[Clinical picture of hemorrhagic fever with renal syndrome in Croatia].

Among many viral hemorrhagic fevers, only hemorrhagic fever with renal syndrome (HFRS) occurs in Croatia. HFRS is a natural focus zoonosis with sudden onset, characterized by high fever and other clinical symptoms, renal insufficiency and hemorrhages. In Croatia, HFRS is caused by two types of hantaviruses--Puumala (PUU) and Dobrava (DOB). The basic pathologic and patophysiologic disorder in HFRS is capillary damage (vasculitis). Incubation of HFRS has not been precisely determined, it is most frequently around two weeks. The disease onset is usually abrupt. At the beginning, general symptoms include high fever and myalgias, especially in the lumbar region, and abdominal pain, as well as strong headaches, malaise and nausea, and often vomiting or diarrhea. In half of the patients respiratory symptoms occur. Later on, some patients may experience hypotension, oliguria and other signs of renal failure, and apart from petechial, severe hemorrhages may also occur in other organs. During typical clinical presentation of the disease, some characteristic symptoms are clearly distinguished in particular stages of the disease. Therefore, the course of HFRS is usually divided into five distinct stages (febrile, hypotensive, oliguric, polyuric and convalescent). Such a course of the disease is more commonly present in case of DOB virus than PUU virus infection. The febrile stage with sudden onset usually lasts from 3 to 7 days, when thrombocytopenia and hemoconcentration, as well as albuminuria and hematuria are almost always recorded. The hypotensive stage lasts from one to 2 days on an average and is characterized by lower blood pressure and signs of renal failure. The oliguric stage usually starts at the beginning of the second week of the disease, when extensive hemorrhage may occur and urea and creatinine reach their highest values. The oliguric stage is followed by the polyuric stage which can last for up to two weeks, and is characterized by excretion of a large quantity of urine of low specific gravity (up to 15 liters during 24 hours). The convalescence (convalescent stage) is slower, may last for several weeks or months, but usually resolves without complications. During the infection caused by PUU virus, the course of disease is usually milder with only two stages. The first one is febrile, followed by the second stage with renal symptoms, and rare and mild hemorrhagic manifestations. This type of disease is mostly encountered during epidemics. The mortality in severe cases of the disease (DOB virus) is 5% to 10%, whereas in PUU virus infection it is less than 1%.