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Transcript
Migration, public health and
compulsory screening for TB and
HIV
Richard Coker
8th October 2003
•
•
•
•
The purpose of screening
Epidemiological trends
What risk?
Effective tools, effective
policies?
• Will compulsion improve
effectiveness?
• Conclusions
On the agenda
• ‘Read This And Get Angry’ Sun, 29 Jan 2003
• ‘The Secret Threat to British Lives’ The Spectator, 25
Jan 2003
• ‘No System to Abuse: immigration and health care in
the UK’ Centre for Policy Studies, May 2003,
• ‘Before It’s Too Late: A New Agenda for Public Health’
Conservative Party consultation paper, August 2003
• Inquiry into ‘Imported Infections’ Cabinet Office,
announced Jan 2003
• ‘Migration and HIV: Improving Lives in Britain’ AllParty Parliamentary Group on AIDS, July 2003
Before It’s Too Late
Advocates 3 tests before permission given to remain in the UK:
1.
2.
3.
They must not pose a risk of transmitting an infectious disease to the public
They must not create undue demand on restricted health resources
They must not create a long-term drain on the public purse
‘those entering the UK through the immigration system
would require [sic] to have such tests at the point of application
and to pay for them, whilst those seeking asylum would be
detained until it was clear the criteria had been met’
Purpose of Screening
• To identify individuals with infection in
order to provide the appropriate care and
treatment for that individual
• To prevent public health consequences of
undetected infectious disease through case
detection
Tuberculosis: key national facts (1)
Since 1988, number of cases of TB
and the rate has increased
•
Proportion born abroad has also
increased
•
Poverty, overcrowding, exposure
risk
•
Treatment of TB costs approx.
£6,000
Tuberculosis case reports, by geographic
origin, England and Wales, 1988 - 2000
7000
6000
No. of cases
•
5000
Unknown origin
4000
Born abroad
3000
Born in the UK
2000
1000
0
1988
1993
1998
1999
2000
Year
Sources: Tuberculosis case reports (1988, 1993, 1998: National TB survey; 1999, 2000: TB Enhanced
surveillance), Population figures: ONS estimates
Tuberculosis: key national facts (2)
• Half of those born abroad who
develop TB do so within 5 years
• Perhaps 0.3% of asylum seekers
have TB at port screening, and of
these only ¼ have infectious
disease
• Number of cases detected through
Heathrow represents less than
0.5% of cases
• Asylum seekers represent a
fraction of immigrants – but it is
principally asylum seekers who
are currently screened
• In one study, screening systems
failed to identify 60% of new
immigrants with TB
Tuberculosis case reports born abroad by
time since entry into the UK
Immigrant-associated TB: a public
health threat?
• Evidence from many sources
– US states with high levels of
TB in foreign-born persons do
not correspondingly have high
rates in those born in US
– From DNA finger-printing,
most TB in London is
reactivation
– From Denmark a study showed
that transmission between
immigrants and native-born
Danes almost non-existent
Correlation between State-Specific Tuberculosis
Case Rates for
Foreign-Born Persons and U.S.-Born Persons in
the United States, 1986 to 1993
HIV: key facts (1)
Heterosexually acquired infection by
sub-category of heterosexual
• At end 2001, estimated
41,000 adults living with
HIV in the UK
• Most heterosexuallyacquired HIV is acquired or
linked to abroad (71% to
Africa)
Sex between men & women (total)
No evidence "high risk" partner: Exposure abroad
No evidence "high risk" partner: Exposure UK
Exposure to "high risk" partner
3500
3000
Number of diagnoses
• Proportion infected through
heterosexual sex is
increasing
exposure
2500
2000
1500
1000
500
0
1985 1986 1987
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Year of diagnosis
Immigrant-associated HIV: a public
health threat?
•
•
Of 2,046 individuals infected in the UK,
at least half were infected through
heterosexual sex with someone
originating from outside Europe
London-based study suggested that 9%
of heterosexually-acquired HIV in black
Africans acquired in UK
•
Migrants returning
•
Potentially many people unaware and
unsuspecting of their HIV status (black
Africans > white)
Origin of HIV infection in those acquiring HIV
heterosexually
Exposure from someone
originating from
someone outside Europe
Exposure from someone
originating from
someone within Europe
Unknown
2 cardinal questions:
• Does screening detect those with the
condition?
• Will screening assist in achieving the
desired public health objective?
Does screening detect those with the
condition?
• HIV: it depends
• TB: it depends
Screening for HIV
• The tests are sensitive and specific
• But focused screening may assume
– That immigrants from high prevalence countries have
prevalence rates that reflect donor countries
– That populations freely able to move don’t pose a threat
(new eastern European border)
– That those not screened will be served by other systems
(illegal immigrants, transient populations)
X-rays to detect TB
Theoretical population with
prevalence rate of
600/100,000
10,000 immigrants screened
Theoretical
population with
prevalence rate
of 40/100,000
10,000 immigrants
screened
Expected number of cases of disease
60
4
Number of cases of TB detected through Xray screening
45
3
Number of cases of TB missed through Xray screening
15
1
but
100
100
Proportion of people identified with TB
who actually have it
31%
3%
Number of people without
classified as having TB
TB,
X-ray at screening and 6 months
later, Swiss asylum seeker
Will screening assist in achieving the
desired public health objective?
• TB
– Evidence is lacking
• No clinical trials
• DH-funded transmission and economic model due to report
shortly
• HIV
– Screening only confers public health benefit if effective
action follows
– Evidence is lacking
• Refusing entry to HIV-infected immigrants
– May reduce burden of disease, costs, and future
transmission
– May stigmatise, ensure evasive practices
– How often should people be screened?
– Illegal in asylum seekers
• Should they be isolated? For how long?
• Does the risk arise because of status or behaviour?
Coercion and protection of the public
health
• Long historical tradition, with little
evidence of benefit of detention or
compulsory screening
• May show that the ‘government is seen to
be taking firm, decisive action and the
epidemic appears to be under control’ (Panos
Institute)
• Coercive measures may be
counterproductive
Step 1:
Demonstrate
Risk
Step 2:
Demonstrate
Intervention’s
Effectiveness
Step 3:
Assess Economic
Costs
Step 4:
Assess Burdens
on Individuals
Step 5:
Assess Fairness
of Policy
Public Health Authorities Bear the Burden of Justification
Conclusion (1)
• Increases in HIV and TB rates are linked to
immigration, but have been difficult to quantify
• These changes may reflect, in part, global trends
• Most TB occurs in people after entry
• There is probably a substantial population of HIVinfected people in the UK unaware of their status
who pose a public health challenge
Conclusion (2)
• Evidence-base to support TB screening of
immigrants is weak
• Screening tests for TB lack validity
• Screening tests for HIV are reliable
• Evidence is lacking regarding screening
immigrants for HIV
• Significant ethical, moral, legal and practical
issues are raised with coercive measures
• Coercive screening practices may result in
unforeseen perverse consequences
Purpose of Screening
• To identify individuals with infection in
order to provide the appropriate care and
treatment for that individual
• To prevent public health consequences of
undetected infectious disease through case
detection