Influenza (4 types + avian ) Flashcards
genome of influenza is …1… which allows a high rate of …..2..
- single stranded RNA
- mutation
differences between the 3 major serotypes (A,B,C) of influenza are based on ?
antigens associated with the nucleoprotein
= influenza types can be distinguised by the specific proteins present inside the virus
Type of virus that influenza virus is ?
enveloped negative-sense single stranded RNA
influenza virus family ? what virus is it ?
orthomyxoviridae
orthomyxovirus
Types of influenza virus responsible for seasonal flu in humans
Type B (infect only humans) , maybe A (infect animals + humans)
Type A classified into subtypes based on ?
- hemagglutinin
- neuraminidase proteins
e.g. Avian flu H5N1 , H9N2
Influenza A viruses are responsible for …1… that usually cause higher …2… than seasonal …3..
- sporadic pandemics
- mortality rates
- influenza epidemics
Type B influenza virus classifed how ?
by lineage e.g. B/Victoria
Influenza virus replication happens where ?
in host cell nucleus
Pathogenesis of influenza ?
- prefers respiratory epithelium
- it multiplies in the ciliated cells of lower resp tract
- cellular synthesis of nucleic acids + proteins is shut down
- ciliated + mucus - producing epithelial cells are shed
risk factors of influenza infection ?
- pregnancy
- age (< 5 yrs or >65 yrs)
- chronic medical conditions e.g. diabetes
- immunosuppressive conditions
- healthcare provision
signs and symptoms of influenza ?
- sudden fever
- pharyngitis
- congestion
- cough
- myalgia
Flu patients are susceptible to secondary infections due to virally produced damage to lung epithelium
3 bacteria that are common causes of superinfection ?
- streptococcus pneumoniae
- haemophilus influenzae
- staphylococcus aureus
Influenza transmitted via how ?
- inhalation of airborne viruses
- self-inoculation
complications of influenza occur most often in who ?
- elderly
- children
- those with chronic diseases
Complications with influenza infection ?
- acute pneumonia in 30-40% hospitalised patients
- secondary bacterial infections
- acute respiratory distress syndrome
Treatment for influenza infection ?
- uncomplicated = relief of symptoms (e.g. fever)
- severe / progressive clinical illness = antivirals , neuraminidase inhibitors (e.g. oseltamivir, zanamivir)
Prevention for influenza infection ?
vaccination
In infleunza infection virus replicates predominately in ….1…. cells because it’s the only site where ..2… is effectively cleaved
- respiratory epithelial cells
- HA (hemagglutinin )
Cold symptoms
cold:
* low / no fever
* sometimes headache
* runny/ stuffy nose
* sneezing
* mild, hacking cough
* slight aches and pains
* normal energy level / may feel sluggish
* mild fatigue
flu symptoms:
- high fever
- headache very common
- clear nose
- sometimes sneezing
- cough, often becoming severe
- often severe aches + pains
- several weeks of fatigue
- sometimes a sore throat
- extreme exhaustion
What do the following influenza viruses infect ?
1. A
2. B
3. C
4. D
- humans and many different animals + can cause influenza pandemic
- amond humans + causes seasonal epidemics
- humans + pigs , generally mild infections and rarely reported
- primarily cattle not known to infect people
How can influenza A virus cause an influenza pandemic ?
emergence of a new and very different INF A virus
with ability infect people and have sustained human to human transmission
why are influenza type A viruses of most significance to public health ?
potential to cause an influenza pandemic
Avian influenza is a ..1… disease caused by viruses that infect ..2..
- contagious
- birds
How are avian influenza A virus strains classified ?
On basis of molecular + pathogenicity criteria
- low pathogenic avian influenza (LPAI)
- highly pathogenic avian influenza (HPAI)
Most strains of Avian influenza are …1… viruses and cause ..2… infection or ..3… disease in poultry
1.LPAI
2.asymptomatic
3.mild
LPAI H6N1, H7N2, H7N3, H7N7, H7N9, H9N2, H10N7, and H10N8 virus strains have infected humans causing disease ranging from ?
from conjunctivitis to non-fatal upper respiratory and lower respiratory tract disease
to severe lower respiratory tract disease and death (H7N9, H10N8)
Rare,sporadic human cases of HPAI virus infection have been detected with which viruses ?
- H5N1
- H5N6
- H7N3
- H7N7
Rare, sporadic human cases of HPAI viruses have caused a wide spectrum of illness from …1.. to ..2…, ….3.., and ..4…
- conjunctivitis
- severe pneumonia
- acute respiratory distress syndrome
- fatal outcomes
Avian flu presentation ?
- cough
- influenza-like illness (non-specific symptoms e.g. headache, rhinorrhoea, sore throat, myalgia)
- dyspnoea
- fever
- wheeze
- tachypnoea
Risk factors for avian infleunza A
- close contact with infected birds
- recent travel to a virus infected country
- visits to live poultry market in endemic countries
- contact with infected humans (carers of family members)
- healthcare personnel using inadequate PPE
How to differentiate clinically between the following: Avian influenza A, influenza, TB, covid-19, bacterial pneumonia, SARS, MERS ?
- PCR for covid-19, avian influenza, SARS, MERS
- sputum / blood culture for bacterial pneumonia (GAS/ S. pneumoniae)
- acid fast stain + culture for TB
- CXR (TB shows fibronodular opacities in upper lobes), also helpful for pneumonia (viral/ bacterial), lung cancer (can detect mass)
Treatment for infleunza pharmacology aspect ?
- antivirals - neuarminidase inhibitors e.g. oseltamivir
- antimicrobials if clinical suspicion of secondary bacterial infection
2 basic approaches for treatment of influenza ?
- symptomatic care
- anticipation of potential complications
best treatments for influenza which aren’t antimicrobials / antivirals ?
- rest + fluid intake
- conservative use of analgesics for myalgia + headache
- cough suppressants
What are useful only if the infection if influenza diagnosed within 12-24 hours ?
- amantidine
- rimantadine
With treatment for infleunza what is important to consider ?
complications for those with severe, complicated or progressive illness, or those who require hospitalisation
Apart from antiviral treatment for influenza the public health management includes personal protective measures like:
- Regular hand washing with proper drying of the hands
- Good respiratory hygiene – covering mouth and nose when coughing or sneezing, using tissues and disposing of them correctly
- Early self-isolation of those feeling unwell, feverish and having other symptoms of influenza
- Avoiding close contact with sick people
- Avoiding touching one’s eyes, nose or mouth
