Parasitic Fungi and Their Victims Help

By — McGraw-Hill Professional
Updated on Aug 30, 2011

Introduction to Parasitic Fungi and Their Victims

Since certain fungi are parasites, it is only to be expected that some will cause the disease or death of their infected hosts. And those that are potentially pathogenic are nearly impossible to escape, because fungal spores float in the air, almost everywhere! [ Study suggestion: Take the lid off an unwanted jar of jelly and leave it open. Soon, you will see the surface completely covered with a fuzzy substance. To what particular phylum in the Kingdom Fungi, do you think this fuzzy coating belongs? Its spores may have been produced and shed many miles away from you!]

Fungal Parasites Of Plants

Most of the parasitic fungi attack plants. Dutch elm disease , for instance, is due to a sac fungus (Phylum Ascomycetes) that was accidentally brought into the United States by infected logs from Europe during World War I. (The disease gets its Dutch name from the fact that it was first observed in Holland in 1919.) Spread from tree to tree by bark beetles, Dutch elm disease has eliminated thousands of native elm trees across the Continental U.S.

Every year, grain farmers lose billions of dollars of crops to fungal infections. One grain infection with especially important implications for human health is ergot ( ER -gaht), a small black sac fungus in the seed heads of wheat or rye plants. If any unwary humans or farm animals are so unfortunate as to eat such infected grain plants, they may come down with ergotism ( ER -goh-tizm). During the Middle Ages in Europe, ergotism was quite common and was given the alternate name, St. Anthony’s fire . People ate a diet heavy with rye and other natural grains baked in their bread. Although baking killed the fungus, it simply released its toxins into the bread. Such poisoning results in vomiting, cramps, great thirst, and burning in the abdomen. (Hence the old name, St. Anthony’s fire.) Happily, modern grain processing techniques clean the ergot fungus from wheat and rye, so that ergotism is rare.

Fungal Parasites Of Humans

Records show that when patients go to a hospital and accidentally acquire an infection, it is more likely to be a fungal infection than one of bacteria or viruses! And the offending parasite is most likely to be Candida ( KAN -dih-dah) albicans ( AL -bih- kans ), a “glowing white” ( candid ) fungus. A close relative of the yeasts, Candida albicans is a common inhabitant of the human mouth, skin, intestine, and vagina.

Candidiasis ( kan -dih- DIE -ah-sis), or an “infestation with” (- iasis ) Candida fungus, tends to occur whenever the number of these fungi in the human body becomes very excessive. This may happen when a person is given a long-term regimen of antibiotics or steroid drugs, which depresses the activity of the immune (self-defense) system . Whenever too many competing organisms (such as bacteria) are killed off, or whenever the immune system becomes too weak, this leaves the door wide open for Candida albicans to overpopulate part of the body and cause a problem. Scattered white patches appear in infested areas, such as the female vagina, along with an inflammation. This is a common cause of vaginitis (vaj-in- I -tis) – “inflammation of the vagina” – in women of reproductive age.

Practice problems for these concepts can be found at:  The Fungi: Not Just Mushrooms Test

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