Equine sentinels and one health: a comprehensive serological survey of Crimean-Congo hemorrhagic fever virus in southeastern and Central Europe.

Overview

• This study investigates the presence of Crimean-Congo hemorrhagic fever virus (CCHFV) antibodies in horses and donkeys in Southeastern and Central Europe to understand the spread of the disease as its tick vectors expand into new areas driven by environmental changes.

Background

• Crimean-Congo hemorrhagic fever (CCHF) is a viral disease transmitted by ticks, affecting humans and considered endemic in parts of Africa, Asia, and Europe.
• The primary vectors of CCHF are ticks of the genus Hyalomma, which have been expanding their range due to factors like climate change, increased global travel, and animal trade.
• Traditionally, Central Europe, including the Czech Republic, was considered low risk or non-endemic for CCHF.

Research Objective

• To assess the prevalence of CCHF virus infection in equids (horses and donkeys) as sentinel animals in Southeastern and Central Europe.
• Sentinel surveillance in animals can help track the spread of vector-borne diseases and the presence of the virus in a region before human cases arise.

Methodology

• Serum samples were collected from horses and donkeys across three countries in Europe:
  • Bulgaria (579 samples)
  • Romania (1,534 samples)
  • Czech Republic (576 samples)
• Samples were tested using an ELISA (enzyme-linked immunosorbent assay) to detect antibodies against CCHFV, indicating past exposure or infection.

Key Findings

• A clear gradient of seroprevalence was observed from southeast to northwest Europe:
  • Bulgaria showed a relatively high seroprevalence of 14.5%, indicating established virus circulation.
  • Romania showed a lower seroprevalence at 1.5%, suggesting some exposure but less widespread infection.
  • The Czech Republic showed 0% seroprevalence, indicating no detected exposure in sampled animals during this study.
• This pattern aligns with the environmental distribution of the primary tick vector, Hyalomma spp., which has traditionally been more abundant in southeastern Europe.
• The findings support the hypothesis that the ticks—and hence CCHFV—are moving northward, influenced by climate change, land-use patterns, and other ecological factors.

Implications

• The study highlights the importance of ongoing surveillance using equids as sentinel animals for early detection of CCHF virus expansion into new areas.
• The northward spread of the tick vectors creates new ecological niches for CCHFV, increasing the potential risk of outbreaks in areas previously considered low risk.
• Public health and veterinary authorities should be aware of these changes to implement preventive measures such as tick control, enhanced monitoring, and public awareness campaigns.
• This research underscores the role of “One Health” approaches, integrating human, animal, and environmental health to understand and control zoonotic diseases like CCHF.