NOROVIRUS

Observations and diagnostic problems

Norovirus is a pathogen that has created many problems for the scientific community; it is cosmopolitan, proves to be extremely virulent and pathogenic (10 viral particles are sufficient), and it affects with great effectiveness the numerous communities that draw from the same source of food distribution (school canteens, hospitals, prisons, industrials, hotels, cruise ships, etc. ); given its very small size (which until recently made it necessary to use the electron microscope) and the "IMPOSSIBILITY" to cultivate or isolate it, for a long time it was recognized only and exclusively through the dosage of antibodies in the blood.
Fortunately, for some years the experimentation has achieved remarkable results, improving the diagnostic potential of Norovirus gastroenteritis through the discovery of specific molecular markers to be detected on fecal samples, a technique that has helped to identify at least 5 Norovirus genogroups: GI, GII, GIII , GIV and GV differentiated respectively in about twenty clusters, of which at least 3 affect the human being.
Nonetheless, Norovirus remains the MAJOR gastrointestinal virus widespread in developed countries.

Spread, contagion, development and symptoms of Norovirus gastroenteritis

Norovirus reaches its peak of diffusion in the winter period and is transmitted through contagion between people or cross-contamination on food, specifically through:

Infected waters

Fecal-oral contamination or vomiting of the infected subject on surfaces and food

Nebulization and diffusion of the drops of flug salivary of the infected, in the air, on surfaces and foods

Ultimately, the Norovirus enters the organism through the oropharynx and, once it has passed the gastric barrier, reaches the small intestine as the primary site of replication.
The foods responsible for Norovirus gastroenteritis are all cold and raw ones; those cooked and cold are associated with contamination by the infected nutritionist, while the foods that can autonomously generate Norovirus infections even without the intervention of catering operators are: oysters, berries, vegetables and drinks; it is therefore deductible that these are products watered with non-drinking water and probably contaminated by black waste water. In the case of oysters, the ambiguous origin or the inadequacy of the farming system is conceivable.
NB. Norovirus is extremely resistant, not at all sensitive to oxygen, therefore endowed with considerable longevity on the surfaces reached; like other viruses, Norovirus is sensitive to heat (but only at temperatures> 60 ° C) and can be easily annihilated by cooking food.
The onset is frequently sudden but (except immunosuppressed, always positive) the resolution is quite rapid; the incubation of the Norovirus varies from about 12 to 72 hours, while the symptoms occur for about 24/48 or 60 hours in all.
Once the number of intestinal Noroviruses necessary to trigger the disease has been reached, the following appear: nausea and vomiting, watery diarrhea and abdominal cramps; the manifestation of flu symptoms such as low-grade fever, headache and muscle pain associated with fatigue and asthenia is not excluded.

Norovirus remedies

Prevention of gastroenteritis: from a hygienic point of view, it is possible to avoid infection by Norovirus by applying all the food safety regulations (masks, clothing, self-control of health, HACCP, etc.), from the source of supply (traceability and traceability) to preparation in the laboratory (cooking or pasteurization, blast chilling, conservation and protection from the atmosphere); the processing processes and the self-control of the personnel who, at the first symptom, must leave the workstation are not excluded.

Treatment of gastroenteritis: in case of Norovirus gastroenteritis, antiviral drugs or specific vaccines are NOT yet available, but (especially for service personnel) it is advisable to follow a diagnostic procedure consisting of:

Microbiological investigations

Direct search for antigen in faeces (ELISA)

Search for viral RNA (RT-PCR or Real-time PCR).

However, there are frequent cases that require more medical attention, specifically all the elderly (who are more prone to dehydration), children and especially the immunosuppressed, hypersensitive or those considered at risk.
The only useful recommendation is to maintain hydration by drinking and not neglecting the saline intake, especially potassium (which is eliminated in large quantities with vomiting and diarrhea). Norovirus immuno-protection is developed during the illness, but lasts only for 8 weeks; it can be deduced that the same subject can be infected several times and even with a certain frequency during the year.