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Traditional Mold Analysis Compared to a DNA-based Method of Mold Analysis with Applications in Asthmatics' Homes
VESPER, S. J. Traditional Mold Analysis Compared to a DNA-based Method of Mold Analysis with Applications in Asthmatics' Homes. CRITICAL REVIEWS IN MICROBIOLOGY. Informa Healthcare, London, Uk, 37(1):15-24, (2011).
Approximately 9% of children have asthma. The medical costs of asthma are approximately $15 billion per year in the US alone and asthma results in about 2,000 deaths per year (Fisk et al. 2007). Lost school and work days run into the millions each year. The IOM’s expert committee (2004) concluded that exposure to moldy, damp indoor environments was associated with asthma. A subsequent review (Sahakian et al. 2008) of more recent publications also linked dampness to mold and asthma/asthma symptoms. The World Health organization has come to the same conclusion and suggest that exposure to molds should be “minimized” (WHO 2009). A meta-analysis of studies associating mold contamination with adverse health effects demonstrated that building dampness and mold were associated with approximately a 30 to 50% increase in a variety of respiratory and asthma-related health outcomes (Fisk et al. 2007). Therefore, it is critical that mold assessments are accurate and meaningful. US EPA researchers developed a DNA-based method of mold analysis called MSQPCR which is sensitive, specific and accurate. The US EPA in conjunction with HUD developed a simple, standard method of sampling homes for mold populations and created a scale called the ERMI to compare the mould burden in homes across the US (Vesper et al. 2007). In four epidemiological studies, higher ERMI values in homes were associated with increased risk of asthma in children. Remediating the water-damage and mould in asthmatics homes resulted in a statistically significant improvement in the child’s health and a reduction in the need for hospitalizations and emergency room visits (Kercsmar et al. 2006). Although these results are from a limited number of studies and have not been corroborated independently by other research groups, they are suggestive of the conclusions that mold problems are not always obvious. Furthermore, discovering hidden mold is possible using the ERMI analysis and subsequently correcting a mold problem may reduce asthma’s costs to the US by reducing hospitalizations and emergency room visits.
Traditional environmental mold analysis is based-on microscopic observations and counting of mold structures collected from the air on a sticky surface or culturing of molds on growth media for identification and quantification. A DNA-based method of mold analysis called mold specific quantitative PCR (MSQPCR) is now available for more than 100 molds. MSQPCR has been applied to studying molds in environments varying from hospitals to homes. Based on a national sampling and analysis by MSQPCR of dust in US homes, a scale for comparing the mold burden in homes was created called the Environmental Relative Moldiness Index (ERMI). The ERMI scale places homes into one of four quartiles, from lowest to highest mold burden. In half of the highest quartile mold burden homes, the mold problem was unsuspected or undetected by traditional methods of mold investigation, indicating that many mold problems are hidden. In four published studies of childhood asthma, higher ERMI values were associated with increased risk of asthma or asthma symptoms. In one study, targeted remediation of mold in asthmatics’ homes produced a 10-fold reduction in the need for hospitalizations or emergency room visits.