Tularemia

Tularemia (also called glandular fever, rabbit fever, tick fever, and deer fly fever) is a highly infectious disease that can be caused by as few as 10 organisms of Francisella tularensis, a gram-negative coccobacillus. There are seven forms of tularemia: ulceroglandular, glandular, oculoglandular, oropharyngeal, pneumonic, GI, and typhoidal (septicemic) tularemia. The disease is fatal in about 5% of patients who don’t receive treatment and in less than 1% of patients who do receive treatment.

F. tularensis is considered a potential bioterrorism agent. If dispersed in aerosol form (the most likely method of dispersion), infected persons would generally develop signs and symptoms of severe respiratory illness, including pneumonia and systemic infection.

Causes

Tularemia is transmitted by the bites of infected ticks and deer flies, via consumption of contaminated food or water, and through contact with the blood of an infected animal (such as by skinning or handling infected carcasses), especially rabbits. The organism gains access to the host by skin or mucous membrane inoculation, inhalation, or ingestion. After inoculation, a papule and high fever develop. (The papule eventually develops into an ulcer.) The incubation period is 3 to 4 days.

In the United States, about 200 human cases of tularemia are reported annually, with most occurring in the south-central and western parts of the country.

Complications

Complications of tularemia include pneumonia, lung abscess, respiratory failure, rhabdomyolysis, meningitis, pericarditis, and osteomyelitis. Death may also occur.

Assessment Findings

Common signs and symptoms present 3 to 4 days after infection but may not present until 14 days. Ulcer at the inoculation site and fever are common, as are weakness and muscle and joint pain. Signs and symptoms also vary according to the form of tularemia the patient is infected with: