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Leslie Z. SokolowLeslie Z. SokolowCenters for Disease Control and Prevention,Centers for Disease Control and Prevention,College of Public Health, Univ. of South FloridaCollege of Public Health, Univ. of South Florida

Analysis of Travel Pathways Analysis of Travel Pathways of Immigrants from Areas of Immigrants from Areas

with Avian Influenzawith Avian Influenza

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Avian influenzaAlso known as bird flu or H5N1

Lethal killerHighly contagious among birds

Can decimate wild and poultry flocks

Can infect without causing illness

Humans have no natural immunity

to current avian influenza strainNot easy for people to become infected

Setting for Pandemic Influenza

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Influenza is a unique viral pathogen Minor mutations all the timeRarely major mutation occurs

When a person is infected with more than 1 strainGenetic material is exchanged between 2 strains

Reassortment can create a novel viral pathogen

Combines worst features of both strainsMore contagious to humans + more resistance to our immune response = better killerbetter killerScenario for 1918 flu pandemic when 50M died

Setting for Pandemic Influenza

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Hint of threat nowNo reassortment between human and bird flu virus has knowingly occurred in many decades397 human cases of avian flu since 2003

63% died (249)

Most cases had contact with sick or dead birdsRare instance of human-to-human transmissionNone of these outbreaks became a pandemic

Reassortment was not factor in these casesThis form of influenza is virulent but not highly contagious to human

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Focus of Focus of

presentation is presentation is

on 3 countries on 3 countries

with highest with highest

case counts

case counts

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Places where people live in close proximity to birds, such as where…

Children play near their family flocks

High-risk locales

PHOTO: www.america.gov

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Places where people live in close proximity to birds, such as where…

Children play near their family flocksIn open-air poultry markets, where birds areslaughtered on site

High-risk locales

PHOTO: www.daylife.com

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Places where people live in close proximity to birds, such as where…

Children play near their family flocksIn open-air poultry markets, where birds areslaughtered on sitePolicy, poverty andculture deter people fromreporting sick birds

High-risk locales

PHOTO: www.daylife.com

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Special risks for US immigrantsImmigrants often maintain strong ties with their country of origin

Might inadvertently introduce avian flu into US while returning from visits to their country of origin if they have become infected while visiting

PHOTO:www.tsinoy.com

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Real Examples

SARS (2003) First brought to North America in a woman who had returned from a visit to Hong Kong

Transmission from this one case resulted in a 257-person outbreak in Toronto

Typhoid feverUS cases more prevalent among foreign-born travelers, accounting for 65% of all cases

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VFR travelersVFR = Visiting Friends and Relatives

Immigrants from a developing country who move to an industrialized country and then return to their home country to visit loved onesUsually travel by air

VFR travelers are uniqueTravel further and to more remote localesAway from home for longer periods of timeUnanticipated circumstances, like illness or death, may require last-minute travel plans

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VFRs: Higher risk of exposureMore likely

To have more close contact with local rural populations

To underestimate their exposure risk

To consume local foods and beverages

Less likelyTo have sought pre-travel medical advice

To have had vaccinations and appropriate preventative medication prior to travel

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VFRs: Higher risk of transmission

Poses substantial risk for US immigrant communities and general population

International travel easy and rapidPossible to get to US from almost anywhere in world in

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VFRs: Higher risk of transmissionRisk for transmission of influenza greatest when

infected people are shedding live virus

Usually by sneezing and coughing

Viral shedding peaks in first 2 days of illness

Person can be infectious >17 days

Infected person might shed virus

without feeling sick themselves

PHOTO: www.martinflufoundtion.org

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VFRs: Live in distinct communities1st generation immigrants tend to cluster together in specific neighborhoods

Family members enter US to join family already hereIn Minneapolis–St. Paul, 24% of residents are foreign born; many from SE AsiaIn Sacramento Valley, 65% of residents are foreign born, most from Central America or SE Asia

These cluster put certain metropolitan areas at greater risk for an epidemic

Furthermore airports used by VFR travelers can be sites for disease transmission

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Study Objectives

Identify US communities with large immigrant populations from areas with confirmed human cases of avian influenza

Identify areas most at risk for experiencing an epidemic if infected travelers return to US

Identify international air routes most likely to be used for travel between US immigrant communities and their home countries

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Study population

VFRs who enter US from the 3 countries with

highest number of avian influenza cases

75% of known cases (298)

Immigrant communities

identified as US counties with

500+ immigrants

AK, HI, PR & territories excluded

298Total107Vietnam 139Indonesia

52EgyptCase CtCounties

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Data sources: Immigrant communities

2000 US Census BureauInclusion in study defined as having been born in the country of interest

Born in VietnamVietnamBorn in IndonesiaIndonesiaBorn in EgyptEgypt

Definition for inclusion

Country of Origin

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Data sources: Air routes

US Bureau of Airline Statistics

T-100 Air Carrier statisticsAll flights that start or end in the US by airline company and service class

Inclusion criteriaInternational flights that ended in US

Only commercial flights with at least 100 passengers

6-month average for passenger volumeOctober 2006–March 2007

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Data sources: Flight choice

Assumption #1: VFRs would select most

convenient and economical route

Only international routes with one or no layovers

Route options that cost less than median price quote,

using Expedia.com

For majority of origination-destination pairings, at

least 25 feasible options were identified

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Assumption #2Once in US, distance from port-of-entry airport to their final community dictated transport mode

Data sources: Flight choice

Traveler would complete trip using ground transportation (car, bus, train)

Closer than 150 miles

Traveler would likely elect to fly to a secondary destination within US

150 miles or further

AssumptionDistance

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GIS Methods

3 map sets created using ArcGIS 9.2One map for each country of origin

DescriptionSet

Proximity of immigrant communities to US port-of-entry airports2

Location of major US immigrant communities1

Air routes used by VFR travelers3

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Map Set 1: Locations of major

immigrant communities

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People born in Viet Nam0 - 99

100 - 999

1000 - 4999

5000 - 9999

10000 - 111017

Counties with Vietnamese immigrants

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People born in Egypt0 - 99

100 - 499

500 - 1999

2000 - 4999

5000 - 13057

Counties with Egyptian immigrants (30)

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People born in Egypt0 - 99

100 - 499

500 - 1999

2000 - 4999

5000 - 13057

Counties with Egyptian immigrants (30)

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People born in Indonesia0 - 99

100 - 499

500 - 999

1000 - 4999

5000 - 11838

Counties with Indonesian immigrants

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Map Set 2: Proximity of major

immigrant communities to port-of-entry airports

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JFK

PHX

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SEA

SFO

RSW

PHL

ORD

MIA

MCO

LAX

LAS

IAH

IAD

EWR

DFW

BOS

! Primary international airport

150-mile radius of airports

508 - 1,499 born in Vietnam

1,500 - 9,999 born in Vietnam

10,000 - 111,017 born in Vietnam

Counties with Vietnamese immigrants

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JFK

PHX

BWI

SEA

SFO

RSW

PHL

ORD

MIA

MCO

LAX

LAS

IAH

IAD

EWR

DFW

BOS

! Primary international airport

150-mile radius of airports

508 - 1,499 born in Vietnam

1,500 - 9,999 born in Vietnam

10,000 - 111,017 born in Vietnam

Counties with Vietnamese immigrants

Many communities

Many communities

not served by portnot served by port--

ofof--entry airportsentry airp

orts

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PHX

SEA

TPA

LAS

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ACY

RDU

MSP

SFORIC

PHLORD

MIA

LAX

IAH

IAD

DTW

BOS

! Primary international airport

150-mile radius of airports

505 - 1,999 people born in Egypt

2,000 - 4,999 people born in Egypt

5,000 - 13,057 people born in Egypt

Counties with Egyptian immigrants

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MIA

LAX

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DTW

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! Primary international airport

150-mile radius of airports

505 - 1,999 people born in Egypt

2,000 - 4,999 people born in Egypt

5,000 - 13,057 people born in Egypt

Counties with Egyptian immigrants

Many communities

Many communities

served by portserved by port--ofof--

entry airportsentry airports

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Legend

! Jakarta via AmsterdamUS States150-Mile radius of airports

IndonesiaINDONESIA_

539 - 999 people born in Indonesia1,000 - 1,999 people born in Indonesia2,000 - 11,838 people born in Indonesia

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!SFO

ORD

MIA

MCO

LAX

JFK

IAH

IAD

EWR

BOS

SEA

150-Mile radius of airports

539 - 999 people born in Indonesia

1,000 - 1,999 people born in Indonesia

2,000 - 11,838 people born in Indonesia

Counties with Indonesian immigrants

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Legend

! Jakarta via AmsterdamUS States150-Mile radius of airports

IndonesiaINDONESIA_

539 - 999 people born in Indonesia1,000 - 1,999 people born in Indonesia2,000 - 11,838 people born in Indonesia

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!SFO

ORD

MIA

MCO

LAX

JFK

IAH

IAD

EWR

BOS

SEA

150-Mile radius of airports

539 - 999 people born in Indonesia

1,000 - 1,999 people born in Indonesia

2,000 - 11,838 people born in Indonesia

Counties with Indonesian immigrants

Many communities

Many communities

served by portserved by port--ofof--

entry airportsentry airports

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Most large immigrant communities have a port-of entry airport within 150 miles3 very large Vietnamese communities (at least 7500 residents) have no major airport near by

VFRs to these communities must take multiple flights when returning from visiting VietnamEach flight puts more travelers at risk, if a VFR is infected

VFR communities with no direct service to home country

Major Hub Local Airport Top Metropolitan Areas Vietnam

DEN Denver-Boulder-Greeley, COMSP Minneapolis-St. Paul, MN-WIPHX Phoenix metro, AZ

None

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Map Set 3: International Air

Routes and Airports Used by VFRs

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Routes from Vietnam

Pacific Ocean

Arctic Circle

Saigon

Ho ChiMinh City

TokyoSeoul

Manila

Taipei

Bangkok

LA, Chicago, Detroit, Wash DC, Dallas, Minneapolis, Newark, NY, SF, Seattle, Portland, Houston

TOKYO

LA, SFMANILA

LA, SF, SeattleTAIPEI

LA, SF, NY, Chicago, Atlanta,Seattle, Detroit, Dallas, Wash DC

SEOUL

LA, SFSAIGON

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Routes from Vietnam

Pacific Ocean

Arctic Circle

Saigon

Ho ChiMinh City

TokyoSeoul

Manila

Taipei

Bangkok

LA, Chicago, Detroit, Wash DC, Dallas, Minneapolis, Newark, NY, SF, Seattle, Portland, Houston

TOKYO

LA, SFMANILA

LA, SF, SeattleTAIPEI

LA, SF, NY, Chicago, Atlanta,Seattle, Detroit, Dallas, Wash DC

SEOUL

LA, SFSAIGON

VFRs returning to the East Coast must either VFRs returning to the East Coast must either travel via Seoul or Tokyo, or make a domestic travel via Seoul or Tokyo, or make a domestic connection in Los Angeles or San Franciscoconnection in Los Angeles or San Francisco

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Routes from Egypt

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Routes from Egypt

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•• Very few flights directly from CairoVery few flights directly from Cairo

•• Most Egyptian VFRs catch flights to US from Most Egyptian VFRs catch flights to US from Dubai or various European citiesDubai or various European cities

•• Difficult to predict routes with so many options Difficult to predict routes with so many options

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Pacific Ocean

Arctic Circle

Dubai

Manila

Shanghai

Hong Kong

Singapore

Jakarta via AmsterdamJakarta via Hong KongJakarta via ShanghaiJakarta via ManilaJakarta via SingaporeJakarta via Dubai

BOSBOSJFK, EWRJFK, EWR

IADIAD

MIAMIAMCOMCOIAHIAH

LAXLAX

SFOSFO

SEASEA

Routes from Indonesia

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Pacific Ocean

Arctic Circle

Dubai

Manila

Shanghai

Hong Kong

Singapore

Jakarta via AmsterdamJakarta via Hong KongJakarta via ShanghaiJakarta via ManilaJakarta via SingaporeJakarta via Dubai

BOSBOSJFK, EWRJFK, EWR

IADIAD

MIAMIAMCOMCOIAHIAH

LAXLAX

SFOSFO

SEASEA

Routes from Indonesia

•• No direct flights from JakartaNo direct flights from Jakarta

•• Most VFRs travel via major Asian cities or via Most VFRs travel via major Asian cities or via AmsterdamAmsterdam

•• Difficult to predict routes with so many optionsDifficult to predict routes with so many options

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Discussion

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Asia: Major ports-of-departure

Countries of Origin

TokyoTaipeiSingaporeShanghaiSeoulSaigonManilaHong Kong

VietnamIndonesiaAsian

Airports

Only Indonesia and Vietnam flights route through Asia

= airport located in country of origin

= airports outside country requiring additional travel

These are the Asian airports of concernEach additional leg may increase exposure to an infected VFR

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Europe: Major ports-of-departure

ViennaParisMilanHeathrowGatwickKievFrankfurtDubaiCairoAthensAmsterdam

IndonesiaEgyptEuropean Airports

Countries of OriginOnly Egypt and Indonesia flights route through EuropeFew flights directly from Cairo

Sick travelers could stop in a multitude of European airports

Indonesia has historic link with AmsterdamDubai grow hub between East and West

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Arrival traffic at US ports-of-entry

4.3%2,185Houston*90.5%Total* Large communities

5.3%2,694Detroit 6.7%3,439Boston*8.5%4,340Wash DC* 9.1%4,674Newark*

15.0%7,686San Francisco* 20.2%10,353New York*21.4%10,967 Los Angeles*

% of Traffic

Ave Daily PassengerPorts-of-Entry

3 airports = 57% of international traffic

LAX, JFK, SFO5 others have >2,100 people arriving daily90.5% of all US arrivals from study countries

Double passenger number to account for departing travelers who are also exposed to infection

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Public Health ActionWhat do we do with this information?

PH authorities can study travel patterns by VFRs to guide surveillance activities aimed at early detection of human cases of avian influenza

CDC has published information specifically for air travel from these countries

“Interim guidance for airline flight crews and persons meeting passengers arriving from areas with avian influenza”

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Airport Medical Quarantine StationsPart of CDC’s mandate

Pre-SARS, no posted medical officers at US airports for >40 years

Post-SARS2004–05: CDC opened 10 new

stations at major US ports of entry

By 2007: 9 more stations opened All but one at an international airport

Similar efforts being conducted by other countries

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ns

nsns

nsnsnsnsns

nsns

ns

nsns ns

nsns

ns

El Paso

Philadelphia

Newark

Dallas

Boston

Houston

Phoenix Atlanta

ChicagoDetroit

Seattle

New York

San Diego

Washington

Los Angeles

Minneapolis

San Francisco

Airport Medical Quarantine Stations

(1) Anchorage, Honolulu and San Juan not shown(2) El Paso is not located at an airport

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Education VFR travelers

Lastly - importance of receiving flu vaccination before traveling to areas where human avian influenza has been confirmed

People who are not infected with the seasonal human strain are less likely to be vessels for genetic reassortment

Need to address obstacles and perceived barriers in culturally appropriate ways to increase vaccination rate among VFR travelers

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AcknowledgementsCenters for Disease Control and Prevention

Jim Tobias, Enterprise GIS David Shay, Influenza DivisionSonja Hutchins and Benedict Truman, Minority Health

University of South FloridaAurora Sanchez-Anguiano, College of Public Health

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Questions?

Feel free to contact me atlsokolow@cdc.gov