Incidence of Tritrichomonas foetus in young replacement bulls following introduction into an infected herd

Prevalence of Tritrichomonas foetus in beef bulls slaughtered at two abattoirs in northern Australia

Bovine trichomoniasis, caused by the protozoal parasite Tritrichomonas foetus, is a highly contagious venereal disease characterised by early pregnancy loss, abortion and pyometra. Persistently infected bulls and cows are the primary reservoirs of infection in infected herds. This research investigated the prevalence of T. foetus infection in bulls from properties located across northern Australia and New South Wales. Preputial samples were collected from 606 bulls at slaughter and tested for T. foetus using the VetMAX‐Gold Trich Detection Kit (Thermo Fisher Scientific). The apparent prevalence of T. foetus infection varied between regions, with northern regions in the Northern Territory, Queensland and Western Australia showing a prevalence of 15.4%, 13.8% and 11.4%, respectively. There was some evidence of an association between infection and postcode (P = 0.06) and increasing bull age (P = 0.054). This study confirms that T. foetus infection is likely to be present in many beef breeding herds and contributing to lower than expected reproductive performance, particularly across northern Australia.

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.

Tritrichomonas foetus Prevention and Control in Cattle

Bovine trichomoniasis has been recognized as a pathogen of the bovine reproductive tract for nearly 100 years. Although characteristics of the causative organism, Tritrichomonas foetus lend to control and there are examples of disease eradication, cattle producers are still faced with this disease. This article highlights the clinical presentation, magnitude of effect, risk factors, epidemiology, and sample collection and suggests applications in developing herd-level control measures for beef cattle producers including testing strategies for control, testing strategies for surveillance, strategies to eliminate trichomoniasis from infected herds, and strategies for prevention in uninfected herds.

Tritrichomonas foetus

Tritrichomonas foetus is a venereal disease of cattle that has a clear pattern of adverse reproductive sequela in the affected female, with a carrier state in the bull in which he shows no outward signs. Given sexual rest and symptomatic treatment, the female returns to reproductive viability. In contrast, the male remains infective and is a risk to other female contacts. Prevention of the disease relies on excluding infected males and females from the population of susceptible cattle. Control of this disease requires a plan to identify, isolate, and treat infected females, and eliminate or cull infected males. Improvements in culture technique and the application of newer methods, such as polymerase chain reaction, enhance the likelihood of detecting infected animals.

The northern Australian beef industry, a snapshot. 2. Breeding herd performance and management

Breeding herd performance and husbandry were surveyed on 375 northern Australian beef properties in 8 regions during 1996 and 1997. Mean branding rates ranged from 62.6% in the Northern Territory to 77.1% in the Maranoa South West regions of Queensland with considerable variation within regional herds. The proportion of herds using controlled mating was highest in the Central Coastal, Central Highlands and Maranoa South West. Mean mating period across all regions varied from 5.6 to 11.8 months. Calving was seasonal with peak activity in the August–December period. Calving commenced earlier in the south (August) than it did in northern regions (September–November). Rainfall influenced the timing of commencement of calving and peak calving activity. The use of pregnancy testing was widespread but selective and often not all females were pregnancy tested. About 97% of properties used weaning strategies with a peak in calf weaning in April–July, and a minor peak in September–October. Although mean weaner ages were similar across regions (5.9–6.9 months), mean weaner liveweight varied markedly with weaners in the more northern regions being lightest (<190 kg) while those in southern regions tended to be >200 kg. Culling criteria for cows and heifers focused on temperament, conformation and reproductive failure; age was also important for cows with a common culling age of 10 years. Bulls were more commonly culled at 7–8 years of age. In addition to age, bulls were culled for physical defects, reproductive problems, temperament and poor quality/performing calves. Four to 5 criteria were commonly used to select bulls. Structural soundness and temperament ranked highest followed by conformation, weight for age, Breedplan and colour. Producers using Breedplan tended to use structural soundness and temperament also as selection criteria. The results suggest that producers associated increasing turn-off weight or decreasing turn-off age more with pasture improvement than with bulls of higher genetic merit for growth. Supplementation of the breeding herd increased in the last half of the calendar year. Supplements containing molasses, urea, phosphate source, salt, and sulphate of ammonia were the most commonly supplied supplementary nutrients. Vaccination for botulism was quite common (>30% of regional survey groups) in all regions except Central Coastal and Maranoa South West regions of Queensland. Comparisons with previous surveys show that there have been marked improvements in breeding herd performance and management over an extended period. The results are discussed in relation to scientific developments over the last 2 decades and future development of the northern Australian beef industry.

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.

Epidemiology of Tritrichomonas foetus in beef bull populations in Florida

The objectives of this study were to estimate the prevalence of herd and individual bull infection with Tritrichomonas foetus in a survey of beef bulls in the state of Florida and to perform an epidemiological investigation of risk factors for the disease. Bulls were tested for T. foetus colonization by a single preputial scraping and culture. Bull infection prevalence within herds was calculated and relationships with bull, herd factors, and production measurements were determined. The survey included 1984 beef bulls in 59 herds throughout Florida; nine bulls in three small herds (<100 cows) were later excluded from the models. An overall prevalence for T. foetus-infected bulls was 6.0% (within-herd prevalence ranged from 0 to 27%). The herd prevalence was 30.4% (i.e. at least one infected bull); infected bulls were found in 11.1 and 39.5% of herds sampled in North and South Florida, respectively. The likelihood of disease was greatest in larger herds in more extensive management settings (> or = 500 cows, 53.9% prevalence; medium-sized herds of 100-499 cows, 10.0% prevalence). Tritrichomonas foetus infection was associated with several bull factors, including age, breed, herd, and herd management practices (bull-to-cow ratio, bulls per breeding group). Tritrichomonas foetus infection continues to be prevalent in beef herds in Florida that use natural service.

Bovine trichomoniasis: Results of a slaughter survey in Colorado and Nebraska

A total of 2,909 bulls was cultured for the presence of Trichomonas fetus at slaughter at 4 abattoirs in Colorado and Nebraska. Samples were collected using the dry pipette preputial scraping technique and were transported to diagnostic laboratories within 24 h. Of the bulls cultured, 5 were positive. The state of the last origin for each animal was Kansas, 1 bull, Montana, 1 bull, Nebraska, 1 bull, and Utah, 2 bulls. These results indicate and incidence of less than 1% (0.172%) of trichomoniasis in the populations tested, even in the states of Colorado and Nebraska where the larger numbers of bulls were cultured.

Bovine Trichomoniasis

Although virtually unknown in Europe since the widespread adoption of artificial insemination (AI), infection by the sexually transmitted protozoan parasite Tritrichomonas foetus (Fig. 1) results in substantial economic losses throughout the major cattle-rearing areas of the world where natural breeding is relied upon. Infection by T. foetus is increasingly recognized as a significant cause of bovine infertility. In this review, Alex Yule, Susan Skirrow and Robert BonDurant summarize the current knowledge of bovine trichomoniasis and the problems of diagnosis and control of this economically important disease.

Prevalence of bovine venereal disease in the Victoria River District of the Northern Territory: likely economic effects and practicable control measures

Area prevalences of bovine Campylobacteriosis and Trichomoniasis in the Victoria River District (VRD) of the Northern Territory were determined by a survey of bulls. Eighty-seven percent of herds were infected with Campylobacteriosis and 65.6 percent were infected with Trichomoniasis. The levels of infection recorded are likely to be causing significant reductions in reproductive rates. Control of Campylobacteriosis is unlikely to be practicable on a district basis, but in some herds it may be possible to implement control measures in select groups subject to good stock control. Trichomoniasis control measures are generally not implementable in the VRD management situation. Computer modelling suggests that control measures are unlikely to be profitable in commercial herds. There is a need for field investigations to confirm this.

Control of venereal disease in infected herds

Losses from trichomoniasis can be controlled by management and treatment strategies. The best strategy for control of campylobacteriosis is vaccination of cows and bulls with a competent vaccine.

Prevalence of postservice pyometra in a herd of beef cows infected with trichomoniasis: A case report

Trichomoniasis was detected in a herd of beef cows during a routine yearly reproductive examination. The examination revealed that 12.6% of the cows (75 597 ) were not pregnant. Of these, 65.3% (49 75 ) had a normal uterus and a functional corpus luteum, suggesting that they were cyclic; 21.3% (16 75 ) had pyometra; 6.7% had inactive ovaries and uterine atrophy and were not cyclic; 4% (3 75 ) had an involuting uterus, suggestive of a recent abortion; and 2.7% (2 75 ) had a mummified fetus. The herd had been on a reproductive herd health program for the past 10 years and had averaged 92-99% pregnant cows during this time. Pyometra was diagnosed by rectal palpation, and trichomonads were detected in the pyometra exudate.

The effect of Tritrichomonas foetus infection on calving rates in beef cattle

The effect of Tritrichomonas foetus var. brisbane infection on calf production by Hereford cows was determined. The mean number of calves produced by cows that were kept continuously with bulls infected with T. foetus for 3 years was 17.6% less than the mean number produced by cows kept with a non-infected bull. Losses in production due to trichomoniasis occurred each year, but were greatest in the first 2 years in cows experiencing infection for the first time.

Diseases of cattle in the Solomon Islands

Between 1967 and 1977 a study was made of diseases of cattle in the Solomon Islands. Tuberculosis was found in only 3 herds and was eradicated by 1975. Brucellosis serology revealed very few reactors and by 1977 the herds involved were considered free of the disease. Significant serological reactions were found to Leptospira interrogans serovars pomona, hardjo, autumnalis and jez-bratislava. There was evidence that infectious bovine rhinotracheitis and mucosal disease were present. Seventeen parasites were identified of which Haematobia irritans exigua, Haemonchus placei, Oesophagostomum radiatum and Ceylonocotyle streptocoelium were widely distributed. Nutritional stress occurred under some forms of husbandry but environmental stress was minimal. The Solomon Islands are therefore in a most favourable situation with regard to diseases of cattle.