41 - Viral Infections of the GI Tract II Flashcards
What virus family is the Poliovirus from?
Picornaviride family
RNA genome
How does the Poliovirus react to acidic pH?
It remains stable
There are three serotypes of the Poliovirus. What are they?
P1, P2, P3
How is the Poliovirus transmitted?
Fecal-oral route
What is the incubation period for the Poliovirus?
6-20 days
What percent of individuals infected with the Poliovirus are asymptomatic?
95%
What is problematic for the spread of the virus?
It can be shed in the stool for weeks following an infection
When did the Poliovirus peak in the US?
1952
We had 21,000 cases of paralysis from the Poliovirus
When was the last endemic case in the US?
1979
Is everywhere free of the Poliovirus?
No
Endemics are still active in
- Afghanistan
- Nigeria
- Pakistan
When a patient is symptomatic, what are the three different types of clinical manifestations of the Poliovirus?
- Abortive Poliomyelitis
- Nonparalytic aseptic meningitis
- Flaccid paralysis
What is abortive poliomyelitis?
- Sore throat
- Fever
- Vomiting and abdominal pain
- Constipation
What is nonparalytic aseptic meningitis?
Nonspecific prodromal symptoms
- Stiffness in back, neck or legs
- Lasts 2-10 days
How common is nonparalytic aseptic meningitis?
Only seen in 1-2% of cases
How common is flaccid paralysis from Poliovirus?
Seen in less than 1% of cases
How do you diagnose Poliovirus?
- Isolate virus in the stool of patient
- Sequence isolate to determine if it originated from wild type or vaccine strain
What type of Poliovirus vaccine was used in the US from 1955 to 1963?
Inactivated polio vaccine
What type of Poliovirus vaccine was used in the US from 1963 to 2000?
Trivalent, live attenuated oral polio vaccine
Given on a sugar cube
How did the trivalent live attenuated oral polio vaccine function?
- Replicates in GI tract
- Shed in stool of vaccinated individual for up to 6 weeks
- Very few cases of VAPP resulted
Vaccine Associated Paralytic Poliomyelitis
What changed in 2000?
Recommendation became to use ONLY the inactivated polio vaccine in the US
How do we create the inactivated polio vaccine?
Contains antigens to all 3 serotypes
- Grown in tissue culture
- Inactivated through formaldehyde
Is there any risk for VAPP in the inactivated form?
NO
What is viral gastroenteritis?
Inflammation of the stomach and intestines
What are the symptoms of gastroenteritis?
- Nausea
- Diarrhea
- Vomiting
How is viral gastroenteritis transmitted?
Fecal-oral transmission
Are the viruses that cause viral gastroenteritis enveloped?
No, non-enveloped
What are the four viruses that cause viral gastroenteritis?
1 - Rotavirus
2 - Norovirus
3 - Adenovirus
4 - Astrovirus
What are the signs of severe dehydration?
- Rapid, weak pulse
- Sunken eyes
- Absent tears
- Skin tenting
- Lack of urination
How do you treat mild dehydration?
Oral rehydration
How do you treat severe dehydration?
IV rehydration
How common is the rotavirus?
- 95% of children are infected by 5 years of age
- 2.7 million cases per year in US
When is rotavirus most severe?
3-24 months
When is the highest incidence of rotavirus?
3 to 35 months of age
What is the incubation period for the rotavirus?
1-3 days
What symptoms do you see with rotavirus?
- Vomiting and diarrhea for 4-7 days
- Occasional cough and coryza
- High fever
Why is the rotavirus of concern?
There is a risk of complications from acute infections in very young or malnourished
Is rotavirus a major opportunistic pathogen for HIV patients?
NO
What do we see in cases of immunocompromised children?
Severe and prolonged disease in children
Are there seasonal peaks of rotavirus?
Yes, depends on the region and season…
February/March is the peak in Iowa
Do a lot of viral particles have to be ingested in order to cause an infection?
No - the infectious dose is less than 10 particles
How many particles are found in a stool?
10 billion particles
What type of diarrhea does the rotavirus cause?
MALABSORPTIVE diarrhea
What other virulence factor does rotavirus have?
It produces a toxin (NSP4) that causes Ca++ release
What else do we see with rotavirus pathology?
Villi blunting
Shortening and thickening instead of long narrow villi
How do you diagnose the rotavirus?
EIA from stool sample
Less commonly EM, RT-PCR
How do you treat rotavirus?
- Oral rehydration therapy
- IV rehydration therapy (severe dehydration)
How do you prevent rotavirus?
Prevent fecal-oral transmission
- Sanitize toys
- Handwashing
- IgA in colostrums
- Vaccines
There are two types of the rotavirus vaccine. What are they?
There are two live, attenuated oral vaccines
- Rotateq
- Rotatrix
What does Rotateq protect against?
Protective against G1-G4, G9
What is the Rotateq vaccine a product of?
Product of reassortment between human and bovine rotaviruses
What type of vaccine is the Rotatrix vaccine?
Live attenuated strain
of Human rotavirus
G1P1A[8]
What is the current recommendation for rotavirus vaccination?
universal vaccination of
infants before 12 wks
What is the norovirus?
A major contributor to foodborne illness in the US
Is the norovirus common?
Yes, it causes 96% of outbreaks of nonbacterial gastroenteritis in the US
What is the incubation period of the norovirus?
24-48 hours
What symptoms do you see with the norovirus?
- Nausea, vomiting and diarrhea for 24-60 hours
- Low grade fever in half of patients
What age groups does the norovirus affect?
All age groups
What is the pathology of the norovirus?
Similar to the rotavirus
What virus family is the norovirus a member of?
The calicivirdae family
Is the norovirus enveloped?
No
What type of person does the norovirus show preference for?
Specific histo blood group antigens
How large of an infectious dose is needed to cause a norovirus infection?
As little as 100 virions
How is the norovirus transmitted?
Fecal-oral route
What are the ways in which the fecal-oral route of transmission is accomplished?
- Person to person (close contact, droplets from vomit)
- Fomites
- Water
- Contaminated food (food handler, contamination prior to preparation)
We commonly think of the norovirus being spread in schools, but it also spread ________
In long-term care facilities like nursing homes
What type of genome does the adenovirus have?
dsDNA genome
What are the unique features of the adenovirus
- Naked capsid
- Fiber protein at vertices
What serotypes of the adenovirus causes gastroenteritis?
40 and 41
What is the incubation period for the adenovirus?
8-10 days
What population do we typically see the adenovirus in?
Children primarily
How is the virus shed?
Through the GI tract
Is there seasonal variation in the adenovirus?
NO
What are the symptoms of the adenovirus?
- Watery, non-bloody diarrhea for 7-8 days
- May be accompanied by vomiting and fever
How do you diagnose the adenovirus?
Antibody testing
What is another virus of the Caliciviridea family that causes gastroenteritis?
Sapoviruses
What are the “star-shaped” viruses that can also cause gastroenteritis?
Astroviruses
What population is susceptible to the astrovirus?
- Infants
- Young children
- Elderly
- Healthy adults exposed to contaminated food or drink
