LEPTOSPIROSIS

Leptospirosis is caused by coil-shaped bacteria of the genus Leptospira, acquired most commonly through direct or indirect contact with infected urine of different animals, mainly rats. Although universally distributed, tropical regions harbor more favorable conditions. Isolated cases are found, but epidemics related to floods are also seen. Penetration is through the skin and mucosa, after which a 7- to 13-day incubation period ensues, and then the spirochetes disseminate to the liver, skin, capillaries, muscles, lungs, and other organs. The disease has an icteric and an anicteric form. The majority may be oligosymptomatic or asymptomatic. In the symptomatic form, after 3 to 7 days of a septicemic stage with fever, myalgias, arthralgias, prostration, and vomiting, an immune stage develops, with an improvement of the fever and the appearance of diverse manifestations of organ involvement, mainly jaundice, renal failure, and different hemorrhagic manifestations. The basis of the manifestations seems to be a capillaritis, possibly toxic in nature. In the lungs, this leads to alveolar hemorrhage of varying intensity. Most cases are very mild with slight cough and hemoptysis; pneumonia and respiratory failure may develop. Some cases seem to evolve into ARDS. Chest radiographs show patchy opacities, diffuse or localized. Coalescence occurs in the severe forms. Diagnosis may be made by the demonstration of Leptospira in urine, spinal fluid, or tissue, in the first week. The most consistent diagnostic method, however, is macroagglutination of the serum. Other serologic tests may also be used, but interpretation depends on the clinical setting. Treatment with antibiotics, preferably penicillin or tetracycline, has to be started in the first week to be effective. Prophylaxis is directed toward improvement of sanitary conditions and personal protection in selected cases. Vaccination of pets and humans is being researched.