While contracting an infectious disease is the last thing you’d expect when tucking into a healthy frozen snack, as recent headlines across the nation can attest, this is reality – imported foods can bring imported viruses with them. In this case, it was hepatitis A.
While hepatitis A is not normally a major concern in Australia, the recent outbreak across the nation tied to a brand of frozen berries has put the virus at the forefront of the national news agenda. Nanna’s mixed frozen berries, imported from China, were at some point somehow contaminated with infected faecal matter before packing and exporting. Up to 2 percent of the Australian population may have consumed the berries, but due to the long incubation period of the virus, it could be many weeks before all cases of the disease are identified and contained, despite product recalls. At current count, 14 Australians have been infected as a result of consuming the dodgy berries.
Hepatitis A is an infectious viral disease of the liver, and it is usually spread through direct contact with food or water that’s been contaminated with the faeces of an infected person. The disease is typically associated with areas with unsafe drinking water, poor sanitation and low personal hygiene standards, though outbreaks can also occur in places with generally higher hygiene standards through risky practices such as needle sharing and unsafe sex.
The hepatitis A virus (HAV) is one of the five known hepatitis viruses (A, B, C, D and E). Each virus causes a different disease, and as such previous infection with – or vaccination against – a different hepatitis virus does not provide immunity against contracting hepatitis A. Unfortunately for those who have consumed contaminated frozen berries recently, the virus is resistant to both heating and freezing.
False-colour electron micrograph of hepatitis A virus particles. Creative Commons licensed photo by Sanofi Pasteur.
Unlike hepatitis B and C, hepatitis A doesn’t cause chronic liver disease. The infection carries a low mortality rate (which does increase with age) and has no specific treatment – the virus is cleared by the immune system. HAV has an incubation period of between 28 and 50 days before symptoms start to show. While many people, especially young children (who are at high risk of contracting the disease, as outbreaks are common in childcare centres) show no symptoms at all – making it easier to pass the virus on – symptoms in older children and adults typically include fever, nausea, jaundice, abdominal pain and dark urine. Symptoms can last for several weeks (although some people are sick for several months), but full recovery usually follows. Relapses (followed by full recovery) or further complications are rare, but do occur.
The current contaminated berry debacle has raised a number of questions about food and health that seem difficult to answer, or even think about. Many of us are used to simply choosing the easiest, cheapest option when grocery shopping, paying little mind to where our food is coming from and what kind of journey it’s been through to make it onto our plate and into our bodies. While there have been calls for increased safety standards for future shipments of Chinese produce, others, such as independent senator Nick Xenophon, have criticised Australia’s own screening of imported foods: Australia does not routinely test imported fruit for viruses, including HAV, as the current methods of analysis used do not allow for the detection of viruses at the low levels at which they are commonly present. Further to this is the question of whether we should be importing food to begin with at all – with issues of food miles, Australian jobs and the local economy in play. But consumer demand for access to seasonal products year round at the lowest possible price seems set to ensure food will continue to be imported from foreign markets, where production costs are much lower – and health and safety standards may be difficult to qualify.
So with these practices set to continue, it seems clear that we need to be looking at ways to prevent future outbreaks that may arise as a result of imported foods – whether from an innocuous-seeming berry smoothie or some other unforeseeable, future food-based pathogen. Outside of reviewing safety standards and screening processes, vaccination seems a good place to start.
Is vaccinating the Australian population against hepatitis A worth it? Creative Commons licensed Flickr photo by Sanofi Pasteur.
The hepatitis A vaccine is highly effective and provides long-term protection (over 10 years), starting within 2–3 weeks of the first of two doses. Unlike the hepatitis B vaccine, which has been provided free to all Australian babies since 2000, the HAV vaccine is not included under the National Immunisation Program Schedule. It is usually given to travellers to endemic areas (including China), workers in childcare or rural and remote communities, sewage workers, injecting drug users, health care workers, men who have sex with men, patients with existing chronic liver disease, Aboriginal and Torres Strait Islander children, and patients with haemophilia: all people with an increased chance of contracting the disease. There is also a combined hepatitis A and B vaccine, recommended for people at risk of exposure to both viruses who have not previously been vaccinated against hepatitis B.
Unfortunately, there are currently no vaccines for hepatitis C or E; whilst hepatitis D is a defective virus which relies on the presence of hepatitis B to replicate – therefore, immunisation against hepatitis B also provides immunity against hepatitis D, which can be the most severe form of the disease..
So, this latest outbreak begs the question: should we all be getting hip to the hep by vaccinating everyone against hepatitis A? While it once seemed unnecessary to vaccinate those living in areas with high sanitation standards and low rates of the virus, increasing imports of foreign processed food and the inability to test that food for viruses means it’s difficult to predict when the next outbreak could occur. As the food industry (among other markets) becomes more globalised, perhaps the way we think about how pathogens spread – and how we think about immunisation scheduling, as a result – needs to change.
As long as there’re no faeces on them and you don’t care about calories, eat as many fresh berries as you like. Creative Commons licensed Flickr photo from cookbookman.
Hepatitis A can be a mild disease for many people, most of whom make a full recovery with no relapses and no treatment. This, along with the cost involved of vaccinating all children, are presumably the reasons for not including the hepatitis A vaccine on the National Immunisation Program Schedule. However, complications can occur and lead to liver failure and death, especially in older patients and those with underlying chronic liver disease. When we are regularly importing food and other products from areas where HAV is endemic, it certainly makes sense that we should also be vaccinating those who are most at risk – not just travellers, who are currently the main recipients of the vaccine, but those over 50, those with liver disease, and so on.
We can never predict what the next big outbreak around the corner is going to be – but when we have the tools to protect ourselves at our disposal, we should absolutely be using them. While there’s no way to prevent infection from ever occurring, we can do our best to contain the spread of disease and to protect the most vulnerable in our communities – whilst, of course, always keeping an eye out for what the next threat might berry well be.
[Header image: Creative Commons licensed Flickr photo from dandelion14.]
