Spore Allergen Information - Aerobiology Research Laboratory

Fungi are eukaryotic organisms; they contain a rigid cell wall. They are not plants or animals but they belong in their own classification.

Classification Scheme:

Fungi reproduce by sexual or asexual means. The Class of the Fungi Imperfecti do not have a perfect or sexual reproductive phase. Other Classes, such as the Basidiomycetes, have a sexual phase.

Fungi are multinucleate and grow in long, filamentous patterns. The filaments or hyphae may be divided by cross walls or septae or they may lack any septae. A mass of hyphae is called mycelia. The reproductive organs of hyphae which produce spores (conidia) are called conidiophores. The spores are what are released in the air. Some fungi do not produce hyphae and consequently do not produce conidiophores or conidia (Candida sp., is a common yeast that causes human infection) Those that produce spores and get airborne are called aeroallergens. An example is Penicillium. Fungi are found in decaying materials, such as leaves and trees, on fences, in soil, water, air and also food. The field of Aerobiology deals with those that are found in the air. Some fungi are considered opportunistic and usually cause disease in people who have abnormal immune systems. These fungi, usually do not cause serious infections in the immunocompetent host but can cause serious illness in immuno-compromised patients. In contrast dimorphic fungi are those that are capable of causing disease in people with normal immune systems.

Aspergillus species spores, for example, are often found in the air and consequently inhaled. They are also small enough to enter deep into the lungs. They almost never cause infections in people with normal or healthy immune systems. This fungus can, however, in immuno-suppressed people cause life-threatening infections. Those at risk are patients undergoing cytotoxic chemotherapy, immunedeficient (AIDS) patients, those suffering from malnutrition, diabetes, and high dose corticosteroid therapy.

There are thousands of spores found in the air that we breathe but only a few of them can cause human disease. Some of them are of great importance in agriculture and the food industry. We try to identify those spores that are found in air samples and only those, which could cause human health problems or damage to agriculture crops. The importance of food contamination or spoilage by fungi is the role they play in food poisoning. Some of them also produce mycotoxins which can be released in the air or found in the food we eat and can cause health problems.

Not all fungal spores found in air samples have the potential to cause disease and are called saprophytic. Some, however, exist in such high numbers during a long period of time throughout most of the year that they are considered important. The number one spore that fits in this category is Cladosporium species. This can be compared to the normal human bacterial flora found in the body. People have many different types of bacteria in most parts of the body. These are there to protect from potentially pathogenic bacteria. Without these "good" bacteria the body has less defense against invasion from the disease causing ones.