Hot Topic Meeting by:

Royal College of Physicians of Edinburgh & The Scottish Executive Health Department

Pandemic Flu

Planning Scotland’s Health Response

5th June 2007

Queen Mother Conference Centre

Clinical characteristics of ‘Flu’

Dr Dermot H KennedyConsultant Physician in Infectious Diseases (Retd.)Glasgow

“Influenza A is an unvarying disease due to a varying virus”

E. Kilbourne New York 1975

VariationComplicated:

- by pandemic virus- by co-infecting

bacteria- by risk factors

Uncomplicated:- by age- by virus type

THE MENUClinical features of:• Typical influenza A

- milder complications

• Serious complications- respiratory- non respiratory

• Variation by pandemic outbreak

Clinical Spectrum of Influenza A

Incidence / range of systemic features

Collated from 10 studies of 520 virologically confirmed adult cases 1937-1992 ( after Nicholson Ch. 19 in ‘Human Influenza’ )

MILDER COMPLICATIONS OF INFLUENZA A

- TRACHEOBRONCHITIS- OTITIS MEDIA- SINUSITIS

- POST INFLUENZAL ASTHENIA AND DEPRESSION

Who is at risk of influenza?

‘Typical’ Influenza A:

• Age <2 >65yrs• Chronic disease : respiratory, cardiac,

renal, diabetes, immunosuppression• ‘at risk’ settings• Risk factor influences presentation /

complications

Pandemic Influenza• As across• + young adults• +pregnant women

Peak mortality 1918

SERIOUS COMPLICATIONS OF INFLUENZA A

RESPIRATORY:. 2y bacterial pneumonia. 1y viral pneumonitis. Mixed viral and bacterial pneumonia

. Exacerbation of COAD, asthma

NON RESPIRATORY:. CNS eg encephalopathy, myositis. CARDIAC eg decompensated CCF

Complications of Influenza A Infection

2y pneumonia due to bacterial suprainfection

The problem :

2y BACTERIAL PNEUMONIA

• Influenza A accounts for 5→10% of all C.A.P.

• Biphasic disease – usually• Pattern different from “CAP norm”, and between

pandemics• Pneumococcal pneumonia commonest

2y bacterial pneumonia

H.influenza

pneumococcus

Staphylococcal pneumonia complicating Influenza A

A sinister synergy

Complications of Influenza A Virus

Iy Pneumonitis due to virus

What is role of cytokine storm?

Often fulminant and fatal Dyspnoea, wheeze, cyanosis, blood Diffuse CXR infiltrates (like ARDS) Pregnant, cardiac, young

Pandemic Influenza 1918/19

• Occurred in 3 waves• Globally estimated 750m-Ib.

ill

Morbidity

• Global mortality 23-50M• UK mortality 240K• Peak mortality - young adults

Mortality

Spanish ‘flu - Heliotrope cyanosis

“We have always been thankful when (facial) colour remains red …there is ample room for hope of recovery

When the colour of the patient’s face is heloitrope or mauvy-blue the prospect is grave indeed…”

1918/19

H5/N1 - Z genotype traced to geese in Guangdong, China 1996

Features Avian Influenza

1997: Hong Kong - 6/18 fatal (33%)

2003/7: Asia - 175/290 fatal (60%)

Majority < 25yr old

Severe disease in: older, late presentation + pneumonia, leuko/lymphopenia (16%)

Vietnamese cases – encephalopathy + diarrhoea

Multi system involvement and Multi organ damage at Post Mortem

COMPARING PANDEMICS

AGE Young Elderly Elderly

adult (young) (young)

‘notable’ S. pyogenes S. aureus S. aureus

BACTERIA + others

’18/’19 ’57/’58 ’68UK MORTALITY 240k 33k 30k E+W

Hot Topic Meeting by:

Royal College of Physicians of Edinburgh & The Scottish Executive Health Department

Pandemic Flu

Planning Scotland’s Health Response

5th June 2007

Queen Mother Conference Centre