Foodborne hepatitis E infection

The ever important hand wash (Photo: Marmotto)

The ever important hand wash (Photo: Marmotto)

So you’ve heard of the hepatitis A virus? Then you probably know that hepatitis is the name of an inflammation of the liver. Hepatitis A is a foodborne disease usually spread by the fecal-oral route, disgusting as it sounds. Hand washing anyone? It is transmitted person-to-person by ingestion of contaminated food or water or through direct contact with an infectious person. Tens of millions of individuals worldwide are estimated to become infected with the hepatitis A virus each year. The infection is self-limited and doesn’t result in chronic infection or chronic liver disease. However, 10–15% of patients might experience a relapse of symptoms during the six months after acute illness. Acute liver failure from hepatitis A is rare. A vaccine is available and vaccination is often recommended when visiting countries with poor hygiene conditions.

And hepatitis B virus? This can be found in blood and body fluids, such as semen and vaginal fluids, so it can be spread during unprotected sex or by sharing needles to inject drugs.  The disease has caused epidemics in parts of Asia and Africa, and it is endemic in China. About a third of the world population has been infected at one point in their lives, including 350 million who are chronic carriers. National and regional prevalence ranges from over 10% in Asia to under 0.5% in the USA and northern Europe.  According to the World Health Organization (WHO), an estimated 600,000 people die every year related to the infection. But most people infected with hepatitis B are able to fight off the virus and fully recover from the infection within a couple of months. The infection can be unpleasant to live with, but usually causes no lasting harm. A vaccine is available, which is recommended for people in high-risk groups, such as injecting drug users.

What about hepatitis C, you might be familiar with that disease as well? The hepatitis C virus is spread primarily by blood-to-blood contact associated with intravenous drug use, poorly sterilized medical equipment and transfusions. The infection is often asymptomatic, but chronic infection can lead to scarring of the liver and ultimately to cirrhosis, which is generally apparent after many years. In some cases, those with cirrhosis will go on to develop liver failure, liver cancer or life-threatening dilation of blood vessels in the oesophagus or stomach called varices. Hepatitis C is the leading reason for liver transplantation, though the virus usually recurs after transplantation. No vaccine against hepatitis C is available.

You can almost forget about hepatitis D virus. It is only present in people already infected with hepatitis B, since it needs the presence of the hepatitis B virus to be able to survive in the body. So the worry is more the hepatitis B virus.

Now this blog was supposed to deal with the hepatitis E virus, a less commonly known variety of the hepatitis family of five virus strains. Hepatitis E infection is very similar to the hepatitis A disease and it is also a foodborne disease. Symptoms of hepatitis E are usually flu-like causing fever, abdominal pain, nausea, muscle and joints aches and loss of appetite. Jaundice is very common in hepatitis E infection, but it is possible to have the disease and not show any symptoms. It is a self-limited disease in most cases, that is it usually requires no medical treatment and will eventually be healed by the bodies immune system. However, during the duration of the infection (usually several weeks), the disease severely impairs a person’s ability to work, care for family members, and obtain food. Hepatitis E occasionally develops into an acute, severe liver disease, and is fatal in about 2% of all cases. Pregnant women, especially those in the third trimester, suffer an elevated mortality rate from the disease of around 20%.

Hepatitis E is prevalent in most developing countries, and common in any country with a hot climate. It is widespread in Southeast Asia, northern and central Africa, India, and Central America. It is spread mainly through fecal contamination of water supplies or food, while person-to-person transmission is uncommon. The hepatitis E virus causes around 20 million infections a year. These result in around three million acute illnesses and around 57,000 deaths annually. The virus is a major cause of illness and of death in the developing world and disproportionate cause of deaths among pregnant women.

Sausages might carry the hepatitis E virus (Photo: mharvey75)

Sausages might carry the hepatitis E virus (Photo: mharvey75)

And the reason for highlighting this disease in a food safety blog? Well, hepatitis E is increasingly being seen in developed nations, with reports of cases in the UK, USA and Japan. Once considered very rare, cases have risen by nearly 40 per cent in a year in the UK. The disease is actually thought to be a zoonosis in that both deer and swine have been implicated as the source of human infections. An investigation by the Animal Health and Veterinary Laboratories Agency in the UK found hepatitis E in 49% of pigs in Scotland. But an even higher prevalence has been reported in other British studies. A limited Hungarian study found the virus in 39% of investigated farms, while the virus was detected in a majority of Chinese pig farms and in more than half of slaughter pigs.

So it shouldn’t be a surprise that the hepatitis E virus has now been found in pork sausages in the UK. The zoonoses report published in September 2013 by the Department for Environment, Food, and Rural Affairs says 10 per cent of sausages sampled were found to contain the virus. Sausages are regarded as particularly dangerous as they often contain liver meat and traces of pig’s blood as well as a casing from the animal’s intestine. To kill the virus, sausages have to be cooked at 70°C for at least 20 minutes.  Most people would not cook sausages for that long. At temperatures of 60°C the virus can survive for at least an hour. Scientists have also warned about the acute risk of hepatitis E from the French delicacy figatellu – a smoked pigs liver sausage produced in Corsica – which is often eaten raw.

So a new food safety scare to add to an already long list. If you’re an avid sausage consumer you might think about vaccination against the hepatitis E virus, but you have to think again. Since hepatitis E is still rare in the developed world there has been no economic incentive to commercialise an earlier developed successful vaccine. The only country to have a preventative vaccine approved for use is China.

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3 thoughts on “Foodborne hepatitis E infection

  1. This is an excellent overview of a problem with potentially enormous public health implications. In regard to HBV, I would also add that the Joint FAO/WHO Expert Committee on Food Additives in its quantitative risk assessment of aflatoxin B concluded that carriers of HBV were 39 times more susceptible to develop primary hepatocellular carcinoma than non-carriers. High prevalence of HBV carriage is common in countries that also have high levels of aflatoxin contamination.

    However, to keep things in perspective, I would also mention a neglected and largely preventable public health problem that disproportionally impacts health care workers. Unsafe injections, mainly accidental needlestick injuries, have been estimated for the year 2008 by WHO to result in 340,000 HIV infections, 15 million HBV infections, 1 million HCV infections, and 3 million bacterial infections. The development of a low-cost, single-use, needle-retractable syringe could prevent most of these.

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