Epidemiological and clinical characteristics of hantavirus infections detected in three geographically close natural foci during the 2014 Croatian outbreak

Abstract

Purpose: The aim of this study was to analyze epidemiological and clinical characteristics of hantavirus infections detected in Croatia during the 2014 outbreak. Methods and Materials: From January to December 2014, a total of 122 patients from three geographically close natural foci in the central mountainous Croatian region (Ogulin, Slunj and Plitvice Lakes surroundings) with clinical symptoms suggestive of hantavirus infection were tested for the presence of IgM/IgG antibodies to hantaviruses. Serologic tests were performed using a commercial IFA for the simultaneous detection of Puumala (PUUV), Dobrava (DOBV), Hantaan (HTNV), Seoul (SEOV) and Saaremaa (SAAV) (Euroimmun, Lubeck Germany). Cross-reactive samples were additionally tested using a western blot (Euroimmun, Lubeck Germany). For hospitalized patients clinical symptoms and laboratory parameters were analyzed. Results: Acute hantavirus infection was confirmed by detection of IgM/IgG antibodies in 57/46.7% patients, while 10/8.2% patients were IgG seropositive (previous exposure to hantaviruses). PUUV infection was detected in 88.1% and DOBV infection in 11.9% patients. Among acute cases, 75.4% were hospitalized. Males were infected more commonly than females (75.4%). The mean patient’s age was 37.9 (range 15- 69) years. Contact with rodents was noted in 59.3% patients. The outbreak started in winter months with majority patients (80.7%) reported from May to July. According to disease severity, mild clinical form was noted in 66.7%, moderate in 18.5% and severe in 14.8% patients. The most common clinical symptoms on admission were high fever (96.3%), chills/shivering (62.9%) and lumbal pain (48.1%). In 11.1% patients, respiratory symptoms with interstitial inflammatory infiltrates on X-ray were reported. Acute renal failure was noted in 74.1% patients but only 3.7% required hemodialysis. Laboratory abnormalities included albuminuria (96.3%), thrombocytopenia (81.5%, elevated urea and/or creatinine levels (70.4%) and elevated transaminases (25.9%). The mean duration of hospitalization was 9.6 (range 4-19) days. Only one PUUV infected patient developed multiorgan failure and died. Conclusion: Our results indicate that central mountainous Croatian regions are still endemic areas for hantavirus infections with circulation of both PUUV and DOBV. Compared to previous Croatian outbreaks, respiratory symptoms that are frequently detected in PUUV infection were reported less frequent.