Tuberculosis– meeting the challenge of a global pandemic at molecular level
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AbstractWe showed that a well established epidemic in rural Bangladesh represented a low rate of recent transmission. A majority of the strains belonged to the ancient East African- Indian (EAI) lineage (Paper I).
Our study found that the total resistance among new cases to any drug was 31%, 2% were MDR. The NTP in Sunamganj is still effective, although the high resistance to INH is alarming (Paper II), and DST services were possible and highly needed.
Due to the low rate of transmission in the high-incidence area, it was likely that most patients had been infected a long time ago. We thus wanted to measure the impact DD could have in similar high incidence settings (Paper IV). In order to study the impact of DD, an introductory review of published studies describing DD in numerous countries was conducted (Paper III). We found the core problem in DD to be a vicious cycle of repeated visits at the same healthcare level, resulting in non-specific antibiotic treatment and failure to access specialized TB services.
To reduce the DD there is an urgent need for alternative means to monitor the epidemic at the local level. We found that a systematic registration of treatment delay in the TB program records of the Amhara Region of Ethiopia could be utilized to estimate the infectious pool of TB. By recording the treatment delay for new TB cases, retreatment cases and failures, and by estimating the number of undiagnosed cases, the total number of infectious days and, hence, an estimate of the infectious pool could be calculated (Paper IV).
Since DD was considerable in the high-incidence setting we wanted to compare to risk-groups in developed countries with a low-rate of TB (Paper V). Health care workers exposed to TB at three Norwegian hospitals as well as a non-exposed control group were tested with both TST and the INF-ã test T-SPOT.TB. Our data indicate that the frequency of latent TB in the total cohort of HCWs is 3% whereas the rate of transmission of TB to exposed individuals is around 2% and occurs through short time exposure. Thus, the risk of TB transmission to health care workers following unprotected TB exposure in a hospital setting in Norway is low.
List of Papers
I. Storla DG, Rahim Z, Islam MA, Plettner S, Begum V, Mannsaaker T, Myrvang B, Bjune G, Dahle UR. Heterogeneity of Mycobacterium tuberculosis isolates in Sunamganj District, Bangladesh. Scand J Infect Dis 2006;38 (8):593-6
II. Storla DG, Rahim Z, Islam MA, Plettner S, Begum V, Myrvang B, Bjune G, Rønnild E, Dahle UR, Mannsåker T. Drug resistance of Mycobacterium tuberculosis in the Sunamganj District of Bangladesh. Scand J Infect Dis, 2007. 39(2): 142-5
III. Storla, DG, Yimer S & Bjune G. A systematic review of delay in the diagnosis and treatment of tuberculosis. BMC Public Health, 2008. Jan 14;8:15. Artikkel i fulltekst i pdf-filen
IV. Storla, DG, Yimer S & Bjune G. Can diagnostic delay be utilized as a key variable for monitoring the pool of infectious TB in a population? (submitted).
V. Storla, DG, Kristiansen I, Oftung F, Korsvold GE, Gaupset M, Gran G, Øverby AK, Dyrhol-Riise AM, & Bjune GA. Use of Interferon Gamma-Based Assay to Diagnose Tuberculosis Infection in Health Care Workers after Short Exposure (submitted).