infectious diseases
Tularemia
Introduction
; it may resemble Typhoid Fever . Symptoms are a primary local ulcerative lesion, regional lymphadenopathy, profound systemic symptoms, and, occasionally, atypical pneumonia. Diagnosis is primarily epidemiologic and clinical and supported by serologic tests. Treatment is with There are 7 clinical syndromes associated with tularemia (see table Types of Tularemia ); clinical manifestations vary by the type of exposure to the organism. The causative organism,F. tularensis, is a small, pleomorphic, nonmotile, nonsporulating aerobic, gram-negative bacillus that enters the body by Ingestion of contaminated food or water Bite of an infected arthropod vector (ticks, deer flies, fleas) Inhalation Direct contact with infected tissues or material Tularemia does not spread from person to person. The organism can penetrate apparently unbroken skin but may actually enter through microlesions. Two types ofF. tularensiscause most cases of tularemia: Type A:This type is a more virulent serotype for humans; it usually occurs in rabbits, hares, and rodents in the US and Canada. Type B:This type usually causes a mild ulceroglandular infection and occurs in rodents and in aquatic environments throughout the Northern Hemisphere, including North America, Europe, and Asia. Hunters, butchers, farmers, and fur handlers are most commonly infected. In winter months, most cases result from contact (especially during skinning) with infected wild rabbits and hares. In summer months, infection usually follows handling of other infected animals or birds or bites of infected ticks or other arthropods. Rarely, cases result from eating undercooked infected meat, drinking contaminated water, or mowing fields in endemic areas. In the Western US, ticks, deer flies, horse flies, and direct contact with infected animals are other sources of infection. Human-to-human transmission has not been reported. Laboratory workers are at particular risk because infection is readily acquired during normal handling of infected specimens. Tularemia is considered a possible agent of Biological Agents as Weapons because inhalation of as few as 10 organisms in the form of an aerosol can cause severe pneumonia. In disseminated cases, characteristic focal necrotic lesions in various stages of evolution are scattered throughout the body. They are 1 mm to 8 cm in diameter and whitish yellow; they are seen externally as the primary lesions on the fingers, eyes, or mouth and commonly occur in lymph nodes, spleen, liver, kidneys, and lungs. In pneumonia, necrotic foci occur in the lungs. Although severe systemic toxicity may occur, no toxins have been demonstrated. 