California's Hepatitis A Outbreaks: Why Is the Virus Spreading?

Hand Washing
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Nearly 450 people in San Diego have become infected with hepatitis A over the last 10 months, making it the largest outbreak of the illness in California in decades.

On Tuesday (Sept. 19), officials in San Diego said the number of hepatitis cases in the city had climbed to 444, up from 421 last week. Of those infected, 305 have been hospitalized, and 16 have died. (For comparison, the city had just 22 cases of hepatitis A in 2015.)

Also this week, Los Angeles declared its own hepatitis outbreak, with 10 cases reported so far. And Santa Cruz County, in northern California, has reported 69 cases of the virus since April. The outbreaks in all three areas are occurring primarily among people who are homeless or who use illegal drugs. But what's causing hepatitis to spread in these areas? [27 Devastating Infectious Diseases]

In general, people become infected with hepatitis A through the "fecal-oral" route — that is, when small amounts of stool from an ill person contaminate objects, food or drinks that are then touched and ingested by another person, according to the Centers for Disease Control and Prevention (CDC).

San Diego officials say the outbreak there is being spread from person to person "through contact with a fecally contaminated environment." This type of contamination can occur when people with the illness don't properly wash their hands after going to the bathroom, according to the CDC.

More than 50 percent of hepatitis cases in San Diego are in homeless people, who are known to be at increased risk for hepatitis A, in part because homelessness presents challenges to keeping good hygiene, such as limited access to toilets and hand-washing facilities, according to a 2009 paper published in the journal Public Health Reports. Clusters of hepatitis A cases have also occurred in some facilities with shared restrooms, including jails and residential drug treatment facilities, San Diego officials said. The infection can also spread through the sharing of equipment related to illicit drug use, according to the Los Angeles County Department of Public Health.

On Sept. 1, San Diego declared a local public health emergency because of the hepatitis outbreak. The city has taken several steps to combat the outbreak, including vaccinating about 19,000 people against hepatitis A to prevent future illnesses, the San Diego Union-Tribune reported. Officials have also installed 40 hand-washing stations throughout the downtown area and have disinfected some city streets with bleach.

The strain of hepatitis involved in the San Diego outbreak is the same as the one in the Santa Cruz outbreak, which suggests the outbreaks are related, according to the County of San Diego's Public Health Services Division. (The strain involved in the LA outbreak has not been reported, but five of the LA cases involved people who visited either San Diego or Santa Cruz before their infection began, officials said.)

The hepatitis A virus can infect the liver and cause inflammation and damage to the organ, according to the National Institutes of Health (NIH). Symptoms can include dark-yellow urine, fever, joint pain, nausea and vomiting. People with the infection usually get better on their own without treatment, the NIH says. But in some cases, the infection can lead to liver failure, particularly in older adults or people who have other liver diseases.

In general, the hepatitis A vaccine is recommended for children at age 1; travelers to countries that have high rates of hepatitis A; users of illegal drugs; people with chronic liver diseases, such as hepatitis C; men who have sexual contact with other men; and people who work with animals infected with hepatitis A, according to the CDC.

Because of the outbreak in San Diego, officials there are also recommending that people get the vaccine if they are homeless, have close contact with the homeless or illicit drug users, or work in jobs where they handle food. It's also recommended that any person who wants to obtain immunity against hepatitis A get the vaccine, San Diego officials said.

Original article on Live Science.

Rachael Rettner

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.