RAPID CITY, S.D. (AP) — The number of confirmed cases of enterovirus 68 in South Dakota has risen to a dozen.

State Epidemiologist Lon Kightlinger tells the Rapid City Journal that a majority of the cases are in the western part of the state.

Enterovirus is a rare germ believed to be the cause of a severe respiratory illness that affects mainly children. There's no vaccine, and it's been linked to hundreds of illnesses nationwide.

Most children recover within a week. Four infected people have died but it's unclear what role the virus played in the deaths.

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