Tularaemia is an infection due to Francisella tularensis transmitted to mammals and birds by the bites of infected blood-sucking flies and ticks.
It is often seasonal. Man may be infected by ticks or accidentally in a laboratory or while skinning infected wild rabbits or hares. The micro organisms enter through dermal abrasions, the conjunctiva or mouth. Contaminated water and infected meat are less common sources of human infection.
Pathology
Focal areas of necrosis occur especially in lymph nodes, spleen, liver, kidneys and lungs. There may be cutaneous, oral or ophthalmic lesions when infection is by these routes.
Clinical features
The commonest presentations is of a papule at the site of inoculation which becomes swollen and painful and suppurates, causing an ulcer up to 2cm in diameter. Regional lymph nodes become tender, enlarged and may suppurate. There may be a systemic illness with fever, often prolonged. Sometimes the conjunctiva is the site of entry, and is inflamed. Occasionally the presentation is only with lymphadenopathy.
Septicaemia is the rarest, but most severe form of the disease. There is a sudden onset of high fever, prostration, aching limbs, vomiting, diarrhoea and mental confusion. Pneumonia, pleurisy and pericarditis are serious complications.
Diagnosis
The organism may be isolated with difficulty and danger by culture on special medial or guinea-pig inoculation. Agglutination and complement-fixation tests become positive after 10-12 days.
Management
Streptomycin, as for plague, or genatmicin is the treatment of choice, though tetracycline(500mg 6-hourly for 2 weeks) is also likely to be effective.
Prevention
Masks should be worn in the laboratory and gloves are used when skinning rabbits and hares in endemic areas. Adequate cooking renders infected meat safe for eating.
It is often seasonal. Man may be infected by ticks or accidentally in a laboratory or while skinning infected wild rabbits or hares. The micro organisms enter through dermal abrasions, the conjunctiva or mouth. Contaminated water and infected meat are less common sources of human infection.
Pathology
Focal areas of necrosis occur especially in lymph nodes, spleen, liver, kidneys and lungs. There may be cutaneous, oral or ophthalmic lesions when infection is by these routes.
Clinical features
The commonest presentations is of a papule at the site of inoculation which becomes swollen and painful and suppurates, causing an ulcer up to 2cm in diameter. Regional lymph nodes become tender, enlarged and may suppurate. There may be a systemic illness with fever, often prolonged. Sometimes the conjunctiva is the site of entry, and is inflamed. Occasionally the presentation is only with lymphadenopathy.
Septicaemia is the rarest, but most severe form of the disease. There is a sudden onset of high fever, prostration, aching limbs, vomiting, diarrhoea and mental confusion. Pneumonia, pleurisy and pericarditis are serious complications.
Diagnosis
The organism may be isolated with difficulty and danger by culture on special medial or guinea-pig inoculation. Agglutination and complement-fixation tests become positive after 10-12 days.
Management
Streptomycin, as for plague, or genatmicin is the treatment of choice, though tetracycline(500mg 6-hourly for 2 weeks) is also likely to be effective.
Prevention
Masks should be worn in the laboratory and gloves are used when skinning rabbits and hares in endemic areas. Adequate cooking renders infected meat safe for eating.
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