Enteric virus Flashcards
Reovirus virology
- transmission
- human infecting reovirus
Double protein capsid w/ segmented ds-RNA genome
- fecal oral
- rotavirus, orthoreovirus
Rotavirus pathogenesis
-target
infection is self-limited but there is a risk of dehydration
- sm. intestine villi
Rotavirus presentation
winter months, children < 5 yrs
Rotavirus virulence factor
nonstructural protein 4 (NSP4): enterotoxin interfering w/ sodium transport pumps
Dx rota on exam
- hx of exposure to other children w/ diarrhea
- NVD
- dehydration,: waterly, bloodless diarrhea w/ decreased urine output
Is there a vaccination for rota>
yes but they are not required
Norovirus virology
- which virus is the prototypical strain
- transmission
positive-sense ss-RNA virus in Caliciviridae
- norwalk virus
- fecal-oral (highly contagious so you can pick it up anywhere)
What makes norwalk virus so contagious
only 100 particles need to establish infection, viral shedding occurs for weeks even after recovery, very environmentally rigid (can survive freezing and boiling), and infect can recur
What is the main different between a rotavirus and norovirus infection
rotavirus takes a few days, norovirus strikes quickly and lasts only 1-2 days; also nausea is more common w/ norovirus because it slows gastric emptying
What are the common sources of infectious outbreaks
cruise ships, summer camps, nursing homes
Picornavirus subtypes (2)
Rhinovirus and enteroviruses
picornavirus enterovirus categories (4)
HepA, pilioviruses, coxsackievirus, other
enterovirus virology
small naked, icosahedral virions, ssRNA, positive sense
enterovirus dual tropism
usually replicate in the gut but sometimes in the CNS
enterovirus: Poliovirus
polio
enterovirus: coxsackie A
herpangina, hand-foot-mouth disease, acute hemorrhagic conjunctivitis
enterovirus: coxsackie B
myocarditis, pleurodynia
enterovirus: echoviruses
meningitis, pediatric febrile illness
Poliovirus pathogenesis
fecal-oral transmission, uses CD155 receptor to enter and infect the gut, spread to blood and lymphnodes
Hows does polio hit the CNS
CD155 found on gray matter CNS cells, crosses BBB or via axonal transport from peripheral nerve
where specifically does the polio virus infect in the CNS
anterior horn of motor neurons in the spinal cord
Presentation of acute paralytic poliomyelitis
flaccid asymmetric weakness and muscle atrophy due to loss of motor neurons and denervation of their associated skeletal muscles
Risk factors for paralytic poliomyelitis
young, old, recent hard exercise, tonsillectomy, pregnancy, immunosuppression
Early presentation of paralytic poliomyelitis
severe muslce pain, spasms, weakness (lower limbs more effected than upper)
Dx polio
lumbar puncture, culture, MRI (anterior horns)
what is Herpangina? when is it most likely to occur
acute febrile illness, small vesicular/ulcerative lesions in the back of the throat and roof of mouth; in the summer in children and young adults
hand-foot-and-mouth disease
- complications?
- most likely causitive agents
spread by fecal oral route w/ skin lesions and oral secretions; symptoms follow viremia/viral invasion of mucus membrane
- rarely aseptic meningitis or myocarditis; pneumonitis, pulmonary edema
- coxs A, enterovirus 71
HFMD pathogenesis
-group at risk
1wk incubation then sore mouth, throat, fever > vesicular eruption in mouth, hands, feet, buttocks, genitalia
-children under 10
Acute hemorrhagic conjunctivitis
- causative agents
rapid-onset painful conjunctivitis
- coxs A24 and enterovirus E70
Viral myocarditis pathogenesis
- most common causative agents
- who is at highest risk
inflammatory disorder of the myocardium, necrosis of myocytes, infiltrate
- adenovirus, enterovirus
- infants and pregnant women/ immunocompromised pts
In which coxsackie infection presentation do you need to do lab work
myocarditis (CBC, cultures, markers of myocardial damage) and pleurodynia
Pleurodynea
sudden occurrence of lancinating chest pain attacks, fever, headache, malaise (pleural friction rub)
pleurodynea pathogenesis
striated muscle around the lungs is the target of coxsackie B
Aseptic meningitis
viral, not bacterial/fungal.. most rule those out.
