A study of the association between delayed type hypersensitivity reaction to mycobacterium tuberculosis and atopy in asthmatic children

The purpose of this study was to investigate if there is an inverse association between Mycobacterium tuberculosis infection and atopy among children living in rural and semi urban areas in El Behira governorate, Egypt. METHODS: All the studied children were BCG vaccinated in their newborn period. In Tuberculin testing, indurations greater than or equal to 5 mm were accepted as positive. For atopy, the most common aeroallergens were used in skin intradermal testing, and reactions > or = 3 mm were accepted as positive. RESULTS: Among 150 studied children whose ages ranged from 4-8 years, 89 patients were purified protein derivative (PPD) negative whereas in 61 patients PPD was positive. Among the PPD negative patients skin intradermal test was positive for atopy in 51.6% (n = 46), while among the PPD positive patients skin intradermal test was positive in 52.4% (n = 32). As the two groups were compared for having positive intradermal skin test reaction, no statistically significant difference was detected between them (p >0.05). CONCLUSIONS: In this study no statistically significant difference was detected between Mycobacterium tuberculosis infection as indicated by positive PPD positivity and atopy tested by skin intradermal injection of common aeroallergens.