Rotavirus

The Rotavirus belong to the family of the Reoviridae . The virus was identified in 1973 by Ruth Bishop with Melbourne.

Almost all the children are infected by a rotavirus during the first five years of their life. This Infection can remain asymptomatic or involve a Gastro-entérite (infantile GEI = gastro-enteritis), whose rotavirus are the leading cause. The infection is often asymptomatic in the adult.

Epidemiology

In the Industrialized countries, the infections with rotavirus account for 15 to 50% of the cases of gastro-enteritises; although these infections are sometimes severe, mortality associated with those remains weak. In France, nearly 300.000 annual episodes would be deducted in the children of less than five years with ten death; its annual cost is estimated at approximately 28 million euros. At the time of the peak of the winter epidemic 2005 - 2006, one estimates that 1  850  000 people consulted their general doctor in 8 weeks for gastro-enteritis; the incidence was of 367 cases for 100  000 inhabitants (the epidemic threshold being fixed at 260 cases for 100  000 inhabitants). Leading cause of infant mortality, the Gastro-entérite with rotavirus is responsible for a half-million death per annum, in the children of less than five years.

It is thus about big problems of Public health. The more so as each year, the epidemic of Gastro-entérite in Rotavirus often agrees with the epidemics of Bronchiolite and Grippe, being able to put in difficulty the pediatric health-care systems.

One recontre of gastro-enteritises with Rotavirus at the time of winter epidemics, but there exist also sporadic cases throughout the year.

Structure

They are not wrapped Virus icosahedral structure and with ARN double bit (bicaténaire). In electronic microscopy, the Virion S from 60 to 80 Nm diameter have the aspect of a wheel, from where them name. Their Capside is made of three layers of Protéine S.

Their Génome consists of eleven segments coding twelve proteins. Seven antigenic groups were identified. Protein VP6 of the transition course of the capsid determines the sérogroupes, has with G. Three of them (has, B and C) the infect human S, mainly group A. the proteins of the external layer, VP4 and VP7, induce as for them, the production of Anticorps. The internal layer is formed by VP2, and proteins VP1 and VP3 are associated with the genome.

Pathogenicity

The transmission channel is oro-fecal direct or indirect, primarily inter-human. The virus is resistant in the medium external during months with 4°C and 20°C.

The pathogenic amount is estimated at approximately 10 to 100 viral particles. A person with a Diarrhée in Rotavirus excretes a great number of viruses (10 ⁸ - 10 ¹ ⁰ particules/ml of saddles) during approximately ten days, the infectious amounts can quickly be acquired by the contaminated hands, the objects, the food, water). The asymptomatic excretion (without clinical signs) is possible and can play a part in the persistence of this disease.

Very resistant to acid pH of the Stomach and to the digestive Enzyme S (Lipase S and Protease S), they infect the epithelial cells mature of the mucous membrane of the villosities of the Small intestine (Entérocyte S). They destroy them partially, involving a shortening of villosities, leaving the place to immature entérocytes with a reduction in the enzymatic activity.

A nonstructural Protéine (NSP4) would seem to play a part in the pathogenesis of the virus and could act like true a Entérotoxine viral

The Superior council of Public health of France, section of the communicable diseases, initially recommends to differ the recommendation from systematic anti-rotavirus vaccination for the infants from less than six months.

HSC, Superior council of Hygiene Belgian recommended, in February 2007, vaccination against the rotavirus in all the infants starting from the 2 months age; no amount of vaccine will be managed beyond the 6 months age considering the increased risk of intestinal invagination observed with a preceding vaccine against the rotavirus in the children of more than 6 months.

The vaccine seems to act more on the gravity of the infection on its incidence.

bonds

  • Data sheet of the Agency of Public health of Canada
  • '' a vaccine against the rotavirus '', Roger Knell, For science, 2006,344, p 50-56
  • a vaccine against the gastroentérite produces in milk of lapines transgenic, Transgenic Research, flight 14, n° December 6th, th and th 2005
  • {{in}} Rotavirus (CDC)

References and notes

  • Bajolet O. Chippeaux-Hyppolite C. Rotavirus and other viruses off diarrhea. Bull Plowshare Pathol Exot 1998 ; 91: 432-437.
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