Viral infection (H) Flashcards
which virus cause hand, foot, mouth disease?
nonpolio enteroviruses
- genus Picornaviridae family of nonenveloped RNA viruses (e.g. coxackievirus A6, coxsackievirus A16, enterovirus A71)
In the Asia-Pacific regions, which virus is the predominant etiologic agent of HFMD?
enterovirus A71
what are the symptoms of HFMD?
incubation 3-6 days, recovery within 7-10 days;
fever, malaise, sore throat, painful vesicles in the mouth, peripheral rash on hands, feet, also can be on buttocks, genitals, elbows, knees
what can be symptoms of severe and atypical cases of HMFD?
severe: brainstem encephalitis, aseptic meningitis, myocarditis, pulmonary edema, death
atypical: rash or lesion that enlarges and coalesces to form bullae; onychomadesis (shedding of the nails) and desquamation of the palms or soles can occur during convalenscence
what is henipavirus ?
enveloped, single-stranded RNA
genus Henipavirus
family Parammyxovirus
which Henipavirus species are highly virulent and cause outbreaks in humans and associated with high case-fatality ratios?
Hendra virus, Nipah virus
what is the henipavirus reservoir hosts?
which animal can transmit hendra virus to humans?
which animal can tranmit Nipah virus to humans?
Pteropid fruit bats (flying foxes)
horses (infected by bat urine)
pigs or bats; also human-to human transmission possible
in eastern China, a new henipavirus species was identified. which henipavirus is this?
Langya virus (LayV)
which country has outbreaks of Henipavirus infection / hendra virus?
Australia
which countries have outbreaks of Nipah virus?
Malaysia (1999), Singapore (1999), Bangladesh, India (yearly) - mostly bat exposure
what are the symptoms of Hendra and Nipah virus infections?
5-16 days incubation period;
severe influenza-like illness with dizziness, headache, fever, myalgias
severe encephalitis; respiratory symptoms
relapsing or late-onset encephalitis can occur months or years after acute illness.
what is case-fatality ratio of Hendra and Nipah?
57%
40-70%
how to prevent Henipavirus infections?
avoid contact with bats, sick horses and pigs and their excretions
do not consume fallen fruit, raw date palm sap, or products made from raw sap
is there a vaccine for Hendra virus?
Australia - Hendra virus vaccine for horses
what is Hepatitis A virus?
nonenveloped RNA;
picornavirus
can HAV be inactivated by cold or heat?
only heat >85 degrees for 1 minute
when is the most infectious period of HAV in infected people?
and how does the virus excreted?
1-2 weeks before the onset of symptoms
through stool and blood
what is the most common vaccine-preventable infections acquired during travel?
Hepatitis A
what is incubation time for HAV?
average 28 days (15-50 days)
what are the severities of HAV infection? in children age <6 years and older children and adults?
mild illness 1-2 weeks; severly disabling disease lasting several months
<6 years - 70% asymptomatic (jaundice is uncommon in symptomatic young children)
older children&adults - usually lasts <2 months, but 10-15% have prolonged or relapsing symptoms over 6-9 months
severe hepatic and extrahepatic complications are rare but more common in older adults and people with underlying liver disease.
symptoms of HAV?
abrupt onset of fever, malaise, anorexia, nausea, abdominal discomfort
followed by jaundice within a few days - hepatitis and liver failure if very severe
how to diagnose HAV?
positive test for HAV IgM in serum - detectable 2 weeks before the onset of symptoms to ~6 months after symptom onset.
what is commercially available for HAV detection/diagnose?
serologic total IgG and IgM tests
what does it mean if total HAV result positive, and IgM negative?
past infection or vaccination - immunity
what does IgM positive mean?
current or recent infection - does not distinguish between immunity derived from infection verses vaccination.
what is the spacing between 2 doses of Havrix (GSK) and Vaqta (Merck)?
Havrix 6-12 months
Vaqta 6-18 months
what age is junior Havrix and Vaqta indicated?
1-18 years old
what is rapid schedule for Twinrix?
0, 7, 21-30 days, 12 months
what is the dose of IG for HAV for infants younger than 6 months old or who is allergic to the vaccine?
1 dose IG at 0.2 ml/kg repeated every 2 months for the duration of travel
what is recommended for infants 6-11 montsh old for HAV?
vaccine - but expect suboptimal immune response and start routine vaccine at 12 months
what to do if people, age >40 years, immunocompromised, and with chronic liver disease travel in less than 2 weeks for HAV vaccine??
IG (0.1ml/kg) in addition to vaccine at separate injection site
Hep A vaccines should not be administered if history of hypersensitivity to any vaccine component. Which vaccine compoents are prone to allergic reaction ?
neomycin
Twinrix, Havrix, and vial stopper, syringe plunger stopper, and tip caps of Vaqta might contain dry natural rubber (latex)
Twinrix - yeast
is HAV vaccine indicated for pregnancy?
yes - if increased risk for HAV during pregnancy, risk for having a severe outcome from HAV (with chronic liver diseaes or HIV)