AUSTIN—Health officials said Thursday that they are investigating a dozen possible cases of typhus in Travis County, further north than the disease is usually seen in Texas.

In Texas, most of the murine typhus cases occur in South Texas, but some cases are reported each year in other parts of the state, the Department of State Health Services said on its Web site. People are infected with typhus from fleas.

Emily Palmer, spokeswoman for the state agency, said there are typically anywhere from about 100 to 170 cases of typhus in Texas each year. She said there were only two cases in Travis County last year.

Carole Barasch, a spokeswoman for the Austin/Travis County Health and Human Services Department, said that there were no reports of typhus from 1997 to 2006 in Travis County.

She said of the 12 suspected cases in Travis County, nine of the people have had to be hospitalized.

Palmer said that the state agency and the Centers for Disease Control and Prevention in Atlanta are working to determine whether the cases are in fact murine typhus.

Symptoms include a headache, fever, nausea, body aches and possibly a rash. The state health department Web site said typhus is easily treated with certain antibiotics.