Influenza

Question 1

What things need to happen for Avian influenza viruses to be pathogenic to humans (4 points)

Answer 1

1) Reassortment - specifically of the polymerase genes (PB1, PB2, PA)
2) Adaption of the HA protein to allow human transmission- change in the binding specificity of the virus HA from α2-3-linked “avian-type” receptors to α2-6-linked “human-type” receptors

3) Change in preferred pH for fusion (high to low)
4) Change in sensitivity to restriction factors.
(last two points claire is a little less clear about but has lost the will in to looking in to it)

Question 2

List order of flu types in susceptability to oseltamavir

Answer 2

H3N2 FluB
H1N1

Question 3

What exact PPE is required for suspected avian flu

Answer 3

as a minimum, this should be a correctly fitted FFP3 respirator, gown, gloves and eye protection

If the patient has to go outside: ask them to where a surgical mask

Same for all airborne HCID
Avian flu listed as HCID include H7N9, H5N1, N5N6, H7N7

Question 4

With regards to avian influenza what is considered the risk period for exposure to ill birds and time of symptom onset

Answer 4

10 days. This is also the period for “active follow up”, i.e calling every day for symptom assessment and “passive follow up”.
Passive follow up is when they are given advice to call in if any symptoms (used only when healthcare workers have been using PPE- why would we bother checking in on healthcare workers hey?!)

The exposure criteria are outlined in the guidance; it is important is to determine if the individual has been within 1 metre of poultry or wild birds, in an affected country, in the 10 days prior to onset of symptoms.

In particular, be aware of persons with:

fever ≥ 38°C OR acute respiratory infection symptoms OR other severe / life-threatening illness suggestive of an infectious process
AND

on questioning, report exposures to birds (including poultry) in affected countries

Incubationof flu is 72 hours
Incubation of covid (FYI) is 2-14 days

Question 5

Name influenza surviellance systems?
Where could you look to assess risk of avian flu risk in a returning travelller?

Answer 5

General resp illnesses surveillance:
DataMart, HPZone

Community:
Syndromic suveillance syndrom
Fludetector

Secondary care survelliance

SARI

World wide
- WHO, CDC health alert network, ECDC
-GISAID (makes fancy phyolgentic trees)

https://www.gov.uk/guidance/high-consequence-infectious-disease-country-specific-risk

Question 6

Mechasim of action of 1)Baloxavir

2) Riamilovir

Answer 6

1) Cap-dependent endonuclease inhibitor (The UK monitors for resistance to this, even though we don’t really use it, It is one off dosing but low barrier to resistance)

2) Guanine analogue (Ribavirin also has this mechanism of action I think). Broad spectrum antiviral, but being thought useful for H5NX.

Question 7

For which flu do you use treatment dose oseltamavir for prophylaxis

Answer 7

H7N9

Resistance to neuraminidase inhibitors has been described for some avian
influenza viruses, particularly H7N9

Therefore give 75mg BD for 5 days

Question 8

Risk facyors leading to avian flu risk

Answer 8

Infection of terrestrial mammals, and transmission between mammals

Transmissibility amoung humans: alpha 2-6
-pH stability of HA
-cleavability of HA

Mutations of polymerase (E627K), PB@ mutations

Re-assortment with virus that is already adapted to mammals (if two viruses infect same cell)

Interactio between humans and resevoir