Gruft, H. (Division of Laboratories and Research, New York State Department of Health. New Scotland Avenue, Albany NY 12201), J. Katz and D. C. Blanchard. Postulated source of Mycobacterium intracellulare (Battey) infection.Am J Epidemiol 102:311–318, 1975. Studies by the United States Public Health Service have shown that skin sensitivity toMycobacterium intracellulare antigens is most frequent along the southeastern seacoast, extending from Virginia down the Florida peninsula and along the Gulf of Mexico. The prevalence is highest along the immediate coast and extends inland for a considerable distance, decreasing with the distance from the coast. Various workers have shown that air bubbles produced by wind and wave action on the sea concentrate organic substances, including bacteria, as they rise to the surface of the water. When the bubbles break at the surface, the organic materials and bacteria are projected into the air, where they may be carried upward by convection and turbulent diffusion and transported long distances inland. It is the thesis of this study that the geographic distribution of skin sensitivity to M. intracellulare antigens may be explained by a marine origin followed by transport to the land of droplets containing the mycobacterium. The studiesreported here offer experimental evidence bearing on this hypothesis. (1) Under the conditions of this study, using sea water at temperatures normally found off the southeastern United States, M. intracellulare survives or at least remains in a steady state resembling the stationary growth phase in broth culture for a considerable periodof time. (2) The mycobacteria are concentrated on air bubbles during the upward passage of the bubbles through a suspension of M. intracellulare in saline solution. (3) When the bubbles burst at the surface, droplets are ejected into the atmosphere with concentrations of mycobacteria many times greater than that in the suspension.