Trichomoniasis has an insidious onset in a herd. Both cows and bulls may carry trichomoniasis but show no outward signs of infection. The pattern of the disease will depend on how many bulls are in use and the proportion of bulls that are infected. Signs may include:

• An extended calving season with more cows calving late in the season.
• A reduced pregnancy rate - typical pregnancy rates in affected herds in Australia may be from 60–80 per cent, depending on the length of the mating period.
• Mucopurulent discharge and inflammation of the vagina, cervix and uterus
• Abortion
• Pyometron

If you suspect bovine trichomoniasis you must notify either Local Land Services (1300 795 299) or the Department of Primary Industries (animal.biosecurity@dpird.nsw.gov.au) within one working day.

A veterinarian can investigate suspect cases of trichomoniasis and provide advice on management specific to your property.

Remember, you have a biosecurity duty to prevent the spread of diseases, such as trichomoniasis, from your animal to anybody else’s animals.

Diagnosis is supported by clinical history and confirmed by culture and DNA-based testing (PCR and RFLP) if trichomonads are observed in the culture. DNA-based testing is to ensure T. foetus has been identified and not non-pathogenic trichomonads.

To confirm a diagnosis of trichomonosis, specimens need to be collected from bulls, preferably after at least two weeks sexual rest, as this allows the number of organisms (if present) to build-up in the prepuce, thereby increasing the chance of detection. Cows that have been pregnancy-tested as empty, are known to have aborted, or have a uterine discharge, should also be sampled.

Detailed instructions on how to collect samples for culture, from both bulls and females are available in the Sample Collection Guide.

Further information on available diagnostic tests and laboratory submission forms.

Tritrichomonas Foetus Enrichment Media (TFEM) and Tricamper sampling tools can be ordered from Elizabeth Macarthur Agricultural Institute.

Bulls may carry the protozoa in microscopic folds of the skin that lines a bull’s penis and the lining of the sheath. Older bulls, in particular, can harbour large numbers of protozoa, and are more likely to be infected than younger bulls.

Infected cows usually recover without treatment within about three to five heat cycles after an abortion. If bulls are still running with them, they will then conceive and calve normally. Immunity in females is short-lived and re-infection may occur if cows are re-exposed to an infected bull. If they are reinfected in the next breeding season, they can abort again.

All infected bulls should be considered permanent carriers, since the bull’s immune system seems unable to rid bulls of the infection. Cows can occasionally remain infected throughout pregnancy and then calve normally. These cows can remain a source of infection for clean bulls introduced in the next breeding season.

The parasites can infect the genital tracts of cattle during mating. They can also be spread by contaminated equipment used for calving or artificial insemination (AI), or if contaminated semen is used for AI.

Bovine Trichomoniasis is not a zoonotic disease and does not infect humans.

Prevention and management

There is no approved, effective treatment or vaccine for trichomoniasis available in Australia. The best way to prevent your herd being infected is to have a comprehensive Farm biosecurity plan. The plan may include:

• Requesting a Cattle Health Statement with the purchase of all cattle
• Purchasing all bulls from reputable vendors, not out of saleyards
• Keeping boundary fences secure
• Testing any stock with an increased risk of infection e.g., bulls from northern Australia prior to purchase

Virgin heifers or bulls are the safest options when introducing stock.

In the case of a confirmed diagnosis of bovine trichomoniasis, the Local Land Services district veterinarian will normally contact the owner of the infected herd and the private veterinarian to offer advice on managing the infection. The general biosecurity duty requires any person dealing with cattle who knows or ought to know of the biosecurity risks associated with trichomoniasis to take steps to prevent, eliminate or minimise the risk as far as is reasonably practicable. It aligns with industry self-management and allows producers to make flexible, risk-based management decisions.

Steps to meet the general biosecurity duty relating to trichomoniasis may include:

• Working with your private veterinarian to develop:
• A herd trichomoniasis elimination plan, or
• A plan to prevent the spread of infection to neighbours or other producers. This should include details on how straying of bulls will be prevented. It may include notification of neighbours so they can take steps to prevent trichomoniasis being introduced to their property.
• Supplying a Cattle Health Statement indicating the cattle have come from a property with confirmed trichomoniasis if selling or agisting heifers (other than virgin heifers or heifers that have not shown signs of coming on heat), cows or bulls.

Other actions may be required to prevent, minimise or manage the spread of bovine trichomoniasis, depending on individual circumstances.

In the vast majority of situations, the best strategy is to cull all infected bulls. In large herds it may be too costly to replace all the bulls at the same time, and splitting the herd into separate mating groups using virgin bulls on a portion may be the preferred option.

The following steps will aid in the eradication of the disease from infected properties:

• Ensure that all internal and external fences are stock proof.
• Separate all bulls from cows and young stock.
• Test all bulls four times at weekly intervals after a minimum of one week’s sexual rest; before they can be assumed to be negative.
• Cull all positive bulls.
• Pregnancy test all joined cows two months after the bulls have come out and cull all empty cows.
• Pregnancy test all joined cows again six months after the bulls come out and cull all empty cows.
• Investigate any cows with vaginal discharge, or any that abort for the presence of the disease.

For the next breeding season, options available include:

• Artificial insemination rather than natural mating
• Natural mating using only virgin bulls
• Use natural mating and replace positive bulls with virgin bulls, or young bulls less than three years of age as they are less able to transmit infection. (This is mainly included as an option for large herds, where it is too expensive to replace all bulls at once. The use of all virgin bulls is preferred, where possible.)

If you use natural mating in the season after the disease is detected, delay joining until three months after the end of calving, to reduce the likelihood that any cows remain infected. As affected herds generally suffer a drawn-out calving, producers will need to decide on a cut-off date after which any cow that has not calved is to be culled. Limit the joining period to three months or less, and test all bulls after completion of the program, culling any infected bulls.

Resources

• Guide – Trichomoniasis Sample Collection