UPDATE – October 10, 2013
To view Bucking Bull Exemption to Quarantine Order 132 – Bovine Trichomoniasis, click here.
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Trichomoniasis is a sexually transmitted protozoal reproductive disease of cattle caused by Tritrichomonas foetus. The disease causes infertility and early embryonic death. The disease can go undetected in a herd until a producer notices poor pregnancy and calving rates. Calf crop losses can approach 50 percent or higher in some herds. Bulls are asymptomatic carriers of the protozoa and infect the cow during breeding. Infected cows will experience fetal loss and then clear the infection and be able to sustain a subsequent pregnancy.
Tritrichomonas foetus causes a sexual transmissible disease (STD) in cattle that is not infectious to humans and does not affect the safety or quality of beef.
The T. foetus protozoa can live in the cow’s reproductive track and on the surface of bull’s penis. In bulls the protozoa will embed into penile crypts and most infected bulls will become permanent carriers. The bull spreads the disease as a mechanical vector during breeding. There are no treatments for this disease. Infected carrier bulls should be culled for slaughter. Up to 90 percent of cows will become infected when bred by a carrier bull. Cows will eventually develop a temporary immunity to the organism and maintain a pregnancy. If there is an extended breeding season, cows that develop temporary immunity may be late bred. With shorter breeding seasons, the cow will not have time to develop immunity and will not get pregnant.
The progression of the disease within a herd is variable depending upon source of the infection and duration of breeding season. Often, the disease is not diagnosed the first year it infects the herd. For example, if an infected open female is unknowingly added to the herd, there would be very little change in reproductive performance during the first year. A small percentage of cows may become infected and became late bred animals. However, one or more bulls likely became infected carriers and will infect up to 90 percent of the cows they breed the following year. Subsequently, more bulls will become infected as the breeding season progresses. In the third year multiple bulls will be infected and up to 50 percent of the cows will likely be open or late bred. If the disease is allowed to persist in the herd, pregnancy rates will recover in subsequent years but reproductive performance will never be optimal.
Many Western states have experienced increased problems with Trichomoniasis. These states have herds with active infections of T. foetus that are under quarantine. For most of these states any bull over 24 months of age or any non-virgin bull must have a negative T. foetus PCR test within 30 days of transport across state lines.
In Hawaii since 2011 all non-virgin bulls entering the state have been required to test negative for Trichomonas. Trichomonas was detected in a bull on the Big Island of Hawaii in 2011. Since then area and slaughter surveillance testing have detected ten infected herds. Currently, nine herds remain infected and are located on the Big Island in Kau (Pahala-Naalehu, South Point), North Kohala and Makakilo on Oahu. All infected herds are geographically or epidemiologically related. Infected herds are under quarantined and one so far has met requirements to have its quarantine removed. Herds where infection is detected are quarantined and are required to test all of their bulls removing to slaughter those that test positive. In addition to testing all of the herd bulls a 120-day period of sexual rest is imposed on the cow herd followed