Contribution of reinfection to recurrent tuberculosis in South African gold miners.
METHODS
A gold mine in South Africa.


OBJECTIVE
To investigate incidence and risk factors for tuberculosis (TB) recurrence and the relative contribution of reinfection and relapse to recurrence.


METHODS
Prospective cohort study.


METHODS
Employees cured of a first episode of culture-positive TB were followed up for recurrence, which was classified as reinfection or relapse by restriction fragment length polymorphism using an insertion sequence (IS) 6110 probe.


RESULTS
Among 609 patients, 57 experienced recurrence during a median follow-up period of 1.02 years, corresponding to a recurrence rate of 7.89 per 100 person-years (py). The culture positive recurrence rate was 5.79/100 py, and was higher in human immunodeficiency virus (HIV) infected patients (8.86/100 py in HIV-infected vs. 3.35/100 py in non-HIV-infected). Among HIV-infected patients, the risk of culture-positive recurrence was higher with decreasing CD4 count (compared with CD4 < 200, hazard ratios for recurrence among individuals with CD4 200-500 and CD4 > 500 were 0.40 [95%CI 0.14-1.09] and 0.14 [95%CI 0.02-1.10], respectively, Ptrend = 0.01). IS6110 genotyping was available on both the initial and subsequent isolate for 16/42 (38%, 14 HIV-infected) patients with culture-positive recurrence, and showed reinfection in 11 (69%).


CONCLUSIONS
HIV-infected gold miners, particularly those who are more immunosuppressed, are at higher risk of TB recurrence. TB control strategies need to take into account reinfection as an important cause of recurrent TB.
Charalambous
S
S
Aurum Institute for Health Research, Johannesburg, South Africa. salomec@auruminstitute.org
Grant
A D
AD
Moloi
V
V
Warren
R
R
Day
J H
JH
van Helden
P
P
Hayes
R J
RJ
Fielding
K L
KL
De Cock
K M
KM
Chaisson
R E
RE
Churchyard
G J
GJ
D000328:Adult; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D006046:Gold; D015658:HIV Infections / Q000150:complications; D006801:Humans; D016867:Immunocompromised Host; D008297:Male; D008875:Middle Aged; D008906:Mining; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors; D013019:South Africa / Q000453:epidemiology; D014376:Tuberculosis / Q000453:epidemiology* / Q000635:transmission
D006046:Gold