Impact of BTV-3 Circulation in Belgium in 2024 and Current Knowledge Gaps Hindering an Evidence-Based Control Program

Area of Science:

• Veterinary Virology
• Epidemiology
• Animal Health

Background:

• The first major bluetongue virus (BTV) outbreak in Europe occurred between 2006-2010 (BTV-8).
• Bluetongue virus type 3 (BTV-3) was first detected in Europe in 2017 and reintroduced in 2023.
• Belgium lost its BTV-free status in 2023 due to BTV-3 outbreaks, with rapid spread in 2024.

Purpose of the Study:

• To describe the geographic spread and impact of BTV-3 in Belgium during 2024.
• To assess the effectiveness of field vaccination and maternal immunity transfer.
• To identify gaps in current management strategies for BTV.

Main Methods:

• Monitoring of BTV-3 geographic spread across Belgium.
• Analysis of livestock data: mortality rates, birth rates, and milk production.
• Evaluation of preliminary field vaccination and maternal immunity data.

Main Results:

• Widespread BTV-3 circulation in Belgium during 2024.
• Significant increases in ruminant mortality and reduced births were recorded.
• A decline in milk production was observed in affected herds.
• Preliminary data suggests some effectiveness of vaccination and maternal immunity.

Conclusions:

• BTV-3 poses a substantial threat to Belgian livestock, causing significant economic losses.
• Further research is needed to address critical gaps in developing evidence-based management strategies.
• Anticipated co-circulation of multiple BTV serotypes and other vector-borne diseases necessitates enhanced collaboration for disease mitigation.