Microbiology - Enteric viruses I & II - Rebecca Greenblatt Flashcards
Reoviruses have a segmented genome, which has what mode of gaining genetic diversity?
Reassortment
Transmission: Rotavirus (reovirus)
fecal-oral
Orthoreoviruses cause:
Mild GI symptoms
Rotavirus causes severe:
dehydration, even though diarrhea is self-limited
What cells does rotavirus act on?
The cells of the small intestinal villi
What does rotavirus have that acts like an enterotoxin?
NSP4 - rotavirus nonstructural protein 4 - interferes with sodium transport pumps - profuse watery diarrhea
Phylogeny: Rotavirus
ds RNA virus
+ sense
icosahedral
naked
Phylogeny: Norovirus
ss RNA virus
- sense
icosahedral
naked
Transmission: Norwalk virus (norovirus)
fecal-oral
IU: Norwalk virus
low
IU: Rotavirus
high
Pathogenesis: Norovirus
Infection damages microvilli in small intestine → malabsorption
Vomiting is more common in what enterovirus?
Norovirus - slows gastric emptying as comparing with rotavirus
What is primary viremia?
Successful virus travels in blood to seed replication site(s). LOW LEVELS in blood.
What is secondary viremia?
New virus travels from replication site(s) to shedding site(s). HIGHER LEVELS in blood.
Phylogeny: Picornaviruses ie Poliovirus, Hep A, Coxsackievirus
Small naked icosahedral \+ sense ss RNA
Coxsackie A causes:
herpangina, hand-foot-and-mouth disease, acute hemorrhagic conjunctivitis
Coxsackie B causes:
myocarditis
pleurodynia
meningitis
Site of replication: Enteroviruses and Picornaviruses
All replicate in gut
T/F: Poliovirus is human-restricted.
True
How does poliovirus enter/infect epithelial/lymphoid cells in the gut lining?
CD155 receptor - found in gut AND cns gray matter cells
then spreads to the blood stream and regional lymph nodes
How does nerve death occur in poliovirus?
Nerve death results both from lytic virus replication and overenthusiastic
immune response
Viruses that produce polyproteins are vulnerable to what class of drugs?
Protease inhibitors
Where is the location of acute poliomyelitis infection?
Infection of the anterior horn motor neurons of the spinal cord (muscle symptoms) and brain stem (respiratory symptoms)
Flaccid asymmetric weakness and muscle atrophy due to loss of motor neurons and denervation of their associated skeletal muscles
Of acute poliovirus infections, 1-2% result in neurologic symptoms.
Transmission: Poliovirus
Fecal-oral
Risk factors: paralytic poliomyelitis
young age, advanced age, recent hard exercise, tonsillectomy, pregnancy, immunosuppression
________ can cause herpangina & has
been associated with severe complications. Fatalities, mostly in infants aged 6-11 months, have been reported.
Enterovirus 71
Most common cause of herpangina:
Coxsackie A
Enterovirus - picornavirus
Symptoms of herpangina:
Acute febrile illness
Small vesicular or ulcerative lesions on the posterior oropharyngeal structures
Typically occurs during the summer
Frequently in children, also young adults
Coxsackie A
What viruses are primarily resonsible for acute hemorrhagic conjunctivitis?
Coxsackie group A24 (CA24) and enterovirus E70 (EV70)
Why should the use of topical steroids be avoided in the treatment of acute hemorrhagic conjunctivitis?
Treatment with topical steroids should be avoided : risk of microbial superinfection of the cornea
Viral myocarditis is most commonly caused by:
Adenovirus;
Enterovirus
Coxsackie B - one of the more severe presentations
T/F: In viral myocarditis, CK-MB and Troponin I may be elevated.
True
What is pleurodynia?
Pleurodynia (ploor-uh-din-ee-uh) (“Devil’s Grip”) is an uncommon complication of infection by coxsackievirus B or a few others
Sudden occurrence of lancinating chest pain attacks
Fever
Malaise
Headache
What is the anatomic structure targeted by pleurodynia?
The striated muscle is the actual anatomic structure targeted by the coxsackievirus B and is responsible for the attacks of severe chest pain.
Transmission: Coxackie B
Fecal-oral
What physical exam finding points in the direction of pleurodynia/Coxsackie B infection?
Pleural/friction rub on lung exam
When is pleurodynia life-threatening?
Infants
In the developed world, >85% of aseptic/viral meningitis is caused by:
Enteroviruses
Very young children with aseptic meningitis can present with what unique symptoms?
Fever w/ cold hands and feet;
Fretful, dislike of being handled,
pale, blotchy skin;
blank staring/unresponsive
Enteroviruses and HSV can cause _______ in infants
septic shock
Ospithotonic positioning may be a sign of _______ or may be seen in an infant who is attempting to compensate for airway edema or stridor.
meningitis
