On August 15, 2016, the Hawaii Department of Health (HDOH) identified raw scallops served at Genki Sushi restaurants on Oahu and Kauai as a likely source of an ongoing hepatitis A outbreak. The product of concern was identified to be Sea Port Bay Scallops (Wild Harvest, Raw Frozen) that originated in the Philippines (states “Product of the Philippines” on the box) and were distributed by Koha Oriental Foods.
As a result, HDOH ordered this product embargoed (not to be sold, purchased, or consumed) throughout the state, and the temporary closure of all Genki Sushi restaurants on Oahu and Kauai.
As of November 30, 2016, HDOH has identified 292 cases of hepatitis A. Seventy-four have required hospitalization. Findings of the investigation suggest that the source of the outbreak is focused on Oahu. Eleven individuals are residents of the islands of Hawaii, Kauai, or Maui, and seven visitors have returned to the mainland or overseas. Onset of illness has ranged between June 12, 2016 and October 9, 2016.
The FDA and CDC are supporting the HDOH in the investigation of hepatitis A virus (HAV) infections linked to scallops supplied by Sea Port Products Corp. On August 17, 2016, the FDA, HDOH, CDC, and state partners informed Sea Port Products Corp. that epidemiological, laboratory, and traceback information indicated that their scallops are the likely source of illnesses. On August 18, 2016, Sea Port Products Corp. initiated a voluntary recall of three lots of frozen Bay Scallops produced on November 23 and 24, 2015. The lot numbers for the recalled scallops are 5885, 5886, and 5887. The products were distributed to California, Hawaii, and Nevada. According to Sea Port Products Corp., the recalled products are not intended for retail sale. The FDA is working with the recalling firm to ensure their recall is effective and that recalled product is removed from the market.
The FDA’s traceback investigation involved working with HDOH to trace the path of food eaten by those made ill back to a common source. The traceback investigation determined that Sea Port Products Corp. imported the scallops that were later supplied to certain Genki Sushi locations in Hawaii, where ill people reported eating.
On August 17, 2016, FDA laboratory analysis of two scallop samples, which were collected on August 11, 2016, were confirmed positive for hepatitis A. These samples were imported by Sea Port Products Corp. and were produced on November 23 and 24, 2015.
The Hepatitis A Virus
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 source 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 shellfish, worldwide, from 1956 to 2016. Adapted and expanded from Richards et al., 1985, Portnoy et al., 1975, and Fiore et al., 2004. Outbreaks that were poorly investigated or had fewer than 30 cases were omitted. Italics indicate the seafood was locally sourced with respect to the cases.
|Hepatitis A outbreaks associated with shellfish, worldwide, from 1956 to 2016|
|Year||# Cases||Implicated food||Location of cases||Source of implicated food||Suspected cause of contamination||Reference|
|1956||629||Oysters||Sweden||Havstenssund Harbor, Sweden||Oysters stored in polluted water||Roos, 1956; Pintó et al., 2009; Portnoy et al., 1975|
|Oysters||Mississippi, Alabama||Pascagoula River, Mississippi||Polluted harvesting areas||Mason and McLean, 1962*|
|1961||459||Clams||New Jersey||Raritan Bay, New Jersey||Polluted harvesting areas||Dougherty and Altman, 1962*|
|1964||123||Clams||Connecticut||Multiple US sources, primarily Rhode Island||Unknown||Ruddy et al., 1969|
|1973||281||Oysters||Texas, Georgia, Louisiana||Louisiana||Stormwater runoff; investigated possible illegal harvesting||Mackowiak et al., 1976; Portnoy et al., 1975|
|1980||312||Oysters||Singapore||Philippines||Suspect contaminated harvesting waters||Lee et al., 2011; Goh, 1981|
|1981||132||Cockles, whelks, mussels, prawns||Southeast England||United Kingdom||Sewage discharge near harvesting beds, insufficient processing||O’Mahoney et al., 1983|
|1982||225||Oysters||Hondo City, Japan||Ariake Bay, Japan||Unknown||Fujiyama et al., 1985|
|1984||75||Mussels and clams||Livorno, Italy||Livorno, Italy; Venice, Italy||Sewage discharge near harvesting beds, improper handling at point of sale||Mele et al., 1989|
|1988||61||Oysters||Alabama, Georgia, Florida, Tennessee, Hawaii||Florida||Untreated sewage from residents and boats, possible illegal harvesting||Descenclos et al., 1991|
|1988||292,301||Clams||Shanghai, China||Qi-Dong, China||Untreated sewage||Halliday et al., 1991|
|1992||800||Raw shellfish||Western France||Loire-Atlantique and Morbihan, France||Unknown||Apaire-Marchais et al., 1995|
|Mussels and clams||Puglia, Italy||Italy||Unknown||Chironna et al., 2002|
|Oysters||New South Wales, Australia||Wallis Lake, Australia||Untreated sewage; stormwater runoff||Conaty et al., 2000|
|1999||184||Coquina clams||Valencia, Spain||Peru||Unknown||Sanchez et al., 2002; Bosch et al., 2001|
|1999||32||Raw shellfish||Bretagne, France||Bay of Pampiol, France||Unknown, harvesting sites near a busy tourist port||Costa-Mattioli et al., 2000|
|2004||882||Mussels and clams||Campania, Italy||Primarily Campania, also other areas of Italy, Turkey||Illegal storage of shellfish in contaminated seawater at point of purchase||Pontrelli et al., 2008|
|2005||39||Oysters||Alabama, Florida, South Carolina, Tennessee||Louisiana||Untreated sewage, possibly from recreational and other boats||Bialek et al., 2007; Shieh et al., 2007|
|2007||111||Oysters||Côtes d’Armor, France||Côtes d’Armor, France||Suspect contaminated water in tanks used on a shellfish farm, nearby untreated sewage||Guillois-Bécel et al., 2009|
|2008||100||Coquina clams||Spain||Peru||Unknown||Pintó et al., 2009; Polo et al., 2010|
|2013||117||Suspect raw foods, especially seafood||Taiwan||Unknown||Unknown||Lung and Kay, 2013|
|2014||30||Raw bivalves: oysters, clams||Taiwan||Unknown||Unknown||Taiwan CDC, 2014|
|2016||292||Scallops||Hawaii||Philippines||Unknown||CDC, 2016; HI DOH, 2016|
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. 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.