Skin-test sensitisation by tubercle bacilli and by other mycobacteria in Ethiopian school-children

Quadruple skin-testing with a range of 22 new tuberculins and PPD-RT23 was carried out on 665 school-children without BCG scars and 666 with BCG scars, in and around the towns of Butajira and Hosana in Shoa district of Ethiopia. Marked differences in patterns of sensitisation were distinguished between the 5 schools visited. In general, Mycobacterium chitae, M. diernhoferi, M. kansasii and M. vaccae were common sensitising agents in all schools, M. avium subspecies brunense, M. gilvum, M. rhodesiae and M. xenopi were absent, and the remaining species investigated were variably present between the schools. Contact with M. tuberculosis and M. leprae appeared greatest in Hosana and the possibility of sensitisation by M. ulcerans around the village of Enseno was discovered. The data also provided indirect evidence of the value of BCG in Shoa district. An interesting observation was the very variable enhancing effect that BCG vaccination had on sensitisation to individual fast growing species.