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# 8.16: Fungi and Human Disease

Difficulty Level: At Grade Created by: CK-12
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Would you eat these mushrooms?

I would not recommend it. But certain red mushrooms, Ganoderma Lucidum , have been found to be good for you. Red Mushrooms comprise a family of more than 200 mushroom species, which are good for our health. Of these, 6 species have a particularly high therapeutic effect.

### Fungi and Human Disease

Fungi cause human illness in three different ways: poisonings, parasitic infections, and allergic reactions. Science on the SPOT: Fungus Fair explores some of these dangerous but also tasty and weirdly wonderful fungi. See http://science.kqed.org/quest/video/science-on-the-spot-fungus-fair/ for details.

#### Fungal Poisoning

Many fungi protect themselves from parasites and predators by producing toxic chemicals. If people eat toxic fungi, they may experience digestive problems, hallucinations, organ failure, and even death. Most cases of mushroom poisoning are due to mistaken identity. That’s because many toxic mushrooms look very similar to safe, edible mushrooms. An example is shown in Figure below .

Poisonous or Edible? The destroying angel mushroom on the left causes liver and kidney failure. The puffball mushroom on the right is tasty and harmless. Do you think you could tell these two species of mushrooms apart?

#### Fungal Parasites

Some fungi cause disease when they become human parasites. Two examples are fungi in the genera Candida and Trichophyton.

• Candida are yeast that cause candidiasis , commonly called a “yeast infection.” The yeast can infect the mouth or the vagina. If yeast enter the blood, they cause a potentially life threatening illness. However, this is rare, except in people with a depressed immune system.
• Trichophyton are fungi that cause ringworm . This is a skin infection characterized by a ring-shaped rash. The rash may occur on the arms, legs, head, neck, or trunk. The same fungi cause athlete’s foot when they infect the skin between the toes. Athlete’s foot is the second most common skin disease in the U.S.

Figure below shows signs of these two infections.

Ringworm produces a ring-shaped rash, but it isn’t caused by a worm. It’s caused by the same fungus that causes athlete’s foot.

#### Fungal Allergies

Mold allergies are very common. They are caused by airborne mold spores. When the spores enter the respiratory tract, the immune system responds to them as though they were harmful microbes. Symptoms may include sneezing, coughing, and difficulty breathing. The symptoms are likely to be more severe in people with asthma or other respiratory diseases. Long-term exposure to mold spores may also weaken the immune system.

Molds grow indoors as well as out. Indoors, they grow in showers, basements, and other damp places. Homes damaged in floods and hurricanes may have mold growing just about everywhere (see Figure below ). Indoor mold may cause more health problems than outdoor mold because of the closed, confined space. Most people also spend more time indoors than out.

The mold growing on the walls and ceiling of this storm-damaged home may be harmful to human health.

### Summary

• Fungi cause three different types of human illness: poisonings, parasitic infections, and allergies.
• Many poisonous mushrooms are eaten by mistake because they look like edible mushrooms.
• Parasitic yeasts cause candidiasis, ringworm, and athlete’s foot.
• Mold allergies are very common.

### Practice

Use this resource to answer the questions that follow.

• http://www.hippocampus.org/Biology $\rightarrow$ Biology for AP* $\rightarrow$ Search: Characteristics of Fungi
1. What is a parasite? How do parasitic fungi obtain nutrients?
2. What are four human diseases caused by fungi?
3. Describe candidiasis.

### Review

1. Explain why you should never eat mushrooms you find in the woods unless you know for certain which type of mushrooms they are.

2. Compare and contrast ringworm and athlete’s foot.

3. How does mold cause allergies?

4. State why indoor mold may cause more health problems than outdoor mold.

### Vocabulary Language: English Spanish

athlete’s foot

athlete’s foot

Infection of the skin between the toes; caused by the fungus Trichophyton.
candidiasis

candidiasis

Infection of the mouth or of the vagina in females; caused by the yeast Candida.
mold allergies

mold allergies

Allergy caused by airborne mold spores.
ringworm

ringworm

Skin infection that causes a characteristic ring-shaped rash; caused by the fungus Trichophyton.

Feb 24, 2012

Apr 14, 2015