Microbiological and immunological aspects of extended manned space flights.

This paper is concerned with alterations in microbial flora and immunologic response of men during exposure to long-term confinement in a sealed cabin. The above changes depend on the environmental parameters, the duration of the exposure to different environmental factors, as well as on work rest schedules. An interchange of micro-organisms between subjects and activation of some species forming the normal human microflora took place in conditions of isolation. It was demonstrated that under these conditions some significant shifts in intestinal microflora occurred, including its general "simplification". It was found that the immunocompetent lymphoid tissue of the animals that had a simplified (reduced in number of species) intestinal microflora was significantly underdeveloped. Some ways of stimulating the immunocompetent systems of astronauts during long-term space flights were considered. Special attention should be paid to the microbiological examination as part of the selection routine for future astronauts.