Aspergillus mold allergy

What it is

Aspergillus is a mold, a kind of fungus, and its spores are common indoors and outdoors.¹ It lives in soil, decomposing plant matter and household dust.³ The CDC also lists building materials, plants, food and water among the places it is found.³

Indoors, Aspergillus is one of the three most common molds, with Cladosporium and Penicillium.⁸ A large study of air samples from US buildings found it among the most common molds in both indoor and outdoor air.⁶ The AAAAI lists it among the most common molds that cause allergy.⁵

Most people breathe in Aspergillus spores every day without getting sick, and it may not be possible to avoid them completely.¹ The illnesses it causes are called aspergillosis. The CDC names five types: two allergic forms, allergic bronchopulmonary aspergillosis (ABPA) and allergic Aspergillus sinusitis, as well as aspergilloma, chronic pulmonary aspergillosis and invasive aspergillosis.² This page covers the allergic side. Aspergillosis does not spread between people or between people and animals.¹

Symptoms it causes

As with other mold allergies, breathing in the spores can cause sneezing, a runny or stuffy nose, itchy, watery eyes and an itchy nose, mouth and lips.⁵ Mold allergy can also trigger asthma symptoms such as wheezing, shortness of breath and chest tightness.⁵ The CDC describes an allergic form in the sinuses, allergic Aspergillus sinusitis, which can cause stuffiness, a runny nose, headache and a reduced sense of smell.²

In some people, Aspergillus causes a more serious allergic lung condition called allergic bronchopulmonary aspergillosis, or ABPA. It is an allergic reaction to Aspergillus fumigatus in which the immune system overreacts to the fungus in the lungs.⁴ The reaction is rare in people with normal immune systems, and ABPA most often affects people who have asthma or cystic fibrosis.⁴ The CDC lists people with asthma, cystic fibrosis or other lung diseases among the groups at risk for allergic aspergillosis.³

ABPA symptoms can include wheezing, shortness of breath and cough, and, rarely, fever.² In people with asthma, the first sign is often that their asthma gets worse. Some people cough up brownish flecks or bloody mucus and feel generally weak or unwell.⁴ Over time, the reaction can damage the airways and cause permanent lung damage.⁴ An allergist can test for Aspergillus allergy and talk through what the results mean.

Where it’s found

Aspergillus is all around us: outdoors in soil and rotting plant matter, and indoors in household dust.³ Building work can stir it up: the CDC notes that dust from hospital construction can expose people to Aspergillus spores.³ Indoor levels of Aspergillus and Penicillium do not closely track the levels outside.⁷

Like other indoor molds, Aspergillus grows where there is moisture, such as around leaks in roofs, windows or pipes, or after a flood.⁸ The CDC advises keeping indoor humidity no higher than 50% all day, fixing leaks in the roof, walls or plumbing, using kitchen and bathroom exhaust fans that vent outside, and removing mold you can see or smell.⁸ The EPA adds that wet or damp items should be dried completely within one to two days, and that moldy hard surfaces can be cleaned with soap and water and then dried completely.⁹