eukaryotic
Animal and Human Parasites and Pathogens Fungi can affect animals, including humans, in several ways. Fungi attack animals directly by colonizing and destroying tissues. Humans and other animals can be poisoned by eating toxic mushrooms or foods contaminated by fungi. In addition, individuals who display hypersensitivity to molds and spores develop strong and dangerous allergic reactions. Fungal infections are generally very difficult to treat because, unlike bacteria, fungi are eukaryotes. Antibiotics only target prokaryotic cells, whereas compounds that kill fungi also adversely affect the eukaryotic animal host. Many fungal infections mycoses are superficial and termed cutaneous meaning skin mycoses. They are usually visible on the skin of the animal. Fungi that cause the superficial mycoses of the epidermis, hair, and nails rarely spread to the underlying tissue Figure 13.26 . These fungi are often misnamed dermatophytes from the Greek dermis skin and phyte plant, but they are not plants. Dermatophytes are also called ringworms because of the red ring that they cause on skin although the ring is caused by fungi, not a worm . These fungi secrete extracellular enzymes that break down keratin a protein found in hair, skin, and nails , causing a number of conditions such as athletes foot, jock itch, and other cutaneous fungal infections. These conditions are usually treated with over-the-counter topical creams and powders, and are easily cleared. More persistent, superficial mycoses may require prescription oral medications.