In nature, transmission is faecal-oral between animals. Deer are undoubtedly collateral victims, contaminated by wild boar excrement, although there is no real continuation of the infection afterwards, as shown by it low presence among these animals. But how does hepatitis E pass from pigs to humans? Even if every part of a pig is good to eat, its waste is one part that doesn’t reach the table…

“The next step is to continue with the One Health collaboration and o find out how the disease is transmitted”, Étienne Thiry reckons. International studies have already revealed a few possibilities. For instance, people who are professionally exposed to pigs (breeders, vets, abattoir workers, etc.) seem to test positive more often than others. For the moment, these results haven’t been confirmed in Belgium, owing to a lack of subsidies to finance the research. 

Other scientific works, especially in Japan, have demonstrated that the infection can be caused by eating raw liver. Normally, the virus is inactivated at 70 degrees and above but sometimes, game is undercooked. In the south of Corsica and in France, it is a cured sausage that is to blame: the figatelli, a cured sausage made from raw pigs’ liver. In Belgium, food habits are different and we still have to determine which factors could play a role in contagion. “In the future, we’ll have to take a closer look at pork-based food”, the professor believes. “Logically, this is the main source to which people might be exposed. Epidemiological studies need to be carried out on a human level. As for vets, we shall focus more on virological aspects. By using new generation sequencing techniques, we’ll be able to characterise the virus much more thoroughly, so that we can specify the relationship between the virus isolated in pigs and wild boar, and the one in humans. For the time being, we believe they are almost identical, based on the knowledge we have. But we haven’t yet explored the whole genome”.

These in-depth analyses will perhaps indirectly allow us to understand the transmission from animal to human. And to develop a vaccine? “There is already a human vaccine in China”, Étienne Thiry explains. “We’re prepared to investigate this problem in animals. A vaccine would be possible, but I don’t think this will be the preferred approach because it would be very expensive. Health and hygiene inspections would be the more likely methods. We suggested this to the Walloon Region, which clearly isn’t ready yet and didn’t accept our project”. 

Because it is an asymptomatic disease, funding isn’t forthcoming… At most, there may be a few signs of inflammation in pigs’ livers. Otherwise, the disease is harmless. Only the “best” viruses manage to find such a good balance between themselves and their host, because it isn’t in their interest to kill the latter. However, this doesn’t mean that a far more virulent strain won’t emerge one day, or that the virus may become more serious after contact with other infections. Despite its inoffensive appearance, it would be worth learning more about hepatitis E…