Susceptibility of Host Immunity to Infectious Diseases in the Spacecraft Environment

Abstract

Introduction:The principles of Disaster and Emergency Medicine are applicable beyond the confines of planet Earth. With the accelerating rate of climate change, natural disasters, and overpopulation, as well as the innate human appetite for knowledge and technological advancement, there has recently been an increased interest in the prospect of long-duration spaceflight with a view to colonize extra-terrestrial bodies, such as Mars. However, there is a need to understand the risk of adverse medical events in the hostile environment of space. For example, previous incidences of infectious disease and immune dysregulation during a short-term mission have threatened to jeopardize the crew dynamic and the mission objectives. The risk of infectious diseases to the astronaut is one of the many knowledge gaps that must be addressed before long-duration flight is considered.Aim:To review how spaceflight impacts an astronaut’s in-flight susceptibility to infectious diseases.Methods:Research was guided by the Microbiology section of the NASA Human Research Roadmap Program. Search terms in the University of Adelaide Library Search database collection included: “infectious diseases + spaceflight,” “astronaut + immunity,” “analog,” and “inflammatory marker.”Results:Studies that have been conducted in-flight and on Earth demonstrate that both the astronaut and the microbe are affected by spaceflight. Stress, microgravity, and the isolated nature of the spacecraft have been found to compromise the immunity of the astronaut, as shown by reduced T cell counts and increased viral shedding of dormant viruses. Microbes have demonstrated rapid adaptation mechanisms, including genetic mutation and increased virulence.Discussion:This paper identifies a significant need for further research into host immunity during spaceflight to mitigate infectious disease risk. It is recommended that in-situ studies and terrestrial space analogs are most effective and that current knowledge on the principles of wilderness and expedition medicine be applied where possible.