Gennady Onishchenko, who heads Russia's consumer rights watchdog, Rospotrebnadzor, said that in mid-May, 16,200 Russians had been bitten by ticks, against 4,500 in May 2006. Four people caught tick-borne encephalitis as of May 5, while no instances of the disease were reported last year.
"So far, 135,000 people have been bitten by ticks, including 34,000 children, and 278 have been infected with tick-borne encephalitis," Onishchenko said.
The Irkutsk Region, the Republic of Khakasia, and the Tomsk and Novosibirsk Regions in Siberia have been the hardest hit.
Onishchenko urged Rospotrebnadzor officials to focus on preventive measures in summer camps for children.
Tick-borne encephalitis is transmitted by the bite of infected ticks and affects the human brain. The incurable disease was first detected in Russia's Far East, which is still a hotbed of infection.