Prevalent infectious tuberculosis in Harare, Zimbabwe: burden, risk factors and implications for control.
METHODS
Harare's high density suburbs.


OBJECTIVE
To investigate the burden, duration and risk factors for prevalent tuberculosis (TB) and explore potential control strategies.


METHODS
Randomly selected adults had TB culture, symptom screen and human immunodeficiency virus (HIV) serology. Prevalent TB was defined as undiagnosed or still culture-positive. Notification data and HIV prevalence in TB out-patients were used to estimate duration of infectiousness (prevalence/estimated incidence).


RESULTS
Among 10 092 participants, 40 (0.40%, 95%CI 0.28-0.54) had prevalent smear-positive TB. HIV (adjusted odds ratio [aOR] 3.1, 95%CI 1.6-6.3, population attributable fraction [PAF] 33%), male sex (aOR 3.1, 95%CI 1.5-6.4, PAF 40%), and overcrowding (PAF 34%) were significant risk factors, with past TB treatment significant for HIV-negative participants only (PAF 7%). Recent household TB contact was not significant (PAF 10%). HIV prevalence was 21.1%; 76.9% of HIV-positive participants were previously untested. Duration of infectiousness was at least 18 weeks in HIV-positive and approximately 1 year in HIV-negative patients.


CONCLUSIONS
Overcrowding, male sex and HIV infection were major risk factors for prevalent smear-positive TB. Reducing diagnostic delay may have greater potential to improve the control of prevalent TB than interventions targeted at household contacts, TB treatment outcomes, or TB-HIV interventions under current levels of awareness of HIV status.
Clinical Research Unit, London School of Hygiene & Tropical Medicine (LSHTM), London, UK. lizcorbett04@gmail.com
E L
EL
Corbett
T
T
Bandason
Y-B
YB
Cheung
B
B
Makamure
E
E
Dauya
S S
SS
Munyati
G J
GJ
Churchyard
B G
BG
Williams
A E
AE
Butterworth
S
S
Mungofa
R J
RJ
Hayes
P R
PR
Mason
D000293:Adolescent; D000328:Adult; D003140:Communicable Disease Control / Q000379:methods*; D017281:Cost of Illness; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D012111:Residence Characteristics / Q000706:statistics & numerical data; D012307:Risk Factors; D012737:Sex Factors; D014376:Tuberculosis / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D055815:Young Adult; D015030:Zimbabwe / Q000453:epidemiology