Department of State Health Services
September 20, 2006
In May 2006 a die-off of rabbits in the vicinity of the Amarillo Airport led to the diagnosis of tularemia (rabbit fever, Franciscella tularensis). In August, a rabbit found dead on a farm north of Groom in Carson County was also confirmed as being infected with the tularemia organism.
A die-off of prairie dogs in Sherman County was determined to be due to plague ( Yersinia pestis) . A similar die-off in Moore County was most likely caused by plague, but confirmation has not been obtained.
Be sure to use an effective insect repellent when outside in areas inhabited by wild rodents, hares or rabbits. This is critical if a die-off is noted. When rabbits, hares and rodents die, the fleas and ticks they carry will begin to seek a new host. While they are generally species specific, a hungry flea or tick will take advantage of the first blood source it comes across. Plague and tularemia cause similar syndromes and usually involve swollen lymph nodes, fever and other “flu-like” symptoms. Both may cause pneumonia, septicemia (blood infection) and vomiting. Tularemia can also cause diarrhea, conjunctivitis, skin ulcers, and sore throat, depending on the route of entry for the organism.
Flea bites and handling, with bare hands, carcasses of animals that have plague are the primary causes of plague infections in the US . Cats that develop plague may develop abscesses, primarily in the throat area or under the jaw. If an abscess ruptures, the fluid will be potentially infectious. Cats also may develop a pharyngitis or pneumonia, and would then be capable of spreading plague organisms via respiratory droplets. Cats and dogs that roam outside may bring fleas home that could carry plague. Good flea control is essential on pets that are allowed to roam in areas with endemic plague.
Tularemia is most often acquired from handling animals that had the disease. The organism may enter the skin through open wounds or cuts that occur while skinning the carcass or handling the raw meat. However, fleas and ticks may transmit the disease. It may also be inhaled in dust, consumed when undercooked meat is eaten or when contaminated water is drunk. Eye infection could occur though exposure to contaminated dust or contact of a contaminated finger with the membranes of the eye.
Both diseases respond well to antibiotics, but if treatment for pneumonic or septicemic plague is not initiated within 24 hours of symptoms developing, the probability of death increases significantly.
West Nile virus (WNV) is active in the region, once again. A patient in Lubbock has been confirmed with the disease. A blood donor in Amarillo was diagnosed as infected, but was not symptomatic. Four other reports of possible human cases are being investigated. In addition, three horses have been confirmed as infected. These were from Hansford County , Hale County , and Randall County.
Humans need to be sure to practice the 4-Ds: dress appropriately when outside; use repellents containing DEET or picaridin; drain standing water; and avoid being out at dusk or dawn. Horse, mule and donkey owners should be sure their animals are immunized against WNV.
For more information contact James Alexander, (806) 655-7151, feel free to e-mail Dr James Alexander at email@example.com in the Amarillo area, or Karen McDonald, (806) 767-0427, firstname.lastname@example.org in the Lubbock area.
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