Pamela Kibsey md frcpc, Clinical Microbiologist, Capital Health Region, Victoria B.C.


CASE HISTORY In May 1999, following months of complaints from nursing staff on a rehab unit in a chronic care hospital, an investigation was undertaken. The nursing staff complained of a “terrible odor” from one patient’s room, and most of them had experienced numerous allergic and fatigue related symptoms. When the room was vacated, extensive growth of a slimy black mold was found inside the closet and other walls of the room. Other rooms in the same ward were also found to harbor this mold. A leaking hot water main was found steaming in the crawl space underneath the rooms. In the end, three wards were eventually evacuated displacing over 60 patients. Most of the building envelope has had to be replaced due to major water damage. The city has lived with “mold hysteria” ever since.

INTRODUCTION Since the mid 1970’s, considerable attention has been given to possible links between indoor air quality and human health.  In part, this has come from recognition that most people spend the vast majority of their time (greater than 85%) indoors and concerns raised about the negative impacts on air quality produced by energy conservation measures introduced in the 1970’s. 

SOURCE Molds are found virtually everywhere in outdoor air. Exposure to mold is essentially universal.  As molds are present in outdoor air, they can be expected to move indoors through open windows, doors ventilation systems and air conditioners. If buildings are not properly constructed, maintained and operated molds can colonize and grow in indoor environments. Spores in the air also deposit on people and animals, making them common carriers of mold into indoor environments. Molds proliferate in environments that contain excessive moisture; such as from leaks in roofs or walls, plant pots and even pet urine. The presence of certain molds such as Fusarium, Trichoderma and Stachybotrys indicates a long-standing water problem. While it is not possible to eliminate molds from indoor air, it should be possible to prevent molds from amplifying indoors. 

CLINICAL SIGNIFICANCE Health effects from exposure to mold have been well established for decades. These include allergic disease, immune mediated disease, irritant and/or toxic mediated disease and infection. 

MOLD DESCRIPTION Most media attention has been focused on the rarer but more dramatic links that have been made between moldy environments and illness. Stachybotrys chartarum (atra) is the most infamous mold in the recent literature. S. chartarum is a greenish black fungus that grows on material with a high cellulose and low nitrogen content. This slow growing saprophytic fungus thrives in straw, grass, sawdust, lumber, fiberboard, gypsum board, ceiling tiles, wallpaper and even lint. The critical factor is these materials become chronically moist or water damaged due to excessive humidity, water leaks, condensation or flooding. S. chartarum is common on the West Coast. The mold itself is found in mycelial mats that are generally pigmented dark olive-gray and appear to be a slimy mass, with smooth margins and may have either a smooth or ridged surface.  The spores are more brownish in color. Identification requires examination under the microscope because, of course, not all black molds are Stachybotrys. S. chartarum is thought to cause disease by the production of trichothecene mycotoxin, which is present in highest concentration in the fungal spores. When the fungus is in the slimy phase, there is likely less harm to health, but as the fungus dries and spores are liberated, there is increased likelihood for toxigenic /allergenic mediated illness. The fungus is not known to either colonize or directly infect human tissues.

 PATIENT SYMPTOMS When S. chartarum spores are released into the air, there is the potential for individuals chronically or acutely exposed to the toxin to report cold or flu-like symptoms. Other reported symptoms include sore throat, headaches, burning sensation in the nose, nose bleeds, chest tightness, fatigue, dermatitis, tearing, general malaise and diarrhea.  

LITERATURE REVIEW There are two outstanding reports linking this fungus to severe human disease and death. In a paper by Croft et al in 1986, they report on an airborne outbreak of trichothecene toxicosis due to heavy infestation of S. chartarum in a house in suburban Chicago. The family of 5 (3 adults, 2 teenagers) living in the house experienced a variety of cold and flu symptoms, including sore throats, headaches, rash, fatigue and generalized malaise over a period of several years.  After mold growth was identified as a potential problem, remediation was undertaken. After the mold-contaminated material was removed from the home, the family’s symptoms disappeared. 

The most serious cluster of cases investigated by the CDC involved 10 infants in Cleveland. These children all presented with idiopathic pulmonary hemorrhage (IPH). Residence in a water-damaged home (especially plumbing leaks or flooding) or a home with mold were two important risk factors. Further work identified several other molds in the homes on these infants. S. chartarum was found in 20 out of 23 homes where infants with this condition lived and in 16 of 28 homes where controls who did not have this condition lived. Simultaneous exposure to environmental tobacco smoke appeared to also increase the risk of acute pulmonary hemorrhage.  

Pulmonary hemorrhage recurred in five of the infants after they returned to their homes; of these infants, one died from pulmonary hemorrhage. The American Academy of Pediatrics now recommends that all cases of sudden infant death syndrome (SIDS) have specific histology stains performed on lung tissue to look for hemosiderin-laden macrophages. It is possible that some cases of IPH may be misclassified as SIDS. There is currently no method to test humans for this toxigenic mold either by skin test or toxin test. Neither spores nor the fungus can be visualized or grown from tissues, but there has recently been one reported case of a positive culture from bronchial alveolar lavage from a child with IPH.  

CLEANUP Little is known about the prevalence of toxigenic molds in homes, nor is a dose-dependent relationship between mold and human disease known for this fungus. Bulk mold should be removed and the area thoroughly cleansed with a bleach solution. Caution must be used for larger areas, as homeowners could actually increase the levels of mold spores in the air by attempting extensive cleanups without the assistance from a professional.

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Bitnum A, Nosal R. 1999. Stachybotrys chartarum (atra) contamination of the indoor environment: health implications.  Paediatr Child Health. 4(2):125-129.

Elidemir O, et al. 1999. Isolation of Stachybotrys from the lung of a child with pulmonary hemosiderosis. Pediatrics. 104: 964-966.

MMWR 1997. Update: pulmonary hemorrhage/hemosiderosis among infants–Cleveland, Ohio 1993-1996. 46:33-35. 

Croft WA, Jarvis BB, Yatawara CS. 1986. Airborne outbreak of trichothecene toxicosis.  Atmos Environ. 20:549-552.

Davies R, Summerbell RC, Haldane D, et al. 1995. Fungal contamination in public buildings: a guide to recognition and management.  Ottawa: Environmental Health Directorate. (American Phytopathological Society website)

American Academy of Pediatrics, Committee on Environmental Health. 1998. Toxic effects of indoor molds. Pediatrics. 101:712-714. 


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