Tularemia is a reportable disease in Oklahoma. Tularemia is a disease caused by the bacteria Francisella tularensis (F. tularensis). Humans typically become infected with F. tularensis following the bite of an infected tick, and less commonly from the deer fly (Chrysops discalis). The ticks associated with tularemia in Oklahoma include the dog tick (Dermacentor variabilis) and the lone star tick (Amblyomma americanum). In addition, humans have also developed the disease following exposure to infected wild animals (especially rabbits). Tularemia was once commonly known as rabbit fever.
Persons with tularemia may experience one or more of the various forms of the disease, which include: ulceroglandular (skin ulcer and swollen lymph nodes), glandular (swollen lymph nodes without an ulcer), oculoglandular (infection in the eye and swollen lymph nodes), oropharyngeal (severe sore throat and swollen cervical lymph nodes), intestinal (abdominal pain, diarrhea, and vomiting), pneumonic (infection of the lungs), and typhoidal (febrile illness not fitting in the other forms). The form of disease that develops depends on a variety of factors including where the bacteria enter the body. The symptoms of tularemia usually begin suddenly three to five days (range one to 14 days) following the exposure and depend on the form of the disease. These symptoms include high fever, chills, fatigue, general body aches, headache, and nausea. The most common form of the disease is ulceroglandular resulting from the bite of an infected tick or handling an infected animal.
Treatment for tularemia with antibiotics (usually gentamicin or streptomycin) is very effective at reducing the severity of the disease. It is important antibiotic treatment for tularemia be started without delay when the disease is suspected. Factors associated with a more severe outcome include increasing age, serious coexisting medical conditions, symptoms of a month or longer before treatment, and inappropriate antibiotic therapy. Overall, 4% of persons with tularemia die due to the disease. Although tularemia can be severe, preventive antibiotic therapy in non-ill persons following a tick bite is not recommended.
Laboratory testing for tularemia typically consists of blood samples used to test for antibodies in the serum. The bacteria can also be cultured from various specimens depending on the form of the disease. Laboratorians must use extreme care while working with F. tularensis as the bacteria can easily be spread in laboratory settings.