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The term "mold" is a catchall term that includes thousands of species of fungi. Mold is a filamentous fungi. Molds
have clusters of spores which are located on the end of tiny stalks. Their spores are the reproductive product of the mature
mold. Exposure to fungal bioaerosols in indoor air has emerged as a significant health problem in residential environments
as well as in occupational settings including offices, enclosed areas, and industrial sites. The study of the branch of biology
that deals with fungi is called mycology.
All living things can be classified into one of five fundamental Kingdoms of life. Each Kingdom is further subdivided
into progressively smaller groups. The seven layers of subgrouping are Kingdom, Phylum, Class, Order, Family, Genus, and Species.
Kingdom Monoera includes the prokaryotes: single-celled organisms that do not possess a nucleus. Examples include
bacteria, actinomycetes, and the blue-green algae. Kingdom Protoctista inludes the simplest eukaryotes: single-celled organisms
that do possess a nucleus. Examples include nucleated algae and slime molds. Kingdom Fungi are nonmotile eukaryotes that
lack flagella and develop from spores. They do not have chorophyll. Examples include yeast, molds, and mushrooms. Kingdom
Plantae are eukaryotes that develop from empbryos and also use chlorohyll. Examples are mosses and vascular plants. Knigdom
Animalia are eukaryotes that are multi-cellular organisms that develop from a blastula (a hollow ball of cells). Examples
are worms, arthropods, and animals.
Since they do not have cholorphyll, fungi must absorb food from others. Since they do not use light to make food,
fungi can live in damp and dark places.
Good fungus can help with many things to make the world a better place. Out of the many kinds of of fungi, the ones
we like to eat are mushrooms. Yeast fungus is used to make beer. Further, yeast is used to make bread and dough rise.
Classically fungi are two broad groups which are yeasts and mold. While not mutually exclusive, mold spores germinate
to produce the branching filaments known as hyphae and yeasts, on the other hand, are solitary rounded forms that reproduce
by making more rounded forms through such mechanisms as buddding or fission.
Fungi do not grow in the air. They originate on surfaces or in substrates. Molds live in conditions of wide ranging
temperatures but need moisture and a food source. Many home building material such as acoustical ceiling tiles, carpets, wallboard,
wallpaper, soiled fibergalss, A/C ducts, filter and insulation are well known substrates for bacterial and/or fungal growth
when they become wet or retain moisture. Water staining, discoloration, and mildew are signs of fungal growth.
Indoor esposure to mold and mildew commonly occurs in reponse to the inadvertent entry of water or moisture into
the house or building. If moisture impacted building materials are allowed to remain, the growth of mold will be promoted.
If the indoor relative humidity levels remain sufficiently high(>50%) then the spread of mold growth will be promoted.
A home's natural immune system against mold growth is the maintenance of dry conditions within the indoor air quality through
proper operation of the heating, ventilating and air condition (HVAC) system. If not inspected regularly, the HVAC system
itself can become a haven for mold and mildew growth.
Components of mechanical HVAC systems may serve as reservoirs or sites of microbial amplification. These include
air intakes near potential sources of comtamination such as standing water, organic debris, or integral parts of the mechanical
system itself, such as humidifiers, cooling coils, or condensate drain pans. Dust and debris may be deposited in the duct
work or mixing boxes of the air handler.
THERE ARE TWO MAIN TYPES OF DISEASES FROM MOLDS:
ALLERGIC REACTIONS AND DISEASE DUE TO FUNGAL TOXINS
ALLERGIC REACTIONS
Fungi and fungal particles can clearly induce an allergic response in sucsceptible individuals. Typical symptoms
are wheezing, cough, rhinorrhea, itchy nose, sore throat, sinus congestion, etc. Elimination of this form of reaction requires
reduction in the amount of fungi in the environment, not just disinfection of the envirnoment.
Asthma remains the most common chronic childhood diseases in the United States. One of the primary causes of asthma
and other allergic reactions is exposure to molds.
FUNGAL DISEASES
Far more feared than allergies are fungal diseases. There has been much debate over the link between toxic fungi
and specific forms of disease. However, certain links are irrefutable. Some of the diseases are from topical exposure and
some caused by ingestion of the offending fungi. Perhaps the best kown of the ingestion syndromes is ergotism, a syndrome
known for hundreds of years. It may present with limb gangrene, hallucinations, and death and thus can be quite dramatic.
It is a vasospactic disorder caused by tingestion of rye products contaminated with ergot alkaloids produced by the mold Claviceps
purpurea. Other mycotoxins that produce illness are stachybotrys, aspergillus, penecillium and candida (a thin walled yeast).
It appears that stachybotrys is a mycotoxin that produces trichothencdene mycotoxins and causes a syndrome in animal known
as stachybotrytoxicosis. In ths syndrome, leukopenia (reduced white blood cell count) and hemorrrhage (bleeding) are prominent
and may lead to death. The scenario regarding this particular mycotoxin is in a state of flux as it affects human beings at
the current time.
Candida are thin walled yeasts that can produce a wide variety of infections. A dramtic change in the epidemiology of
infectious disease has taken place with the advent of new chemotherapeutic agents, new immunosuppressive agents, organ transplantation,
parenteral alimentation, broad-spectrum antibiotics and advanced surgical techniques. In this new scenario, fungal infections
have emerged a a critical issue in the compromised host. Among these, Candida are the most common fungal pathogens.
Aspergillosis is a large spectrum of diseases caused by memebers of the genus Aspergillus. They are generally respiratory
tract diseases. The severity of the disease depends upon the immunologic state of the patient.
WHAT HAVE WE LEARNED HERE?
First, it is indeed clear that mycotoxins are real and that they can produce dramatic symptoms. However, clear linkage
of a toxin to a diseaes is currently a difficulty owing to the novelty of the medicine. Second, given the broad range of fungi
that produce mycotoxins, it seems reasonable to treat ALL fungi with substantial respect. Thus, the goal in interior environments
should be to maintain them in a clean, dry and mold-free state. Identifying the specific fungus that is infesting a wall is
less important than getting rid of it and preventing its return.
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