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The Importance of Recent Infection with Mycobacterium Tuberculosis
in an Area with High HIV Prevalence
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Tuberculosis
virus
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The
proportion of cases of tuberculosis
due to recent infection can be estimated in long-term population-based
studies using molecular techniques. Here, we present what is, to
our knowledge, the first such study in an area with high HIV prevalence.
All
patients with tuberculosis in Karonga District, Malawi, were interviewed.
Isolates were genotyped using restriction-fragment-length polymorphism
(RFLP) patterns. Strains were considered to be "clustered"
if at least 1 other patient had an isolate with an identical pattern.
Results
RFLP
results were available from 83% of culture-positive patients from
late 1995 to early 2003. When strains with <5 bands were excluded,
72% (682/948) were clustered.
Maximum
clustering was reached using a 4-year window, with an estimated
two-thirds of cases due to recent transmission. The proportion clustered
decreased with age and varied by area of residence. In older adults,
clustering was less common in men and more common in patients who
were HIV positive (adjusted odds ratio, 5.1 [95% confidence interval,
2.1-12.6]).
The
proportion clustered found in the present study was among the highest
in the world, suggesting high
rates of recent HIV transmission. The association with
HIV infection in older adults may suggest that HIV has a greater
impact on disease caused by recent transmission than on that caused
by reactivation.
Department of Infectious Diseases, London School of Hygiene and
Tropical Medicine, London, United Kingdom.
07/11/05
Reference
J
R Glynn and others. The Importance of Recent Infection with Mycobacterium
tuberculosis in an Area with High HIV Prevalence: A Long-Term Molecular
Epidemiological Study in Northern Malawi.
Journal
of Infectious Diseases 192(3): 480-487. August 1, 2005.
Articles on Tuberculosis
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