Abstract
Leptospirosis is a zoonosis, with clinical manifestations ranging from the imperceptible to severe, potentially fatal renal and liver failure accompanied by haemorrhage and jaundice. In this case report of a patient with severe leptospirosis, serum levels of procalcitonin decreased ahead of any obvious clinical improvement, and thus may be useful as a prognostic marker. Levels of soluble IL-2 receptor were very high and correlated well with the clinical course.