Alternaria is a common fungal genus found globally, encompassing over 300 species. While generally harmless to most people, its spores are potent allergens that pose a significant health risk. For sensitive individuals, exposure to Alternaria is strongly linked to respiratory problems, primarily triggering asthma and allergic disease.
Identification and Common Habitats
Alternaria is a ubiquitous mold found everywhere in both outdoor and indoor settings. Outdoors, it is a major component of airborne fungal spores, thriving on decaying wood, soil, and various plants. The colonies appear as dark green, brown, or black patches with a velvety texture.
The airborne spores are prevalent during warmer months, peaking in the late summer and early fall. Indoors, Alternaria signals a moisture problem, requiring high humidity to grow. It commonly colonizes damp areas such as shower stalls, window frames, wet wallboard, and carpets.
The lightweight, dry spores are easily dispersed and highly problematic. They become airborne easily, making them easy to inhale and difficult to avoid. This dual presence ensures year-round exposure for sensitive individuals.
Health Risks Primary Allergen and Respiratory Threat
Alternaria is recognized as a clinically relevant fungal allergen because its spores contain highly immunogenic proteins. When inhaled, these spores trigger an immediate allergic response in sensitized people. Symptoms are similar to hay fever, including sneezing, nasal congestion, a runny nose, and itchy, watery eyes and throat.
The mold’s most significant danger is its strong association with asthma exacerbation, particularly in children. Exposure is a major risk factor for developing and worsening asthma, and it has been linked to severe, life-threatening asthma attacks. Sensitivity to this mold is often the most common mold allergy in children with asthma.
In rare cases of heavy, chronic exposure, Alternaria can also contribute to a serious lung condition called hypersensitivity pneumonitis. This involves inflammation of the lung tissue, leading to symptoms like chills, fever, and shortness of breath. The mold also produces mycotoxins, though the primary health risk remains the potent allergenic effect of the spores.
Medical Diagnosis and Symptom Management
Diagnosis of a specific Alternaria allergy involves two main clinical approaches. A skin prick test introduces a small amount of extract beneath the skin’s surface. A localized reaction, such as a raised welt, indicates sensitivity to the mold.
Alternatively, a specific IgE blood test measures the level of immunoglobulin E antibodies against Alternaria antigens. Elevated IgE levels confirm allergic sensitization. These diagnostic methods help healthcare providers create a tailored management plan for the patient.
Symptom management focuses on controlling the allergic response and treating respiratory issues. Antihistamines reduce sneezing, itching, and nasal discharge. Nasal corticosteroids lessen chronic congestion and inflammation. For individuals with asthma, bronchodilators manage acute wheezing and coughing episodes. Long-term reduction of sensitivity is achieved through allergen immunotherapy (allergy shots), which gradually desensitizes the immune system.
Remediation and Prevention Strategies
Controlling the environment is a fundamental strategy for managing an Alternaria allergy. The first step in indoor remediation is to identify and stop the source of moisture, as the mold cannot proliferate without water. Leaks in plumbing, windows, or roofs must be fixed promptly to eliminate the water source.
Reducing indoor humidity levels is critical, and it is recommended to keep the relative humidity below 50% using dehumidifiers and air conditioners. Visible mold should be cleaned using a detergent and water solution, then thoroughly dried to prevent re-growth. For extensive infestations, professional mold remediation services should be engaged to safely remove contaminated materials.
Air filtration is an important preventative measure. Using high-efficiency particulate air (HEPA) filters in HVAC systems or portable air purifiers effectively traps airborne spores. Proper ventilation in high-moisture areas like kitchens and bathrooms prevents condensation. Sensitive individuals should limit outdoor activities during peak spore season, typically late summer.