Sporotrichosis
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fungal infection
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
Sporotrichosis
a chronic disease of humans and animals caused by a fungus of the genus Sporotrichium; a type of mycosis.
In humans the disease affects the skin, subcutaneous tissue, and, less frequently, the mucous membrane and the internal organs. The causative agents of sporotrichosis have been found in plants (shrubs, grass, hay, and cereals), in soil, in street dust, and in food products. The fungus enters the body through injured skin and through the respiratory and gastrointestinal tracts. The infection is spread via the lymph and blood. Numerous hard, painless lymph nodes appear, mainly on the upper extremities. The nodes gradually become soft and open up, forming ulcers that leave irregular scars. The internal organs may be affected in the form of sepsis.
Diagnosis is made on the basis of bacterioscopy, tissue biopsy, and allergic cutaneous reactions. Sporotrichosis is treated with potassium or sodium iodide, or antibiotics; it may be treated locally with aniline dyes or ichthammol. Prophylaxis consists of thorough and timely treatment of injured skin.
In animals the causative agent of sporotrichosis attacks the organism through traumatized skin (wounds and abrasions). Horses, mules, dogs, and cats are mainly affected. The course of the disease is chronic. In horses the skin and lymphatics in the region of the neck and the extremities are affected. Pustules, ulcers, and abscesses are formed. The nodes that erupt on the skin are initially hard and painless; they become soft, forming fistulas that secrete pus. Necrotic lymph nodes (abscesses) subsequently form ulcers with raised edges. In dogs, cutaneous nodes and ulcerations appear over the entire body. Treatment consists of the use of iodine and sulfanilamide preparations. Specific prophylactic measures have not been developed.
REFERENCES
Mashkilleison, L. N. Infektsionnye i parazitarnye bolezni kozhi, 2nd ed. Moscow, 1964.Spesivtseva, N. A. Mikozy i mikotoksikozy, 2nd ed. Moscow, 1964.
I. IA. SHAKHTMEISTER and I. G. LEVENBERO