Study of the antibody response against Mycobacterium tuberculosis antigens in Warao Amerindian children in Venezuela

Mem Inst Oswaldo Cruz. 2004 Aug;99(5):517-24. doi: 10.1590/s0074-02762004000500011. Epub 2004 Nov 3.

Abstract

This study was aimed at investigating alternate methods for serodiagnosis of tuberculosis (TB), which are needed because bacteriologic diagnosis of childhood TB is difficult. A selection of 80 serum and saliva samples were tested from Warao indigenous children under 15 years of age; 34 high TB suspects (28 positive and 6 negative for the tuberculin skin test, TST) and 46 healthy contact children (32 positive and 14 negative for the TST). Several enzyme-linked immunosorbent assay (ELISA) serological tests were developed to test for Mycobacterium tuberculosis-specific antibodies, including serum IgA, IgG, IgE, and secretory IgA (sIgA) in saliva against 3 specific antigens (PPD, HSP60, 38 kDa). Of these, 2 antigens, PPD and 38 kDa, showed significantly higher reactivity. The sensitivity and specificity of these tests for diagnosis remained limited, between 26.5% and 38.2%, and 77.4% and 97%, respectively. Of all the samples studied and combinations realized between all isotypes and antigens combined with 3 isotypes (anti-PPD IgG, IgE, and anti-38kDa sIgA) managed to detect the largest number of patients, showing an improved sensitivity level of 64.7%, although specificity levels dropped to 81.8%. These results were compared with the Omega diagnostics commercial kit results. The commercial kits showed significantly lower reactivity (sensitivity of 20% and 13.33% to Myco G and Complex Plus, respectively) and a specificity of 100%. This study shows that in indigenous populations of Venezuela, where invasive procedures cannot be used to select samples but evaluation with a chest X-ray for radiological studies is available, the combination of 3 specific isotypes may be a useful tool to increase diagnostic accuracy with pulmonary TB in this population, when used together with clinical and epidemiological criteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Antibodies, Bacterial / blood
  • Antibodies, Bacterial / immunology*
  • Antigens, Bacterial / immunology
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Cross-Sectional Studies
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Immunoglobulins / analysis*
  • Immunoglobulins / immunology
  • Indians, South American*
  • Infant
  • Male
  • Mycobacterium tuberculosis / immunology*
  • Sensitivity and Specificity
  • Tuberculin Test / methods
  • Tuberculosis / diagnosis*
  • Tuberculosis / epidemiology
  • Tuberculosis / immunology
  • Venezuela / epidemiology

Substances

  • Antibodies, Bacterial
  • Antigens, Bacterial
  • Immunoglobulins
  • Mycobacterium tuberculosis antigens