Improving diagnosis of TB among HIV infected persons

Alwyn MwingaHIV Implementers Meeting

18 June 2007

Background – what do we know? Focus of TB control programs is Smear

positive cases Source of infection Program performance evaluated by

outcomes of smear positive cases TB programs in high TB/HIV settings

have increasing burden of smear negative disease Smear positive – 65% of total TB cases, 50%

of all cases Zambia 2005 – Sm + - 33% of PTB, 28% of

all cases

Current algorithimSmear negativeAntibiotic, CXRReview in 2-4 weeksIf no improvement, repeat sputum, x-rayIf smear negative, and pt and/or CXR worse,

seek other diagnosis, if no other diagnosis treat as TB

If pt stable, no change in x-ray, repeat sputum in 4 weeks

The prevailing practice

Empiric antibiotics trial = up to 4 weeks

AFB smears = up to 9

CXR = very late after a number of visits

Time before diagnosis = 13 – 44 days

Number of consultations = 5 – 7 times

Not included : HIV status, severity, culture

In the meantime patients die

Change in focus to smear negative disease

Delays in diagnosis Increased mortality in

smear negative disease

Public confidence in program

Transmission potential? – 17% transmission in NY(1999 – Behr, Lancet)

Improving diagnosis of smear negative disease Laboratory

10,000 bacilli/ ml required for positive result

Sample quality Concentration

methods Improved technical

capacity for lab techs Training QA/QC Work load

Introduction of more sensitive techniques

Fluorescent microscopy

Increased diagnosis of smear positive disease

Training, facilities, waste disposal

LED Expanded access to

culture Liquid culture

Improving diagnosis of smear negative disease Clinical evaluation

Include questions to identify HIV risk factors

HIV testing Introduce PICT for TB

suspects Earlier identification

of HIV status and consideration for other OIs

Radiological investigation

Supporting evidence for TB

Introduce earlier in diagnostic algorithm

Improving diagnosis of resistant cases

Introduction of culture for all cases failing treatment Failure at 5 months, 8 months Any smear positive results after an

initial smear negative result Routine culture at diagnosis for all

re-treatment cases