BOISE, Idaho — Central District Health is warning of a possible hepatitis A exposure on a Greyhound bus to Boise. 

Any passengers on the bus - which traveled from Salt Lake City, Utah to Boise on Wednesday, April 10 - who used the on-board bathroom are urged to contact the health department as soon as possible at 208-327-8625. Riders who did not use the restroom on the bus do not need to call.

Hepatitis A is a highly infectious disease that affects the liver. It spreads by entering the mouth after a person touches an object or consumes food or water contaminated with the virus. If an infected patient does not wash their hands well after using the restroom, the virus can spread from that person's hands to other surfaces or food they touch. 

MORE: Health officials warn of hepatitis A spike in Boise region

Symptoms of hepatitis A include tiredness, nausea, vomiting, abdominal pain, loss of appetite, low-grade fever, pale-colored bowel movements and dark urine, joint pain and yellowing of the whites of the eyes and skin. The symptoms can range from mild to severe, and last for months. 

Bus riders who were on the route should call the health department so staff can assess their exposure risk. Anyone who was exposed could get protection from the virus if they receive a vaccine by Tuesday, April 23.