Trichomoniasis receiving attention

By Arden Wohlers DVM
Extension Veterinarian
University of Nebraska Panhandle Research and Education Center

            On January 1, 2008, the Nebraska state veterinarian issued an import order to take immediate action to protect the health status of Nebraska’s cattle industry from imported cows and bulls that may be infected by Tritrichomonas foetus (Trich).  Trich is a protozoan that infects the bull, who is then a lifetime asymptomatic carrier of the disease. The disease is only spread to the cow by breeding. In the cow the disease causes reproductive tract infections and failed pregnancies, resulting in fewer calves for the rancher. Some regions of the country have had chronic problems with Trich for years, causing a reduction in calving percentage by 5 to 10%. Producers in these areas have accepted this loss as normal attrition. However, in a clean area such as Nebraska, where the disease has been largely under control, the introduction of Trich may cause 50% of the cows to abort their calves. This would be economic disaster for a producer and would risk exposing his neighbors’ herds to the disease as well.

Positive diagnosis of Trich is not easy. A suggestive history is the clue to attempt to isolate the organism from the suspect animal. Immediately after a cow aborts her calf, Trich can be obtained from her reproductive tract fluids, but she often clears the organisms from her body, so by the time she is checked the organism is difficult to detect.  Isolating Trich from the carrier bull is easier but still requires proper sample collection and shipping preparation techniques for laboratory analysis.

The bull exhibits no ill effects from the disease but merely acts as a carrier. Once the bull becomes a carrier there is no treatment available to clear him of the infection. The management decision must then be to remove the bull from the herd. Cows can rid themselves from the disease and become pregnant again in a few months. However, the cow’s immunity is short lived and if exposed in succeeding years she may once again abort.

There is a vaccine available that shows effectiveness in the cow, but not in the bull. The vaccine will not clear up a herd’s Trich problem, but will limit the duration of infection and result in more pregnancies. The preferred management techniques for dealing with Trich are to remove all open and late calving cows, test and remove all positive bulls or use only bulls that have never been exposed to the disease. Implementing an AI program followed by a short bull breeding season will bring about faster results.

Ranch biosecurity is of utmost importance in keeping Trich out of your herd. Maintaining fences is the first step but may not be enough. Purchased replacement cattle should be virgin heifers and virgin bulls. When older bulls must be purchased they should be tested culture negative three times or PCR tested negative once within 30 days of purchase. The new import order tightens up the biosecurity for Trich on cattle entering Nebraska. For cattle to enter Nebraska they must be represented by a certificate of veterinary inspection signed by an accredited veterinarian.  The certificate will state that the animals may not have come from a known infected herd, that they are virgin heifers or virgin bulls under 24 months of age or they are cows at least 120 days pregnant or they are bulls that have been properly sampled and tested negative at an accredited laboratory.  There are some exceptions to allow animals to enter Nebraska for slaughter or exhibition.

Consult with your veterinarian about the disease and the import order if you have concerns or visit the NDA website at www.agr.ne.gov and look under animal health.  The Beef Issues Group will have a Trichomonas information meeting at The Panhandle Research and Extension Center on Wednesday, January 30 at 2 pm.

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