Beginning in September 2016, several states, CDC, and the FDA investigated a multistate outbreak of foodborne hepatitis A. Epidemiologic and traceback evidence indicate that frozen strawberries imported from Egypt are the likely source of this outbreak. Although no discovery has been done to date to confirm how the Egyptian strawberries made it to consumers, we have learned that Tropical Smoothie had a bulk purchasing agreement with Patagonia. Patagonia bought from VLM Canada. It is also our understanding that VLM Canada bought from ICAPP and that VLM USA was the importer. It appears that the strawberries entered the US in Norfolk into VLM USA’s possession and then were transferred to Preferred Freezers Storage, Inc. in Chesapeake into Patagonia’s possession. From there, ITI picked up the berries and delivered them to either Sysco Hampton Roads or Sysco VA. Sysco delivered them to Tropical Smoothie franchisees.
Nearly all ill people interviewed reported drinking smoothies containing strawberries at Tropical Smoothie Café locations prior to August 8, in a limited geographical area, including Maryland, North Carolina, Virginia, and West Virginia, but there have been a small number of cases outside of that geographic area with no Tropical Smoothie Café exposure.
In total, 134 people with hepatitis A have been reported from nine states: Arkansas (1), California (1), Maryland (12), New York (3), North Carolina (1), Oregon (1), Virginia (107), West Virginia (7), and Wisconsin (1). Of these cases, 129 people reported eating a smoothie containing strawberries from Tropical Smoothie Café and 5 cases reported having no exposure to Tropical Smoothie Café. There have been no cases reporting illness from this same exposure since September 23, 2016. The latest illness onset date among these cases was October 1, 2016. The investigation into these cases is ongoing. Of the 134 cases, 52 ill people have been hospitalized and no deaths have been reported.
FDA traceback information indicated that the frozen strawberries served in the Tropical Smoothie Café locations were from the International Company for Agricultural Production & Processing (ICAPP), imported from Egypt. On August 8, 2016, Tropical Smoothie Café reported that they removed the Egyptian frozen strawberries from their restaurants in Maryland, North Carolina, Virginia, and West Virginia and switched to another supplier out of an abundance of caution. Information available at this time does not indicate an ongoing risk of hepatitis A virus infection at Tropical Smoothie Cafes.
On October 30, 2016, the International Company for Agricultural Production & Processing (ICAPP) recalled all of its frozen strawberries that were imported into the U.S. since January 1, 2016. The recalled products were distributed for sale to and use in food service establishments nationwide. The FDA reports that hepatitis A virus contamination was found in four samples of ICAPP frozen strawberries.
What is Hepatitis A?
Exposure to hepatitis A virus (“HAV”) can cause an acute infection of the liver that is typically mild and resolves on its own. The symptoms and duration of illness vary a great deal, with many persons showing no symptoms at all. Fever and jaundice are two of the symptoms most commonly associated with HAV infection.
Throughout history, hepatitis infections have plagued humans. The “earliest accounts of contagious jaundice are found in ancient China.” According to the CDC:
The first descriptions of hepatitis (epidemic jaundice) are generally attributed to Hippocrates. Outbreaks of jaundice, probably hepatitis A, were reported in the 17th and 18th centuries, particularly in association with military campaigns. Hepatitis A (formerly called infectious hepatitis) was first differentiated epidemiologically from hepatitis B, which has a long incubation period, in the 1940s. Development of serologic tests allowed definitive diagnosis of hepatitis B. In the 1970s, identification of the virus, and development of serologic tests helped differentiate hepatitis A from other types of non-B hepatitis.
Until 2004, HAV was the most frequently reported type of hepatitis in the United States. In the pre-vaccine era, the primary methods used for preventing HAV infections were hygienic measures and passive protection with immune globulin (IG). Hepatitis A vaccines were licensed in 1995 and 1999. These vaccines provide long-term protection against HAV infection.
Hepatitis A is the only common vaccine-preventable foodborne disease in the United States. This virus is one of five human hepatitis viruses that primarily infect the human liver and cause human illness. Unlike hepatitis B and C, hepatitis A does not develop into chronic hepatitis or cirrhosis, which are both potentially fatal conditions. Nonetheless, infection with the hepatitis A virus (HAV) can lead to acute liver failure and death.
Where does Hepatitis A Come From?
Hepatitis A is a communicable (or contagious) disease that often spreads from person to person. Person-to-person transmission occurs via the “fecal-oral route,” while all other exposure is generally attributable to contaminated food or water. Food-related outbreaks are usually associated with contamination of food during preparation by a HAV-infected food handler. The food handler is generally not ill because the peak time of infectivity—that is, when the most virus is present in the stool of an infected individual—occurs two weeks before illness begins.
Fresh produce contaminated during cultivation, harvesting, processing, and distribution has also been a source of hepatitis A. In 1997, frozen strawberries were the source of a hepatitis A outbreak in five states. Six years later, in 2003, fresh green onions were identified as the sourse of a HAV outbreak traced to consumption of food at a Pennsylvania restaurant. Other fruits and vegetables, such as blueberries and lettuce, have also been associated with HAV outbreaks in the U.S. as well as in other developed countries. HAV is relatively stable and can survive for several hours on fingertips and hands and up to two months on dry surfaces. The virus can be inactivated by heating to 185°F (85°C) or higher for one minute, or disinfecting surfaces with a 1:100 dilution of household bleach in tap water. HAV can still be spread from cooked food if it is contaminated after cooking.
Although ingestion of contaminated food is a common means of spread for HAV, it may also be spread by household contact among families or roommates, sexual contact, or by direct inoculation from persons sharing illicit drugs. Children are often asymptomatic, or have unrecognized infections, and can pass the virus through ordinary play, unknown to their parents, who may later become infected from contact with their children.
What are the Symptoms of Hepatitis A?
Hepatitis A may cause no symptoms at all when it is contracted, especially in children. Asymptomatic individuals will only know they were infected (and have become immune, given that you can only get hepatitis A once) by getting a blood test later in life. Approximately 10 to 12 days after exposure, HAV is present in blood and is excreted via the biliary system into the feces. Although the virus is present in the blood, its concentration is much higher in feces. HAV excretion begins to decline at the onset of clinical illness, and decreases significantly by 7 to 10 days after onset of symptoms. Most infected persons no longer excrete virus in the feces by the third week of illness. Children may excrete HAV longer than adults.
Seventy percent of HAV infections in children younger than six years of age are asymptomatic; in older children and adults, infection tends to be symptomatic with more than 70% of those infected developing jaundice. Symptoms typically begin about 28 days after contracting HAV, but can begin as early as 15 days or as late as 50 days after exposure. The symptoms include muscle aches, headache, anorexia (loss of appetite), abdominal discomfort, fever, and malaise.
After a few days of typical symptoms, jaundice (also termed “icterus”) sets in. Jaundice is a yellowing of the skin, eyes, and mucous membranes that occurs because bile flows poorly through the liver and backs up into the blood. The urine will also turn dark with bile and the stool light or clay-colored from lack of bile. When jaundice sets in, initial symptoms such as fever and headache begin to subside.
In general, symptoms usually last less than two months, although 10% to 15% of symptomatic persons have prolonged or relapsing disease for up to 6 months. It is not unusual, however, for blood tests to remain abnormal for six months or more. The jaundice so commonly associated with HAV can also linger for a prolonged period in some infected persons, sometimes as long as eight months or more. Additionally, pruritus, or severe “itchiness” of the skin, can persist for several months after the onset of symptoms. These conditions are frequently accompanied by diarrhea, anorexia, and fatigue.
Relapse is possible with hepatitis A, typically within three months of the initial onset of symptoms. Although relapse is more common in children, it does occur with some regularity in adults. The vast majority of persons who are infected with hepatitis A fully recover, and do not develop chronic hepatitis. Persons do not carry HAV long-term as with hepatitis B and C.
Fulminant Hepatitis A
Fulminant hepatitis A, or acute liver failure, is a rare but devastating complication of HAV infection. As many as 50% of individuals with acute liver failure may die or require emergency liver transplantation. Elderly patients and patients with chronic liver disease are at higher risk for fulminant hepatitis A. In parallel with a declining incidence of acute HAV infection in the general population, however, the incidence of fulminant HAV appears to be decreasing.
HAV infects the liver’s parenchymal cells (internal liver cells). Once a cell has been penetrated by the viral particles, the hepatitis A releases its own toxins that cause, in essence, a hostile takeover of the host’s cellular system. The cell then produces new viral components that are released into the bile capillaries or tubes that run between the liver’s parenchymal cells. This process results in the death of liver cells, called hepatic necrosis.
The fulminant form of hepatitis occurs when this necrotic process kills so many liver cells—upwards of three-quarters of the liver’s total cell count—that the liver can no longer perform its job. Aside from the loss of liver function, fulminant hepatic failure can lead to encephalopathy and cerebral edema. Encephalopathy is a brain disorder that causes central nervous system depression and abnormal neuromuscular function. Cerebral edema is a swelling of the brain that can result in dangerous intracranial pressure. Intracranial hypertensions leading to a brain stem death and sepsis with multiple organ failure are the leading causes of death in individuals with fulminant hepatic failure.
Incidence of Hepatitis A Infection
Hepatitis A is much more common in countries with underdeveloped sanitation systems and, thus, is a risk in most of the world. An increased transmission rate is seen in all countries other than the United States, Canada, Japan, Australia, New Zealand, and the countries of Western Europe. Nevertheless, infections continue to occur in the United States, where approximately one-third of the population has been previously infected with HAV.
Each year, approximately 30,000 to 50,000 cases of hepatitis A occur in the United States. Historically, acute hepatitis A rates have varied cyclically, with nationwide increases every 10 to 15 years. The national rate of HAV infections has declined steadily since the last peak in 1995. Although the national incidence—1.0 case per 100,000 population—of hepatitis A was the lowest ever recorded in 2007, it is estimated that asymptomatic infections and underreporting kept the documented incidence-rate lower than it actually is. In fact, it is estimated that there were 25,000 new infections in 2007.
In 2007, the CDC reported a total of 2,979 acute symptomatic cases of HAV. Of these, information about food and water exposure was known for 1,047 cases, leading to an estimate that 6.5% of all infections were caused by exposure to contaminated water or food. In 2,500 of the cases, no known risk factor was identified.
Hepatitis A outbreaks associated with fresh, frozen, and minimally processed produce, worldwide, from 1983 to 2016. Adapted and expanded from Sivapalasingam et al., 2004 and Fiore, 2004. Italics indicate instances where the food was locally sourced with respect to the cases. The implicated foods were raw unless listed otherwise.
|Hepatitis A outbreaks associated with fresh, frozen, and minimally processed produce, worldwide, from 1983 to 2016
||Location of cases
||Source of implicated food
||Suspected cause of contamination
||Infected pickers or packers
||Reid et al., 1987
||Ramsay and Upton, 1989
||Unknown, suspected to be from Mexico
||Believed to have occurred prior to distribution, since multiple restaurants involved
||Rosenblum et al., 1990
||Suspect an infected picker at farm
||Sivapalasingam et al., 2004; Niu et al., 1992
||Imported salad ingredients
||Pebody et al., 1998
||Michigan, Maine, Wisconsin, Arizona, Louisiana, Tennessee
||Grown in Mexico,
processed and frozen at a single California facility a year before consumption
|Inconclusive due to time between harvest and consumption, suspect barehanded contact with berries at harvesting, coupled with few latrines and handwashing facilities on site
||Hutin et al., 1999
||One of two Mexican farms or a farm in California
||Believed to be contaminated before arrival at restaurant
||Dentinger et al., 2001
||Green onions or tomatoes
||Green onions: California or Mexico
||Wheeler et al., 2005; Datta et al., 2001; Fiore, 2004
||New Zealand, one orchard
||Inadequate bathroom facilities in fields, workers had barehanded contact with product, polluted groundwater from nearby latrines a possibility
||Calder et al., 2003
Tennessee, Georgia, North Carolina
|Mexico, two farms
||Contaminated during or before packing at farm
||CDC, 2003; Wheeler et al., 2005
||Unknown; imported and domestic product involved
||Product suspected to be imported due to concurrent outbreaks elsewhere at the time, source of contamination unknown
||Donnan et al., 2012
||Unknown; imported product suspected
||Identical strain to the 2009 Australian outbreak
||Petrignani et al., 2010
||Likely Turkey, single batch of product
||Unable to determine when and where contamination occurred. Virus was slightly different from one in the 2009 Australian and Dutch outbreaks.
||Gallot et al., 2011
||Pomegranate seeds (frozen)
||Suspect product contamination before export. Some history of travel to endemic areas among workers at Canadian processing facility, but less likely as only one product was associated with illness.
||CDC 2013; Swinkels et al., 2014
Other frozen berries may have been involved
|Denmark, Finland, Norway, Sweden
||Suspected Egypt and Morocco based on virus strain and import history
||Unknown, some cases matched the strain of the larger 2013 European outbreak (see below)
||Nordic Outbreak Investigation Team, 2013
||Italy (90% of cases), Austria, Bulgaria, Denmark, England, Finland, France, Germany, Ireland, the Netherlands, Norway, Poland, Sweden
||Multiple food items containing frozen mixed berries (cakes, smoothies); Bulgarian blackberries and Polish redcurrants were the most common ingredients in the implicated lots
||Unknown, no single source found. Some cases also related to travel to Italy.
||Severi et al., 2015; EFSA 2014; Chiapponi et al., 2014; Rizzo et al., 2013; Guzman-Herrador et al., 2014; Fitzgerald et al., 2014
||Pomegranate arils (frozen)
||Arizona, California, Colorado, Hawaii, New Hampshire, New Jersey, New Mexico, Nevada, Utah, Wisconsin
||Collier et al., 2014; CDC 2013
||Arkansas, California, Maryland, New York, North Carolina, Oregon, Virginia, West Virginia, Wisconsin
Estimates of the annual costs (direct and indirect) of hepatitis A in the United States have ranged from $300 million to $488.8 million in 1997 dollars. In one study conducted in Spokane, Washington, the combined direct and indirect costs for each case of hepatitis A from all sources ranged from $2,892 to $3,837. In a 2007 Ohio study, each case of HAV infection attributable to contaminated food was estimated to cost at least $10,000, including medical and other non-economic costs. Nationwide, adults who become ill miss an average of 27 workdays per illness, and 11 to 22 percent of those infected are hospitalized. All of these costs are entirely preventable given the effectiveness of a vaccination in providing immunity from infection.