The Philadelphia Department of Health declared a public health emergency Aug. 1 over the city's hepatitis A outbreak, reports CNN.
Health officials have reported 154 hepatitis A cases in the city this year. Philadelphia typically experiences two to nine cases a year. About 67 percent of people who contracted the illness reported using drugs, and 26 percent reported homelessness.
"We've seen, in other cities, similar outbreaks tied to homelessness and illicit drug use so [we] believe this outbreak is the same," James Garrow, a spokesperson for the health department, told CNN. "There hasn't been a specific change, just a bad situation that has been going for a while."
As part of the emergency declaration, Philadelphia will offer free hepatitis A vaccines for at-risk populations.