Mosquito-borne viruses in Finland

Area of Science:

• Virology
• Arbovirology
• Epidemiology

Background:

• Inkoo virus is the Finnish representative of the California encephalitis virus group.
• Mosquito-borne viruses pose a significant public health concern globally.
• Understanding the distribution and prevalence of arboviruses is crucial for disease prevention.

Purpose of the Study:

• To characterize the Inkoo virus and its antigenic relationship with other California group viruses.
• To determine the geographical distribution and prevalence of Inkoo virus antibodies in various hosts in Finland.
• To investigate the presence of other mosquito-borne viruses in Finland.

Main Methods:

• Virus isolation from mosquito pools (Aedes communis/punctor).
• Serological assays (hemagglutination inhibition) to detect antibodies in humans, livestock, and wildlife.
• Antigenic characterization and comparison with known California group viruses.

Main Results:

• Inkoo virus was isolated and distinguished from other related viruses, showing antigenic similarity to Jamestown Canyon virus.
• Inkoo virus antibody prevalence increased northward in humans (16%–69%) and cows (37%–88%).
• Antibodies were common in large mammals (reindeer, moose, foxes), less so in hares, rare in hazel grouse, and absent in other birds and small mammals.

Conclusions:

• Inkoo virus is antigenically related to Jamestown Canyon virus and shows a distinct geographical distribution in Finland.
• Evidence suggests the presence of another California group virus in Finland based on hare serum reactions.
• The study also indicates potential past Batai virus and current alphavirus activity in Finland, with the overwintering mechanism of these viruses remaining undetermined.