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Flashcards in GI viruses Deck (35):
1

List two groups of viruses that infect the GI tract

Enteroviruses- do not cause diarrhea

Viruses with the primary symptom of diarrhea

2

List the four groups that comprise the enteroviruses

Polioviruses
enteroviruses
coxackie viruses
echoviruses

3

Enteroviruses are shed in large numbers in the feces, are acid stable, and resist _____

alcohols and detergents

4

List six syndromes that are consistently present in enterovirus infection

Rash (all except polio)
aseptic meningitis
pericarditis/ myocarditis
paralysis
hepatitis
colds

5

What type of virus is most stronly associated with myocarditis

coxackie viruses

6

A high percentage of enterovirus infections are _____ especially in children

asymptomatic

7

Diagnosis of enterovirus is primarily based on:

clinical presentation- many strains, so specific testing is limited AND there are no specific therapies so identifying the specific virus is not useful

8

True or false: there are no antivirals available for enteroviruses

True

9

What is the best approach to treating enteroviruses?

1. start with prevention- hand hygiene, food handling
2. vaccines for hepatitis A and polio virus
3. mostly self limited illnesses, supportive care as necessary

10

How is polio virus transmitted?

Fecal-oral route, replicates in gut mucosa.
Enters through Peyer's patches and M cells in the gut

11

For all members of the enterovirus, CNS disease requires ______ and _______

high viral titers
persistent secondary viremias

12

What causes paralysis in polio infection?

Viral replication in and killing motor neurons of the anterior horn of the spinal column

13

Describe post-polio syndrome:

nervous system recovers in young people so mild paralytic damage is "masked"
as people age, they become less able to compensate for CNS damage and the original paralytic symptoms return
NOT due to return of polio virus

14

List families of viruses associated with diarrhea

Major: rotavirus, norovirus, astrovirus

Some serotypes of adenovirus and coronavirus

15

Describe the transmission of viruses that cause diarrhea

transmitted by the fecal-oral route, are very stable, are acid resistant, and large amounts of
virus are shed in stools

16

True or false: shedding of virus stops as soon as diarrhea symptoms subside

False, continued shedding for extended periods of time

17

In the US, rotavirus has a seasonal peak in the _____

winter

18

True or false: most people are seropositive for rotavirus by age 4

true, 90%

19

Describe the clinical syndrome of rotavirus infection

1-3 day incubation periods
abrupt onset of watery stools that become clear as colonic material is flushed out
fever is possible but would be mild
usually self limiting, high mortality in resource poor areas due to dehydration

20

What tests exist to diagnose rotavirus infection

electron microscopy
ELISA antigen capture assay that uses stool samples

** no antivirals, so usually make dx based on season, pt age, clinical presentation

21

What is the best strategy for preventing rotavirus infection?

Live attenuated vaccine
Safe food and water supplies

22

Describe the epidemiology of norovirus

No seasonality
extremely contagious- outbreaks in schools, institutional settings, cruise ships high rates of infection in household contacts
thought to be the cause of 30% of gastroenteritis in older children and adults

23

Describe the clinical syndrome of norovirus

Abrupt onset of diarrhea, nausea, vomiting, abdominal cramps
Self limiting, resolves within 24-48 hours

24

Describe the transmission of norovirus

fecal-oral route, via contaminated food or water

25

How is diagnosis of norovirus made?

Clinical presentation
Public health my follow local outbreaks

No culture, possible but not practical to do electron microscopy, RT-PCR
- no antivirals so therapeutic focus is on avoiding dehydration

26

Describe the epidemiology of astroviruses

Common cause of viral gastroenteritis
75% of children 4 years old are seropositive

27

Describe the clinical presentation of astrovirus

3-4 day incubation then diarrhea, nausea, headache, malaise for 2-4 days.
Vomiting can occur but not as common as in norovirus
Fever is not common

28

How is diagnosis of astrovirus made?

Symptoms and age of patient
No culture, possible to do electron microscopy on stool but not practical
NO vaccines or antivirals

29

What is the best way to prevent astrovirus infection?

hand washing, good hygiene, proper food handling and preparation procedures,
and clean water supplies.

30

Describe symptoms seen in adenovirus gastroenteritis

Short incubation period
Acute onset of diarrhea, nausea, occasionally vomiting, possible low grade fever

31

What strains of adenovirus cause GI illness?

40,41, 38

32

Gastroenteritis caused by coronavirus is most commonly seen in ________

children, under 1 yr of age

33

Describe the clinical presentation of coronavirus

Gastroenteritis is diarrhea that has occult blood, is less water and more mucoid

coronavirus also causes colds, SARS

34

Of all the viruses that cause diarrhea there is a vaccine for only one:

rotavirus

35

Describe current thinking on why enterovirus does not cause diarrhea but other gastroenteric viruses do

Structural protein of rotavirus acts similarly to cholera toxin, there is a capsid protein on astrovirus that is a toxin that disrupts actin filaments, coronavirus causes inflammation that leads to the occult blood and mucus in the stool

thought that other enteric viruses might have toxic activity