Hepatitis A Outbreaks Explained

The US is not immune to hepatitis A outbreaks


Although hepatitis A is a self-limited disease—meaning that it usually runs a short course and will resolve on its own—it’s still a serious public health problem. About 80 percent of adults infected with hepatitis A experience uncomfortable symptoms, including anorexia, jaundice, and pain at the level of the liver. Even though we have a vaccine that protects against hepatitis A, the virus is highly contagious and U.S. outbreaks do happen.

On September 1, 2017, San Diego County declared a public health emergency due to an ongoing hepatitis A outbreak. As of September 19, 2017, 16 people had died of hepatitis A, and 305 people were hospitalized. The San Diego hepatitis A outbreak is the largest U.S. outbreak in recent history.

Hepatitis A

The hepatitis A virus causes liver infection.

Hepatitis A is a single-stranded RNA virus that belongs to the Picornaviridae family. Hepatitis A virus is similar to enteroviruses, such as poliovirus and coxsackievirus, which attack the gastrointestinal system before spreading to other tissues.

Like enteroviruses, the hepatitis A pathogen is hardy and can withstand temperatures as low minus 20 degrees Celsius and low pHs. The gut is a low-pH environment, which makes sense because there are acids in the stomach. Importantly, heating food that is contaminated with hepatitis A virus at temperatures above 85 degrees Celsius and chlorinating water supplies can kill the virus.

The route of transmission for hepatitis A is primarily fecal-oral. In other words, the hepatitis A virus is spread by means of microscopic fecal particles that make their way into food or water or onto objects such as toys (i.e., fomites).

Hepatitis A can be spread due to the following:

  • improper handwashing by food handlers
  • improper handwashing by caregivers who are exposed to child (or adult) feces
  • food contaminated during growing, harvesting, and processing
  • contaminated water sources, including certain wells and flooding

With respect to ingestion, in addition to contaminated drinking water, undercooked shellfish, fruits, and vegetables are documented sources of hepatitis A infection.

Crowded conditions, such as those experienced in day care and nursing homes, bolster the transmission of hepatitis A.

Because hepatitis A is not a chronic disease and people aren’t infected with it for a very long time, transmission is sporadic. Under the right conditions, sporadic transmissions can trigger an outbreak.

According to the CDC, in 2014, there were 1239 reported cases of hepatitis A in the United States—a 30 percent decrease from 2013.

Children who are infected with hepatitis A are often asymptomatic, which means that they don’t have symptoms. More specifically, about 70 percent of children younger than six years are asymptomatic. Even if hepatitis A infection does manifest in children, jaundice is uncommon. Of note, asymptomatic children still spread the infection to adults.

The majority of older children and adults who are infected with hepatitis A experience the following symptoms:

  • loss of appetite
  • fever
  • nausea
  • vomiting
  • dark urine
  • joint pain
  • gray- or clay-colored stools
  • abdominal pain

After exposure to the hepatitis A virus, it takes between 15 and 45 days for infection to take hold. Initial symptoms include fever, anorexia, abdominal pain, and nausea. Jaundice occurs after several days and is usually preceded by changes in urine and fecal color. Symptoms usually last fewer than eight weeks. Between 10 and 15 percent of infected individuals experience symptoms for up to six months.

Although death due to hepatitis A infection is uncommon, the elderly and people with chronic liver disease (e.g., hepatitis B or hepatitis C) are at greatest risk for dying of hepatitis A. Liver inflammation results in elevated liver enzymes (i.e., serum aminotransferase) and bilirubin levels. The best way to diagnose hepatitis is using a blood test to detect virus-specific IgM antibodies.

People who are infected with hepatitis A can’t get infected again. They develop lifelong IgG antibodies to the virus. Some populations are at higher risk for hepatitis A infection, including the following:

  • travelers to countries where hepatitis A is common
  • men who have sex with men
  • people with clotting disorders, such as hemophilia
  • recreational drug users
  • homeless people who have limited access to running water and proper sanitation
  • people working with nonhuman primates (chimps, marmosets, and other primates can transmit hepatitis A)
  • people who work closely with children (such as babysitters)
  • people with chronic liver disease
  • international adoptees from countries where hepatitis A is endemic

Of note, travelers to areas where hepatitis A is endemic should receive hepatitis A vaccination even if their trips are short or they are staying at closed resorts.

No specific treatment for hepatitis A exists. People infected with hepatitis A are advised to receive adequate nutrition and plenty of rest.

Hepatitis Outbreaks

The 2017 hepatitis A outbreak in San Diego County is the largest recent outbreak in U.S. history. Although the outbreak first gained national attention in September 2017, it’s been simmering for months. In an attempt to combat the spread of the virus, city officials vaccinated several thousand people, including many people living in homeless encampments. San Diego has a large number of homeless people.

In addition to vaccinating people, San Diego has taken other preventive measures, including setting up portable bathrooms and handwashing stations as well as keeping many public bathrooms open 24/7. Moreover, the city has started power-washing the streets with bleach to hopefully kill the virus. This measure was inspired by Los Angeles, who has yet to experience the outbreak. Nevertheless, public health officials in Los Angeles, which lies more than 100 miles north of San Diego, are apprehensive.

Before San Diego, the last big outbreak of hepatitis A in the United States occurred in Beaver County, Pennsylvania. The outbreak was secondary to green onions used as an ingredient in a Mexican restaurant. Overall, 601 people were infected with the virus, 124 were hospitalized, and three died. (The Mexican restaurant was a Chi-Chi's chain restaurant, which was already undergoing bankruptcy proceedings at the time.)

According to a study published in the New England Journal of Medicine that examined the hepatitis outbreak in Pennsylvania, between October 3 and October 6, 2003, 91 percent of 240 restaurant patrons examined became sick after eating the mild salsa, which used green onions harvested in Mexico as an ingredient. The remaining patrons who fell ill were exposed to green onions in other menu items.

According to the authors:

"An increasing proportion of reported food-borne outbreaks have been linked to fresh produce. Recommended control measures include ensuring that field workers are healthy and have access to adequate sanitary facilities and ensuring that water used to irrigate and rinse produce is not contaminated with feces. In food-service settings, consideration should be given to the possibility that contaminated produce might cause more widespread contamination of other produce and of the preparation area. Health care providers can assist in determining the source of food-borne outbreaks of hepatitis A by immediately notifying local and state health authorities when cases are identified."

The authors also note that because children are at higher risk of carrying hepatitis A, they should be kept away from areas where produce is harvested.

Here are some other notable hepatitis A outbreaks:

  • In August 2016, in Hawaii, there was an outbreak linked to raw scallops served at sushi restaurants. The scallops were harvested in the Philippines.
  • In 2016, there was a nine-state outbreak linked to frozen strawberries. There were 56 hospitalizations and zero deaths.
  • On May 31, 2013, there was a ten-state outbreak traced to pomegranate seeds from Turkey. There were 71 hospitalizations and zero deaths.

Hepatitis A Prevention

Although there is no cure for hepatitis, there is an effective vaccine. Ever since the introduction of the hepatitis A vaccine in 1995, there’s been a 92 percent reduction in the cases of hepatitis A in the United States.

The hepatitis A vaccine is recommended for high-risk populations, people who may become gravely ill if not immunized, or anybody else who wants it.

The hepatitis vaccine is almost 100 percent effective. In order to confer long-term protection, two doses of vaccine are given, spaced at least six months apart. The vaccine is recommended for children aged 12 months and older. The vaccination is also recommended for previously unvaccinated adults who belong to high-risk populations or live in areas where hepatitis A is spread.

Currently, there are two single-antigen hepatitis A vaccines in the United States: HAVRIX (GlaxoSmithKline) and VAQTA (Merck & Co). There’s also a combined hepatitis A and hepatitis B vaccine called TWINRIX (GlaxoSmithKline), which is given to adults aged 18 years older in three or four doses. All of these hepatitis vaccines are inactivated (i.e., not live).

If an unvaccinated person is exposed to hepatitis A, shortly after exposure—within two weeks—she has two options to prevent infection. First, the person can get vaccinated. Second, immune globulin can be administered, which offers protection for about three months. Both options are equally effective; however, the effects of immune globulin aren't lifelong.

 A Word From Verywell

The outbreak of hepatitis in a large American city like San Diego proves that even in developed nations with modern sanitation, hepatitis A can pose a substantial threat to public health. Furthermore, the recent outbreak shines a light on the special risk that homeless people share with respect to hepatitis A. Many homeless people live in crowded areas and lack regular access to sanitation and running water.

If you’re concerned that you may be at risk for hepatitis A infection, contact your primary care physician and request the hepatitis A vaccine, which is available to anybody who wants it. You should also ask your primary care physician about receiving the hepatitis A if you plan on traveling to an area of high risk, including countries in Central America, South America, Asia, and Africa.

If you suspect that you’ve been exposed to hepatitis A, contact your physician immediately. Either hepatitis A vaccine or immune globulin confer protection to the hepatitis A virus if administered within two weeks of exposure. (The virus takes about two weeks to take hold.)

In addition to vaccination, there are certain steps that you can take to limit your exposure to hepatitis A in areas where hepatitis A is endemic.

  • Wash your hands regularly—especially after using the bathroom, before preparing food, and after changing diapers.
  • Hand sanitizer that is more than 60 percent alcohol can be used instead of soap and water to clean your hands.
  • Avoid touching your eyes, nose, and mouth unless your hands are clean.
  • Avoid kissing, hugging, and sharing cutlery with people who may be sick.
  • Avoid contact with people who appear sick.
  • Eat only food that is fully cooked and served hot.
  • Eat eggs that are hard-cooked.
  • Make sure that dairy products are pasteurized.
  • Wash all fruits and vegetables in clean water and peel them yourself.
  • Avoid eating food served by food vendors.
  • Avoid foods that are served at warm temperatures.
  • Avoid eating salads.
  • Avoid condiments made with fresh vegetables like salsa.
  • Drink bottled or carbonated water only with the seal intact.
  • Avoid tap water.
  • Avoid ice made of tap water.
  • Avoid flavored popsicles or flavored ice.


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