Influenza Flashcards
What is influenza (illness)?
- a contagious viral respiratory illness
What is the incidence of influenza worldwide?
- 3-5 million cases of severe illness
What is the make-up of the influenza virus?
- single-stranded family of RNA viruses referred to as Orthomyxoviridae
- classified as wither type A,B, or C
Influenza __ is responsible for up to 90% of epidemic influenza
A
What are the different subtypes within influenza A based on?
- based on the surface hemagglutinin (HA) or neuraminidase (NA) glycoproteins
Influenza __ has never been seen in humans
C
How is influenza spread?
- respiratory droplets caused by coughing and sneezing
When are most healthy adults able to infect others with influenza?
- 1 day before symptoms start and 5-10 days after becoming sick
What is the typical incubation period of influenza?
- 1-4 days (average 2 days)
The seasonal flu vaccine this year is a _____ vaccine
quadrivalent
What is the common clinical presentation of influenza?
- fever
- muscle pain
- headache
- non-productive cough
- malaise
- sore throat
- rhinitis
(these usually RESOLVE in 1 week of presentation - cough and malaise persist for more than 2 weeks)
What are the general complications of influenza vs a common cold?
Influenza: respiratory failure, especially with chronic conditions
Common cold: congestion, sinus or ear infection
Describe the complications of influenza?
- diffuse viral pneumonitis - the clinical syndrome most likely to result in hospitalization (can lead to shock and resp. failure)
- pneumonia - secondary bacterial infection
- dehydration
- worsening of concurrent medical conditions (asthma, diabetes, congestive HF)
- viral myocarditis is a rate complication
- acute coronary syndrome
- exacerbations of chronic pulmonary conditions
What are the bacteria that cause secondary bacterial pneumonia?
- staphylococcus aureus
- streptococcus pneumoniae
- hemophilus influenzae
- other gram negative bacilli
Samples for influenza testing include what?
- nasopharyngeal swab
- nasal wash
- nasal aspirate
- blood for antibodies
A viral culture provides test result in _____ days
3-10
Viral culture detects both influenza ___ and ___
A and B
What test is done that identifies the presence of influenza A and B viral nucleoprotein antigens in respiratory specimens, and display the result in a qualitative way (positive vs negative)
Rapid influenza diagnostic tests
What is the advantages of rapid influenza tests?
- produce quick result in 15 minutes or less
- simple to perform
- some RIDRs are approved for office/bedside use
What is the disadvantage of rapid influenza tests?
- sensitivity (10-69%) false negative results are common especially when influenza activity is high
- although specificity is high, false positives can also occur, especially during times when influenza activity is low
- Some RIDTs distinguish between influenza A or B virus infection while others do not. They do not provide information about influenza A subtypes or specific strain information
Describe serological testing
involves testing serum samples for influenza antibody to diagnose a recent infection. Two sample are collected, one within the 1st week of illness and the second 2-4 weeks later. If antibody levels are higher in the second sample than the first, it is likely that the influenza virus was present
Describe how neuramidase inhibitors work?
they bind to the protein of the virus and does not allow the virus to leave and spread throughout the body
- also cause clumping of the virons and do not allow them to spread
- 2 mechanisms that neuramidase inhibitors stop the spread
____ is extensively converted to its active metabolite by hepatic esterases (drug interactions involving competition for esterase have NOT been reported)
Oseltamivir
Clearance of oseltamivir carboxylate is by ______ and ______ by an anionic transporter system. Reduce the dose in renal impairment
glomerular filtration
tubular secretion
