California Gov. Jerry Brown declared a state of emergency Friday because an outbreak of deadly hepatitis A has killed at least 18 people in the state, and forced almost 500 to be hospitalized.

According to the San Diego Union Tribune:

The declaration allows state health officials to buy additional doses of the hepatitis A vaccine to try to halt the outbreak, which is already the nation’s second largest in more than two decades. … The outbreak began in San Diego’s homeless community late last year, but has since spread outside the region. Los Angeles and Santa Cruz counties are also now experiencing outbreaks. So far, 581 people in California have been sickened with the liver virus, more than half of whom have ended up in the hospital. The virus is particularly dangerous, and can be fatal, for people who already have other liver diseases, such as hepatitis B or C. Federal health officials said last week that, even with the ongoing efforts to slow the spread of the disease, California’s outbreak could last years.

Although Hepatitis A is commonly transmitted by eating contaminated food, California’s outbreak is spreading from person to person, predominantly among the homeless community and drug users.

In spite of half a dozen measures aimed at curtailing the spread of the deadly virus — which is highly contagious and survives for long periods of time — the city and county of San Diego have been unable to stop its spread.

Basic sanitation is the most effective form of prevention. But installing portable hand-washing stations, sanitizing city streets, and distributing vaccines have barely impacted the outbreak.

The Associated Press reported Friday that U.S. Rep. Darrell Issa (R-CA) called on the federal government to provide emergency funding to halt the spread of hepatitis A. He reportedly said the outbreak has brought statewide totals to three times the number of reported cases in 2015.

The only other outbreak more serious in the past two decades occurred in 2003 in Pennsylvania, when 900 people were infected after eating contaminated green onions at a restaurant.

The emergency proclamation grants the California Department of Public Health (CDPH) the ability to purchase vaccines immediately and directly from manufacturers, and to distribute them as needed.

Tim Donnelly is a former California State Assemblyman and Author, currently on a book tour for his new book: Patriot Not Politician: Win or Go Homeless. He also ran for governor in 2014.

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