With such an exciting year in the norovirus world, Hepatitis A has been overshadowed by the more “spectacular” norovirus outbreaks. If you follow the blog regularly, you caught a few warnings about possible Hepatitis A exposures at restaurants, caused by ill food handlers, and the European berry outbreak earlier this year. Compared to the norovirus episodes, though, these instances were few and far between, with only a small number of resulting illnesses. Not as sensational as hundreds falling ill on their dream cruise vacations with explosive diarrhea and vomiting…
A recent, and ongoing, Hepatitis A outbreak in the U.S. has brought this other enteric virus back into the spotlight. On the heels of a similar outbreak that occurred in Europe earlier this spring, at least 87 people across eight U.S. states have become ill with acute Hepatitis A infections. Frozen berries served in smoothies were the cause of the outbreak in Europe earlier this year, which affected at least 71 people, and frozen berries are again the guilty party. Before we get into the details of the outbreak, though, I’d like to back up and explain a little more about Hepatitis A in general.
Hepatitis A is caused by the Hepatitis A virus (HAV), which is an enteric virus like norovirus, but belongs to a different virus family. In spite of belonging to different virus families, both norovirus and HAV are structurally similar- both are RNA viruses rather than DNA viruses, covered in a protein capsid but no envelope (some viruses have an extra layer, the viral envelope). HAV replicates in the liver. It can result in both jaundice and gastrointestinal symptoms, although some infected people are asymptomatic. Symptoms may include fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, dark urine, clay-colored feces, joint pain, and jaundice (yellowing of skin/eyes).
Unlike norovirus, HAV symptoms may take up to 6 weeks to appear from the time of exposure. This results in a lag in reporting of illnesses during an outbreak, and also means that a person may unwittingly spread the virus for a couple weeks before showing symptoms. Illness can last from several weeks to 6 months. Illness may result in hospitalization but fatalities are rare. As with many viruses, there is no specific treatment for HAV- vaccination is the best defense. For those who have not been vaccinated, a vaccine or immune globulin injection can prevent illness after exposure if received in a timely fashion.
Hepatitis A virus is transmitted via the fecal-oral route, particularly in contaminated water or food. The virus can also be transmitted by close contact with people who are infected. Thus, as with norovirus, frequent and thorough handwashing (with soap and water) is an effective preventative. Additional details are available at the CDC website, including recommendations for who should seek prevention or treatment in specific exposure scenarios.
Fresh produce is a common vehicle for HAV transmission, as evidenced by the recent berry outbreaks. The produce may be contaminated pre-harvest by contaminated water, or during post-harvest processing, storage, and preparation. This may include transmission via food handling by ill food service workers. Because produce is often eaten uncooked, there is no preparation step that inactivates the virus prior to consumption, and there is no good test available to screen foods for HAV prior to consumption. Freezing and washing are not sufficiently effective against HAV. Hepatitis A virus can also survive for a long time in the environment. As with norovirus, these features make HAV a notable food safety concern, and mean that prevention of contamination is extremely important (and, thus, awareness; proper training of employees; and implementation of correct food processing and handling techniques).
Now- the ongoing outbreak. In this instance, the source of the outbreak is a frozen berry mix sold in Western U.S. Costcos and also distributed through East Coast Harris Teeters. The Townsend Farms Organic Antioxidant Blend frozen fruit mix- containing cherries, blueberries, raspberries, strawberries, and pomegranate seeds- was quickly identified as the culprit. The most recent reports indicate that the pomegranate seeds were contaminated. No illnesses have been linked to blend distributed by Harris Teeter (marketed under the HT brand). Specific details on the recalled berry blends can be found here.
The strain of HAV has been identified as genotype 1B, which is usually found in North Africa and the Middle East, not in the West. However, berries from the blend originated in a number of countries, including Turkey- the source of the pomegranate seeds. This is the same type of HAV implicated in the recent European outbreak as well as an outbreak in British Columbia that occurred in 2012. While the Canadian outbreak’s cause was not definitively identified, it was linked to berries as well. Clearly, there are implications for global scale food safety concerns.
The CDC first reported the current outbreak on May 31st. That initial report listed 30 illnesses affecting five states; over the past 11 days, the numbers have risen to 87 cases across eight states. Consumers are advised to dispose of the product if they have it and to seek the vaccine or immune globulin shots if they have eaten the berries. Vaccines are preferred for those 40 years old and under; immune globulin is safer for those over 40. If already ill with symptoms consistent with HAV, officials recommend you seek medical attention. Approximately 2/3 of those ill in the outbreak are women. Thirty-six people have been hospitalized, and the illness has affected people from age 2 to 84.
The number of reported illnesses is expected to change in the coming weeks (remember the lag time between exposure and onset of symptoms). Again, the CDC website has useful information and recommendations specific to both the current outbreak and to HAV in general. The following links are organized by date so you can follow the development of the investigation as it began to unfold on the 31st of May.