Prevalence of Toscana virus antibodies in residents of Croatia V. Punda-Polic ´ 1,2 , A. Jeronc ˇic ´ 3 , B. Mohar 1 and K. S ˇ is ˇko Kraljevic ´ 1,4 1) Department of Medical Microbiology, Split University School of Medi- cine, 2) Department of Clinical Microbiology, Split University Hospital, 3) Department for Research in Biomedicine and Health, Split University School of Medicine and 4) Department of Microbiology, Institute of Public Health, Split, Croatia Abstract To assess the prevalence of Toscana virus (TOSV) infection among healthy residents of Croatia we tested sera from 2016 persons, for IgG antibodies to TOSV, by an enzyme immunoas- say. A total of 755 (37.5%) persons had IgG antibodies to TOSV: 53.9%, 33.6% and 6.1% among residents of the islands, coastal area and mainland of Croatia, respectively. Risk factors signifi- cantly associated with seropositivity to TOSV were: living on islands (OR, 11.10; 95% CI, 6.02–20.50; p <0.001) or in coastal areas (OR, 6.96; 95% CI, 3.81–12.71; p <0.001) and increase of age (OR, 1.03; 95% CI, 1.02–1.03; p <0.001). Keywords: Croatia, Phlebovirus, seroprevalence, Toscana virus Original Submission: 22 December 2011; Revised Submis- sion: 24 February 2012; Accepted: 7 March 2012 Editor: L. Kaiser Article published online: 12 March 2012 Clin Microbiol Infect 2012; 18: E200–E203 10.1111/j.1469-0691.2012.03840.x Corresponding author: V. Punda-Polic ´, Department of Clinical Microbiology, Split University School of Medicine and Split University Hospital, Spinc ˇic ´eva 1, 21000 Split, Croatia E-mail: vpunda@kbsplit.hr Toscana virus (TOSV) (family Bunyaviridae, genus Phlebovirus) is an arbovirus transmitted by sandflies (Phlebotomus spp). TOSV is neurovirulent and causes aseptic meningitis during the summer time in both residents of and travellers to Medi- terranean countries [1–4]. No information on TOSV circulation in Croatia is avail- able. The aim of this study was to determine the prevalence of TOSV antibodies among the healthy population of differ- ent regions in Croatia. Croatia is situated between central and south-eastern Eur- ope, lying along the east coast of the Adriatic Sea (Fig. 1). The Croatian littoral is composed of the northern (Istria and Primorje) and southern part (Dalmatia), which is subdivided into northern, central and southern Dalmatia. The Adriatic coast and islands are characterized by the Mediterranean cli- mate, which is favourable for maintaining sandfly vectors of TOSV [5]. The mainland parts of Croatia, which have the continental climate, are considered sandfly-free areas. From 2007 to 2009 we collected blood specimens from 2016 healthy inhabitants of island, coastal or continental parts of Croatia, aged 8 months to 88 years, who came to hospital for laboratory check-ups or blood donation. Infor- mation regarding age, gender and site of residence was col- lected. The ethical committee of Split University Hospital approved the study. Presence of anti-TOSV IgG was investigated using a com- mercial enzyme immunoassay (rEIA, Enzywell Toscana Virus IgG/IgM, DIESSE, Siena, Italy). Previous studies of rEIA had revealed its sensitivity and specificity for IgM to be 100%, and for IgG to be 100 and 96.6%, respectively [6]. The data were analyzed using SPSS version 19.0. Chi- square tests, odds ratios (OR) and multiple logistic regres- sion were used to estimate associations with seropositivity and to evaluate potential risk factors for TOSV infection. Of the total of 2016 sera, anti-TOSV IgG were found in 755 (37.5%). Seroprevalence differed significantly among sites, ranging from 4.7% in Brod-Posavina County to 67.7% on the island of Lastovo (Fig. 1, Table 1). Islanders were more seropositive than inhabitants of coastal (v 2 = 69.82, p <0.001) or mainland areas (v 2 = 139.33, p <0.001). Inhabit- ants of coastal areas were more seropositive than those from mainland regions (v 2 = 61.46, p <0.001). Prevalences among the coastal and continental counties, as well as between the islands, were compared (Table 1). With regard to islands data, a decrease in risk of TOSV infection was determined for the northern-most islands of Istria and Primorje (Fig. 1) relative to islands of central (OR = 0.52; 95% CI, 0.33–0.84; p 0.007) or southern Dalma- tia (OR = 0.61; 95% CI, 0.35–1.04; p 0.070 borderline signifi- cance). All endemic sites (coastal or island) had significantly higher risk of TOSV infection, compared with the continental coun- ties (OR from 6.46 to 21.39; p <0.001). An increased probability of acquiring the infection with age was observed. Seroprevalence rate increased from 10.2% in ª2012 The Authors Clinical Microbiology and Infection ª2012 European Society of Clinical Microbiology and Infectious Diseases RESEARCH NOTE VIROLOGY