Topeka ? Health officials confirmed Tuesday that a northeast Kansas woman has the state’s first case of monekypox and the first case west of the Mississippi River.

Preliminary results from tests conducted by the Kansas Department of Health and Environment indicated a woman bitten by a prairie dog around June 1 has the disease. Samples were being sent to the Centers for Disease Control and Prevention in Atlanta for analysis.

“We were fairly confident, because the woman was bitten by a prairie dog and had all the symptoms,” said KDHE spokeswoman Sharon Watson.

Llelwyn Grant, spokesman for the CDC, said 20 cases have been confirmed nationwide, including seven in Wisconsin and four each in Indiana and Illinois.

An additional 81 cases, including the one from Kansas, are under investigation.

The young Kansas woman was bitten by a prairie dog while visiting a northwest Missouri man. She first became ill June 10 and was hospitalized Sunday. Watson said the woman, who was not identified by age or hometown, was expected to be released Tuesday from St. John Hospital in Leavenworth.

Three family members were given the smallpox vaccine on Monday as a precaution, Watson said. The vaccine is proven to reduce the risk of monkeypox among humans.

Monkeypox, a west African disease not previously seen in the Western Hemisphere, is related to smallpox but is not as lethal. It causes rashes, chills and fever.

The prairie dog at the Missouri home is still alive and not showing any signs of monkeypox, although a second prairie dog in the same household died.

Nanci Gonder, spokeswoman for the Missouri Department of Health and Senior Services, said a 38-year-old man had not been hospitalized and recovered from monkeypox at home after contacting a local health clinic.

Tests resulted in a presumptive positive for monkeypox, Gonder said. Confirmation from the CDC is expected by week’s end.