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1、Gastrointestinal Viruses,急性胃肠炎病毒e,Gastrointestinal Viruses急性胃肠炎病,Viral Gastroenteritis,It is thought that viruses are responsible for up to 3/4 of all infective diarrhoeas. Viral gastroenteritis is the second most common viral illness after upper respiratory tract infection.In developing countries,
2、viral gastroenteritis is a major killer of infants who are undernourished. Rotaviruses are responsible for half a million deaths a year.Many different types of viruses are found in the gut but only some are associated with gastroenteritis.,急性胃肠炎病毒e,Viral GastroenteritisIt is th,Associated with gastr
3、oenteritis,RotavirusesAdenoviruses 40 41Caliciviruses嵌杯病毒Norwalk like viruses or SRSV (Small Round Structured Viruses)AstrovirusesSRV (Small Round Viruses)CoronavirusesToroviruses,急性胃肠炎病毒e,Associated with gastroenteriti,Found in the gut, not normally associated with gastroenteritis,PolioCoxsackie AC
4、oxsackie BEchoEnteroviruses 68-71Hepatitis AHepatitis EAdenoviruses 1-39Reoviruses,急性胃肠炎病毒e,Found in the gut, not normally,Found in the gut as opportunistic infection,CMVHSVVZVHIV,急性胃肠炎病毒e,Found in the gut as opportunis,Gastrointestinal Viruses,急性胃肠炎病毒e,Gastrointestinal VirusesVirusG,Gastrointestina
5、l Viruses,Infants: Rotavirus A; Adenovirus 40,41; Coxsackie A24 virusInfants, children, and adults Norwalk virus; Calicivirus嵌杯病毒; astrovirus; Rotavirus B; Reovirus.,急性胃肠炎病毒e,Gastrointestinal VirusesInfant,Human Rotavirus,急性胃肠炎病毒e,Human Rotavirus急性胃肠炎病毒e,Important Characteristics,70 nm round, double
6、 shelled, enclosing a genome of 11 segments of double stranded RNA.,急性胃肠炎病毒e,Important Characteristics70 nm,急性胃肠炎病毒e,急性胃肠炎病毒e,Groups of Rotaviruses,Group A subtypes 1, 2, 3, 4 (main human pathogens)(Further 7 subtypes) also infect animals (monkey, calf, mouse) Group B Infects pigs and ratsFound to c
7、ause extensive outbreaks in China in past decade Group C Infects Pigs (Occasionally Man) Group D Infects birds Group E Infects pigs,急性胃肠炎病毒e,Groups of Rotaviruses Group A,急性胃肠炎病毒e,急性胃肠炎病毒e,Pathogenesis,Essentially an ingestion disease (faecal-oral route) Incubation is short : 1 to 3 daysIllness: Sud
8、den onset watery diarrhoea, with or without vomiting. May last up to 6 days (or longer if immunocompromised). The disease is self limiting.Complications: Dehydration may result, this can be severe and life threatening in young children.,急性胃肠炎病毒e,PathogenesisEssentially an ing,Pathogenesis,Group A: M
9、ain pathogen of infantile diarrheaGroup B : Cause epidemic adult diarrheaGroup C: Cause human or animal sporadic diarrhea,急性胃肠炎病毒e,PathogenesisGroup A: Main path,急性胃肠炎病毒e,急性胃肠炎病毒e,Immunity:sIgA,Lab. DiagnosisIEM, Cell culture,PAGE of RNA segments,PCRLatex agglutination ELISA,急性胃肠炎病毒e,Immunity:sIgALa
10、b. Diagnosis急性胃,Treatment,treatment of dehydration by oral and/or intravenous fluids and electrolytes,急性胃肠炎病毒e,Treatmenttreatment of dehydrat,Prevention,Non specific factors: improved hygiene, education, clean waterSpecific - Breast feeding helps to provide passive immunity in the newborn (from mate
11、rnal antibodies), Vaccination is still experimental.,急性胃肠炎病毒e,PreventionNon specific factors,Enteric Adenoviruses,Naked DNA viruses, 75 nm in diameter. Fastidious enteric adenovirus types 40 and 41 are associated with gastroenteritis.Associated with cases of endemic gastroenteritis, usually in young
12、 children and neonates. Can cause occasional outbreaks.Possibly the second most common viral cause of gastroenteritis (7-15% of all endemic cases).Similar disease to rotavirusesMost people have antibodies against enteric adenoviruses by the age of three.Diagnosed by electron microscopy or by the det
13、ection of adenovirus antigens in faeces by ELISA or other assays.,急性胃肠炎病毒e,Enteric AdenovirusesNaked DNA,Astroviruses,Small RNA viruses, named because of star-shaped surface morphology, 28 nm in diameter.Associated with cases of endemic gastroenteritis, usually in young children and neonates. Can ca
14、use occasional outbreaks.Responsible for up to 10% of cases of gastroenteritis.Similar disease to rota and adenoviruses.Most people have antibodies by the age of three.Diagnosed by electron microscopy only, often very difficult because of small size.,急性胃肠炎病毒e,AstrovirusesSmall RNA viruses,Caliciviru
15、ses,Small RNA viruses, characteristic surface morphology consisting of hollows. particles 35 nm in diameter.Associated mainly with epidemic outbreaks of gastroenteritis, although occasionally responsible for endemic cases.Like Norwalk type viruses, vomiting is the prominent feature of disease.Majori
16、ty of children have antibodies against caliciviruses by the age of three.Diagnosed by electron microscopy only, often difficult to diagnose because of small size.,急性胃肠炎病毒e,CalicivirusesSmall RNA viruses,Norwalk-like Viruses,Small RNA viruses, with ragged surface, 35 nm in diameter, now classified as
17、 caliciviruses.Always associated with epidemic outbreaks of gastroenteritis, adults more commonly affected than children.Associated with consumption of shellfish and other contaminated foods. Aerosol spread possible as well as faecal-oral spread.Also named winter vomiting disease, with vomiting bein
18、g the prominent symptom, diarrhoea usually mild.Antibodies acquired later in life, in the US, only 50% of adults are seropositive by the age of 50.Diagnosis is made by electron microscopy and by PCR.,急性胃肠炎病毒e,Norwalk-like VirusesSmall RNA,急性胃肠炎病毒e,急性胃肠炎病毒e,Other Possible Diarrhoeal Viruses,Coronavir
19、usesRNA viruses with a crown-like appearanceNot convincing associated with gastroenteritis at presentSmall Round VirusesSmall virus-like particles with a smooth surface, 22-28nm in diameterMay possibly be parvoviruses, enteroviruses, or cubic bacteriophagesOccasionally seen in the faeces of endemic or epidemic cases of gastroenteritis,急性胃肠炎病毒e,Other Possible Diarrhoeal Viru,Gastrointestinal Viruses,急性胃肠炎病毒e,Gastrointestinal VirusesVirusG,
