Hepatitis E Virus and Food
1. What is hepatitis?
Hepatitis is an inflammation of the liver which is often caused by an infection with the hepatitis virus. There are five main types of this virus (A, B, C, D and E). Hepatitis B, C and D are most commonly spread by exposure to infected blood or body fluids whereas hepatitis A is more commonly spread from person-to-person by the faecal oral route. Both hepatitis A and E have been associated with travel to countries with poor sanitation, in particular to exposure to contaminated water. In recent years in developed countries, hepatitis A and E have increasingly been linked to consumption of contaminated food.
Get more on hepatitis A and advice on imported frozen berries
2. What are the symptoms of hepatitis infection?
Infection may occur with limited or no symptoms, or may include symptoms such as jaundice (yellowing of the skin and eyes), dark urine, extreme fatigue, nausea, vomiting and abdominal pain. More severe symptoms can occur in pregnant women and people with very weak immune systems. Hepatitis A appears only as a limited duration infection and does not result in long term illness. Hepatitis B, C and D can cause similar short term infections, but in some people, the virus remains in the body, resulting in long term disease and ongoing liver problems. Hepatitis E virus causes similar short term infection as hepatitis A infection, usually resolving in 4 to 6 weeks. It can however, result in liver failure in patients with pre-existing liver disease and may lead to chronic hepatitis in immunosuppressed patients.
For more information on hepatitis see the Health Protection Surveillance Centre (HPSC) website
3. What do we know about hepatitis E infection in humans?
The average time between exposure to the hepatitis E virus and infection is 40 days (range 21 to 56 days). Symptoms are typical of hepatitis infections (see Q2). Approximately half of infected people do not develop symptoms at all, but they can still spread the virus to other people. There are four types of hepatitis E virus of public health significance. Genotypes 1 and 2 are found in humans only and genotypes 3 and 4 may be found in both animals and humans.
Hepatitis E has been traditionally associated with developing regions of the world, where poor hygiene conditions leave people vulnerable to infection. In the developed world, hepatitis E infections were normally associated with travel to parts of the world where the virus is endemic. Travel related infections tend to be caused by hepatitis E genotypes 1 and 2. However, over the past decade it has become apparent that a significant proportion of hepatitis E infections in developed countries are not linked to travel and are in fact due to exposure of the patient in their domestic country. These ‘home grown’ infections are more likely to be caused by hepatitis E genotypes 3 and 4. In Germany, where data is collated on hepatitis E infections, between 40 and 220 cases per year are notified with two thirds not related to travel. Generally however, data are not available on the incidence of hepatitis E in most EU countries and therefore, there is limited information on transmission pathways.
Hepatitis E virus infections have been linked to the consumption of raw or undercooked pork or game meat. Transmission through occupational exposure to animals, particularly pigs, has also been reported. Direct spread of hepatitis E from one person to another is very rare, though the virus has passed between people through blood transfusion.
4. What is the situation regarding human hepatitis E infections in Ireland?
Hepatitis E was classed as a notifiable disease in Ireland at the end of 2015. This means that there is a legal obligation on clinicians and clinical laboratories to inform the public health authorities when they find a case of the disease. The availability of this information will give a better picture of the prevalence of hepatitis E in Ireland over time. Based on preliminary data, there were 90 cases reported to the HPSC in 2016. We are not aware of any foodborne outbreaks but given the recent recognition of pig meat as a source of hepatitis E virus, it is possible that some of the 90 illnesses may be as a result of consumption of undercooked pork meat or liver.
5. What is the situation regarding hepatitis E virus contamination in food?
The main source of hepatitis E virus in food in Europe is pig meat and pig liver. A study in 2010, carried out in the Czech Republic, Italy and Spain looked at 113 samples each of pig faeces, pig liver and pig meat to see if the hepatitis E virus could be detected. Researchers detected hepatitis E virus genetic material (ribonucleic acid - RNA) in 30% of pig faeces, 5% of pig liver and 3% of pig meat samples. In a study conducted in UK slaughterhouses, researchers found hepatitis E virus RNA in 13% of 40 pig faeces and 3% of 40 pig liver samples. They did not find hepatitis E virus RNA in 40 samples of muscle meat in a processing plant, but did find it in 10% of 63 sausages purchased at retail. Other studies in USA and Europe have shown similar findings.
Most studies looking at the frequency at which foods are contaminated by hepatitis E detect the virus by looking for its RNA (the genetic material of the virus). This is a very sensitive method, but does not indicate if the virus is alive (infective), because detecting the RNA does not tell researchers anything about whether the rest of the virus structure that is needed for infectivity is intact or not. Consequently, these studies are likely to overestimate the level of infectious hepatitis E virus in pig liver and pig meat. A 2017 report by the European Food Safety Authority (EFSA) estimates that less than 10% of pigs carry infectious virus particles at the time of slaughter.
6. Can I catch hepatitis E from eating food?
Reports are emerging regarding hepatitis E infection in humans from eating raw or undercooked pig meat or pig liver products, but the evidence is limited. EFSA looked at the matter in 2011 and noted that pork pies, liver pate, wild boar, under-cooked or raw pork, home-made sausages, meat (in general), unpasteurised milk, shellfish and ethnic foods were cited as risk factors in the scientific literature. A case control study in Germany found ‘any offal’ and ‘wild boar meat’ were risk factors for hepatitis E infection in cases covered by the study. Another small case control study in France found ‘raw pig liver sausage’ was a risk factor.
The 2017 report by EFSA concluded that raw and undercooked pork meat and pork liver were the most common cause of hepatitis E virus in the EU. The report estimates that less than 10% of pigs carry infectious virus particles at the time of slaughter.
7. Can cooking kill hepatitis E virus?
There are only a few studies that have looked at how cooking can be used to kill hepatitis E virus and the findings differ. For example, one study in 2012, using a high fat food paste (~50% fat) containing pig liver infected with hepatitis E virus, suggested that 71oC for 20 minutes was needed to kill the virus completely. Other studies in various food matrices including pig liver, suggest that 71oC for 10 minutes or even 70oC for 5 minutes would be sufficient to kill the hepatitis E virus. Many factors in cooking including time, temperature, number of infectious virus particles present and the composition of the food, will affect the rate at which the hepatitis E virus will be killed, if present. Experimental studies on heat inactivation have tended to look at worse case scenarios e.g. high virus load, food conditions that favour survival of viruses. This may explain some of the different findings.
8. What can I do to protect myself from hepatitis E virus if present in pork or products containing pork?
On balance, the FSAI is of the opinion that its current recommendation to cook pork and products containing pork (e.g. sausages) thoroughly to a minimum temperature of 75oC at the centre of the thickest part is sufficient to protect consumers from pathogenic micro-organisms, including hepatitis E virus. Normal grilling or frying of sausages until they are well browned and firm inside with no traces of pink meat, usually results in centre temperatures in excess of 85oC. However, it is not recommended to rely on visual cues alone for determining thorough cooking and it is better to use a meat thermometer to check the temperature of cooked meat and meat products before consuming them. In addition, effective hand washing and hygiene precautions in the kitchen are essential to prevent foodborne illness through handling of raw meat or cross contamination of cooked food by raw food.
Last reviewed: 11/7/2017