Microbial and immunological responses relative to high-altitude exposure in mountaineers.

Purpose: High-altitude exposure is often associated with gastrointestinal disorders, inflammation, and an increased risk of infection. We suspected microbial and immunological responses to high-altitude exposure in mountaineers resulting from changes in the balance of the intestinal microflora.

Methods: We investigated fecal samples and serum of seven mountaineers who took part in a 47-d German expedition to the Nepalese Himalayas in 2002, for microbial response by changes in different fecal bacterial population groups (fluorescent in situ hybridization), immune response by serum levels of IgG-, IgM-, and IgA anti-LPS (E.