Hepatitis E virus

Hepatitis E virus is a small RNA virus, and the first virus in this reference. It causes hepatitis E, an infection of the liver. Two of its types, genotypes 3 and 4, are zoonotic and matter to the curesmith: pigs are their main reservoir, along with wild boar and deer, and the animals carry the virus without becoming ill. The other two types, genotypes 1 and 2, infect only humans and spread through contaminated water, chiefly in developing countries. In Europe and other industrialised regions, almost all locally acquired cases are genotype 3, from pork, and diagnosed cases have risen roughly tenfold over two decades.

The virus concentrates in the liver, where it replicates, so pork liver and products made from it carry the highest risk. A large share of pig herds carry it, and surveys have found infectious virus in a small but real proportion of pork livers on sale. The classic vehicle is a raw pork-liver sausage. Figatellu, a traditional dried sausage containing about a third raw pig liver and made with no cooking step, has caused documented outbreaks when eaten raw, despite a recommendation on the label to cook it. Raw and lightly processed pork sausages are the wider concern.

**How it endangers cured meat.** This is the one hazard in this reference that curing and drying do not reliably remove. When infectious virus is present in the raw pork or liver, the ordinary cure does little to it: in controlled work, infectious virus fell by less than about 1.3 log over three weeks of raw-sausage curing, and by only about 2.3 log over eight weeks of drying, so a dried or fermented raw-pork product can remain infectious if the starting material carried the virus. Freezing does not reliably inactivate it either. Only thorough cooking is a dependable control. The virus resists 56 degrees C, the temperature reached by light frying, and is reliably inactivated at a core of about 71 degrees C held for several minutes. A spreadable liver sausage cooked to a 70 degrees C core is made safe by that heating step; a raw dried product has no such step.

For most healthy people hepatitis E is a self-limiting illness that clears in a few weeks. Its seriousness falls on particular groups. In people with weakened immunity, such as transplant recipients, genotype 3 can become a chronic infection that damages the liver. In pregnancy the disease can be severe, with a high risk of death, though this is seen mainly with the waterborne genotypes rather than the pork-associated one. It can also cause neurological complications.

Because the cure does not remove it, control sits with the raw material and with cooking. It rests on sourcing pork and pork liver from herds and suppliers with good control of the virus, on treating raw pork-liver products as needing thorough cooking rather than raw consumption, and on clear labelling where a product is meant to be cooked. This places it with Meat Quality, the safety of the raw material, rather than with the curing forces, because no curing step can be relied on to make an infected raw product safe.