Issue link: https://hi.iaq.net/i/191637
Climate Change, the Indoor Environment, and Health 161 INFECTIOUS AGENTS AND PESTS bacteria, and M. leprae, the agent of leprosy. Some of these organisms have emerged as agents of lung infection in patients who have underlying lung diseases that lead to impaired clearance of respiratory secretions. Those diseases are best exemplified by cystic fibrosis, a genetic disease in which impairment and dysfunction of the airway-lining cilia lead to the airwaywidening condition known as bronchiectasis. Bronchiectasis is a common feature of the other syndromes in which nontuberculous mycobacterial infections occur, including primary ciliary dyskinesia, alpha-1 antitrypsin deficiency, and hyper-IgE recurrent-infection syndrome (Zoumot and Wilson, 2010). The role of environmental exposure, including exposure to the indoor environment, in nontuberculous mycobacterial infection has recently received intense interest. The nontuberculous mycobacteria live in temperate and tropical waters and soils throughout the world. Unlike M. tuberculosis and M. leprae, which depend almost exclusively on human-to-human spread for their propagation, the nontuberculous mycobacteria are environmental opportunists that live in biofilms and can survive otherwise hostile environments because of their waxy cell walls (Falkinham, 2010). Feazel et al. (2009) showed recovery of M. avium complex genetic signatures from biofilms collected from inside showerheads in homes. Other organisms were also detected, including legionellae. Falkinham et al. (2008) reported a case of pulmonary infection with a particular species of M. avium complex that was recovered from the home water supply; this suggested spread from the household water to the patient. That potential mechanism of spread has been expanded on by Chan and Iseman (2010). The occurrence of pulmonary nontuberculous mycobacterial infection is highest in cystic fibrosis patients who have the mildest forms of disease, especially in women (Rodman et al., 2005). Fomites Increasing relative humidity and temperature outdoors will probably lead to increased indoor dampness and dampness-related health effects. As is the case with many infectious-disease vectors, the effects of temperature and relative humidity may increase or decrease the survival of viruses and bacteria and facilitate the persistence of infectious fomites (Boone and Gerba, 2007). Increases in environmental temperature decrease the survival of many viruses. For example, the H5N1 avian influenza virus persisted on duck feathers and on surfaces for long times but only at lower temperatures (Wood et al., 2010; Yamamoto et al., 2010). The combination of a stable indoor environment and increased dampness may actually decrease the transmission of some respiratory viruses and increase the survival of other pathogens on fomites, such as the ones that harbor bacteria and mold Copyright © National Academy of Sciences. All rights reserved.