Abstract
BackgroundTuberculosis (TB) remains a major world health problem. Around 2 billions of people are infected by Mycobacterium tuberculosis, the causal agent of this disease. This fact accounts for a third of the total world population and it is expected that 9 million people will become infected each year. Only approximately 10% of the infected people will develop disease. However, health care workers (HCW) are continually exposed to the bacilli at endemic sites presenting increased chance of becoming sick. The objective of this work was to identify LTBI (latent tuberculosis infection) among all asymptomatic HCW of a Brazilian Central Hospital, in a three year follow up, and evaluate the humoral response among HCW with previous and recent LTBI to recombinant HspX and GlcB from M. tuberculosis.MethodsFour hundred and thirty seven HCW were screened and classified into three different groups according to tuberculin skin test (TST) status: uninfected, previous LTBI and recent LTBI. ELISA test were performed to determine the humoral immune response to HspX and GlcB.ResultsThe levels of IgG and IgM against the HspX and GlcB antigens were the same among HCW with recent and previous LTBI, as well as among non infected HCW. However, the IgM levels to HspX was significantly higher among HCW with recent LTBI (OD = 1.52 ± 0.40) than among the uninfected (OD = 1.09 ± 0.50) or subjects with previous LTBI (OD = 0.96 ± 0.51) (p < 0.001).ConclusionIgG and IgM humoral responses to GlcB antigens were similar amongst all studied groups; nevertheless IgM levels against HspX were higher among the recent LTBI/HCW.
Highlights
Tuberculosis (TB) remains a major world health problem
The World Health Organization (WHO) estimated 8.9 million of new cases of TB in 2004 and that one third of the world's population is infected by Mycobacterium tuberculosis (M. tb) [1,2]
Our findings show that the optical density (OD) range of IgG and IgM against the HspX and GlcB antigens was the same among health care workers (HCW) with recent and previous latent TB infection (LTBI), as well as among non infected HCW (Table 2)
Summary
Tuberculosis (TB) remains a major world health problem. Around 2 billions of people are infected by Mycobacterium tuberculosis, the causal agent of this disease. This fact accounts for a third of the total world population and it is expected that 9 million people will become infected each year. Tuberculosis (TB) remains one of the world's major public health problems. The World Health Organization (WHO) estimated 8.9 million of new cases of TB in 2004 and that one third of the world's population is infected by Mycobacterium tuberculosis (M. tb) [1,2]. Of low cost and relatively simple to administer, the TST suffers from a number of well-documented performance and logistical problems, such as the need for individuals to return for test reading, the variability and subjectivity in test application and reading and low specificity [5,6]
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