Flashcards in Microbiology - Enteric viruses I & II - Rebecca Greenblatt Deck (42):
Reoviruses have a segmented genome, which has what mode of gaining genetic diversity?
Transmission: Rotavirus (reovirus)
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
ds RNA virus
ss RNA virus
Transmission: Norwalk virus (norovirus)
IU: Norwalk virus
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
Coxsackie A causes:
herpangina, hand-foot-and-mouth disease, acute hemorrhagic conjunctivitis
Coxsackie B causes:
Site of replication: Enteroviruses and Picornaviruses
All replicate in gut
T/F: Poliovirus is human-restricted.
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
Viruses that produce polyproteins are vulnerable to what class of drugs?
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.
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.
Most common cause of herpangina:
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
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:
Coxsackie B - one of the more severe presentations
T/F: In viral myocarditis, CK-MB and Troponin I may be elevated.
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
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
What physical exam finding points in the direction of pleurodynia/Coxsackie B infection?
Pleural/friction rub on lung exam
When is pleurodynia life-threatening?
In the developed world, >85% of aseptic/viral meningitis is caused by:
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;
Enteroviruses and HSV can cause _______ in infants