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INITIAL SYMPTOMS:
Lymphadenopathy associated with a skin ulcer (ulceroglandular type) or ulcers of the mouth/throat, (oropharyngeal), or the eyes (oculoglandular). [CCDM]
FINDINGS:
About 75-85% of cases are the ulceroglandular/glandular form. Other forms are oculoglandular, oropharyngeal, typhoidal, and pulmonary. [Harrison, p. 629-30] Ulceroglandular tularemia usually presents as a painful skin ulcer followed by painful regional lymphadenopathy. (The anthrax ulcer is not painful.) The lymph nodes may suppurate. Lymphatic vessels may become inflamed and nodular. Hepatosplenomegaly may be found in patients with tularemia. A relative bradycardia was detected in 42% of cases in one series. [ID, p. 62, 1446-51] Fever may be recurrent. Pharyngeal tularemia is another syndrome that may be seen in outbreaks. A pharyngeal membrane was reported in a few cases. In some patients, vesicles resembling herpes simplex are seen at the primary inoculation site. Skin rashes have been reported in up to 35% of cases and include pustules, erythema nodosum, erythema multiforme, diffuse maculopapular rash, and urticaria. Sometimes found are leukocytosis, thrombocytopenia, elevated transaminases, myoglobinuria, and pyuria. There is usually little or no sputum in pneumonic tularemia. Hemoptysis is uncommon. Ovoid or cavitary lesions are uncommon. In typhoidal tularemia, patients have diarrhea, abdominal pain, and vomiting. Pneumonia is common. Stools rarely contain blood, but infected children may develop foci of necrosis in the bowel. [PPID, p. 2595-9] Pneumonia has a case fatality rate of <2% with treatment and 7% without treatment. [ABX Guide: Francisella tularensis] "A nonspecific roseola-like rash may appear at any stage of the disease." [Merck Manual, p. 1265] Oropharyngeal tularemia may present as a stomatitis. [Cohen, p. 1229]
COMPLICATIONS:
Pneumonia may complicate any type of tularemia. It is common in typhoidal tularemia. Chest x-rays may show infiltrates, hilar lymphadenopathy, and pleural effusions. Mesenteric lymphadenitis and abdominal pain may follow ingestion of undercooked, infected game. [ID, p. 62, 1446-51] Brain abscesses may complicate meningitis. Fever, headaches, meningismus, vomiting, and diarrhea are symptoms of typhoidal tularemia. Severely ill patients with renal failure may have elevated creatine phosphokinase, myoglobinuria, and pyuria. Acute renal failure is associated with fatal disease. Other complications of severe disease are DIC and hepatitis; [PPID, p. 2595-9] Rare complications are mediastinitis, lung abscess, and meningitis. [Merck Manual, p. 1265]
DIFFERENTIAL DIAGNOSIS:
The differential diagnosis for ulceroglandular tularemia includes bubonic plague, chancroid, sporotrichosis, anthrax, and staphylococcal and streptococcal lymphadenitis. The differential diagnosis for glandular tularemia (lymphadenopathy without an ulcer) includes cat-scratch disease, tuberculosis, lymphogranuloma venereum, and bubonic plague. [ID, p. 62, 1446-51]
EPIDEMIOLOGY:
"Outbreaks of human tularemia usually occur in association with animal epizootics." Humans may be infected by biting insects, by handling infected meat or carcasses, and by consuming contaminated water or undercooked meat. Inhalation exposures occur in medical laboratory workers, hunters (pelts), and farmers (soil, grain, or hay dust). Reservoirs: ticks, some domestic animals, and wild animals (rabbits, voles, muskrats, beavers). Other vectors are mosquitoes (Russian Federation and Sweden) and deer flies. Drinking contaminated water is another source of infection. [CCDM, p. 652] Outbreaks have been reported after landscaping, mowing, and brush cutting. Farmers may become ill after handling hay contaminated with excreta of infected animals. The bacteria have been isolated from many species of birds. [ID, p. 1448] Ulceroglandular is the most common type of tularemia. Typhoidal tularemia (systemic disease with no indication of localized inoculation) is common, while the other five types are uncommon or rare. [Merck Manual, p. 1265]
BIODEFENSE:
In a bioterrorist attack using an aerosol, pneumonic tularemia is the most likely result. However, intentional air release could also cause other forms of tularemia. [JAMA. 2001;285: 2763-73] As a bioweapon, the expected clinical syndrome is a flu-like illness with pleuritic chest pain, dyspnea, skin rash, pharyngitis, conjunctivitis, and abnormal chest x-ray (infiltrates, cavitary lesions, and/or hilar adenopathy). [Cecil, p. 196, 630]
For updated text and symptoms of infectious diseases, see iddx.com.