Download a local perspective from Coventry

TB: The Coventry perspective
Dr Thekli Gee
University Hospitals Coventry & Warwickshire
Outline
TB in Coventry:
• Epidemiology
• Resources
• New diagnostic approaches
Epidemiology
Occurrence
• Nearly a third of the
world’s population is
infected with TB
• TB kills almost 3 million
people per year.
Tuberculosis notifications
England & Wales
1913 - 2006
chemotherapy
BCG vaccination
Source: Statutory Notifications of Infectious Diseases (NOIDs)
Coventry TB rate by year 1999-2006
Coventry
2007
Rate per 100,000 population
35
30
25
20
rate
Coventry PCT
West Midlands
England & Wales
Linear (Coventry PCT)
15
10
5
0
1999
2000
2001
2002
2003
2004
2005
2006
Tuberculosis case reports and rates by region/country,
England, Wales and Northern Ireland, 2006
Coventry
2007
Coventry
Why Is TB Increasing?
Why Is TB Increasing?
Multiple contributing factors:
•
•
•
•
•
•
Homelessness
Intravenous drug use
HIV infection
Drug-resistant strains of TB
Reduced TB control and treatment resources
Immigration from high TB prevalence areas
Tuberculosis case reports by place of birth and ethnic
group, England, Wales and Northern Ireland, 2001 - 2006
Changing populations
• Coventry City council
– 1215 asylum seekers on housing list
• Coventry refugee centre
– 8000 asylum seekers & refugees
registered
– 1571 registered at Meridian Health Centre
Changing populations
• Afghanistan
• Iraq
• Iran
• Burundi
• Democratic Republic of
Congo
• Ethiopia
• Eritrea
• Somalia
• Sudan
• Zimbabwe
Resources
Increasing numbers of TB cases

Increased demand on TB services
Impact on resources
• Hospital & community TB services
– TB clinic
– TB nurse time
• Infection control
– Isolation facilities
– TB incidents
• Occupational health
– Pre-employment screening
– HCW contacts
• Laboratory services
Impact on resources
• Hospital & community TB services
– TB clinic
– TB nurse time
• Infection control
– Isolation facilities
– TB incidents
• Occupational health
– Pre-employment screening
– HCW contacts
• Laboratory services
TB incidents at UHCW NHS Trust
• 23 incidents in since January 2007
– 18 Patients
•
•
•
•
Not isolated early enough / at all during admission
Mostly medical wards
2 Cardiothoracic ward
1 haematology day unit
– 5 Health care workers
• 3 qualified nurses
• 1 nursing student
• Ward host
Impact on resources
• Hospital & community TB services
– TB clinic
– TB nurse time
• Infection control
– TB incidents
– Isolation facilities
• Occupational health
– Pre-employment screening
– Annual reminders
– HCW contacts
• Laboratory services
2007
Impact on resources
• Hospital & community TB services
– TB clinic
– TB nurse time
• Infection control
– TB incidents
– Isolation facilities
• Occupational health
– Pre-employment screening
– Annual reminders
– HCW contacts
• Laboratory services
2006
TB national strategy
2004
2007
2006
2007
Controlling TB:
1. Diagnosing primary cases
2. Treating active disease
3. Preventing transmission
4. Identifying secondary cases
5. Controlling latent infection
Current diagnostic test for latent TB
• Diagnosis of latent TB
relies on the tuberculin
skin test.
• 101 years old
– Developed 1907 by
Charles Mantoux
• The oldest diagnostic
test still in use.
The skin test enters its 6th decade of use.
(Canada 1957)
Tuberculin skin tests
• Mantoux test
48-72 hours later
• Heaf test
No longer available
Tuberculin skin tests
• Poor specificity:
– antigenic cross-reactivity
• BCG
• environmental mycobacteria
• Poor sensitivity:
– 75-90% in active disease
• lower in disseminated TB and HIV infection
• Need for return visit
– 50% DNA rate
• Operator variability
– inoculation & reading
• Painful inflammation & scarring
• Boosting effect if used repeatedly
New approaches
TB Interferon-g release assays
(TIGRA)
• Principle of TIGRA
– Detect IFN-g produced by effector T-cells
that recognise M. tuberculosis proteins
ESAT-6 & CFP-10
• Absent in BCG
• Absent in most non-tuberculous Mycobacteria
– Exceptions: M. marinum, M. kansasii
Two Tests available
T-Spot.TB®
QuantiFERON Gold®
Detects individual effector Tcells that produce IFN-g in
response to M.tuberculosis
antigens
Measures IFN-g in the
supernatant of the antigen
stimulated cells
Enzyme linked immunospot
technique (ELISPOT).
Enzyme linked
immunosorbant assay
technique (ELISA)
T-Spot.TB®
Sensitivity
Immunocompetent 83-97%
Immunocompromised <1% indeterminate results
+ malnourished
+ children
Quantiferon Gold®
70-89%
20-24% indeterminate results
T-Spot.TB®
Sensitivity
Immunocompetent 83-97%
Immunocompromised <1% indeterminate results
+ malnourished
+ children
Specificity
99.99%
Quantiferon Gold®
70-89%
20-24% indeterminate results
98%
T-Spot.TB®
Sensitivity
Immunocompetent 83-97%
Immunocompromised <1% indeterminate results
+ malnourished
+ children
Quantiferon Gold®
70-89%
20-24% indeterminate results
Specificity
99.99%
98%
Cost
(including labour etc)
£55-60
per test
£30
per test
T-Spot.TB®
Sensitivity
Immunocompetent 83-97%
Immunocompromised <1% indeterminate results
+ malnourished
+ children
Quantiferon Gold®
70-89%
20-24% indeterminate results
Specificity
99.99%
98%
Cost
(including labour etc)
£55-60
per test
£30
per test
Problems
•Must process within 8 hours of
venepuncture
•Must process within 8 hours of
venepuncture
-in tube assay?
•Expertise in cell separation
•Not reliable enough in the
Immunocompromised & children
Method - T-Spot.TB®
• Specimens must be processed within 8 hours of venepuncture
ELISPOT
-ve
+ve
ELISPOT Reader
Role of TIGRAs
• Detection of latent TB:
– TB contacts
– Healthcare workers
• New employment screens
• Following TB exposure incidents
– Before starting immunosuppression
• anti-TNF-α drugs e.g infliximab
• Pre-transplantation
• Detection of active extra-pulmonary TB
– If difficult to diagnose by conventional methods
– Closely competing diagnoses e.g. Sarcoid vs TB
Contact tracing:
When to use a TIGRA
– NICE:
• Following positive Mantoux test
– Most cost effective
– May miss some cases
– CDC
• In place of Mantoux test
– Shifts burden of work from TB nurses to lab
Business case
• Laboratory service
– 5 day to 6 day service
– Warwickshire wide (Network)
• TIGRA
– Tspot.TB
– Microbiology / Immunology
Summary
• TB increasing in Coventry
• Increased demand on resources
• New approaches considered
– e.g. TIGRAs