Letters to the Editor

Indian Pediatrics 2002; 39:880-881

B.C.G. and T.T.

In the article "Prevalence of Tuberculous Infection in Children Below Fourteen Years in Rural Haryana "(1), two misconceptions need to be clarified rightaway.

1. The cutoff point for the tuberculin test has always been 10 mm or more and not more than 10mm as stated by the authors. A 10mm reading in the tuberculin test should be considered as positive(2,3).

2. The authors have reported "many children with no (0mm) reaction to tuberculin despite having received the B.C.G., vaccine and say this could be due to poor reactivity to BCG; waning of immunity, error during administration or a poor quality vaccine. However, considerable data is now available to show that using the tuberculin test as a means of testing B.C.G. efficacy is a pretty crude method of assessing the vaccine efficacy. Several reports(4) have shown a persistence of invitro lymphocyte responses to tuberculin in skin test negative children immunized with B.C.G. in infancy. Also some authors(5) have shown that in the absence of a positive tuberculin test, cell mediated immune reaction could be elicited by leukocyte migration inhibition test indicating that an absent skin response does not mean an absent cell mediated immune response. Therefore in individuals who have no (0mm) reaction to tuberculin test, it is clearly recommended that further tests to evaluate the immunity to tuberculosis are needed before labeling the negative response as lack of immunity due to poor vaccine or poor technique.

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References

1. Pattanaik D, Singh KB, Guresh K, Anand K, Kant S, Kapoor SK. Prevalence of Tuberculous Infection in Children Below Fourteen Years in Rural Haryana. Indian Pediatr 2002; 39: 70-74.

2. Seth V. Diagnosis and Treatment of Tuberculosis. In: Tuberculosis in Children. Ed. Seth V. Indian Pediatr. New Delhi, 1991, 14-17.

3. Jacobs RF. Management of a Child who has previously received B.C.G. Pediatr Infect Dis J 1988; 12: 892-893.

4. Spirer Z, Asaf E, Zakuth V. Persistence of invitro lymphocyte response to tuberculin in skin test negative children immunized with B.C.G. in infancy. Acta Pediatr Scand 1977; 66: 569-574.

5. Seth V, Kukreja N, Sundaram KR, Seth SD, Malaviya AN. In vitro and in vivo correlation of cell mediated immune response after B.C.G. in preschool children in relation to their nutritional status. Indian J Med Res 1982; 75: 360-363.