Leptospirosis diagnosis: Competancy of various laboratory tests

Leptospira can be found in virtually all tropical and temperate areas of the world and is presumed to be the most wide spread zoonoses in the world.Humans contact leptospirosis through mucosal or percutaneous exposure to leptospires in environments contaminated by the urine of chronically infected animal sources.Despite being common, the diagnosis of leptospirosis is often not made unless a patient presents with textbook manifestations of the so called Weil's disease, such as fever plus jaundice, renal failure and pulmonary haemorrhage. Leptospiral infection often has minimal or no clinical manifestations; of the cases in which fever develops, as many as 90% are undifferentiated febrile illnesses. Because of the variety of clinical symptoms seen in the symptomatic cases, leptospirosis at its onset is often misdiagnosed as aseptic meningitis, influenza, hepatic disease or fever (pyrexia) of unknown origin. Moreover, clinicians may fail to recognize that transmission of leptospirosis can occur in the urban setting because it is incorrectly perceived to be a rural disease. Therefore, diagnosis is based on laboratory tests rather than on clinical symptoms alone. In developing countries, laboratory facilities may be inadequate for diagnosis despite a high prevalence of the disease. Of substantial clinical importance, the syndrome of leptospiral pulmonary haemorrhage has emerged in recent years, in diverse places around the world.