What is Norovirus Infection?

Norovirus is the leading cause of acute gastroenteritis, causing 685 million cases a year. Know its symptoms, how to hydrate to recover without sequelae, and the measures to avoid its contagion.

The diarrheal diseases are the second leading cause of death of young children, and according to WHO, annually kill more than half a million children under five in the world. These deaths could be prevented if everyone had access to safe water and adequate sanitation and hygiene services.

The noroviruses are the most common cause of acute gastroenteritis, with 685 million cases a year, of which 200 million occur in children under five, of whom 50,000 dies, mostly in developing countries. However, noroviruses are also a problem in high-income countries, where they cause an estimated $ 60 billion annually in health care loss and lost productivity for those affected. Up to 90% of the population has antibodies against Norovirus, a fact that reveals how frequent exposure to this pathogen is.

Norovirus outbreaks are more common in winter. There are different types, and not all of them affect humans. Also, the infection depends on some antigens that determine the person’s blood group, so not all individuals have the same susceptibility to infection. Norovirus affects the small intestine, which justifies the acute gastroenteritis it produces.

After the spread of Norovirus by contact with a sick subject or by drinking contaminated water or food, a picture of nausea, vomiting, and diarrhea occurs, usually resolving spontaneously within a few days. The most important thing is to ensure adequate hydration of the affected person. Diarrhea itself is bothersome but not dangerous if dehydration is avoided.

Unlike rotavirus, there is not yet a vaccine available to prevent norovirus infection. That is why it is important to observe the hygiene measures that are discussed later to avoid contagion. Once the infection has passed, it seems that there is a certain degree of immunity for a few months, but after it is lost so that this disease can be suffered several times again throughout life.

Causes of norovirus infection

The Norovirus is a genus of RNA virus type, belonging to the Calicivirus. Other viruses in the same family are the Vesiviruses (which affect pigs, cats, and marine mammals), Lagovirus (rabbit hemorrhagic fever), Sapovirus( gastroenteritis in humans), and Nebovirus (gastroenteritis in cows). The first Norovirus described in 1972: the Norwalk virus, which is considered the prototype of this group.

Noroviruses are spread from person to person by the fecal-oral route mostly. If you have contact with the feces of an infected person, the infection is acquired very quickly. For example, when changing the diaper of a child with norovirus diarrhea, if the hand is put in the mouth after poor hand hygiene, transmission is likely to occur. Also, vomiting can transmit this virus.

Norovirus infections are very common in the form of outbreaks in communities such as nurseries – this is the case of a recent outbreak in a nursery in Zigong (China) that has affected dozens of children’s homes, cruise ships, or military establishments. Of course, secondary infections also occur in the family once a family member has become ill, especially if they do not carry out sufficient hygiene measures.

Risk of contagion of Norovirus from contaminated food

Another route of infection is through any food that has had contact with water contaminated by stools with the presence of Norovirus. This includes ingesting contaminated water or swimming pools where sick individuals have previously remained because it is easy to swallow a small amount of water surreptitiously. It is also possible that shellfish, fish, or industrial ice may be contaminated.

Norovirus is also relatively resistant to heat up to 140ºC, so eating steamed mussels can pose a risk of contagion. Chlorine can inactivate the virus, but it must be at a sufficient concentration, at least 5.25%.

For all the above, health authorities’ public health measures in the control of outbreaks are essential to avoid contagions.