A major outbreak of hepatitis A that has killed 17 people in San Diego may have spread to Maricopa County in Arizona, officials warn. Fortunately, it appears that authorities have managed to contain the virus, with only 15 getting sick and no deaths, but it’s an alarming new development in the case that involves homeless communities.

San Diego County declared a public health emergency after hepatitis A spread through homeless populations due to poor hand-washing habits. So far, it has killed 17, hospitalized 337, and infected a total of 481 individuals. There have also been reports of cases in Los Angeles and Santa Cruz.

The outbreak in Arizona was believed to have been caused by someone who traveled form San Diego to Maricopa County earlier this year, as the strain that the sick person had matched the strain in San Diego.

“Since early 2017, the Public Health Services Division, in the County of San Diego Health and Human Services Agency, has been investigating a local Hepatitis A outbreak,” reads a statement from San Diego County. “The majority of people who have contracted hepatitis A are homeless and/or illicit drug users, although some cases have been neither. The outbreak is being spread person-to-person and through contact with a fecally contaminated environment. No common sources of food, beverage or drugs have been identified that have contributed to this outbreak, though investigation is ongoing. The Centers for Disease Control and Prevention (CDC) notes that person-to-person transmission through close contact is the primary way people get hepatitis A in the United States.”