Ruth Correll: Ticks, biting flies can transmit diseases

It is tick and biting fly season, and precautions should be taken for external parasite control.  One reason is to prevent transmission of a blood-borne disease known as anaplasmosis. 

Presence of anaplasmosis in your herd can have significant economic impact.  Symptoms of anemia, unthriftiness and weakness are some of the signs, and only a veterinarian can give a diagnosis. 

Anaplasmosis is a disease of cattle that is caused by the blood parasite anaplasma marginale.  The organism infects red blood cells and causes anemia.  Anaplasmosis also infects sheep and goats and some wild ruminants, including white-tailed deer without signs of the disease, but these animals can possibly serve as a reservoir for the disease.  The disease is common in the southeastern U.S.

Outbreaks of anaplasmosis usually happen in summer and fall when ticks are prevalent.  Some of the common signs are fever, weakness, depressed attitude, decreased appetite, decreased milk production and a white or yellow color to the gums, white of the eye or vulva.  Aggressive behavior is also common, especially in beef cattle.  Abortions may happen in females, and temporary infertility can happen in males. 

Anaplasmosis is primarily transmitted by blood-sucking insects.  Biting flies and some species of ticks are the main insect carriers but people spread anaplasmosis by using the same needle between multiple numbers of cattle.  The disease can also be transmitted due to the improper cleaning of instruments during dehorning, castration or tattooing.  It takes less than a drop of blood to transmit anaplasmosis from an infected cow to a non-infected cow. 

Cattle less than 2 years old rarely show any signs, even if they become infected.  Cattle older than 2 years old have more severe symptoms and are more likely to die.  Whether an animal shows any signs, if it becomes infected, it is usually infected for life.  These carrier animals are immune to future disease, but become a persistent source of infection for other cattle. 

If anaplasmosis is suspected, producers should contact their veterinarian to confirm the diagnosis.  There are other diseases that can appear similar.  There are tests to find carrier animals.  The veterinarian can prescribe the use of tetracycline products that can be fed in feed or mineral supplements. 

In this area, there is a constant potential for exposure, and total prevention or elimination of the disease from a herd is not realistic.  Therefore, the goal is to prevent and minimize clinical and subclinical disease and production losses. 

Producers should assume there is a good chance they have carrier animals in their herd that look perfectly healthy but can be a source of infection, so practices that could potentially spread the disease, such as reusing needles or not properly disinfecting equipment, should be eliminated. 

Control of ticks and flies will also decrease the spread of the disease.  Recently, a vaccine has been approved for use.  Not all states have approval to use this vaccine, but fortunately Tennessee does.  This product is relatively expensive compared to other vaccines. 

Biosecurity measures are key to the control of anaplasmosis.  Have your veterinarian screen herd additions or purchase animals from test negative herds.  Use approved pest control products to control flies and ticks.  Also, single use of needles, proper cleaning of equipment between animals and vaccination are important parts of an anaplasmosis control program.  If you suspect anaplasmosis in your herd, contact your veterinarian for a thorough investigation and advice regarding elimination and future prevention. 

For more information, contact the UT-TSU Extension Office in Wilson County at 615-444-9584.  You can also find us on Facebook or visit extension.tennessee.edu/wilson.  Ruth Correll, UT Extension-TSU Cooperative Extension agent in Wilson County, may be reached at 615-444-9584 or acorrell@utk.edu.