fungal infection
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Fungal infections
Several thousand species of fungi have been described, but fewer than 100 are routinely associated with invasive diseases of humans. In general, healthy humans have a very high level of natural immunity to fungi, and most fungal infections are mild and self-limiting. Intact skin and mucosal surfaces and a functional immune system serve as the primary barriers to colonization by these ubiquitous organisms, but these barriers are sometimes breached.
Unlike viruses, protozoan parasites, and some bacterial species, fungi do not require human or animal tissues to perpetuate or preserve the species. Virtually all fungi that have been implicated in human disease are free-living in nature. However, there are exceptions, including various Candida spp., which are frequently found on mucosal surfaces of the body such as the mouth and vagina, and Malassezia furfur, which is usually found on skin surfaces that are rich in sebaceous glands. These organisms are often cultured from healthy tissues, but under certain conditions they cause disease. Only a handful of fungi cause significant disease in healthy individuals. Once established, these diseases can be classified according to the tissues that are initially colonized.
Superficial mycoses
Four infections are classified in the superficial mycoses. Black piedra, caused by Piedraia hortai, and white piedra, caused by Trichosporn beigleii, are infections of the hair. The skin infections include tinea nigra, caused by Exophiala werneckii, and tinea versicolor, caused by M. furfur. Where the skin is involved, the infections are limited to the outermost layers of the stratum corneum; in the case of hairs, the infection is limited to the cuticle. In general, these infections cause no physical discomfort to the patient, and the disease is brought to the attention of the physician for cosmetic reasons.
Cutaneous mycoses
The cutaneous mycoses are caused by a homogeneous group of keratinophilic fungi termed the dermatophytes. Species within this group are capable of colonizing the integument and its appendages (the hair and the nails). In general, the infections are limited to the nonliving keratinized layers of skin, hair, and nails, but a variety of pathologic changes can occur depending on the etiologic agent, site of infection, and immune status of the host. The diseases are collectively called the dermatophytoses, ringworms, or tineas. They account for most of the fungal infections of humans.
Subcutaneous mycoses
The subcutaneous mycoses include a wide spectrum of infections caused by a heterogeneous group of fungi. The infections are characterized by the development of lesions at sites of inoculation, commonly as a result of traumatic implantation of the etiologic agent. The infections initially involve the deeper layers of the dermis and subcutaneous tissues, but they eventually extend into the epidermis. The lesions usually remain localized or spread slowly by direct extension via the lymphatics, for example, subcutaneous sporotrichosis.
Systemic mycoses
The initial focus of the systemic mycoses is the lung. The vast majority of cases in healthy, immunologically competent individuals are asymptomatic or of short duration and resolve rapidly, accompanied in the host by a high degree of specific resistance. However, in immunosuppressed patients the infection can lead to life-threatening disease. See also Fungi; Medical mycology.
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fungal infection
Oxford Food & Fitness Dictionary:
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fungal infections
Diseases caused by fungi which either digest dead tissue such as skin (e.g. athlete's foot) or parasitically feed on living tissue in the body (e.g. thrush). Fungal infections of the skin are usually characterized by itchy, red patches that may develop into pus-filled blisters. They tend to be very contagious and occur in warm, dark, moist regions of the body (e.g. in the groin). Primary treatment usually consists of washing with soap and water, drying thoroughly, and applying an antifungal agent. You are advised to consult a doctor if you suffer repeated or persistent fungal infections.
Gale Encyclopedia of Public Health:
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Fungal Infections
Fungal infections of the skin are among today's most common infectious diseases, and they occur worldwide. Superficial fungus infections fall into three broad categories: the dermatophytes (ringworm), tinea versicolor, and cutaneous candidiasis (yeast infection).
Tinea Corporis (Ringworm of the Skin). The typical lesion is an itchy, round or oval patch of skin with central clearing and a red scaly margin— hence the name "ringworm." If it occurs in the groin, it is called "jock itch" or "tinea cruris." If there are only two or three rings of infection, topical therapy with antifungal creams will be sufficient. For widespread infection, oral antifungal pills may be necessary.
Tinea Capitis (Fungal Infection of the Hair). Fungal infections of the scalp are most common in children. The infection presents as round scaly patches of hair loss, often with broken-off stubbly hairs. The infection must be treated with oral antifungal therapies. The prognosis is excellent and shaving the scalp is not necessary.
Tinea Pedis (Fungus of the Feet, or Athlete's Foot). Tinea pedis is the most common type of fungal infection, presenting as itchy, scaling, and/or macerated webspaces. There may be a powdery white scaling of the bottom of the feet. Sometimes the infection presents as blisters on the bottom of the feet. The infection can spread to the groin (tinea cruris). Topical antifungals will cure the webspace infections but oral antifungals are necessary to treat the blistering infections. Afflicted individuals should keep their feet dry and spray their shoes with antifungal sprays.
Tinea of the Nails (Onychomycosis). Toenails are more commonly affected than fingernails. The nail becomes opaque, yellowish, thickened, and crumbly with the accumulation of material under the nail. There may be an associated athlete's foot infection. Oral antifungals are necessary to cure the problem.
Candidiasis (Yeast Infections). Yeast infections occur in closed spaces on the skin, such as the corner of the mouth, under breasts, in armpits, and in the groin. It is a red, moist, and often odorous tender rash, and is more severe in patients taking antibiotics or who have systemic diseases such as diabetes. Heat and sweat aggravate the problem. Candidiasis can also occur in the mouth (oral thrush) or as a yeast vaginitis. Treatment is with topical antiyeast creams and/or oral medication. To prevent recurrence, the area must be kept dry.
Tinea Versicolor. Tinea versicolor presents on the upper trunk—as brown spots in the winter and white spots in the summer. It is easily treated by washing the area with antidandruff shampoos, but the therapy must be repeated monthly to prevent recurrence.
— SUSAN SWIGGUM; JOHN ADAM
Oxford Dictionary of Sports Science & Medicine:
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fungal infections
Disease such as athlete's foot and dhobie itch, which are caused by a fungus. Fungi thrive in damp, warm, unclean environments. Infections can be prevented by keeping the skin dry and scrupulously clean. Antifungicides (e.g. miconazole cream) can be used to treat acute infections.
Columbia Encyclopedia:
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fungal infections
fungal infection, infection caused by a fungus (see Fungi), some affecting animals, others plants.
Fungal Infections of Human and Animals
Many fungal infections, or mycoses, of humans and animals affect only the outer layers of skin, and although they are sometimes difficult to cure, they are not considered dangerous. Athlete's foot and ringworm are among the common superficial fungal infections. Fungal infections of the mucous membranes are caused primarily by Candida albicans (see candidiasis). It usually affects the mouth (see thrush) and the vaginal and anal regions.
The fungi that affect the deeper layers of skin and internal organs are capable of causing serious, often fatal illness. Sporotrichosis is an infection of farmers, horticulturists, and others who come into contact with plants or mud. The disease affects the skin and lymphatic system and, in rare cases, becomes disseminated. Blastomycosis is caused by a yeastlike fungus that reproduces by budding. The North American variety, caused by Blastomycosis dermatitidis, occurs more often in men and seems to be limited to the central and E United States and Canada. Wartlike lesions appear most often on the skin, sometimes spreading to the bones and other organs. The South American variety of blastomycosis is caused by B. brasiliensis. Chytridiomycosis, caused by Batrachochytrium dendrobatidis, is a deadly fungal skin infection in amphibians, which it kills by damaging to the animals' normally permeable skin, thus disrupting the transport of air and moisture.
Among the fungi that infect the deeper tissues is Coccidioides immitis, which causes coccidioidomycosis, sometimes called valley fever, a lung infection that is prevalent in the SW United States. Cryptococcosis is another fungus disease that may be localized in the lung or disseminated, especially to the central nervous system. It has a worldwide distribution, affecting men twice as often as women. The causative agent (Cryptococcus neoformans) has been isolated in pigeon excretions. Histoplasmosis, which is caused by spores of the fungal genus Histoplasma, is a severe infection that shows varied symptoms. In acute cases ulcers of the pharynx and enlargement of the liver and spleen are present. In other forms tubercularlike lesions of the lung occur. In its benign form no symptoms may be present.
Fungal infections sometimes follow the use of antibiotics, which kill nonpathogenic as well as pathogenic bacteria, thereby providing a free field in the body for fungal invasion. Opportunistic fungal infection occurs when a fungus enters a compromised host, as in the case of such diseases as AIDS. Treatment for fungal infections includes systemic antifungal agents, such as amphotericin B, fluconazole, and itraconazole, and agents usually used topically, such as clotrimazole (Lotrimin) and miconazole (Monistat).
Fungal Infections of Plants
Serious damage is done to crops each year by fungal infections of plants such as smuts, rusts, ergots, and mildews. Dutch elm disease, a disease that has seriously depleted the number of elm trees in the United States, is caused by the fungus Ceratostomella ulmi. Such diseases are usually fought with fungicides or by developing resistant plants. See also diseases of plants.
Dictionary of Cultural Literacy: Health:
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fungal infection
(fung-gul)
An infection caused by fungi, such as athlete's foot and chlamydia. (See under “Life Sciences.”)
Mosby's Dental Dictionary:
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fungal infection
n
An infection caused by a fungus or yeast organism.
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McGraw-Hill Science & Technology Encyclopedia
McGraw-Hill Encyclopedia of Science and Technology. Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.
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Food and Fitness: A Dictionary of Diet and Exercise. Copyright © 1997, 2003 by Oxford University Press. All rights reserved.
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Gale Encyclopedia of Public Health
Encyclopedia of Public Health. Copyright © 2002 by The Gale Group, Inc. All rights reserved.
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Oxford Dictionary of Sports Science & Medicine
The Oxford Dictionary of Sports Science & Medicine. Copyright © Michael Kent 1998, 2006, 2007. All rights reserved.
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Columbia Encyclopedia
The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2012, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/.
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Dictionary of Cultural Literacy: Health
The New Dictionary of Cultural Literacy, Third Edition Edited by E.D. Hirsch, Jr., Joseph F. Kett, and
James Trefil. Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin. All rights reserved.
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