gastrointestinal tract viruses Flashcards
what are enteroviruses
stable at acid ph
enteroviruses many serotypes in 5 groups
3polioviruses
23 coxsackie viruses
6 coxsackie b viruses
what are systemic gi viruses
poliovirus
faecal oral spread
disease distant from portal of entry
long incubation period
immunity IgG IGA
what are localised gi virus infections
rotavirus
localised
faecal oral spread
entry infection disease same site
short incubation period
immunity igA
what is localised viral gastroenteritis
short illness of a few days
nausea watery diarrhoea abdo pain vomiting
secretory not inflammatory diarrhoea
non bloody
dehydration and electrolyte losses
how are gi viruses spread
feacal oral route
person to person
environmental
food/water borne
what is treatment for gi viruses
supportive-self limiting
very limited role for antivirals
what is prevention for gi viral infections
sanitation
hand washing
soap alcohol gel if enveloped
isolation measures
vaccination-rotavirus, polio
breastfeeding
who are least impacted by git viruses
adults
why are neonates vulnerable to gi viruses
immature immune system
can get overwhelming sepsis
why are infants vulnerable to gi viruses
risk of dehydration
why are under 5s vulnerable
nursery transmission
vulnerable to dehydration
why are older adults vulnerable
loss of good impact from immune system
immunosenesence
what viruses are associated with gastroenteritis
childhood infections
rotavirus (most common)
norovirus (second most common)
rotaviruses what is it
transmission by faecal oral route
24-72 hour incubation period
vomiting + diarrhoea
4-6 day duration
roatvirus can be secreted for days and weeks after
non enveloped wheel like structure
rna genome 11 segments
viruses can be grown in tissue culture
human and animal viruses cows and primates
what is the pathogenesis of rotavirus in the small intestine
following ingestion, the virus multiplies in the columnar cells of the villi of the small intestine
damage to villi leads to loss of water and electrolytes, diarrhoea and dehydration
what are rotaviruse symptos
most severe symptoms in young children
asymptomatic infections common in adults and older children
symptomatic infections again common in ppl more than 60 years
endemic but occasional outbreaks
what diagnostic technique is used for rotavirus
pcr
add primers nucleic acids to synthesise additional dna using taq polymerase
multiply and measure
the earlier on you find the virus the more you can multiply
for rna viruses how would you do a pcr
reverse transcriptase
what are other techniques to diagnose rotavirus
electron microscopy
antigen lateral flow test
nucleic acid
stool culture, microscopy for parasites, amoebas, cysts, ECG, AXR, UandE,LFTS
u+ E (electrolyte imbalance, dehydration)
what rotavirus vaccines are available
live attenuated vaccine or live animal-human virus re assortment
caution in immunocompromised
short lived protection
on the wards what is the best diagnostic method for rotavirus
immunoassay lateral flow test in faeces to detect rotavirus antigen
viruses are responsible for what proportion of infective diarrhoea cases
3/4
what is the second most common viral illness
gastrointestinal viral infections
what is norovirus (calicavirus family)
non enveloped family rna
affects all ages
transmission by faecal oral routes
short lived vomiting and diarrhoea aka- winter vomiting disease
incubation period 24-48 hours
duration illness 24-48 hours
sapoviruses-another cause of gastroenteritis and are in calicavirus, dont cause outbreaks
occasional childhood disease
really infective only takes ten viruses to be infected
ro (measurement of how infectious something is in terms of how many people it will infect) 2 for every one person who has norovirus, they will infect 2 other people
