influenza Flashcards
how many types
3: A, B, C
which type if more virulent and occurs more frequently
A
which type presents a milder course of disease but still has potential to cause outbreaks
B
which type causes mild or asymptomatic disease, similar to the common cold
C
which types can be further categorised into subtypes depending on their principle H and N antigens?
A and B
transmission occurs via
droplets, aerosols, or direct contact with respiratory secretions from an infected person
usual incubation period
1-3 days
what does incubation period mean
the period between exposure to an infection and the appearance of the first symptoms
symptoms usually appear suddenly or take a while?
suddenly
symptoms include…
chills
fever
headache
extreme fatigue
myalgia
dry cough
sore throat
nasal congestion
complications - respiratory and non-respiratory
- usually respiratory in nature and may include bronchitis, secondary bacterial pneumonia or otitis media (in children)
- non-respiratory complications rarer and may be cardiac or neurological in nature
influenza is usually self limiting with recovery occurring within how many days?
2-7 days
classifications of influenza (not types!)
uncomplicated
complicated (either needing hospitalisation, having signs or symptoms of LRTI, CNS involvement or exacerbation of an underlying condition)
risk of more serious illness is greater for those in at risk groups….
children under 6 months
pregnant females, including females up to 2 weeks PP
adults over 65
pt with long term conditions e..g respiratory, renal, hepatic, neurological or cardiac disease, DM or morbid obesity (BMI ≥ 40 kg/m²), or those with severe immunosuppression)
patients with this BMI are at risk of more serious illness
BMI ≥ 40 kg/m² - morbid obesity
which two antivirals are used for both treatment and post exposure prophylaxis of influenza?
oseltamivir and zanamivir
oseltamivir and zanamivir are used for both treatment and post exposure prophylaxis of influenza. there is evidence that some strains of influenza are more likely to develop resistance to which one of these?
oseltamivir
the risk of developing oseltamivir resistance is considered to be greater for which type ?
A , risk if higher in pt who are severely immunocompromised
the risk of developing oseltamivir resistance is higher in which set of pt
severely immunocompromised
can you give amantadine HCl for treatment or post exposure prophylaxis of influenza A
No not recommended
treatment of suspected or confirmed influenza - when treatment with oseltamivir is indicated, it should be started…
ASAP ideally within 48 hours of symptom onset
for treatment of suspected or confirmed influenza, when treatment with oseltamivir is indicated, it should be started ASAP ideally within 48 hours of symptom onset. can be be started later than this ?
treatment initiation beyond 48h onset is unlicensed and clinical judgement should be used
there is evidence to suggest the risk of mortality may be reduced even if treatment is started up to 5 days after symptom onset
treatment if suspected or confirmed influenza - where treatment with inhaled zanamivir is indicated, it should be started…
ASAP ideally within 48 hours (36 hours in children) of symptom onset
treatment initiation beyond this time is unlicensed and clinical judgement should be used
treatment if suspected or confirmed influenza - where treatment with IV zanamvir is indicated , it should be started
ASAP and within 6 days of symptom onset
for those with uncomplicated influenza but considered to be at serious risk of developing complications, offer this antiviral drug
oseltamivir
for patients in at risk group (including pregnant🤰but excluding severely immunocompromised), offer this antiviral and do not wait for lab test results to treat
oseltamivir
when would a pregnant female be given zanamivir first line?
meets additional criteria
treamtent should be discussed with a local infection specialist
what to do when you are considering treatment for severely imunocompromised paeople + which treatment to offer
consider the subtype of influenza causing infection, or if not yet know, take into account the current dominant circulating strain
1st line oseltamivir unless strain has higher risk of resistance, in which case offer inhaled zanamivir
if unable to use inhaled due to underlying severe resp disease or inability to use device (including under 5), offer oseltamivir and assess repsonse to therapy
for patients with uncomplicated influenza who require treatment due to being at serious risk of devleoping complications etc and they have suspected or confirmed oseltamivir resistant influenza, offer …
inhaled zanamivir
if unable to use this, consider IV (unlicensed)
what to do with pt who have complicated flu
all pt should be tested and treated
often in hospital
do not wait for lab results to treat
treatment of complicated flu for pt where there is risk of reduced GI absoprtion, or if inital oseltamivir unsuccessful
inhaled zanamivir
treatment of complicated flu for pt who are not severely immunosuppressed
1st line oseltamivir
who should be offered post exposure prophylaxis following exposure to a person in the same household or residential setting with influenza like illness (when influenza is circulating)?
contacts in at risk group who arent adequately protected through vaccination (e.g. due to infection by different circulating strain or exposure within 14 days post vaccination)
when does flu vaccine start giving you protection
after 14 days
who may be considered for antiviral prophylaxis post-exposure regardless of vax status?
certain populations that are susceptible to localised outbreaks e..g care homes, prisons, detention centres
when is oseltamivir given 1st line regardless of risk of resistance of circulating or index strain
when its used for post exposure prophylaxis in pt in at risk group (including pregnant, but excluding severely immunocompromised
what are the treatment options available for post exposure prophylaxis and when should they be started
prophylaxis should be started ASAP following exposure
ideally within 48h for oseltamivir
ideally within 36h for inhaled zanamivir
initation beyond these times is unlicnesed, seek specialist advoce
1st line for post exposure prophylaxis for pt in at risk group (incl pregnant females, EXCL severely immunosuppressed and children under 5)
oseltamivir regardless of risk for resistance of the circulating or index case strain
post exposure prophylaxis for pt exposed to a strain with suspected or confirmed oseltamivir resistance
inhaled zanamivir
treatment post exposure prophylaxis for severely immunosuppressed pt EXCL under 5
oseltamivir if risk for resistance is low
if risk for resistance is high, suspected or confirmed, offer inhaled zanamivir
post exposure prophylaxis treatment for pt at higher risk of oseltamivir resistance who are unable to used inhaled zanamivir (due to underlying severe respiratory disease or unable to use device)
oseltamivir and advice pt to seek immediate medical attention if symptoms develop subsequently
post exposure prophylaxis treatment for pt who are exposed to suspected or confirmed oseltamivir resistance influenza who are unable to use inhaled zanamivir
seek specialist advice
monitor pt closely for influenza like illness
arrangements made for prompt treatment if symptoms develop
post exposure prophylaxis for a child who is severely immunocompromised
seek specialist advice
by which route can oseltamivir be given
by mouth
how long is oseltamivir given for TREATMENT of influenza
BD 5 days
10 days if immunocompromised
how long is oseltamivir given for PREVENTION of influenza
OD for 10 days, for up to 6 weeks
up to 12 weeks if immunocompromised
which route can zanamivir be given via
inhalation of powder
iV infusion
