A Larimer County resident became sick with tularemia in late July and was hospitalized for the illness in early August, according to local health officials. The man may have been exposed while mowing a property in Weld County outside Windsor where rabbits had been plentiful this summer but had recently declined. An environmental investigation of the property by Weld County’s health department found no rabbit carcasses or conclusive evidence of tularemia; however, the mowed property is the most likely site of exposure.

Image/Gorman Lewis, U.S. Fish and Wildlife Service
Image/Gorman Lewis, U.S. Fish and Wildlife Service

The patient developed symptoms of fever, sore throat, and swollen glands several days after mowing the field. He was treated for more common causes of such symptoms, but after two courses of treatment with different antibiotics and no improvement, he was hospitalized in Fort Collins where a tularemia infection was confirmed. He was released after several days of treatment with appropriate antibiotics and is expected to make a full recovery.

Earlier in July, a wild rabbit die-off in Fort Collins was found to be caused by tularemia, and in August a similar die-off was confirmed in Jefferson County. On July 16, Broomfield reported the first human case of tularemia this year in Colorado in a subdivision where numerous rabbits had been found dead. Health officials from both the Larimer County and the Weld County health departments are reminding residents to take precautions against this bacterial infection by avoiding sick or dead animals and preventing pets from coming in contact with wild animals.

Tularemia is a bacterial infection most frequently transmitted to people who have handled infected animals, especially rabbits, hares, beavers, and muskrats, although many kinds of animals can become infected. The bacteria are also shed in their urine and feces, and can persist in the environment for a month or more. Infection can also be transmitted by the bite of infected insects, most commonly ticks and deer flies. Tularemia is not considered contagious from person-to-person.

LISTEN: Tularemia in the United States 2001-2010: An interview with a CDC Epidemiologist

Typical signs of infection in humans can vary tremendously based on the site of infection, but generally include fever, chills, and swollen glands. If tularemia is caused by the bite of an infected insect or from bacteria entering a cut or scratch, it usually causes a skin ulcer at the site of entry and swelling of nearby glands. Eating food or drinking water containing the bacteria may produce a throat infection, stomach pain, diarrhea and vomiting. If inhaled through aerosols created by mowing, the bacteria can enter the lungs and cause coughing, chest pain, and pneumonia. Tularemia may be life-threatening but can be effectively treated with antibiotics, and medical attention should be immediately sought if someone suspects exposure.