beef herds managed under extensive conditions.

Prevalence and risk factors associated with Tritrichomonas foetus infection in cattle in the state of Paraíba, Brazil

The objective of this study was to determine the prevalence of Tritrichomonas foetus infection and to evaluate risk factors associated with this infection among cattle in the state of Paraíba in northeastern Brazil. Samples of cervicovaginal mucus from 290 females and smegma from 59 males [beef, 31; mixed aptitude (beef and dairy), 10; and dairy, 18] from 31 farms were collected. Modified Diamond's medium and polymerase chain reaction (PCR) were used for the laboratory diagnosis of T. foetus infection. Univariate analysis and logistic regression were performed to test for potential risk factors in addition to prevalence mapping. No sample was positive for T. foetus in culture, and the prevalence of T. foetus infection using PCR was 3.7% (13/349) [confidence interval (CI) 95%, 2.1%-6.4%]. In total, 19.3% (6/31) of the farms had at least one animal positive for T. foetus. The contact of females with males from other farms [Odds ratio, 5.9; 95% CI, 1.5-22.4; p = 0.009] was identified as a risk factor for T. foetus infection. This study demonstrates that T. foetus infection is prevalent among dairy cows in the state of Paraíba, Brazil. Sexual resting, removal of positive females, and avoiding contact of females with males from other farms are recommended to reduce the risk of infection.

Trichomonas

The most widely known trichomonad in veterinary medicine is Tritrichomonas foetus. It is the etiologic agent of bovine tritrichomonosis, a sexually transmitted disease in extensively managed herds throughout many geographic regions worldwide. The same trichomonad species is also regarded as the causative agent of chronic diarrhea in the domestic cat, although more recent studies observed molecular differences between bovine- and feline-derived T. foetus. Trichomonosis in cats has a worldwide distribution and is mainly present among cats from high-density housing environments. Other trichomonads are found as inhabitants of the gastrointestinal tract in birds, such as Trichomonas gallinae. Particularly, Columbiformes, Falconiformes, Strigiformes, and wild Passeriformes can be severely affected by avian trichomonads. Diagnosis of trichomonosis is often complicated by the fragility of the parasite. To ensure valid test results, it is essential to collect and handle specimens in the right way prior to analysis. Cultivation tests, the specific amplification of parasites, or a combination of both test methods is the most efficient and most commonly used way to diagnose trichomonosis in animals. Bovine tritrichomonosis is mainly controlled by the identification and withdrawal of infected animals from bovine herds. The control of feline and avian trichomonosis relies mainly on preventive measures.

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): Trichomonosis

Trichomonosis has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on the eligibility of trichomonosis to be listed, Article 9 for the categorisation of trichomonosis according to disease prevention and control rules as in Annex IV and Article 8 on the list of animal species related to trichomonosis. The assessment has been performed following a methodology composed of information collection and compilation, expert judgement on each criterion at individual and, if no consensus was reached before, also at collective level. The output is composed of the categorical answer, and for the questions where no consensus was reached, the different supporting views are reported. Details on the methodology used for this assessment are explained in a separate opinion. According to the assessment performed, trichomonosis can be considered eligible to be listed for Union intervention as laid down in Article 5(3) of the AHL. The disease would comply with the criteria as in sections 3, 4 and 5 of Annex IV of the AHL, for the application of the disease prevention and control rules referred to in points (c), (d) and (e) of Article 9(1). The animal species to be listed for trichomonosis according to Article 8(3) criteria is cattle as susceptible and reservoir.

Risk factors associated with bovine trichomoniasis in beef cattle identified by a questionnaire

Bovine trichomoniasis is a venereal disease that causes substantial economic losses to the cattle industry worldwide. It has been endemic in the USA since its discovery in the 1930s. The reasons for this long-lasting endemism are poorly understood. The main objective of this study was to identify herd-level risk factors for trichomoniasis in Wyoming beef cattle. A questionnaire was sent to all Wyoming beef cattle producers. The overall response proportion was 23.4 %. Questionnaires were returned from producers throughout the state in different geographical regions and with various herd sizes. In total, 863 questionnaires were analysed for correlation between the disease endemism and 25 variables. Tritrichomonas foetus infections were found to be significantly (P<0.05) associated with neighbouring a positive herd(s), grazing on public allotments and commingling with other herds. In addition, a delay in fixing broken fences approached statistical significance (P = 0.078). This study provides producers with valuable information and useful suggestions on how to effectively control and reduce the risks of bovine trichomoniasis.

Sensitivity of a real-time polymerase chain reaction for Tritrichomonas fetus in direct individual and pooled preputial samples

The objective of this study was to evaluate the sensitivity of a commercially available real-time polymerase chain reaction (PCR) test for the detection of Tritrichomonas fetus in individual and pooled direct preputial samples. Two samples were collected and processed once a week from nine T. fetus-infected bulls (n = 121) and placed into either an InPouch TF or 2 mL of PBS. Preputial samples were also collected into both media and PBS from 1016 other bulls. All pouches were cultured and evaluated as per manufacturer's instructions. The prepuce samples collected directly into PBS were individually evaluated using real-time PCR by a commercial diagnostic laboratory. Direct preputial samples were then randomly divided for pooling into groups of 5 and 10 samples, ensuring that every pool had one sample from a known infected bull before testing using real-time PCR. Sensitivity was estimated for culture and real-time PCR of the 121 direct and culture-enriched individual samples from nine infected bulls. There were no differences (P = 0.12) among the sensitivity estimates for culture, 95.0% (95% confidence interval [CI]: 89.6%-97.7%); real-time PCR of culture-enriched samples, 95.9% (95% CI: 90.7-98.2); and direct preputial samples, 90.1% (95% CI: 83.5-94.2). There was also no significant difference (P = 0.08) between the sensitivity of real-time PCR for direct preputial samples in 110 pools of 5 (83.6%, 95% CI: 75.6-89.4) or 10 samples (77.3%, 95% CI: 68.6-84.1). The use of three sequential direct samples, collected in PBS at weekly intervals and tested by real-time PCR, increased the sensitivity to 100% for pools of 5 and 96% for pools of 10. In conclusion, direct preputial samples collected in PBS and tested by real-time PCR individually have comparable sensitivity to culture and real-time PCR in enriched samples. The use of pooled direct preputial samples appears to be relatively sensitive. However, this strategy requires repeated sampling to optimize sensitivity. Real-time PCR testing of preputial samples collected directly into PBS with the option of pooling would decrease the cost associated with screening bulls, and increase the feasibility of large epidemiological studies and active surveillance.

Molecular determination of Tritrichomonas spp. in aborted bovine foetuses in Eastern Anatolian Region of Turkey

Tritrichomonas foetus is the causative agent of venereal trichomonosis in cattle causing infertility, pyometra and abortions. The objectives of this study were to determine the positivity rate of Tritrichomonas spp. in abomasal content of aborted foetuses from Eastern Anatolian Region of Turkey, using staining, culture and PCR methods and to present the isolates found in the region. A total of 246 abomasal content of aborted foetuses were tested and 14 of 246 (5.7%) were Tritrichomonas spp. positive only by polymerase chain reaction (PCR). Positivity was not attained by staining or culture method. Four of the positive samples in PCR were confirmed to be T. foetus by sequencing of the amplified 5.8S rRNA gene and flanking ITS regions. Nucleotide sequences of TR-Erzurum T. foetus isolates have been entered into the GenBank sequence database under accession numbers KC236423 through KC236426. This preliminary study suggests that future studies are needed on the systematic relationships and epidemiology of T. foetus isolates in the region.

Morphological and molecular identification of non-Tritrichomonas foetus trichomonad protozoa from the bovine preputial cavity

Tritrichomonas foetus is the causative agent of bovine trichomonosis. This protozoan is found in the preputial cavity of bulls and is transmitted to cows during coitus. Currently, the diagnosis of this parasite is based on microscopic examination of preputial washings or scrapings, but it was recently recognized that other trichomonads similar in size, shape, and motility to T. foetus can be present in preputial samples. Despite the serious consequences of an incorrect diagnosis for bovine trichomonosis, the precise speciation of these other trichomonads has remained uncertain. Here, a total of 12 non-T. foetus isolates were microscopically examined. On the basis of morphological criteria, seven of these isolates were identified as Tetratrichomonas sp., whereas four other isolates coincided with the description of Pentatrichomonas hominis. In the last isolate, a third non-T. foetus species was identified as belonging to the genera Pseudotrichomonas or Monocercomonas: the first time that species of either of these genera have been reported in preputial samples. To confirm these data, small subunit rRNA gene sequences were obtained by PCR from the 12 trichomonad isolates. These new sequences were analysed in a broad phylogeny including 72 other parabasalid sequences. From our phylogenetic trees, we confirmed the taxonomic status of non-T. foetus organisms isolated from preputial samples (Tetratrichomonas, Pentatrichomonas, and Pseudotrichomonas) and suggested the existence of two Tetratrichomonas species, despite their morphological similarity. The route of transmission of the non-T. foetus organisms identified in the bovine preputial cavity is discussed and we confirm that the PCR assay using the previously described T. foetus-specific primers TFR3 and TFR4 could be a useful alternative method for the diagnosis of bovine trichomonosis.

Improved detection of Tritrichomonas foetus in bovine diagnostic specimens using a novel probe-based real time PCR assay

A Tritrichomonas foetus-specific 5' Taq nuclease assay using a 3' minor groove binder-DNA probe (TaqMan MGB) targeting conserved regions of the internal transcribed spacer-1 (ITS-1) was developed and compared to established diagnostic procedures. Specificity of the assay was evaluated using bovine venereal microflora and a range of related trichomonad species. Assay sensitivity was evaluated with log(10) dilutions of known numbers of cells, and compared to that for microscopy following culture (InPouch TF test kit) and the conventional TFR3-TFR4 PCR assay. The 5' Taq nuclease assay detected a single cell per assay from smegma or mucus which was 2500-fold or 250-fold more sensitive than microscopy following selective culture from smegma or mucus respectively, and 500-fold more sensitive than culture followed by conventional PCR assay. The sensitivity of the conventional PCR assay was comparable to the 5' Taq nuclease assay when testing purified DNA extracted from clinical specimens, whereas the 5' Taq nuclease assay sensitivity improved using crude cell lysates, which were not suitable as template for the conventional PCR assay. Urine was evaluated as a diagnostic specimen providing improved and equivalent levels of T. foetus detection in spiked urine by both microscopy following culture and direct 5' Taq nuclease detection, respectively, compared with smegma and mucus, however inconclusive results were obtained with urine samples from the field study. Diagnostic specimens (n=159) were collected from herds with culture positive animals and of the 14 animals positive by 5' Taq nuclease assay, 3 were confirmed by selective culture/microscopy detection (Fisher's exact test P<0.001). The 5' Taq nuclease assay described here demonstrated superior sensitivity to traditional culture/microscopy and offers advantages over the application of conventional PCR for the detection of T. foetus in clinical samples.

An improved molecular assay for Tritrichomonas foetus

Tritrichomonas foetus (T. foetus) is the causative agent of bovine trichomonosis, a sexually transmitted disease leading to abortion (from 1 to 8 months gestation), infertility, and occasional pyometra. The annual losses to the U.S. beef industry are estimated to be in the hundreds of millions of dollars. Currently, the "gold standard" diagnostic test for trichomonosis in most countries is the cultivation of live organisms from reproductive secretions. The cultured organisms can then be followed by PCR assays with primers that amplify T. foetus to the exclusion of all other trichomonad species. Thus, negative results present as null data, indistinguishable from failed PCR amplification during T. foetus specific amplification. Our newly developed assay improves previously developed PCR based techniques by using diagnostic size variants from within the internal transcribed spacer 1 (ITS1) region that is between the 18S rRNA and 5.8S rRNA subunits. This new PCR assay amplifies trichomonad DNA from a variety of genera and positively identifies the causative agent in the bovine trichomonad infection. This approach eliminates false negatives found in some current assays as well as identifying the causative agent of trichomonad infection. Additionally, our assay incorporates a fluorescently labeled primer enabling high sensitivity and rapid assessment of the specific trichomonad species. Moreover, electrophoretic separation of amplified samples can be outsourced, thus eliminating the need for diagnostic laboratories to purchase expensive analysis equipment.

Development of a simulation model to evaluate the effect of vaccination against Tritrichomonas foetus on reproductive efficiency in beef herds

OBJECTIVE

To develop a model to evaluate the effect of vaccination against Tritrichomonas foetus on reproductive efficiency in beef herds.

SAMPLE POPULATION

A beef herd of 300 cows and 12 bulls (8 bulls < or = 3 years old and 4 bulls > 3 years old).

PROCEDURE

The model was developed by use of data for various risk factors and vaccine efficacy. The reference herd was considered to be one in which T. foetus had been diagnosed and bulls were tested for T. foetus before the breeding season. Five thousand iterations were run for each of 13 simulations, with each simulation representing a separate combination of risk factors.

RESULTS

In all simulations, vaccination resulted in significantly higher calving incidence than nonvaccination. Shared grazing was found to be the most significant risk factor for a decrease in calving incidence attributable to T. foetus infection, followed in importance by lack of testing before the breeding season and a higher proportion of old bulls. Combinations of risk factors contributed to a loss of income of up to 22%, some of which could be blunted by vaccination.

CONCLUSIONS AND CLINICAL RELEVANCE

Highest calving incidence is achieved when all bulls are tested for T. foetus before the breeding season and all bulls with positive culture results are culled. Avoiding all risk factors is better than vaccinating, but when this is not feasible for a given herd, the results of this simulation indicate that proper vaccination can decrease economic losses attributable to abortions caused by T. foetus.

Evaluation of a PCR test for the diagnosis of Tritrichomonas foetus infection in bulls: effects of sample collection method, storage and transport medium on the test

The objectives of this study were to determine the detection limit of a PCR test for Tritrichomonas foetus, to investigate the effect of sampling method, guanidinium thiocyanate (GuSCN), and sample storage, and to confirm the accuracy of the test on field samples. Serial 10-fold dilutions of culture material were used to determine the detection limit. For the sample handling trial, five positive bulls were sampled by sheath washing and scraping on six occasions over a period of 18 days (n=29 samples) and eight control bulls were sampled three, four or six times (n=28 samples). Samples were cultured, while portions with and without GuSCN were subjected to DNA extraction within 6h, after 30 h and after 5 days at 4 degrees C. PCR and agarose gel electrophoresis was performed. A two-tailed chi-square test was used to test for differences between treatments. The PCR assay showed a specificity of 98%. Its sensitivity declined with storage time, from 90% at 6h to 31% at 5 days. Sampling method and GuSCN had no effect on test sensitivity. The detection limit of the assay was 100 organisms. Parallel testing of 193 field samples gave complete agreement between culture and PCR results.

Breeding soundness evaluation of extensively managed bulls in Costa Rica

This paper describes the results of single breeding soundness evaluations (BSE) in 898 Bos indicus, Bos taurus and B. indicus x B. taurus bulls, 1 to 12 yr old, extensively reared in different climatic regions of Costa Rica and representing approximately 2% of the total breeding bull population. Thirty-three percent (n = 296) of the bulls were classified as unsound for breeding owing to clinical problems (9.1%, n = 82), low scrotal circumference (SC) being the most common finding, followed by unsatisfactory sperm morphology (23.9%, n = 214). The prevalence of bulls unsound for breeding was lowest in Bos indicus (29%, P < 0.01), intermediate in B. taurus (41%), and highest in B. indicus x B. taurus (48%). The percentages of abnormal sperm heads, acrosomes and midpieces tended to be higher in the ejaculates of bulls with softer testicular consistency (P < 0.001), a long scrotum (P < 0.01) or a low SC (P < 0.05), and such bulls were more often classified as being unsound for breeding (P < 0.05). Frequencies of sperm abnormalities were higher in bulls < 2 yr of age than in older males (P < 0.01) and were highest in B. indicus x B. taurus bulls (P < 0.001). The results confirm differences between species in their adaptability to a tropical environment and support earlier evidence of an association between SC, testicular consistency and scrotal length clinical parameters, and testicular function in bulls.

Prevalence of Tritrichomonas foetus infection in beef bulls in northwestern Spain

The purpose of this study was to investigate the prevalence of Tritrichomonas foetus infection in beef bulls in north-western Spain. The study area comprised of 350 herds (5909 cows and 102 bulls) managed under extensive or semi-extensive systems where natural mating alone or alternated with artificial insemination are used. The targets of this survey were bulls of 1 year of age or older. Preputial smegma samples were taken from 70 bulls (68.6% of bull population) servicing a total of 184 herds (52.6%) and 4136 cows (69.9%). Data collected at sampling included farm location, herd size, age, breed, private or communal bull and previous infertility problems in the herd. The percentage of infected bulls was 2.9% (2 of 70). Age of infected bulls was 5 and 7 years and both were of the local breed, Asturiana de los Valles. These results confirm the presence of T. foetus infection in Spain and the necessity to include this disease in the differential diagnosis of reproductive failure in rangeland grazing cattle.

Detection of Tritrichomonas foetus by PCR and DNA enzyme immunoassay based on rRNA gene unit sequences

Tritrichomonas foetus is the causative agent of bovine tritrichomonosis, a sexually transmitted disease leading to infertility and abortion. Diagnosis is hampered by putative contamination of samples with intestinal or coprophilic trichomonadid protozoa which might be mistaken for T. foetus. Therefore, we developed a PCR test optimized for applicability in routine diagnosis. Amplification is based upon primers TFR3 and TFR4 directed to the rRNA gene units of T. foetus. In order to avoid potential carryover contamination by products of previous amplification reactions, conditions were adapted to the use of the uracil DNA glycosylase system. Furthermore, documentation and interpretation of results were facilitated by including a DNA enzyme immunoassay for the detection of amplification products. Specificity was confirmed with genomic material from different related trichomonadid protozoa. The high sensitivity of the test allowed the detection of a single T. foetus organism in diagnostic culture medium or about 50 parasites per ml of preputial washing fluid. The present methods are thus proposed as (i) confirmatory tests for microscopic diagnosis following diagnostic in vitro cultivation and (ii) a direct T. foetus screening test with diagnostic samples.

Pathogenesis, diagnosis, and management of trichomoniasis in cattle

Trichomoniasis is a disease of the pregnancy, but apparently not of either the cow or the bull, except in the case of postcoital pyometra. Its self-limiting nature in the cow and chronic nature in the bull mean that a positive diagnosis for the herd can more easily be obtained from bulls than from cows. Incubation of preputial scrapings or washings (or pyometritic fluid, if available) in a selective growth medium such as the InPouch system is the diagnostic method of choice. The diagnosis is based on identification of the morphology and characteristic rolling motility of the trichomonad. "High tech" molecular approaches may eventually offer greater diagnostic sensitivity than can culture methods, but currently they are no more accurate. In addition, serologic screening of the female herd (but interestingly, not the bulls) may become possible and may allow the practitioner to at least determine whether exposure has occurred in an unvaccinated herd. Control in an infected herd involves no pharmacologic treatment but rather culling of infected bulls, retention of younger, culture-negative bulls, and segregation of the female herd by reproductive status.

Bovine vaginal antibody responses to immunoaffinity-purified surface antigen of Tritrichomonas foetus

Bovine trichomoniasis is a prevalent sexually transmitted disease of cattle caused by the protozoan Tritrichomonas foetus. Currently, diagnosis is most often made by culture. In order to provide a faster immunodiagnostic approach, a specific enzyme-linked immunosorbent assay (ELISA) was investigated. A protective surface antigen (TF1.17 antigen) of T. foetus was immunoaffinity purified and used in an ELISA to detect antibodies in vaginal mucus from heifers inoculated with T. foetus. In preliminary studies, antibodies of the immunoglobulin A (IgA) isotype were detected in mucus from all experimentally infected heifers which were tested at 6 weeks postinoculation, whereas IgG1 and IgG2 were not. In addition, IgA responses detected in postinoculation samples were all greater than those detected in preinoculation samples, unlike those detected by a whole-cell antigen ELISA. For these two reasons, IgA antibodies appeared to be useful diagnostically. Further investigation of IgA antibodies used vaginal mucus collected weekly from heifers inoculated intravaginally with 10(2), 10(4), or 10(6) T. foetus organisms. Heifers with positive cultures for T. foetus had similar IgA responses to TF1.17 antigen over the 10 weeks of infection regardless of the initial inoculum dose. This indicates that if the dose is sufficient to establish infection, the magnitude and duration of the immune response are no longer dependent on dose. All of the infected animals receiving all dosages responded with high absorbance values in the IgA anti-TF1.17 antigen ELISA by 6 weeks postinoculation, and all absorbance values remained high at 10 weeks. To determine the duration of the IgA response, four other heifers inoculated with 7 x 10(6) T. foetus organisms were studied through 24 weeks postinoculation. IgA antibody responses to TF1.17 antigen were still high at 24 weeks, even though some heifers cleared the infection several weeks earlier. These results indicate that experimentally infected heifers produced detectable long-lasting IgA responses to TF1.17 antigen in vaginal mucus, which may be useful in a herd test for the diagnosis of bovine trichomoniasis.

Protozoal causes of reproductive failure in domestic ruminants

Protozoan parasites are a significant cause of abortion and infertility in domestic ruminants. Toxoplasma gondii, a widespread cause of abortion in sheep and goats, and Sarcocystis spp., which cause a common, frequently asymptomatic infection of domestic ruminants, both have a two-host life cycle. Carnivorous definitive hosts spread the infection through their feces and domestic ruminants are intermediate hosts. A similar, recently recognized protozoa, Neospora sp., has emerged as an important cause of reproductive disease, especially as an abortifacient in dairy cattle. Neospora is presumed to also have a two-host life cycle, although the definitive host(s) has not been identified. The venereally transmitted Tritrichomonas foetus is an important cause of pregnancy loss in naturally bred cattle throughout the world. In the absence of effective methods for vaccination or treatment, control of these parasites is based on management procedures to reduce infection and transmission.

Detection of bovine trichomoniasis with a specific DNA probe and PCR amplification system

Trichomoniasis is a widespread, economically important venereal disease of cattle which causes infertility and abortion. Effective control of trichomoniasis has been impeded by the insensitivity of traditional diagnostic procedures, which require the isolation and cultivation of the parasite, Tritrichomonas foetus, from infected cattle. We developed a 0.85-kb T. foetus DNA probe by identifying conserved sequences in DNAs from T. foetus that were isolated from cattle in California, Idaho, Nevada, and Costa Rica. The probe hybridized specifically to DNAs of T. foetus isolates from different geographic areas but not to DNA preparations of Trichomonas vaginalis, bovine cells, or a variety of bacteria from cattle. The probe detected DNA from a minimum of 10(5) T. foetus organisms. To improve sensitivity, a partial sequence of the probe was used to identify oligonucleotide primers (TF1 and TF2) which could be used to amplify a 162-bp product from T. foetus DNAs by PCR. A chemiluminescent internal T. foetus sequence probe was hybridized to Southern blots of the amplification product. This system detected as few as one T. foetus organism in culture media or 10 parasites in samples containing bovine preputial smegma. Analysis of 52 clinical samples showed that 47 (90.4%) of the 52 samples were correctly identified, with no false-positive reactions. In comparison, the traditional cultivation method detected 44 (84.6%) of the 52 samples from T. foetus-infected and uninfected bulls. These results indicate that the PCR-based amplification system could be a useful alternative method for the diagnosis of bovine trichomoniasis.