The fungi — molds, yeasts and mushrooms — are a vitally important life form that most people know very little about.
For example, fertile soil can contain up to a million fungus cells, spores and colonies per gram (about the size of a sugar cube), and their mass far outweighs that of all the bacteria in that same soil sample.
A fungus can consist of many cells (multicellular) or only of one cell (unicellular). Some species are vital for life, since they help degrade the world's organic waste — dead plants and animals — that would otherwise accumulate and make the earth uninhabitable.
Some kinds of fungi, such as certain mushrooms and cheese molds, are good to eat, while others are deadly poisonous. Some species grow on or in other plants and animals making them ill, while other species grow in association with specific plants to help them flourish. Some species produce life-saving antibiotics, while other species help bread rise or are used to produce alcoholic beverages.
There are more than 100,000 different kinds or species of fungi. However, only about 200 are able to cause disease in humans and other animals. Over the last 20 years, the incidence of serious fungal infections has been increasing in the human population.
A recent example of how a fungus can become a possible global threat is the yeast Candida auris. It was first identified in Japan in 2009, but was later found in collections dating to 1996 in South Korea. Scientists have been unable to establish where this fungus originated, but today it seems to be everywhere. It is being found in a number of countries where it is causing severe illness in hospitalized patients and people in long-term-care facilities. It has caused bloodstream infections, wound infections, and ear infections. It can quickly lead to death in patients who have weakened immune systems or other medical problems.
In the United States, the CDC has confirmed more than 587 cases of this fungal disease over the past several years. Nearly half of the patients who become infected with this fungus die within 90 days. Strains of this fungus have been found to be resistant to some or all anti-fungal medicines currently available, which makes it difficult to treat and contain. It can also be difficult to identify, and a lot of research will be needed to try and contain this possible global threat.
Larrie Stone is a retired Dana College science professor.