Clinical and epidemiological features of hospitalized acute Q fever cases from Split-Dalmatia County (Croatia), 1985-2002.

BACKGROUND: Q fever shows a wide diversity of clinical manifestation. Q fever is endemic in northern Croatia, but the epidemiological and clinical characteristics of this disease in various ecological areas of southern Croatia are unclear. MATERIAL/
METHODS: From January 1985 to December 2002, acute Q fever cases hospitalized at Split University Hospital were analyzed. Acute Q fever was defined as fever (>38 degrees C) with clinical findings in lung and/or liver verified by serologic testing with Coxiella burnetii phase II antigen.
RESULTS: During the period of observation, 155 acute Q fever cases were hospitalized. The mean incidence of acute Q fever in the study region was 0.20/100,000/year (95%CI:0-0.78) in the coastal area and 4.64/100,000/year (95%CI:0.44-8.85) in the non-coastal areas, with a male predominance (chi2=60.0; p=0.0000) and a mean male to female ratio of 4.2:1. People of essentially all ages (4-76 years) were affected, the highest rate of infection being recorded in 20- to 49-year-old age groups. In contrast to adults, girls were more frequently affected than boys (2:1). No case of acute Q fever was recorded on any of the nearby islands. Clinically, acute Q fever most commonly presented with both pneumonia and hepatitis (60.0%), followed by pneumonia (25.8%), hepatitis (9.0%), and nonspecific febrile illnesses (5.2%).
CONCLUSIONS: C. burnetii is endemic in rural, coastal, and non-coastal areas of southern Croatia and is associated with stock breeding. In these areas, Q fever occurs sporadically and epidemically. Males 20-49 years of age were the prevalent cases.