Since late 2016, more than 27,000 cases of hepatitis A—a contagious liver infection—have been reported, according to the Centers for Disease Control and Prevention (CDC). Although it is usually spread via contaminated food or water, health officials believe the opioid epidemic may contribute to the uptick of the illness, possibly through the sharing of contaminated needles.

But it’s not only injection drug users who are at risk of acquiring the virus; anyone who uses illegal substances or hasn’t been vaccinated can get hepatitis A. People experiencing homelessness, those just released from prison, men who have sex with men and travelers to certain countries are also at higher risk. Symptoms of the illness include nausea, stomach pain, fatigue, fever and jaundice (yellow skin or eyes).

Individuals who get hepatitis A may feel sick for a few weeks to several months, and some may require hospitalization, especially if they have other health issues or are older, says the CDC.

As a precaution, the agency encourages individuals to assess their risk of infection and to get vaccinated if they’re vulnerable.

For more information, visit cdc.gov and search for hepatitis outbreaks.