SAN DIEGO — More than 480 people in San Diego have become infected with hepatitis A over the last 10 months, in the largest outbreak of the illness in California in decades. But why is it so hard to stop?
About 20 new cases of hepatitis A per week have been reported during this outbreak, Dr. Eric McDonald, director of San Diego County's Epidemiology and Immunization Services Branch, said at a news conference here yesterday (Oct. 5), part of an infectious diseases conference called IDWeek 2017. Most of the hepatitis A cases have been among people who are homeless or use illegal drugs, or who have close contact with those populations. Of the 481 people who have been infected, 337 (70 percent) have been hospitalized and 17 (4 percent) have died, officials said.
Dr. Monique Foster, of the Centers for Disease Control and Prevention's (CDC) Division of Viral Hepatitis, said it's not uncommon for large hepatitis A outbreaks like this to last a long time — around one to two years — before they are completely halted.
Though the hepatitis A virus isn't typically deadly, it can infect the liver and cause inflammation and damage to that 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. [27 Devastating Infectious Diseases]
Hepatitis A spreads when small amounts of stool from an ill person contaminate objects, food or drinks that another person then touches and ingests. This can happen when people with the illness don't properly wash their hands after going to the bathroom, according to the CDC. In San Diego, officials have installed 66 portable handwashing stations in the streets to address the hygiene issue, with 100 more stations on the way. The virus can also spread among drug users, also through poor hygiene when sharing equipment related to illicit drug use.
One reason specialists and doctors have a hard time stopping the spread of hepatitis A is its long "incubation period" — the time it takes a person to show symptoms after he or she is infected — which lasts on average 28 days. But it can be up to 50 days, Foster said.
"People infected today probably won't show symptoms for four weeks," Foster said. This makes it hard for people to recall what they were doing, or who they had contact with, at the time they were exposed to hepatitis, Foster said, and both of those factors help officials track and control outbreaks. It also means people who don't yet appear sick can infect others, causing more cases.
In addition, the long incubation period means that by the time officials notice a cluster of hepatitis A cases, the outbreak has likely been going on for at least a month, Foster said. And once officials do identify an outbreak, it can take six weeks to determine whether efforts to control the outbreak are working, McDonald said.
Another challenge in the San Diego outbreak is the specific population at risk for contracting hepatitis A in this outbreak: people who are homeless or who use illicit drugs. This is a population that has limited access to clean toilets and handwashing facilities, which are important to preventing the spread of hepatitis A.
Additionally, vaccination with the hepatitis A vaccine is one of the key ways to prevent the infection, the CDC says. But in the current outbreak, it took time to get these vaccinations to the groups at risk for the disease, McDonald said. To get vaccines to this "target" group, officials used unique strategies, including administering vaccines in emergency rooms, where it is easier to track down homeless people, and jails, where illicit drug users may be vaccinated before they end up back on the streets, officials said. Officials also established teams of people to go to homeless encampments and administer vaccinations.
"It takes time to set up systems in order to deliver vaccines," McDonald said. "I think those systems are [now] strongly in place here to address the ongoing outbreak."
As of Sept. 30, more than 54,000 adults in the area had been vaccinated against hepatitis A as part of the efforts to stem the current outbreak, McDonald said.
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.
Prior to the San Diego outbreak, the hepatitis A vaccine was not specifically recommended for people who are homeless, but now, the state of California is recommending that this vaccine be given to the homeless population. CDC officials will also consider whether this should become a national recommendation, Foster said.
Original article on Live Science.
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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.