Fungal Contamination in Public Buildings: Health Effects and Investigation Methods
2. Health Effects of Indoor Molds (Continued)
2.2 Effects of Molds in Sensitive Groups
Some sub-populations have been found to be at increased risk of developing rare conditions following exposure to molds. Exposure to extremely high mold contamination has been associated with pulmonary hemorrhages in infants, and increased risk of invasive mycose has been observed in people with immune suppression.
2.2.1 Pulmonary hemorrhage
Exposure to indoor molds has been a suspected cause of idiopathic pulmonary hemorrhage in infants and young children. In most cases, the suspected etiologic agent was Stachybotrys chartarum (also known as S. atra), a hydrophilic fungus (i.e. requiring very damp conditions to grow) that produces cellulase and is therefore able to use cellulose as a substrate. Stachybotrys chartarum produces at least four families of compounds: atranones, macrocyclic trichothecenes, spirolactones and cyclosporin-like compounds (Sakamoto et al. 1993; Jarvis et al. 1995; Hinkley et al. 1999). There appear to be two chemotypes present in North American strains: those that produce all of the families of compounds and those that do not produce tricho-thecenes, but do produce the others. Both types appear to occur together (Nielsen et al. 2002).
In Cleveland, Ohio, 10 infants aged less than one year were diagnosed with pulmonary hemorrhages and hemosiderosis between January 1993 and December 1994. Each of these cases was matched for age with three controls. Data collection was performed by a questionnaire administered to parents and sampling of molds on surfaces and in the air. Mean concentrations of viable mold conidia in the air were higher in houses of cases compared to houses of controls (total viable fungi: 29,227 CFU/m3 vs. 707 CFU/m3; Stachybotrys chartarum: 43 CFU/m3 vs. 4 CFU/m3). A 10-CFU/m3 increase in the concentration of viable Stachybotrys chartarum conidia was associated with a significantly increased risk of acute pulmonary hemorrhage (OR 9.83, 95% CI 1.08 3×106). Nine out of 10 cases lived with smokers, compared to 16 out of 30 controls (OR 7.9, 95% CI 0.9 to 70.6), suggesting that exposure to environmental tobacco smoke may act synergistically with the factors associated with damp buildings (Montaña et al. 1997; Etzel et al. 1998). A review panel mandated by the US Centers for Disease Control and Prevention (CDC) to reassess this investigation concluded that the methodology used to collect mold samples and to calculate airborne counts of viable spores was inappropriate (CDC 2000).
No other published epidemiologic study has investigated the association between exposure to S. chartarum and pulmonary hemorrhage, but cases of pulmonary hemorrhage have been reported in infants and young children exposed to it (Elidemir et al. 1999; Flappan et al. 1999) or to other hydrophilic, cellulolytic fungi (Novotny and Dixit 2000). In the Cleveland hospital where the initial outbreak occurred, 30 infants were hospitalized with acute pulmonary hemorrhage between 1993 and 2002. Twenty-six out of 29 infants lived in water-damaged buildings, and 25 out of 28 in homes containing toxigenic fungi (Dearborn et al. 2002).
In 2000, the CDC created three new working groups to develop better protocols for investigation of future clusters. Briefly, a review of patient records from the Cleveland cases by pediatric and other specialists indicated that there were no known potential causes for the disease reported in the original studies. A clear case definition was developed should any additional clusters of infant pulmonary hemorrhage be detected. Most of the babies included in the original studies and subsequent infants studied would be included by the new definition (Dearborn et al. 2002). A second working group concluded that the fungal exposure assessments in the original study were inadequate. Several investigation techniques were described in case of future reports of clusters of idiopathic pulmonary hemorrhage. Some of these techniques would not have been available at the time of the original investigation (CDC 2001). A third group devel oped a protocol for surveillance and CDC has begun a surveillance program in conjunction with the states (CDC 2004).
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