Tularemia has been identified recently as the cause of a die-off in captured wild prairie dogs (Cynomys Zudovicianus) (Figure) at a commercial exotic animal distributor in Texas. The Texas Department of Health and CDC immediately notified all state health departments and are investigating the outbreak.
Until shipments were halted on August 1, 2002, approximately 250 of an estimated 3,600 prairie dogs that passed through the Texas facility had died. The sick animals were believed to be part of a single shipment of prairie dogs that were caught in South Dakota starting on May 18 and shipped to the Texas distributor on June 16. All prairie dogs that were shipped by the Texas facility after June 16 or by the South Dakota trader after May 18 are being recalled.
Potentially infected prairie dogs were distributed to wholesalers, retailers, and persons in Arkansas, Florida, Illinois, Michigan, Mississippi, Nevada, Ohio, Texas, Washington, and West Virginia and exported to Belgium, the Czech Republic, Japan, The Netherlands, and Thailand. States and countries that received shipments of potentially infected animals have been notified. Unusually high numbers of sick or dead prairie dogs were reported from Texas and the Czech Republic.
Tularemia is caused by infection with Francisella tularensis. The incubation time in humans is normally 2-6 days but can be 1-14 days. The disease usually begins suddenly with high fever, chills, head and muscle aches, and a feeling of weakness. Chest discomfort and a dry cough are common. Other symptoms might appear depending on how the infection is acquired. For example, if the bacteria enter through a break in the skin, an ulcer will usually develop at the site of entry, accompanied by regional lymphadenopathy. In the United States, humans usually acquire tularemia by handling wild rabbits (e.g., while skinning the animal) or by being bitten by infective ticks and certain flies (e.g., deer flies and horse flies). Two known F tularensis biotypes exist in the United States. Type A is more virulent than type B, but both can result in severe and sometimes fatal illness. F tularensis recovered from the sick prairie dogs was type B.
Adults who have handled sick or dead prairie dogs from the suspected shipments in the last 2 weeks are being advised to take doxycycline (100 mg twice daily for 14 days) or ciprofloxacin (500 mg twice daily for 14 days). Because these drugs have a higher risk for side effects in children, children who are considered at risk should not take antibiotics but have their temperature monitored for 14 days. Persons who have been in contact with prairie dogs during the preceding 2 weeks and who have fever and other symptoms suggesting tularemia should see their physician. Preferred drugs for treatment of tularemia are gentamicin and streptomycin.
To report human tularemia cases that might be associated with prairie dog exposure or to inquire about shipment of potentially infected prairie dogs, state health departments should contact CDC's Division of Vector-borne Infectious Diseases, telephone 970-221-6400, fax 970-221-6476, e-mail email@example.com.
Reported by: C Lindley DVM, S Avashia, MD, K Hendricks, MD, J Rawlings, MD, J Buck, Texas Dept of Health. J Kool MD, K Gage, PhD, M Schriefer, PhD, D Dennis, MD, M Chu, PhD, Div n/Vector-borne Infectious Diseases; J Peterson, PhD, J Montenieri, D Kim, MD, T Demarcus, M Cetron, MD, Div of Global Migration and Quarantine, National Center for Infectious Diseases, CDC.
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