US distribution of tularemia changing gradually
From 2001 to 2010, there were 1,208 cases of tularemia reported to the CDC via the National Notifiable Diseases Surveillance System, according to an MMWR report.
Among the reported cases, 64% were confirmed and 35% were probable. The average annual incidence was 0.041 cases per 100,000 persons. The incidence was highest among children aged 5 to 9 years (0.071 cases per 100,000 persons) and among men older than 55 years (0.11 cases per 100,000 persons).
Forty-seven states reported cases of tularemia, but 59% of the cases were reported from six states: Missouri, Arkansas, Oklahoma, Massachusetts, South Dakota and Kansas. Most of cases (77%) occurred from May to September.
Francisella tularensis can be transmitted through arthropod bites, direct contact with infected animal tissue, inhalation of contaminated aerosols or ingestion of contaminated food or water. It is a Tier 1 select agent because of its low infectious dose, ability to infect by aerosol and a history of being used as a bioweapon.
The clinical symptoms of tularemia in humans depend on the route of exposure. Percutaneous inoculation typically presents as a cutaneous ulcer at the site of inoculation and a tender regional lymphadenopathy. Inhalation of F. tularensis can develop as primary pneumonia. The ingestion route presents as oropharyngeal disease, including tonsillitis or pharyngitis with cervical lymphadenopathy.
“Clinicians should consider tularemia in patients with a compatible clinical profile, particularly in children and elderly males with acute fever and regional lymphadenopathy,” the researchers wrote. “This report shows that the distribution of tularemia might be gradually changing; therefore, tularemia should be considered even in areas where it has rarely been reported.”
Disclosure: The researchers report no relevant financial disclosures.