Recent transmission of tuberculosis involving retired patients

• Published in: The Journal of infection Vol. 53; no. 6; pp. 370 - 376
• Main Authors: Cafrune, P.I., Riley, L.W., Possuelo, L.G., Valim, A.R.M., Borges, M., Ribeiro, M.O., Rossetti, M.L.R., Zaha, A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-12-2006; Elsevier
• Subjects: Adolescent; Adult; Age Factors; Aged; Bacterial diseases; Biological and medical sciences; Brazil; Brazil - epidemiology; Female; General aspects; Genotype; Genotyping; Human bacterial diseases; Humans; Incidence; Infectious diseases; Male; Medical sciences; Middle Aged; Mycobacterium tuberculosis; Mycobacterium tuberculosis - classification; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - isolation & purification; Polymorphism, Restriction Fragment Length; Recent transmission; Retired patients; Retirement; Rio Grande do Sul State; Risk Factors; Sex Factors; Tuberculosis; Tuberculosis - epidemiology; Tuberculosis - transmission; Tuberculosis and atypical mycobacterial infections; South America; Brazil; America; Brazil; Retired patients; Rio Grande do Sul State; Tuberculosis; Genotyping; Recent transmission; Infection; Human; Mycobacterium tuberculosis; Mycobacteriales; Transmission; Bacteriosis; Mycobacteriaceae; Bacteria; Actinomycetes; Mycobacterial infection
• ISSN: 0163-4453; 1532-2742
• DOI: 10.1016/j.jinf.2005.12.027

The reported incidence of tuberculosis (TB) in three different regions of Rio Grande do Sul State in Brazil varies considerably. We used IS
6110-RFLP and spoligotyping methods to genotype
Mycobacterium tuberculosis isolates obtained from 268 patients between 1998 and 2000 in order to assess the levels of recent transmission of TB in the three regions. The degree of clustering of the strain types did not differ among the three regions; neither did other characteristics such as demographic features, underlying medical conditions, or the proportion of resistant TB. As reported previously, male patients were at greater risk of developing TB and our data suggest that part of this may be related to the higher rates of recent transmission among them (
P
<
0.05). In addition, we found that retired patients were almost 3 times more likely to be infected with cluster-pattern strains than patients reporting any other occupation (
P
<
0.05), and more than 3 times more likely than non-retired patients in the same age group (
P
<
0.05) to be infected with cluster-pattern strains. We conclude that recent transmission is not a major factor contributing to the differences in TB incidence in the three regions of Rio Grande do Sul. The reason for the suggested high proportion of recent transmission TB cases among the retired people needs further studies.