If you experience that you never get nauseous despite people in your immediate vicinity being knocked out, you can actually be immune. About 20 percent of all people in Sweden have a gene variant, a kind of broken gene, that makes the virus unable to infect the cells in the intestine.
Researchers at the Karolinska Institute and Linköping University wanted to find out how the protective variant has spread throughout history and if it has always existed. The researchers analyzed the genetic material from about 4,300 ancient individuals from the last 10,000 years. The data comes from a large database of ancient DNA that collects information from a large number of studies.
Came from the south
The broken gene variant came to Europe with early farmers from present-day Turkey around 6,000 BC. Then it increased significantly in occurrence when we became farmers and more sedentary.
When we started living in larger groups close to each other and had toilets connected to the residence, the stomach flu virus spread much more easily. Many of those who got stomach flu and lacked protection simply died, says Hugo Zeberg, one of the researchers behind the study.
Winter vomiting disease is caused by calicivirus and spreads during the winter half-year. The disease passes in a couple of days, but a passed infection only provides temporary protection. The same person can become ill several times in a short period.
Can be devastating
The occurrence of the gene variant that protects now seems to have reached a plateau. The explanation is that it is not particularly common to die from winter vomiting disease in Sweden anymore.
But if it enters, for example, an elderly care ward, it is still a feared disease.
Like all medals, the protection against winter vomiting disease has a downside. Research has shown that those who have the gene variant have an increased risk of stomach ulcers and gallstones.
These are usually associated with stress and high fat intake, which was probably less common during the early farmers' lives, says Hugo Zeberg.
The study is published in the journal Molecular Biology and Evolution.
Petra Hedbom/TT
Facts: Winter vomiting disease
TT
Winter vomiting disease is caused by calicivirus, which is highly contagious. Norovirus is the variant of calicivirus that most often affects humans.
A sick person can excrete large amounts of virus in the stool and through vomiting. The virus can survive for a long time in the environment and infect from, for example, textiles.
The incubation period is 12-48 hours. The symptoms are nausea, vomiting, diarrhea, abdominal pain, headache, and fever.
The virus can spread in different ways: through direct or indirect contact with infected people, through food that has been handled and contaminated by a person who is or has recently been sick.
Source: Public Health Agency
