Crimean-Congo Hemorrhagic Fever Virus, Greece

Anna Papa

, Persefoni Sidira, Victor Larichev, Ludmila Gavrilova, Ksenia Kuzmina, Mehrdad Mousavi-Jazi, Ali Mirazimi, Ute Ströher, and Stuart Nichol

Author affiliations: Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece (A. Papa, P. Sidira); D.I. Ivanovsky Institute of Virology, Moscow, Russian Federation (V. Larichev, L. Gavrilova, K. Kuzmina); Swedish Institute for Communicable Disease Control, Stockholm, Sweden (M. Mousavi-Jazi, A. Mirazimi); National Veterinary Institute, Uppsala, Sweden (A. Mirazimi); Linköpings University Institute of Clinical and Experimental Medicine, Linköping, Sweden (A. Mirazimi); Centers for Disease Control and Prevention, Atlanta, Georgia, USA (U. Ströher, S. Nichol)

Abstract

Seroprevalence of Crimean-Congo hemorrhagic fever virus (CCHFV) is high in some regions of Greece, but only 1 case of disease has been reported. We used 4 methods to test 118 serum samples that were positive for CCHFV IgG by commercial ELISA and confirmed the positive results. A nonpathogenic or low-pathogenicity strain may be circulating.

Crimean-Congo hemorrhagic fever (CCHF) virus (CCHFV; genus Nairovirus, family Bunyaviridae) causes severe disease in humans and circulates in many areas of Africa, Asia, and Europe. The disease is characterized by a sudden onset of high fever, chills, severe headache, dizziness, and back and abdominal pains; additional signs and symptoms include nausea, vomiting, diarrhea, and neuropsychiatric and cardiovascular changes. In severe cases, hemorrhagic manifestations are present, ranging from petechiae to large areas of ecchymosis and bleeding from different sites of the body. Case-fatality rates range from 10% to 50% (1). Humans become infected with CCHFV through tick bites, mainly from Hyalomma spp. ticks, or by direct contact with blood or tissues from viremic livestock or infected humans. The geographic range of CCHFV is the most extensive among tick-borne viruses related to human health, coinciding with the distribution of Hyalomma spp. ticks (1).

Greece is a country in the south of the Balkan Peninsula. Although sporadic cases or outbreaks of CCHF are often observed in other Balkan countries, including Bulgaria, Albania, and Kosovo (2–5), only 1, fatal, CCHF case has been reported in Greece (6). The causative strain, Rhodopi-2008, clusters with other pathogenic Balkan CCHFV strains; however, it differs by >20% at the nucleotide level from the CCHFV strain AP92, which was isolated from Rhipicephalus bursa ticks collected in 1975 from goats in Vergina village in northern Greece (7). Human disease has not been associated with the AP92 strain, and only a few mild cases associated with an AP92-like strain have been reported in Turkey (8).

Recent studies have shown that the seroprevalence of CCHFV antibodies (IgG) in the general population of Greece is ≈4%, but large differences are seen between regions (range 0%–27%) (9–11). All of these studies used commercial ELISA kits to detect CCHFV IgG. Our aim was to retest these IgG-positive samples by using additional serologic methods to evaluate the accuracy of the results of the earlier studies.