Millions of species of fungi exist, but only a few hundred can actually make people sick. Some of the more well-known fungal infections include athlete’s foot, jock itch, and yeast infections, but there are many others. Fungi live in a variety of environments, including human skin and even deeper within our bodies. Some species of fungi are extremely common and well-researched, while others are rarer and still require studying.
Each species can infect humans in different ways, but the most typical methods are through inhaling spores or entering through a wound.
Candida typically lives inside the body and on the skin without causing any issues. However, it can sometimes grow out of control or move deeper into the body, causing an infection. Candida fungi are responsible for many different infections, with the most well-known being vaginal yeast infections and some respiratory conditions.
In recent years, experts have discovered a new multidrug-resistant type of Candida, called Candida auris, that poses a global threat.
One of the most common molds in America, Aspergillus lives both indoors and outdoors. Over 180 species of Aspergillus exist, but fewer than 40 can cause infection. Many people breathe in the spores of these fungi without developing any issues. People with weaker immune systems, however, may develop allergic reactions or infections in the lungs or other organs.
One of the more well-known types, Aspergillus niger is a black mold that grows on some produce. Many people confuse A. niger for the much more dangerous Stachybotrys colonies, which are the toxic black molds associated with poor air quality.
A yeast-like fungus, Pneumocystis specimens are extremely widespread and frequently appear in the lungs of healthy people. ]Some studies suggest that up to 20% of adults are asymptomatic carriers of Pneumocystis. However, Pneumocystis is often the source of an opportunistic infection in people with weak immune systems or another health condition. This infection, Pneumocystis pneumonia, primarily affects individuals with HIV/AIDS, as well as people with cancer or chronic lung disease.
In the United States, Blastomyces is most prevalent in the areas around the Ohio and Mississippi River valleys, as well as the Great Lakes. However, it can thrive in any location with moist soil and plenty of decomposing leaves and wood. People traveling through these areas will often inhale the fungal spores. Most people do not get sick, but some develop an infection called blastomycosis.
Symptoms usually include coughing and fever but may worsen without treatment.
Valley fever, known medically as coccidioidomycosis, is an infection resulting from the Coccidioides fungus. These species live in the soil of the southwestern United States. Like many of the more common fungi, people breathe in Coccidioides spores while traveling through these regions—usually when the wind blows dust into the air on hot days.
Valley fever can clear up on its own, but some individuals need antifungal medications to aid their recovery.
The fungus Sporothrix lives in soil and plant matter, like moss, hay, and rose bushes. Because of this, the infection it causes—sporotrichosis—is often called rose gardener’s disease. People most commonly develop this infection when the spores enter through a cut on the hands or arms. The first symptom is usually the growth of a small, painless bump.
Though rare, a pulmonary form of the infection can also occur, causing breathing issues and coughing.
Sometimes called black fungi, black yeasts are a group of microfungi that encompass many different species. This group can cause a range of infections that fall under an umbrella term: phaeohyphomycosis. In humans, these infections are almost always fatal, and symptoms usually include swelling, eye infections, and lesions.
Black yeasts are highly resistant to environmental stresses. Species like Piedraia hortae or Hortaea werneckii are capable of thriving in extreme locations where other fungi cannot, such as sea-side rocks and other regions of high salinity.
Historically, experts believed the Scedosporium genus of fungi and its resulting infections were rare. Over the last several years, they have realized Scedosporium is much more widespread and is an emerging opportunistic pathogen.
The most recognized species, S. apiospermum, lives in water. Infections of this fungus are often the result of near-drowning events in which a person breathes in or consumes infected water. Scedosporium infections are extremely variable, affecting many different parts of the body and causing a large range of symptoms.
Rather than a specific genus of fungus, mucormycetes are a group of various molds that live in decaying leaves, wood, and compost piles. Some of the fungi that fall into this category are of the Mucor species—from which the group gains its name— Rhizomucor, Apophysomyces, or Lichtheimia, among others.
Mucormycetes cause a serious but rare infection called mucormycosis that can spread to many organs, including the lungs, gastrointestinal tract, and brain.
One of the rarest fungal infections in the United States, emergomycosis stems from the Emergomyces species of fungi. Researchers recently renamed this infection and the responsible fungus due to new DNA analysis. Emergomycosis infections resemble many other fungal infections, making them difficult to identify. Usually, the cases involve small, red lesions on the skin.
This infection can be fatal. Emergomyces fungi exist in dirt around the world.
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