Viral (I-P) Flashcards
which type of influenza virus cause human illness and seasonal epidemics?
which subtypes circulate in humans worldwide?
A&B
A(H1N1), A(H3N2)
B-yamagata, B-Victoria
what is influenza virus?
RNA virus of the Orthomyxovirus genus
4 types: ABCD
what does Novel influenza refer to?
viruses with a subtype different from seasonal influenza, and is caused by influenza A among animals
avian influenza A
swine-origin variant viruses Av
incubation time of influenza?
when is the infectious period? (for healthy ppl vs infectious period for children, immunocompromised, severely ill)
-1-4 days
-1 day before symptoms to 5-7 days after symptom onset
-greatest within 3-4 days of illness onset and is correlated with fever; upto 10 days after symptom onset for children, etc.
In temperate regions, the Norther Hemisphere, influenza epidemics are expected in which months?
10-3
In temperate regions, the Southern Hemisphere, influenza epidemics are expected in which months?
April - September
globally, annual influeza epidemics results in how many cases of severe illness and how many respiratory deaths?
3-5 million severe cases, 290,000-650,000 deaths
what groups are at increased risk for influenza complications?
-65 and older
-children<2 years
-pregnant people and people within 2 weeks post-partum
-medical conditions: asthma, blood disorders, BMI >40, chronic lung disease, endocrine disorders, heart disease, immunocompromise, kidney disease, liver, metabolic disroders, neurologic and neurodevelopment conditions, history of stroke
-American Indians and Alaska Natives
-people living in nursing homes and other long-term care facilities
what is zoonotic influenza?
Influenza A viruses circulating among animal populations which occasionally infect humans.
wild birds, domestic poultry, swine, bats, cats, dogs, ferrets, horses, sea lions, seals
Avian Influenza A (H5) Lineage viruses - which countries were affected?
what is reported case-fatality ratio?
Egypt, Indonesia, China, Russia
37%
Avian influenza A (H7N9) virus - what is case-fatality ratio?
which country has been affected?
40%
China, Hong Kong Special Administrative Regions (SAR), Macau SAR, Malaysia, Taiwan
what are the symptoms of influenza?
abrupt onset of signs and symptoms - nonproductive cough, fever, headache, malaise, muscle aches, rhinitis, sore throat, vomiting, rash
illness without fever can occur in older adults and infants
children -nausea, vomiting, dairrhea
what are symptoms of variant influenza viruses (e.g. avian influenza) ?
often severe pneumonia or respiratory failure and a high case-fatality ratio
what are the complications of influenza virus infection?
viral pneumonia and secondary bacterial pneumonia.
co-infections with other viral or bacterial pathogens, encephalopathy, exacerbbation of underlying medical conditions, GBS, myocarditis, myositis, parotitis, seizures, death.
what is the treatment of influenza?
when should the treatment be initiated?
within 48 hours of symptom onset;
-oseltamivir (Tamiflu) - all ages
-peramivir (intravenous) - 2 and up
-zanamivir (inhaled) -7 and up for treatment, 5 and up for prophylaxis
-baloxavir (oral) - acute uncomplicated influenza,12 and up
what is the treatment dose of oseltamivir?
for 5 days:
<1 year: 3mg/kg BID
1 and up: <15kg - 30mg BID
15-23kg - 45mg BID
23-40kg - 60mg BID
>40kg - 75mg BID
what is the prophylaxis of oseltamivir?
7 days:
<3 months old - not recommended due to limited data in this age group
3 month - 1 year - 3mg/kg/dose QD
1 and up: same dosing as treatment but once a day dosing
when do you do postexposure prophylaxis for influenza outbreak?
-only within 48 hours of exposure
-all suspected avian influenza viruses (treatment dose)
what are the 3 categories of influenza vaccines?
- inactivated (cell-based, high-dose, adjuvanted)
- live attenuated
- recombinant
who should get 2 doses of influenza vaccines 4 weeks apart?
children aged 6 months to 8 years who have never received an influenza vaccine, or who have not previously received a lifetime total of 2 or more doses, require 2 doses of age-appropriate influenza vaccine given 4 weeks apart.
what is the age indication for cell-based inactivated vaccein, live attenuated influenza vaccine and recombinant influenza vaccine?
what is indication for other inactivated influenza vaccine (IIV)?
2 and up for cell-based inactivated
2-49 years for LAIV
18 and up for RIV
6 months and up for IIV
what is japanese encephalitis virus?
single-stranded RNA
genus Flavivirus
japanese encephalitis virus is closely related to which viruses?
dengue, West Nile, Saitn Louise encephalitis virus
what mosquito species are associated with japanese encephalitis?
culex species
what animals are responsible for japanese encephalitis virus host?
wading birds and pigs
JE virus - in temperate areas of Asia, which season is the peak?
summer and fall
what is the overall incidence of JE among people from nonendemic countries traveling to Asia?
<1 case per 1 million travelers
expatriates and travelers who stay for prolonged periods in rural area with active JE virus transmission, what is the risk to get JE?
6-11 cases per 100,000 per year
what are the symptoms of JE?
incubation 5-15 days
-sudden onset of fever, headache, vomiting
-mental status changes, focal neurologic deficits, generalized weakness,
-movement disorders (like parkinsonian syndrome with mask-like facies, tremor, cogwheel rigidity, choreoatetoid movements)
-acute flaccid paralysis like poliomyelitis
-seizures
<1% develop neurologic disease
-acute encephalitis
-milder forms: aseptic meningitis, undifferentiated febrile illness
-case fataility rate 20-30%; 30-50% serious neurologic, cognitive, or psychiatric sequelae
how to diagnose JE?
JE virus-specific IgM-capture ELISA on CSF or serum
what is age indication for IXIARO?
2 month and up
who should get JE vaccine?
moving to JE endemic country, longer-term (>1 month), frequent travelers