Time and Place:
- Pogosta disease was first described in the Pogosta region of Northern Karelia in 1974.
- The disease is reported from all parts of Finland, however, North Karelia remains the region with highest incidence, with rates as high as 80 per 100,000.
- Extensive epidemics were recorded in 1974, 1981 (thousands of cases), 1988 and 1995.
- Incidence peaks during August to September.
- Disease incidence follows a seven-year cycle.
- Highest rates are reported in the age group 45 to 65.

Graph Notes:
1. 2,183 laboratory-confirmed cases were reported during 1981 to 1996 (average rate 2.7 per 100,000 per year).
Individual years:
1995 – Cases were distributed throughout the country, with highest incidence in central Finland, Savo and North Karelia.
2003 – Included 105 cases in Lansi-Suomi and 50 in Ita-Suomi.

Seroprevalence surveys:
1.7% of ‘suspected rubella’ in Finland (1973 to 1989)
11% of persons suspected of having viral infection – 17% in western Finland, 9% in northern and southern Finland
0.6% of women of childbearing age (1992)
5.2% of humans (Sindbis virus, 1999 to 2003)
27.4% of resident grouse (Tetrao urgallus, T. tetrix, Bonasa bonasia, Lagopus lagopus) in 2003, 1.4% in 2004

The principal vectors are mosquitoes (Culex and Culiseta species), and the presumed reservoirs are tetranoid and migratory birds.
- During an epidemic in 1981, 65% of black grouse and capercaillie were found to be seropositive.

A recent report of Hemorrhagic Fever and Renal Syndrome (HFRS) activity in Finland reminds us that this country continues to report the highest rates for Hantavirus infection in the region. In the attached graph, I’ve compared disease reporting in Finland with that of neighboring countries.

Update: Appeared in ProMED