Of the 250 cases of the viral TBE, 51 were diagnosed on Saaremaa and Muhu islands. The average incidence was 18.7 per 100,000 people nationally but Saaremaa's figure was 147 and Hiiumaa island's was 79.

Other top counties for TBE were Lääne, Harju and Rapla in western and northern Estonia. TBE rates dropped in southern Estonia.

Lyme disease or borreliosis, caused by a bacterium, was diagnosed on 2,303 occasions in 2011 (up from 1,721). The most cases were confirmed in Tallinn (i.e., the diagnosis was made by a doctor in Tallinn), where the figure hit 435. Saaremaa was second with 363 but Saaremaa was the only county where the incidence decreased.

Incidence of Lyme per 100,000 people was highest in the two island counties - Hiiumaa with 1,654 and Saaremaa with 1,045. The average countrywide was only 172. The southeast and northeast corner of the country had the lowest incidence.

TBE is an incurable viral illness that can cause serious neurological damage, but is relatively low in infectiousness and can be prevented by vaccination. Survivors have lifelong immunity. There is no vaccine or immunity for Lyme but it can be effectively treated with a prompt course of antibiotics. Neither of the illnesses are known to be transmitted by humans. 

Warmer winters have been implicated in the increase in the diseases on the islands, but no one definitive cause has been identified.

Kristopher Rikken