The alert increases in United Kingdom for Kawasaki norovirus. The report from the UK Health Safety Agency (UKHSA) is indeed reporting an increase in norovirus cases, the spread of which has actually doubled this year. What are the symptoms of contagion?

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The Alarm in the United Kingdom

In the UK, there have been numerous cases of norovirus in recent weeks, a total number of laboratory reports which by mid-November more than double the average of recent seasonsaccording to the UKHSA report.

Also, the number of outbreaks in the Norovirus Hospital Outbreak Reporting System (since the start of the 2024/2025 season) is 26% higher than in the last 5 seasons.

Norovirus infections are one of the leading causes of acute gastroenteritis worldwide in people of all age groups. The new genotype 17 variant of the virus, known as Kawasaki, appeared in the winter of 2014-15 – reports the NIH (England’s National Institutes of Health). Since its emergence, it has become the predominant genotype in Hong Kong, China and several major cities in mainland China and Japan before spreading to the rest of the world.

Symptoms of norovirus infection

The incubation period of the virus is 12-48 hours – reminds the ISS website – while the infection lasts from 12 to 60 hours. The symptoms are those common to gastroenteritis, namely nausea, vomiting, diarrhea, abdominal cramps, and in some cases a mild fever occurs.

The disease usually does not cause serious consequences, and most people recover in a day or two without complications. Currently, there is no specific treatment or vaccine against norovirus. In general, the only recommendation is to stay hydrated by consuming plenty of fluids to counteract dehydration.

Dehydration can be a more serious complication, especially for children, the elderly and the vulnerable, and may require specific medical care. The mechanisms of immunity to this virus are poorly understood, and according to the CDC, the acquired protection lasts only a few months: this means that a person can contract the virus several times in a lifetime.

What differentiates the variant and the transmission

The Kawasaki GII.17 Kawasaki variant is different from some strains compared to other Norovirus variants and has 2 characteristic amino acid insertions in the most exposed antigenic surface region of the main viral capsid protein, the NIH study explains. These changes have the potential to alter the antigenic properties or binding preference between the virus and the host cell, raising concerns about the global spread of this variant and its replacement by variants.

Norovirus itself is known for being highly infectious: just 10 virus particles are enough to cause an infection, the ISS website explains, given their persistence in the environment, which allows them to reproduce and spread. spread even weeks after the initial infection.

How contagion occurs

Noroviruses are difficult to control: transmission occurs directly from person to person, via faecal-oral or aerosol routes, or through infected water or food, but also through contact with contaminated surfaces. Outbreaks are often associated with eating raw seafood, salads, berries, contaminated water, cold foods, sprouts, herbs and spices. To try to keep them, it is necessary to apply strict sanitary measures.