Six cases have been reported in Ada and Elmore counties since Jan. 1.

BOISE, Idaho — Public health officials say there is a spike of hepatitis A cases in the Boise region, with six cases reported among Ada and Elmore county residents since Jan. 1.

Normally, the area sees just one or two cases a year.

The Central District Health Department sent a bulletin to health care providers in the region Tuesday, warning that the infections are being spread locally. All of the six patients so far are men between the ages of 30 and 60.

"We know that something is going on in the community," CDHD spokesperson Christine Myron said. "Hepatitis can be really tricky because it has a long incubation period. A person can be exposed and not get any symptoms until maybe four weeks after they've been exposed."

Hepatitis A causes inflammation of the liver and is typically spread person-to-person through fecal-oral transmission. It can spread through food that has been handled by someone with hepatitis A, or contact with someone infected with the illness.

Symptoms include nausea, lack of appetite, fever and abdominal pain. It can also cause jaundice, which is yellow-tinged skin and eyes.

Hepatitis A can be prevented by a vaccine.