What does Chaetomium in my house mean?

Chaetomium usually signals a moisture problem. It grows on damp building materials and was found in 49% of 794 water-damaged buildings in one study; a large materials study found it especially associated with concrete and floor-related materials. Finding it is a reason to locate and fix the water source and remove damaged materials, not a diagnosis of illness.

Chaetomium globosum, the most common species, can produce chaetoglobosins A and C when it grows on building materials, and relatively low levels of these compounds are toxic to cells in laboratory studies. Laboratory toxicity does not directly tell us what happens in people at typical indoor exposure levels, and human health effects of these specific toxins are not well established.

Is Chaetomium the same as black mold?

No. Black mold usually refers to Stachybotrys chartarum. Chaetomium and Stachybotrys are different fungi, but both are common in buildings that have stayed wet after water damage.

Can Chaetomium cause infections?

Rarely. Members of the Chaetomium family are generally environmental fungi, and their role as human pathogens has received little attention. Some species can grow at high temperatures, which may allow them to cause opportunistic infections. Reported examples include eye, skin, and toe infections caused by chaetomium-like fungi, and in one case peritonitis in a kidney transplant patient.

Chaetomium Mold: Water Damage, Mycotoxins, and Health Risks

Overview

Chaetomium is a genus of molds closely tied to water damage. In a study of 794 water-damaged buildings, Chaetomium species were isolated from 49% of them.^[1] Along with other moisture-loving fungi, it is very common on damp building materials.^[2]

Its most common species, Chaetomium globosum, can produce mycotoxins called chaetoglobosins when it grows on building materials.^[1] Related species can also cause rare opportunistic infections in people.^[3]

Classification

Phylum: Ascomycota
Family: Chaetomiaceae
Genus: Chaetomium
Most common indoor species: C. globosum

The classification of Chaetomium was substantially revised by a 2016 study of 145 isolates collected from indoor air, swab, and dust samples in 19 countries. The researchers recognized 30 indoor taxa, including seven new species, and moved many "chaetomium-like" species into new or separate genera.^[4] In that collection, C. globosum was by far the most abundant indoor species (74 of 145 isolates), followed by C. cochliodes (17 of 145).^[4]

Where Chaetomium Is Found

Members of the Chaetomium family are ubiquitous fungi that live in soil enriched with manure or cellulose-rich plant material.^[3] Indoors, they grow on damp building materials, which is why they are so closely associated with water damage.

A study of more than 5,300 samples from materials with visible mold growth found Chaetomium species to be very common on damp building materials. They were particularly associated with concrete and other floor-related materials, together with several Aspergillus and Mucor species.^[2]

Health Significance

Mycotoxins

C. globosum produces chaetoglobosins A and C when cultured on building material, and relatively low levels of these compounds have been shown to be lethal to various cell lines in the laboratory. In a study of 30 C. globosum isolates grown for four weeks, 16 produced detectable chaetoglobosin A and every isolate produced chaetoglobosin C.^[1]

Laboratory cell toxicity is an important signal, but it does not establish what happens in people at typical indoor exposure levels. Human health effects specific to chaetoglobosins are not well established, and mold-damaged buildings usually contain a mix of fungi, bacteria, and other contaminants.

Opportunistic infections

Chaetomium-family fungi have largely been ignored as human pathogens. However, some species can grow at high temperatures, which may enable them to act as opportunistic pathogens.^[3] Researchers have described chaetomium-like species isolated from eye, skin, and toe infections, as well as Chaetomium anamorphosum from a kidney transplant patient with fungal peritonitis.^[3] All of the newly described species had previously been misidentified as a different fungus, which suggests such infections may be under-recognized. Even so, they are rarely reported.

Chaetomium vs. Black Mold

People often find Chaetomium and Stachybotrys chartarum (black mold) in the same places, because both grow on building materials that have stayed wet after water damage. Other common molds of water-damaged buildings include Penicillium chrysogenum and Aspergillus versicolor, the two most common species in the large building materials study.^[2] See our pages on Penicillium, Aspergillus niger, and Cladosporium, and our article on black mold poisoning symptoms and treatment.

What to Do About Chaetomium at Home

Find and fix the moisture source. Chaetomium is a marker of water damage; cleaning without drying the building will not solve the problem.
Remove damaged porous materials. Moldy drywall, wallpaper, carpet padding, and similar materials usually need to be removed and replaced.
Use professionals for large areas. Extensive growth, growth inside walls, or contamination after flooding is best handled by a qualified remediation company.
Protect sensitive people. People with asthma, lung disease, or weakened immune systems should avoid the work area during remediation.

When to See a Clinician

See a clinician if you have persistent cough, wheezing, sinus symptoms, or other health concerns you associate with a damp or moldy building, and mention the exposure. People with weakened immune systems should seek care promptly for skin, nail, or eye infections that do not heal, or for fever.

This page is for educational purposes and is not medical advice. Consult a qualified healthcare provider about mold exposure and symptoms.

Chaetomium