New study takes the temp of winter crow sickness

Winter malaise, caused by norovirus, is today considered the single most common cause of infectious diarrheal diseases worldwide. Only a few virus particles are required to be infected and only one gram of feces can hold up to ten billion virus particles.

Carl-Johan Fraenkel, an infectious doctor and a medical hygienist, dissertates with a dissertation at Lund University that examines various aspects of the spread of winter mumps in hospitals.

- I was surprised at the percentage of hospital staff affected, he says.

In the dry air of hospital environments, norovirus causes major problems through its contagiousness. Carl-Johan Fraenkel's study shows that the risk of an outbreak increases if the patient shares rooms with other patients, is over 80 years of age, has other illnesses, falls ill in the ward or vomits.

Between 2017 and 2018, Fraenkel, together with Lund University of Technology, collected air samples from patients who were affected, and precisely vomiting he believes may be the key to understanding why the virus is spreading so successfully in specific hospital environments.

- We saw that the norovirus was common in the air during or before an outbreak in the ward, most commonly if the patient had recently vomited. We can't really show causation, but it could be that air pollution is more common than we previously thought, he says.

Carl-Johan Fraenkel does not want to go so far as to call winter sickness a straight-through airborne infection, something that an ongoing research project at Lund University is trying to clarify and publish in 2021. Clearly, many virus particles are not required for a person to fall ill , he says.

- It could be enough to breathe them in for a short while, says Carl-Johan Fraenkel.

He calls the norovirus the "perfect infection". The study in itself testifies to a slowdown in virus development in recent years, but it is unclear whether the trend is temporary or persistent. The virus is stable and difficult to kill with disinfectant, and our immune system is also unable to provide any long-term protection against new norovirus variants.

The hospital environment's focus on hand hygiene may not be enough to curb norovirus, as Carl-Johan Fraenkel's study shows thrives in the dry air where particles are generally smaller and travel lighter.

Good hand hygiene is thus not enough, he notes:

- There may be other things besides hand hygiene that we have to work with as well, such as the hospital's ventilation system.