Maine has seen a recent increase in hepatitis A cases, with four during the past three months, the Maine Center for Disease Control and Prevention reported Monday.

While the year-to-date number of cases – six – is normal, “this increase in cases is unusual for this length of time,” the Maine CDC said in a news release.

There were eight cases of hepatitis A per year for the previous three years, 2014-16, according to the Maine CDC website.

“Outbreaks in several other U.S. states and European countries have shown that, while anyone not vaccinated against hepatitis A can get the illness, certain groups are at greater risk than others,” the CDC said. “Symptoms can range from a mild illness to a severe sickness that can last several months. Most adults with hepatitis A have symptoms, including tiredness, low appetite, stomach pain, nausea, dark urine and jaundice.”

Hepatitis A spreads “from person to person by swallowing something that is contaminated with feces, from someone who is infected with hepatitis A (for example, contaminated food and water, or through fecal-oral sexual contact). Most infections occur from contact with a household member or sex partner who has hepatitis A.”

The agency recommends that to protect against hepatitis A, people should get vaccinated and always wash hands after using the bathroom, changing a diaper, having sex, and before preparing or eating food.

Maine experienced an increase in hepatitis B cases in 2016, fueled by the opioid crisis.

This story will be updated.