Presentation on theme: "Foodborne viruses; Rotavirus. 2 Global Impact of Gastroenteritis www.who.int/vaccine_research/diseases/diarrhoeal/en/print.html."— Presentation transcript:
Foodborne viruses; Rotavirus
2 Global Impact of Gastroenteritis
3 FOODBORNE GASTROENTERITIS Bacterial Agents Campylobacter spp. Salmonella spp. E. coli STEC, ETEC, Other Shigella spp. S. aureus C. perfringens C. botulinum L. monocytogenes V. cholerae V. parahemolyticus V. vulnificus Vibrio spp. B. cereus Y.enterocolitica Strep spp., Grp A Brucella spp. Viral Agents Norovirus Hepatitis A Rotavirus Sapovirus Astrovirus Other ??? Protozoan Agents Giardia intestinalis Cryptosporidium parvum Cyclospora cayatenensis Toxoplasma gondii Trichinella spp
Rotavirus; Virology Family: Reoviridae dsRNA, 11 segments, non- enveloped 7 serogroups A-G; only A, B, C infect humans Many serotypes within serogroup A responsible for 90% of cases worldwide. However… Serotype prevalence varies geographically Reassortments and antigenic drift occur 5
Based on the antigenicity of VP7 and VP4, group A rotaviruses have been serologically classified into G serotypes and P serotypes, respectively. Recently, genotypes of group A rotavirus, G type and P type defined by VP7 gene and VP4 gene, respectively, have been commonly utilized to characterize rotaviruses because these types generally represent the G and P serotypes [Estes and Kapikian, 2007].
Rotavirus; an introduction Most common cause of severe diarrhea among infants and young children Nearly every child in the world has been infected with rotavirus at least once by the age of five Immunity develops with each infection, so subsequent infections are less severe; adults are rarely affected
Fact Sheet sheets/rotavirus-fact-sheet.pdf sheets/rotavirus-fact-sheet.pdf Although rotavirus was discovered in 1973 and accounts for up to 50% of hospitalisations for severe diarrhoea in infants and children, its importance is still not widely known within the public health community, particularly in developing countries. In addition to its impact on human health, rotavirus also infects animals, and is a pathogen of livestock.
Rotavirus An estimated 527,000 children died in 2004; approximately 85% of those occurred in South Asia and sub-Saharan Africa In 2009, the World Health Organization (WHO) recommended inclusion of rotavirus vaccination in all national immunization programs
Transmission Children can spread the virus both before and after they become sick with diarrhea. The virus spreads by the fecal-oral route; this means that the virus must be shed by an infected person and then enter a susceptible person’s mouth to cause infection. Rotavirus can be spread by contaminated Hands Objects (toys, surfaces) Food Water
Pathogenesis Largely unknown As many as 50% infections subclinical It infects and damages the cells that line the small intestine and causes gastroenteritis (which is often called "stomach flu" despite having no relation to influenza).
Rotavirus; Epidemiology Human reservoir Transmission: person-to-person fecal - oral; very rarely waterborne, foodborne respiratory? Characteristics that facilitate spread Virus shed in very large amounts; prolonged shedding Small infectious dose Environmental stability
Rotavirus: Clinical Features Incubation period h Duration of illness to 8d Most severe illness in infants 6m – 2yrs Fever, vomiting, diarrhea Dehydration with severe electrolyte abnormalities Exacerbating factors: malnutrition, immunodeficiency & poor sanitation Decrease in illness severity with age
Diagnosis Most children admitted to hospital with gastroenteritis are tested for rotavirus A. Specific diagnosis of infection with rotavirus A is made by finding the virus in the child's stool by enzyme immunoassay. Other methods, such as electron microscopy and PCR Reverse transcription-polymerase chain reaction (RT-PCR) can detect and identify all species and serotypes of human rotavirus
Prevention Good hygiene (hand washing) and cleanliness Vaccines are very effective. CDC recommends routine vaccination of infants with either of the two available vaccines: RotaTeq® (RV5), which is given in 3 doses at ages 2 months, 4 months, and 6 months Rotarix® (RV1), which is given in 2 doses at ages 2 months and 4 months. Very effective (85% to 98%) in preventing severe rotavirus disease in infants and young children
22 Rotavirus; Vaccines RotaTeq® Pentavalent vaccine containing G1, G2, G3, G4, P Licensed by FDA in 2006 Rotarix® Monovalent contains genotype G1P Relies on heterotypic immunity Licensed by FDA in 2008 Widely used in Brazil
A note Vaccinated and unvaccinated children may develop rotavirus disease more than once because there are many different types of rotavirus and because neither vaccine nor natural infection provides full immunity (protection) from future infections. Usually a person’s first infection with rotavirus causes the most severe symptoms.