Preliminary Report: Epidemiology of Infections Due to the Atypical Acid-Fast Bacilli

¹ The Florida State Board of Health, Bureau of Preventable Diseases, Jacksonville, Florida.

1. The atypical mycobacteria are distinct bacteriologic entities differing from M. tuberculosis both in cultural and biochemical characteristics and in animal pathogenicity. They need to be more adequately defined bacteriologically.

2. The atypical mycobacteria need to be considered as actual or potential human pathogens with variations in pathogenicity by groups. They are less capable than M. tuberculosis of producing progressive pulmonary disease.

3. Of all our known cases, elderly white men constitute the group of largest number. Preliminary data suggest that the colored race, and especially the colored male, has the higher attack rate.

4. Men who were born and have lived most of their lives in the rural southeast are most commonly involved with the non-photochromogens.

5. People found to harbor these organisms belong chiefly to the low socio-economic stratum.

6. There is in our series a distinct seasonal variation in the occurrence and/or recognition of newly identified cases.

7. The available data suggest a clustering by families of those exhibiting evidence of exposure to these bacteria, but conclusive evidence of transmission from man to man has not been obtained.

8. The habitat of these organisms remains uncertain; they could be derived from an extra-human source—possibly the soil.

9. Production of overt disease by these bacteria may be related to previous pulmonary abnormality and lowered pulmonary resistance.

10. All aspects of these infections must have additional study.