Fungi, molds, and risk

When inhaled, microscopic fungal spores or fragments of fungi may cause allergic rhinitis. Because they are so small, mold spores may evade the protective mechanisms of the nose and upper respiratory tract to reach the lungs and bring on asthma symptoms. The buildup of mucus, wheezing, and difficulty in breathing are the result. Less frequently, exposure to spores or fragments may lead to a lung disease known as hypersensitivity pneumonitis.

Molds are present in our exterior environments, and, hopefully, to a lesser extent in our interior environments. People allergic to molds may have allergic symptoms from spring to late fall. The mold season often peaks from July to late summer. Unlike pollens, molds may persist after the first killing frost. Some can grow at subfreezing temperatures, but most become dormant. Snow cover lowers the outdoor mold count drastically, but does not kill molds. After the spring thaw, molds thrive on the vegetation that has been killed by the

winter cold. In the warmest areas of the world, however, molds thrive year-round and can cause perennial allergic problems. Molds growing indoors can cause perennial allergic rhinitis even in the coldest climates.

If indoor areas show signs of amplification identified by visual assessment, air sam­pling, and contact/liquid sampling, amplification must be suspected. Amplification is the process whereby biological organisms continue to increase over time. If this increase is not controlled, sufficient mold spores and vegetative structures may be present to create indoor air problems.

Hot spots of mold growth in the home include damp basements and closets, bathrooms (especially shower stalls), places where fresh food is stored, refrigerator drip trays, house plants, air conditioners, humidifiers, garbage pails, mattresses, upholstered furniture, and old foam rubber pillows.

6.1.1 What Is the Difference between Molds, Fungi, and Yeasts?

Molds and yeasts are two groups of plants in the fungus family. Yeasts are single cells that divide to form clusters. Molds consist of many cells that grow as branching threads called hyphae. The seeds or reproductive particles of fungi are called spores. They differ in size, shape, and color among species. Each spore that germinates can give rise to new mold growth, which in turn can produce millions of spores.

6.1.2 How Would I Become Exposed to Fungi That Would Create a
Health Effect?

The route of exposure may be inhalation or ingestion accompanied by inhalation. When inhaled, microscopic fungal spores or fragments of fungi may cause health prob­lems. Because they are so small, mold spores may evade the protective mechanisms of the nose and upper respiratory tract to reach the lungs and bring on asthma symptoms. The buildup of mucus, wheezing, and difficulty in breathing are the result. Less frequently, exposure to spores or fragments may lead to a lung disease known as hypersensitivity pneumonitis.

6.1.3 What Types of Molds Are Commonly Found Indoors?

In general, Alternaria and Cladosporium (Hormodendrum) are the molds most commonly found both indoors and outdoors throughout the U.S. Aspergillus, Penicillium, Helmintho-sporium, Epicoccum, Fusarium, Mucor, Rhizopus, and Aureobasidium (Pullularia) are also common.

6.1.4 Are Mold Counts Helpful?

Similar to pollen counts, mold counts may suggest the types and relative quantities of mold present at a certain time and place. For several reasons, however, these counts prob­ably cannot be used as a constant guide for daily activities. One reason is that the number and types of spores actually present in the mold count may have changed considerably in 24 h because weather and spore dispersal are directly related. Many of the common aller-genic molds are of the dry spore type—they release their spores during dry, windy weather.

Other molds need high humidity, fog, or dew to release their spores. Although rain washes many larger spores out of the air, it also releases some smaller spores into the air.

6.1.5 What Can Happen with Mold-Caused Health Disorders?

Fungi or microorganisms related to them may cause other health problems similar to an allergy. Fungi may lodge in the airways or a distant part of the lung and grow until they form a compact sphere known as a "fungus ball." In people with lung damage or serious underlying illnesses, Aspergillus may grasp the opportunity to invade and actually infect the lungs or the whole body. In some individuals exposure to these fungi can also lead to asthma or to an illness known as "allergic bronchopulmonary aspergillosis." This latter condition, which occurs occasionally in people with asthma, is characterized by wheezing, low-grade fever, and coughing up of brown-flecked masses or mucous plugs. Skin testing, blood tests, X-rays, and examination of the sputum for fungi can help establish the diag­nosis. The occurrence of allergic aspergillosis suggests that other fungi might cause similar respiratory conditions.

Inhalation of spores from fungus-like bacteria, called actinomycetes, and from molds can cause a lung disease called hypersensitivity pneumonitis. This condition is often asso­ciated with specific occupations. Hypersensitivity pneumonitis develops in people who live or work where an air-conditioning or a humidifying unit is contaminated with and emits these spores. The symptoms of hypersensitivity pneumonitis may resemble those of a bacterial or viral infection such as the flu. If hypersensitivity pneumonitis is allowed to progress, it can lead to serious heart and lung problems.

Дата добавления: 2015-11-16