Bluetongue in Italy: Part I

Area of Science:

• Veterinary Virology
• Epidemiology
• Climate Change Impact on Disease

Background:

• Bluetongue virus (BTV) outbreaks in the Mediterranean Basin began in 1998, initially affecting Turkey and Greece.
• The epidemic expanded significantly in 1999-2000, involving continental Greece, Bulgaria, and Balkan states with BTV serotypes 4, 9, and 16.

Purpose of the Study:

• To document the unprecedented spread and characteristics of the bluetongue epidemic in the Mediterranean and Europe.
• To analyze the pattern of BTV spread in Italy prior to vaccination implementation.
• To investigate potential contributing factors such as climate, soil, and insect vectors, and to postulate origins of BTV introduction.

Main Methods:

• Retrospective analysis of bluetongue virus (BTV) spread patterns across the Mediterranean and Balkan regions.
• Geographical mapping of BTV serotypes (BTV-2, BTV-4, BTV-9, BTV-16) and their expansion.
• Discussion of epidemiological data in relation to environmental factors and potential virus introduction pathways.

Main Results:

• The epidemic was the largest ever in Europe, characterized by northward spread to 44°N and multi-seasonal persistence, suggesting potential endemicity.
• BTV-2 emerged in Tunisia (1999) and spread to Algeria, Italy (Sardinia), France (Corsica), and Spain (Balearic Isles) by 2000.
• BTV-9 also appeared in peninsular Italy in autumn 2000, alongside BTV-4, -9, and -16 in the eastern Mediterranean.

Conclusions:

• The bluetongue epidemic demonstrated significant geographical penetration and persistence, indicating a potential for widespread endemicity.
• Environmental factors, including climate and insect vectors, likely played a crucial role in the disease's incidence and overwintering.
• Understanding the origins and spread dynamics is vital for future bluetongue virus control strategies in Europe.