Neither plants nor animals, fungi belong to a group of their own. There are about 99,000 known species of fungal organisms, including yeasts, rusts, smuts, mildews, molds, and mushrooms.
Fungi are found in almost any habitat, including the International Space Station (ISS), where they were found to decompose food, with some spores surviving 5 months in microgravity.
Many live on the land, mainly in soil or on plant material. They are one of the most widely distributed organisms on the Earth.
They feature in foods, such as mushrooms and baker's yeast, and they have important roles in medicine and the environment. This article will look at some of the hazards and uses of fungi in health.
Fungal infections and health issues
Ringworm is a common fungal infection.
The Centers for Disease Control and Prevention (CDC) estimate that there are about 1.5 million different species of fungi on Earth, some 300 of which cause illness in humans.
Fungal diseases often stem from common fungi found in the environment. Most fungi are not dangerous, but some can be harmful to health.
Fungal infections are described as opportunistic or primary. Infections that affect many areas of the body are known as systemic infections, while those that affect only one area are known as localized.
Opportunistic fungal infections take advantage of the weakened immune system. They are common in patients whose immune systems are compromised, for example, because of HIV or AIDS or other medical problems.
These types of infections can be particularly aggressive and can spread rapidly to other organs. Sometimes they can be fatal.
Opportunistic fungal infections include aspergillosis, candidiasis, and mucormycosis.
Primary fungal infections can occur in people with a normal immune system. They can cause serious health problems. Some primary fungal infections are more common in certain geographic areas.
Primary fungal infections tend to develop at a slow rate. In some cases months or years may pass before a person seeks medical attention. For most people with a normal immune system, the fungal infections do not spread to organs deep in the body.
Paracoccidioidomycosis, coccidioidomycosis, and histoplasmosis are examples of primary fungal infections.
Localized fungal infections affect only one area of the body. When normal balances that are responsible for keeping fungi in check are upset, localized fungal infections can occur. Some kinds of antibiotics kill harmful bacteria but they can also kill also helpful bacteria. As a result, fungal growth can remain unchecked.
In time, the resulting overgrowth can cause symptoms, but they are typically mild. In most cases as soon as the bacteria begins to grow back, the balance is restored and the problem usually resolves. Localized fungal infections usually involve areas such as the skin and nails, vagina, mouth or sinuses.
People who live or work in damp places where mold is present have a higher chance of developing respiratory diseases, skin irritation, and other health problems. There may also be a higher risk of cancer.
Who is at risk?
A fungal infection can affect any person, even those who are relatively healthy. People come in contact with fungi on a daily basis. They are constantly breathing in fungal spores each day without getting sick.
A person with a weakened immune system is more likely to develop a fungal infection. Some people are born with a weak immune system. Others may have an illness that attacks the immune system such as HIV or AIDS. Certain medications, including corticosteroids and cancer chemotherapy, can lower the body's ability to fight infections.
The most common fungi to cause skin infections are the tinea group of fungi, which causes ringworm and athlete's foot. Another common type is candida, which is responsible for thrush.
Athlete's foot is a common fungal infection of the toes and feet. Thrush is a common fungal infection of the mouth and vagina. Fungal infections of the skin, nails, and vagina are common, but they are not usually serious, and they do not spread deeper into the body.
Fungal infections in healthy people with a normal immune system do not normally affect the internal organs.
Internal fungal infections of the heart, lungs, brain and other organs sometimes occur. These can be life threatening.
Treatment for fungal infections
Fungal infections are generally treated using antifungal medicines.
Topical preparations are effective in treating many fungal infections.
These may come in the form of creams, sprays, solutions, tablets, shampoos, oral medications, or injections. Most kill the infection by damaging the wall of the fungus, causing the fungal cell to die.
Antiviral drugs are another effective treatment for fungal infections.
Several drugs are available that are effective against fungal infections, but the structure and chemical makeup of some fungi can make them difficult to kill.
Antiviral drugs are applied directly to the fungal infection on the skin or another surface. Antiviral drugs can be administered by mouth or, for serious infections, injected.
Serious fungal infections may require several months of treatment. Common drugs for serious fungal infections include fluconazole, anidulafungin, and micafungin. Each is used to treat a different type of infection. They may cause adverse side effects, so they should always be administered by a doctor.
Use of fungi in science and medicine
Fungi make important contributions in managing disease in humans and animals. Penicillin is based on fungi. Fungi are involved in the industrial processing of more than 10 of the 20 most profitable products used in human medicine. Drug discovery and research are ongoing.
Many important medications are based on fungi.
Bread yeast is important in baking, but studies of bakers yeast also led to the discovery of basic cellular biochemistry and metabolism.
In 1929 Alexander Fleming isolated a substance from mold, and from there, penicillin was discovered. It was the first of a series of antibiotics derived directly from fungi that revolutionized the medical world.
Penicillin from fungus was first used successfully to treat an infection caused by a bacteria in 1941. After this, many previously fatal diseases caused by bacteria became treatable.
Several new groups of fungal agents have been discovered. The widely used antifungal agent Griseofulvin is derived from fungi. Griseofulvin is used to treat dermatophytes. It accumulates in the hair and skin following topical application.
Sordarins are another complex molecule with a narrow range of action against yeasts and yeast-like fungi. The compounds inhibit protein biosynthesis, and they have become an important treatment option against several fungal pathogens of humans.
Cyclosporin A is a metabolite of several fungi. It is a powerful immunosuppressant in mammals. It is commonly used after bone marrow and organ transplants in humans.
Ergots contain alkaloids, and they work by acting on the sympathetic nervous system. This results in the inhibition of noradrenaline and sclerotin, and this, in turn, causes blood vessels to dilate.
Ergot alkaloids have a number of medicinal uses, the most common being for migraines. The vasodilator activity helps to reduce tension during the onset of an attack. The drugs also help to reduce blood pressure.
The soil-borne fungus, aspergillus terreus produces a secondary metabolite called lovastatin, and Phoma species produce squalestatin.
Statins are commonly used to reduce or remove low-density lipoproteins (LDL), the "bad" cholesterol, from blood vessels in humans, decreasing the risk of an arterial blockage and therefore, also, of a heart attack, stroke, or diabetes.
In the body, lovastatin inhibits HMG CoA reductase and squalestatin inhibits squalene synthase. By blocking these enzymes, the body works to remove cholesterol complexes from inside the blood vessels.
Fungi are found throughout the environment, and they are important for humans. Discoveries such as penicillin and the resulting antibiotics greatly changed the medical world for the better.
Ongoing work continues to find ways that fungi can help doctors better understand the human body and treat illnesses.