GI Infections 6

Question 1

VP4 is the _____ antigen and its function is _________

Answer 1

“P” (Protease sensitive) antigen for the attachment to cellular receptors

has a projection out of the rotavirus capsid

Question 2

what is the diagnostic and infective stage of cryptosporidium?

Answer 2

oocyst

Question 3

describe the differences in the timing of the virus being shed in feces between norovirus and rotavirus

Answer 3

norovirus: 1 month after ingestion
rotavirus: peaks after 8 days

Question 4

serotypes of rotavirus are based on group _____ and are classified based on ________. what are the most common serotypes?

Answer 4

Group A;
VP7 protein;
G1-G4 are the predominant strains in the US (G1 being most common)

Question 5

what viruses commonly cause non inflammatory diarrhea in kids less than 5 years old

Answer 5

adenovirus, rotavirus and astrovirus

Question 6

for diagnosis of cryptosporidium cause of diarrhea, you would see _______ on microscopic stool examination using a ________ stain

Answer 6

thick walled oocysts using a Ziehl Neelsen stain for the oocysts

Question 7

cryptosporidium is a common cause of acute/chronic diarrhea in AIDS patients

Answer 7

chronic

Question 8

what is a common risk factor for infection by cryptosporidium?

Answer 8

contaminated drinking or recreational water (swimming pools), due to municipal supply contamination through sewage/agricultural waste
the oocysts are able to resist chlorination

Question 9

kids from 6-32 weeks are given what type of vaccine for rotavirus

Answer 9

live attenuated (usually won’t give live attenuated vaccine to kids less than 1 year old)

Question 10

_______ is considered to be the most common cause of diarrhea in humans and death in children less than 5 years old

Answer 10

rotavirus

Question 11

which protein in rotavirus is important for the attachment to cellular receptors

Answer 11

VP4 protein (P antigen)

Question 12

G serotypes of rotavirus are based on _____ protein

Answer 12

VP7 protein

Question 13

what is the age group of patients typically infected with rotavirus?

Answer 13

older than 6 months but younger than 5 years old

Question 14

group ______ rotavirus is the most common cause of infantile gastroenteritis in the US

Answer 14

group A rotavirus

Question 15

what is a dsRNA virus that causes non inflammatory diarrhea

Answer 15

Rotavirus (naked)

Question 16

______ is the cause of 90% of all outbreaks of viral gastroenteritis

Answer 16

norovirus

Question 17

the pathogenesis of rotavirus is similar to that of what bacterial cause of non inflammatory diarrhea?

Answer 17

EPEC because both disturb the structure of microvilli (blunting of the villi)

Question 18

VP7 is the _____ antigen

Answer 18

“G” (glycoprotein) antigen for different G serogroups of rotavirus

Question 19

which virus is associated with ingestion of raw shellfish? what is its biology?

Answer 19

norovirus (winter vomiting disease)

naked ss + RNA

Question 20

_________ is a virus part of the calciviridae family

Answer 20

norovirus

Question 21

_____ (thin/thick) walled oocyst is responsible for intestinal auto infection

Answer 21

thin

Question 22

describe the seasonality of norovirus infection

Answer 22

peaks in the winter

“winter vomiting disease”

Question 23

rotavirus replicates primarily in the _________. discuss the changes that occur with infection

Answer 23

villous epithelium of the SI → columnar epithelium at the villous tips are replaced by irregular cuboidal crypt-like cells leading to defect in fluid and electrolyte regulation

Question 24

what is the stage of cryptosporidium that is shed in the feces?

Answer 24

thick walled oocyst

Question 25

the core of the rotavirus cottons: gene segments, viral _____ dependent _____ polymerase and capping enzymes

Answer 25

viral RNA dependent RNA polymerase

Question 26

why is a live attenuated vaccine for rotavirus given to infants that are only 2 months old?

Answer 26

because the incidence if very high and starts very early (6 months) so the implementation of the vaccine must be earlier than this

Question 27

in food poisoning due to ingestion of preformed toxins, the patient typically will develop symptoms within ______ hours after ingestion of the contaminated food

Answer 27

within 6 hours

Question 28

which pathogens that cases non inflammatory diarrhea requires 100 viral particles to cause infections but sheds 10^6 particles in the feces making transmissibility very easy

Answer 28

rotavirus (11 segments dsRNA)

Question 29

describe the biology of astroviruses

Answer 29

family: astroviridae - small NON ENVELOPED - + ssRNA (like norovirus)

Question 30

is vomiting associated with norovirus infection?

Answer 30

yes (50% of patients have vomiting) but won't see vomiting in rotavirus infection

Question 31

the ingestion of preformed toxins in B. cereus is found in ______ (food type) and causes _________

Answer 31

rice; emesis (emetic preformed ST neurotoxin)

Question 32

describe the seasonality of rotavirus infections

Answer 32

- high income countries: during winter/spring | - low income countries: year long

Question 33

in infection by cryptosporidium, the _____ (life cycle form) is infectious when shed

Answer 33

oocyst

Question 34

Rotavirus is acquired via ____ or _____

Answer 34

fecal-oral or water borne with incubation period of 1-3 days

Question 35

groups of rotaviruses is classified based on the antigenic epitopes on ________

Answer 35

protein VP6

Question 36

P serotypes of rotavirus are used on ______ protein

Answer 36

VP4 protein

Question 37

describe the biology of norovirus

Answer 37

- family: calciviridae - small NON ENVELOPED - + ssRNA

Question 38

an AE of the live attenuated vaccine for rotavirus is ______

Answer 38

intussusception

Question 39

cruise ship outbreaks with diarrheal and vomiting disease; the most likely causal pathogen is ______

Answer 39

norovirus

Question 40

describe the structure and biology of rotavirus:

Answer 40

- family: reoviridae - wheel shaped - NON EVELOPED - 11 segments of dsRNA

Question 41

what are some (4) viral causes of non inflammatory diarrhea?

Answer 41

- norovirus - rotavirus - adenovirus - astrovirus ALL ARE NAKED VIRUSES