Gastrointestinal
Viruses
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,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,
Associated with
gastroenteritis
? Rotaviruses
? Adenoviruses 40 41
? Caliciviruses嵌杯病毒
? Norwalk like viruses or SRSV (Small
Round Structured Viruses)
? Astroviruses
? SRV (Small Round Viruses)
? Coronaviruses
? Toroviruses
Found in the gut,not normally
associated with gastroenteritis
? Polio
? Coxsackie A
? Coxsackie B
? Echo
? Enteroviruses 68-71
? Hepatitis A
? Hepatitis E
? Adenoviruses 1-39
? Reoviruses
Found in the gut as
opportunistic infection
?CMV
?HSV
?VZV
?HIV
Gastrointestinal Viruses
Virus Genome Typical disease incubation Duration
Rotaviruses,
Group A,B,
C
ds-segmented
RNA
Major cause of
diarrhea in children
1-3 days
24-56 h
5-8 days
3-7 days
Caliciviruses
Norwalk
agents
ssRNA Infects adults and
children
Epidemic viral
gastroenteritis
1-3 days
18-24 h
1-3 days
12-48 h
EAd 40,41 Linear
dsRNA
diarrhea in
children
7-8 days 8-12 d
Astrovirus +ssRNA Infects mainly
children and elderly
1-4 days 1-4 d
Gastrointestinal Viruses
? Infants,
Rotavirus A; Adenovirus 40,41;
Coxsackie A24 virus
? Infants,children,and adults
Norwalk virus; Calicivirus嵌杯病毒 ;
astrovirus; Rotavirus B; Reovirus,
Human Rotavirus
Important Characteristics
? 70 nm round,
double
shelled,
enclosing a
genome of 11
segments of
double
stranded RNA,
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 rats
Found to cause extensive outbreaks in
China in past decade
? Group C Infects Pigs (Occasionally Man)
? Group D Infects birds
? Group E Infects pigs
Pathogenesis
? Essentially an ingestion disease (faecal-oral
route)
? Incubation is short, 1 to 3 days
? Illness,Sudden 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,
Pathogenesis
?Group A,Main pathogen of
infantile diarrhea
?Group B, Cause epidemic
adult diarrhea
?Group C,Cause human or
animal sporadic diarrhea
Immunity:sIgA
Lab,Diagnosis
? IEM,
? Cell culture,
? PAGE of RNA segments,
? PCR
? Latex agglutination
? ELISA
Treatment
? treatment of dehydration by oral
and/or intravenous fluids and
electrolytes
Prevention
? Non specific factors,improved hygiene,
education,clean water
Specific - Breast feeding helps to
provide passive immunity in the
newborn (from maternal antibodies),
Vaccination is still experimental,
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 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 rotaviruses
? Most people have antibodies against enteric adenoviruses by
the age of three,
? Diagnosed by electron microscopy or by the detection of
adenovirus antigens in faeces by ELISA or other assays,
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 cause
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,
Caliciviruses
? 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,
? Majority of children have antibodies against
caliciviruses by the age of three,
? Diagnosed by electron microscopy only,often
difficult to diagnose because of small size,
Norwalk-like
Viruses
? Small RNA viruses,with ragged surface,35 nm in diameter,
now classified as 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 being
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,
Other Possible Diarrhoeal Viruses
Coronaviruses
? RNA viruses with a crown-like appearance
? Not convincing associated with gastroenteritis at
present
Small Round Viruses
? Small virus-like particles with a smooth surface,
22-28nm in diameter
? May possibly be parvoviruses,enteroviruses,or
cubic bacteriophages
? Occasionally seen in the faeces of endemic or
epidemic cases of gastroenteritis
Gastrointestinal Viruses
Virus Genome Typical disease incubation Duratio
n
Rotaviruses,
Group A,B,
C
ds-
segmented
RNA
Major cause of
diarrhea in children
1-3 days
24-56 h
5-8 days
3-7 days
Caliciviruses
Norwalk
agents
ssRNA Infects adults and
children
Epidemic viral
gastroenteritis
1-3 days
18-24 h
1-3 days
12-48 h
EAd 40,41 Linear
dsRNA
diarrhea in
children
7-8 days 8-12 d
Astrovirus +ssRNA Infects mainly
children and
elderly
1-4 days 1-4 d
Viruses
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,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,
Associated with
gastroenteritis
? Rotaviruses
? Adenoviruses 40 41
? Caliciviruses嵌杯病毒
? Norwalk like viruses or SRSV (Small
Round Structured Viruses)
? Astroviruses
? SRV (Small Round Viruses)
? Coronaviruses
? Toroviruses
Found in the gut,not normally
associated with gastroenteritis
? Polio
? Coxsackie A
? Coxsackie B
? Echo
? Enteroviruses 68-71
? Hepatitis A
? Hepatitis E
? Adenoviruses 1-39
? Reoviruses
Found in the gut as
opportunistic infection
?CMV
?HSV
?VZV
?HIV
Gastrointestinal Viruses
Virus Genome Typical disease incubation Duration
Rotaviruses,
Group A,B,
C
ds-segmented
RNA
Major cause of
diarrhea in children
1-3 days
24-56 h
5-8 days
3-7 days
Caliciviruses
Norwalk
agents
ssRNA Infects adults and
children
Epidemic viral
gastroenteritis
1-3 days
18-24 h
1-3 days
12-48 h
EAd 40,41 Linear
dsRNA
diarrhea in
children
7-8 days 8-12 d
Astrovirus +ssRNA Infects mainly
children and elderly
1-4 days 1-4 d
Gastrointestinal Viruses
? Infants,
Rotavirus A; Adenovirus 40,41;
Coxsackie A24 virus
? Infants,children,and adults
Norwalk virus; Calicivirus嵌杯病毒 ;
astrovirus; Rotavirus B; Reovirus,
Human Rotavirus
Important Characteristics
? 70 nm round,
double
shelled,
enclosing a
genome of 11
segments of
double
stranded RNA,
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 rats
Found to cause extensive outbreaks in
China in past decade
? Group C Infects Pigs (Occasionally Man)
? Group D Infects birds
? Group E Infects pigs
Pathogenesis
? Essentially an ingestion disease (faecal-oral
route)
? Incubation is short, 1 to 3 days
? Illness,Sudden 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,
Pathogenesis
?Group A,Main pathogen of
infantile diarrhea
?Group B, Cause epidemic
adult diarrhea
?Group C,Cause human or
animal sporadic diarrhea
Immunity:sIgA
Lab,Diagnosis
? IEM,
? Cell culture,
? PAGE of RNA segments,
? PCR
? Latex agglutination
? ELISA
Treatment
? treatment of dehydration by oral
and/or intravenous fluids and
electrolytes
Prevention
? Non specific factors,improved hygiene,
education,clean water
Specific - Breast feeding helps to
provide passive immunity in the
newborn (from maternal antibodies),
Vaccination is still experimental,
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 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 rotaviruses
? Most people have antibodies against enteric adenoviruses by
the age of three,
? Diagnosed by electron microscopy or by the detection of
adenovirus antigens in faeces by ELISA or other assays,
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 cause
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,
Caliciviruses
? 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,
? Majority of children have antibodies against
caliciviruses by the age of three,
? Diagnosed by electron microscopy only,often
difficult to diagnose because of small size,
Norwalk-like
Viruses
? Small RNA viruses,with ragged surface,35 nm in diameter,
now classified as 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 being
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,
Other Possible Diarrhoeal Viruses
Coronaviruses
? RNA viruses with a crown-like appearance
? Not convincing associated with gastroenteritis at
present
Small Round Viruses
? Small virus-like particles with a smooth surface,
22-28nm in diameter
? May possibly be parvoviruses,enteroviruses,or
cubic bacteriophages
? Occasionally seen in the faeces of endemic or
epidemic cases of gastroenteritis
Gastrointestinal Viruses
Virus Genome Typical disease incubation Duratio
n
Rotaviruses,
Group A,B,
C
ds-
segmented
RNA
Major cause of
diarrhea in children
1-3 days
24-56 h
5-8 days
3-7 days
Caliciviruses
Norwalk
agents
ssRNA Infects adults and
children
Epidemic viral
gastroenteritis
1-3 days
18-24 h
1-3 days
12-48 h
EAd 40,41 Linear
dsRNA
diarrhea in
children
7-8 days 8-12 d
Astrovirus +ssRNA Infects mainly
children and
elderly
1-4 days 1-4 d
