First evidence of Crimean-Congo haemorrhagic fever virus circulation in Bosnia and Herzegovina.

Background: Crimean-Congo haemorrhagic fever (CCHF) is a widespread tick-borne zoonosis with reported detection of virus and/or virus-specific antibodies from over 57 countries across Africa, Asia, Europe and the Middle East and is endemic in the Balkans. Detection of Crimean-Congo Haemorrhagic Fever Virus (CCHFV) antibodies in domestic ruminants has been important in providing initial evidence of virus circulation and in localising CCHFV high-risk spots for human infection.

Objectives: The present study investigated the possible exposure of sheep to CCHFV in Bosnia and Herzegovina (B&H).

Methods: To investigate the presence of anti-CCHFV antibodies in sheep, all sera (n = 176) were tested using multi-species double antigen enzyme-linked immunosorbent assay (ELISA). Reactive sera were further complementary tested by adapted commercial indirect immunofluorescence assay (IFA) using FITC-conjugated protein G instead of anti-human immunoglobulins.

Results: CCHFV specific antibodies were detected in 17 (9.66%) animals using ELISA test. All negative sera were determined as negative by both tests, while 13 out of 17 ELISA-positive reactors were also determined as unambiguously positive by IFA test. The age group with the highest proportion of seropositive rectors were the oldest animals.

Conclusions: This is the first report of anti-CCHFV antibodies in sheep from B&H providing the evidence of CCHFV circulation in the country's sheep population. So far, these findings indicate the circulation of the virus in the westernmost region of the Balkans and point to the potential CCHFV spread further out of this endemic area.