1 - Influenza Flashcards
What is influenza?
Contagious viral respiratory illness
What are the 3 types of the influenza virus?
A, B, and C
Which types of influenza can cause disease in humans? Which causes the majority of disease?
Types A and B; type A causes about 90% of influenza
What are different subtypes of influenza A based on?
Surface hemagglutinin (HA) or neurominidase (NA) glycoproteins
What are the primary subtypes of influenza A affecting humans?
H3N2 and H1N1
____ is the most effective way to prevent influenza infection
Vaccination
Describe how influenza spreads
- Respiratory droplets caused by coughing and sneezing are transferred to surfaces
- Uninfected person touches a surface w/ influenza on it and then touches their mouth or nose
How long are people infected w/ influenza contagious?
1 day before symptoms develop and 5-10 days after symptoms develop
What is the typical incubation period for influenza?
1 to 4 days (average 2 days)
The current vaccine for influenza is ___valent
Quadrivalent
What are the early symptoms of influenza?
- Fever (usually very high)
- Muscle pain
- Headache
- Non-productive cough
- Malaise
- Sore throat
- Rhinitis
How long does it take early symptoms of influenza to resolve?
Usually about 1 week; cough and malaise may persist for more than 2 weeks
What are some symptoms of influenza that rarely occur from the common cold?
- Fever
- Headache
- Aches and pains
- Weakness
- Bedridden
What are some symptoms of the common cold that rarely occur from influenza?
- Runny, stuffy nose
- Sneezing
What are some complications of influenza?
- Respiratory failure, especially w/ chronic conditions (ex: asthma)
- Pneumonia or other secondary bacterial infections
- Dehydration
- Worsening of concurrent medical conditions
- Viral myocarditis (*rare)
What are some complications of the common cold?
- Congestion
- Sinus or ear infection
What is most likely to cause hospitalization when infected w/ influenza?
Viral pneumonitis
____ and _____ increase during flu season
Acute coronary syndromes and exacerbations of chronic pulmonary conditions
What are the monitoring parameters for px w/ influenza?
- Monitored daily for resolution of sx (fever, myalgia, headache, malaise, non-productive cough, sore throat, rhinitis)
- Sx should resolve w/in about 1 week
- If px continues to exhibit sx beyond 10 days or worsening of sx after 7 days, refer b/c may be a secondary bacterial infection
What are common causes of secondary bacterial infections associated w/ influenza?
- Staph aureus
- Strep pneumoniae
What are some possible samples for influenza testing?
- Nasopharyngeal or throat swab
- Nasal wash
- Nasal aspirate
- Blood for antibodies
Viral culture for influenza provides results in ____ days
3-10
Why should a viral culture be done for influenza?
- Subtypes can be determined
- Surveillance for new strains that may need to be included in next years vaccine
Viral cultures detect influenza ____
A and B
What are rapid influenza diagnostic tests?
Immunoassays that can identify the presence of influenza A and B viral nucleoprotein antigens in respiratory specimens
What are the advantages of rapid influenza diagnostic tests?
- Quick results w/in 30 mins or less
- Simple to perform
What are the disadvantages to rapid influenza diagnostic tests?
- False negative results are common
- Only some can distinguish between influenza A and B
- Do not provide info on influenza A subtype
What is used to identify the presence of influenza viral RNA in respiratory specimens?
Latest reverse transcription-polymerase chain reaction (RT-PCR)
What are advantages to RT-PCR for influenza testing?
- Improved sensitivity
- Produces results w/in 20 mins
What are disadvantages to RT-PCR for influenza testing?
Result is highly dependent on sampling site
What is serological testing for influenza?
- Testing serum samples for influenza antibody to diagnose recent infection
- 1 sample taken w/in first week of illness and 2nd sample taken 2-4 weeks later; if Ab levels are higher in 2nd sample, it is likely the influenza virus was present
How is oseltamivir excreted and what does this mean?
- Glomerular filtration and tubular secretion
- Reduce dose in renal impairment
_____ can decrease the renal excretion of oseltamivir carboxylate
Probenecid
What are common side effects of oseltamivir and how can they be lessened?
- GI (nausea, vomiting, diarrhea)
- Ingestion w/ food
When must oseltamivir be initiated in order to have decrease illness resolution?
W/in 48 hours of illness onset
When is antiviral treatment indicated for influenza?
Recommended as early as possible for any px w/ confirmed or suspected influenza who:
- Is hospitalized
- Has severe, complicated, or progressive illness
- At higher risk for influenza complications
What are some examples of px at higher risk for influenza complications?
- Children under 2
- Adults 65 y/o and older
- Immunosuppressed
- Pregnant or w/in 2 weeks after delivery
- Morbidly obese
What are the 2 neuraminidase inhibitors in Canada?
- Oseltamivir
- Zanamivir
Is there an advantage to combination therapy w/ antivirals?
No, oseltamivir alone has best efficacy
Is there a need for higher doses of oseltamivir in severe influenzal illness?
No, showed to eradicate the virus faster, but had no influence on survival
Who is recommended for the annual influenza vaccination?
All persons aged 6 months and older
What is used as a preservative in the influenza vaccination?
Thimerosal
The influenza vaccination contains ___ virus
Inactivated (killed)
How long does it take to develop immunity after receiving the quadrivalent flu vaccine?
2 weeks
What is an adjuvanted vaccine? Is the influenza vaccine adjuvanted?
- Vaccine that includes a substance that boosts an individual’s immune response to the vaccine (ex: squalene oil and/or vitamin E)
- Influenza vaccine is not
Does the administration of a second dose of influenza vaccine in elderly or immunocompromised px have an advantage?
No
Who should not receive the influenza vaccination?
- People who have had a previous anaphylactic
- People w/ IgE-mediated hypersensitivity to eggs
- People currently experiencing high fever
- People w/ serious acute febrile illness (can get vaccine when sx subsided)
