GI Infections 6 Flashcards
VP4 is the _____ antigen and its function is _________
“P” (Protease sensitive) antigen for the attachment to cellular receptors
has a projection out of the rotavirus capsid
what is the diagnostic and infective stage of cryptosporidium?
oocyst
describe the differences in the timing of the virus being shed in feces between norovirus and rotavirus
norovirus: 1 month after ingestion
rotavirus: peaks after 8 days
serotypes of rotavirus are based on group _____ and are classified based on ________. what are the most common serotypes?
Group A;
VP7 protein;
G1-G4 are the predominant strains in the US (G1 being most common)
what viruses commonly cause non inflammatory diarrhea in kids less than 5 years old
adenovirus, rotavirus and astrovirus
for diagnosis of cryptosporidium cause of diarrhea, you would see _______ on microscopic stool examination using a ________ stain
thick walled oocysts using a Ziehl Neelsen stain for the oocysts
cryptosporidium is a common cause of acute/chronic diarrhea in AIDS patients
chronic
what is a common risk factor for infection by cryptosporidium?
contaminated drinking or recreational water (swimming pools), due to municipal supply contamination through sewage/agricultural waste
the oocysts are able to resist chlorination
kids from 6-32 weeks are given what type of vaccine for rotavirus
live attenuated (usually won’t give live attenuated vaccine to kids less than 1 year old)
_______ is considered to be the most common cause of diarrhea in humans and death in children less than 5 years old
rotavirus
which protein in rotavirus is important for the attachment to cellular receptors
VP4 protein (P antigen)
G serotypes of rotavirus are based on _____ protein
VP7 protein
what is the age group of patients typically infected with rotavirus?
older than 6 months but younger than 5 years old
group ______ rotavirus is the most common cause of infantile gastroenteritis in the US
group A rotavirus
what is a dsRNA virus that causes non inflammatory diarrhea
Rotavirus (naked)
______ is the cause of 90% of all outbreaks of viral gastroenteritis
norovirus
the pathogenesis of rotavirus is similar to that of what bacterial cause of non inflammatory diarrhea?
EPEC because both disturb the structure of microvilli (blunting of the villi)
VP7 is the _____ antigen
“G” (glycoprotein) antigen for different G serogroups of rotavirus
which virus is associated with ingestion of raw shellfish? what is its biology?
norovirus (winter vomiting disease)
naked ss + RNA
_________ is a virus part of the calciviridae family
norovirus
_____ (thin/thick) walled oocyst is responsible for intestinal auto infection
thin
describe the seasonality of norovirus infection
peaks in the winter
“winter vomiting disease”
rotavirus replicates primarily in the _________. discuss the changes that occur with infection
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
what is the stage of cryptosporidium that is shed in the feces?
thick walled oocyst
the core of the rotavirus cottons: gene segments, viral _____ dependent _____ polymerase and capping enzymes
viral RNA dependent RNA polymerase
why is a live attenuated vaccine for rotavirus given to infants that are only 2 months old?
because the incidence if very high and starts very early (6 months) so the implementation of the vaccine must be earlier than this
in food poisoning due to ingestion of preformed toxins, the patient typically will develop symptoms within ______ hours after ingestion of the contaminated food
within 6 hours
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
rotavirus (11 segments dsRNA)
describe the biology of astroviruses
family: astroviridae
- small NON ENVELOPED
- + ssRNA (like norovirus)
is vomiting associated with norovirus infection?
yes (50% of patients have vomiting) but won’t see vomiting in rotavirus infection
the ingestion of preformed toxins in B. cereus is found in ______ (food type) and causes _________
rice; emesis (emetic preformed ST neurotoxin)
describe the seasonality of rotavirus infections
- high income countries: during winter/spring
- low income countries: year long
in infection by cryptosporidium, the _____ (life cycle form) is infectious when shed
oocyst
Rotavirus is acquired via ____ or _____
fecal-oral or water borne with incubation period of 1-3 days
groups of rotaviruses is classified based on the antigenic epitopes on ________
protein VP6
P serotypes of rotavirus are used on ______ protein
VP4 protein
describe the biology of norovirus
- family: calciviridae
- small NON ENVELOPED
- ssRNA
an AE of the live attenuated vaccine for rotavirus is ______
intussusception
cruise ship outbreaks with diarrheal and vomiting disease; the most likely causal pathogen is ______
norovirus
describe the structure and biology of rotavirus:
- family: reoviridae
- wheel shaped
- NON EVELOPED
- 11 segments of dsRNA
what are some (4) viral causes of non inflammatory diarrhea?
- norovirus
- rotavirus
- adenovirus
- astrovirus
ALL ARE NAKED VIRUSES
