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Air Travel & Infectious Disease

Air Travel & Infectious Disease. Dr David Hagen Consultant in Communicable Disease Control UK Health Protection Agency JAA Advanced Aviation Medicine Course June 2011. Incorrect Public Perception of risk whilst flying. Sick passenger = higher risk for other passengers

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Air Travel & Infectious Disease

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  1. Air Travel & Infectious Disease Dr David Hagen Consultant in Communicable Disease Control UK Health Protection Agency JAA Advanced Aviation Medicine Course June 2011

  2. Incorrect Public Perception of risk whilst flying • Sick passenger = higher risk for other passengers • Little direct evidence of on-board transmission • Airport terminals – eating, drinking, socialising, toilet facilities • Previous outbreaks – passengers were on same holiday so acquired prior to flight • Public Health Authorities have propagated the myth • There are existing guidelines and plans

  3. Methods of transmission • 1) Direct Contact • Touching • Kissing • Sexual Contact • Body lesions • Close contact: family, household, sexual

  4. 1) Direct Contact • Sexually Transmitted Diseases • Crew?

  5. 2) Indirect Transmission • Contaminated surfaces • Viruses particularly, can survive for long periods • Washrooms, handles, surfaces, handrails • Influenza

  6. 2) Indirect Transmission • Petri Dish after a sneeze

  7. 3) Droplet Transmission • Large Particles • Sneezing • Coughing • Talking

  8. 4) Airborne Transmission • Rarer than you think • Coughing • Dry particles • Nuclei • Chickenpox, TB measles

  9. 5) Faecal - oral • Contaminated food and water • Outbreaks • Hygiene • Disinfection of aircraft

  10. 6) Vector-borne transmission • Mosquito • Malaria • West Nile • Dengue • Disinsection of aircraft

  11. Infectious Disease: Interventions

  12. International Health Regulations (IHRs) 2005 • WHO member states • ‘protect against, control and provide a public health response to the international spread of disease in ways that are commensurate with and restricted to public health risks, and which avoid unnecessary interference with international trade and traffic’

  13. International Health Regs • 1) Four diseases: • Smallpox • Poliomyelitis due to wild-type virus • Human influenza caused by new subtype • Severe Acute Respiratory Syndrome (SARS)

  14. International Health Regs • 2) Other risks which may be chemical, biological & radiological • 3) Public Health Emergencies of International Concern (PHEICs) • National Focal Point for each country

  15. Guidance on infectious disease

  16. Tuberculosis – guidance based on: • CDC Review of six incidents showed that 2 had possible transmission on long-haul flights • 2600 pax, no active disease • 3 Factors: • Within 2 rows • Over 8 hours duration • Highly infective case

  17. Tuberculosis • 3rd Ed June 2008 • MDR TB, although more difficult to treat is not more transmissible • 10% world population carry latent infection • No real evidence that recent expensive lookbacks have yielded results

  18. Severe Acute Respiratory Syndrome (SARS) • 2003 • Respiratory droplet and faecal-oral • Rapid spread to 2 dozen countries in N America, S America, Europe & Asia

  19. SARS – The illness • Coronavirus • Long incubation (3-10 days) • Not infectious until symptoms present • General infection control measures

  20. SARS – The spread • Newly emerging Global Threat • November 2002 • Guangdong province • Physician travelled to Hong Kong by air

  21. SARS – The response • WHO travel alerts • WHO travel advisories • Crew and airport advice given • Household advice for cases • Healthcare facilities infection control advice • Public areas - advice

  22. SARS – The cost • Worldwide flights fell by 3% (mid-June 2003) compared to year before • Cost 40b USdollars • China flights dropped by 45% • Public perception of risk of air travel

  23. Pre-requisites for pandemic influenza • New influenza A sub-type: Haemagglutinin (H) • unrelated to immediate (pre-pandemic) • predecessor. • Little or no pre-existing population immunity • Causes significant clinical illness • Efficient person-to-person spread

  24. 1918: “Spanish Flu” 1957: “Asian Flu” 1968: “Hong Kong Flu” 40-50 million deaths 1 million deaths 1 million deaths Circulating influenza strains in humans and pandemics in 20th Century H3N2 H2N2 H1N1 >H1N1-2009 1920 1940 1960 1980 2000

  25. The Influenza virus • 1) An RNA virus • 2) Three types: A, B, and C • 3) A & B are major human pathogens: give rise to ‘normal’ epidemics in winter • 4) Only influenza A virus is recognised as having potential to cause a pandemic

  26. Influenza A virus N N H H 16 haemagglutinins (H); 9 neuraminidases (N)

  27. Pandemic Flu – Travel Restrictions • Modelling suggests that 99% restrictions on world-wide air travel would delay the peak by only 1-2 weeks

  28. Pan Flu – The ‘Layered Approach’ • Causes of influenza-like illness in passengers will be varied • Asymptomatic infected passenger will not be detected on screening • Travellers who incubating illness may develop symptoms en-route (long-haul)

  29. The Layered Approach • Pre-embarkation measures • En route measures • Upon arrival measures

  30. Pre-embarkation Measures • Fitness to Fly • Self-administered medical questionnaire • Questioning pax by trained staff • Thermal imaging • Airline staff screening at check-in & departure gate (assisted by ground-based medical support)

  31. En-route measures • Existing IATA Guidelines • Cabin crew • Maintenance crew • Cargo crew • Bird strike • Passenger agents • And more

  32. ICAO definition of communicable disease

  33. IATA Flu Hygiene Flyer

  34. Captain notifies ATS

  35. Airport Ops notifies event

  36. WHO: Passenger Locator Card • WHO endorsed • To obtain public health information • 2 rows in front and 2 rows behind • For use by country’s public health agency

  37. PLCs 2 rows either side

  38. Airflow Pattern on Aircraft • Modern aircraft have little fore and aft flow, and circular flow laterally.

  39. Arrival Measures • Mirrors pre-departure screening • Self-administered questionnaire • Staff questioning or administers questionnaire • Thermal screening

  40. What to do with positives • Medical examination • Isolation of ill • Quarantine of those not yet ill • National legislation required as well as facilities

  41. Time line: the H1N1 pandemic experience

  42. Norovirus • Worldwide • Direct, indirect & droplet transmission • Low infective dose • 24-48 hr incubation • Sudden onset • Self-limiting illness • Most common cause of outbreaks • WHO Aircraft disinfection document

  43. The End • Any questions?

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