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Biodefense Reference Library
Foreign Animal and Zoonotic Disease Center
One Medicine: One Health (Zoonotic Disease)
Online Course
Presented
by
Stephen M. Apatow,
Director of Research and Development
Humanitarian Resource
Institute Biodefense Reference Library
Foreign Animal and Zoonotic Disease Center
[Vitae][Email]
ZOONOTIC DISEASES
FUNGAL
DERMATOMYCOSES
Centers for Disease Control and Prevention: Division of Parasitic
Diseases
Ringworm...Microsporidiosis
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
(Ringworm, Dermatophytosis, Tinea, Trichophytosis, Microsporosis,
Jock Itch, Athlete's Foot)
AGENT:
Organisms are subclassified into: 1. Geophilic - inhabit soil 2.
Zoophilic - parasitic on animals 3. Anthropophilic - Primarily infects humans
All can produce disease in humans. Grouped in three genera 1. Microsporum
2. Trichophyton 3. Epidermophyton
RESERVOIR
AND INCIDENCE
Fungal spores remain viable for long periods on carrier animals
and fomites. Exposure to reservoir hosts harboring different dermatophytes
determines the type and incidence of infection in humans. Microsporum canis
can be carried by up to 89% of nonsymptomatic cats. Up to 50% of people exposed
to infected cats, both symptomatic and asymptomatic, have acquired infection.
Pets may also acquire disease from humans. **T. mentagrophytes is most commonly
transmitted to man from rodents, M. canis from dogs and cats, and T. verrucosum
from cattle and horses.
TRANSMISSION:
Direct or indirect contact with asymptomatic animals or with skin
lesions of infected animals Contaminated bedding Equipment Fungi in air, dust,
or on surfaces of room (spores persist on contaminated surfaces).
DISEASE
IN ANIMALS:
In rodents is often asymptomatic and not recognized until people
are affected. In cats is often asymptomatic. Dogs often show classic skin
lesions. Varying severity of dermatitis occurs with local loss of hair. Deeper
invasion produces a mild inflammatory reaction which increases in severity
with the development of hypersensitivity.
DISEASE
IN MAN:
Often mild, self limiting; scaling, redness, and occasionally vesicles
or fissures. Thickening & discoloring of nails. May show circular lesions
which clear in the center forming a ring. Fungal infections in man are categorized
as to the location on the body: 1. Tinea capitis - Scalp & hair 2. Tinea
corporis - Body (extremities, arm and hand, are most often affected in infections
acquired from lab animals.) 3. Tinea pedis - foot 4. Tinea unguium - Nails.
DIAGNOSIS:
KOH mount of skin scrapings, Fungal culture.
TREATMENT:
Macerated (moist softening and fissuring) stage- aluminum subacetate
("Domeboro") solution soaks with potassium permanganate for secondary infections.
Athlete's feet may respond better to 30% aqueous aluminum chloride or the
carbol-fuchsin paint than to antifungal agents. Broad spectrum antifungal
creams and solutions containing imidazoles or ciclopirox) instead of tolnaftate
and haloprogin help to combat diphtheroids and other gram-positive organisms
present at this stage and alone may be adequate therapy. Dry and scaly stage-
several topical creams, liquids, or lotions are recommended (miconazole,
clotrimazole, ketoconazole, econazole, sulconazole, oxiconazole, ciclopirox
or naftifine. Betamethasone dipropionate with clotrimazole is recommended
for acutely inflamed tinea lesions. For severe cutaneous infections, griseofulvin
or ketoconazole is recommended.
PREVENTION/CONTROL:
Screen newly received animals. Routine sanitization of contaminated
environment, equipment, and caging. Gloves, protective clothing, wash hands
after exposure.
SPOROTRICHOSIS
Centers for Disease Control and Prevention: Division of Bacterial
and Mycotic Diseases
Sporotrichosis
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
AGENT:
Sporothrix schenckii, dimorphic fungus.
RESERVOIR
AND INCIDENCE
Distributed worldwide with sporadic outbreaks. Saprophyte that
grows on soil or vegetation. Has been reported in horses, dogs, cats and many
other species. 19 cases of Sporotrichosis have been reported in man following
contact with feline abscesses or ulcers (12 of these were veterinarians).
TRANSMISSION:
Penetrating injury, or contact with plant or soil. Transmission
from feline to man by direct contact with lesions (penetrating injury NOT
required). Inhalation can lead to pulmonic disease.
DISEASE
IN ANIMALS:
Lesions can be anywhere but are usually located on distal extremities,
head, or base of tail. Appear as draining puncture wounds, cellulitis. Can
ulcerate and become nodular with seropurulent exudate. May cavitate and
expose muscle and bone. May lead to disseminated disease which is usually
fatal.
DISEASE
IN MAN:
The most common clinical form is cutaneolymphatic; it begins with
a nodule or pustule at the point where broken skin allowed inoculation. The
infection may remain confined or may eventually spread and produce SC nodules
along the enlarged lymph ducts. These nodules may ulcerate, and a gray or
yellowish pus appears. Disseminated forms, which are rare, may give rise to
localizations in different organs, especially the bones and joints, as well
as in the mouth, nose, kidneys, or the SC tissue. Pulmonary sporotrichosis
can be confused with TB.
DIAGNOSIS::
Biopsy and histo fungal culture cytology of impression smear of
exudate. Organisms are numerous in cats but are difficult to detect in man,
horses, and dogs. Organism can also be found in feces of infected cat. Antigen
tests are used to diagnose disseminated disease.
TREATMENT:
Potassium iodide, Amphotericin B, or itraconazole.
PREVENTION/CONTROL:
Gloves when handling infected animals. Wash with iodine or chlorhexidine.
CRYPTOCOCCOSIS AND HISTOPLASMOSIS
Centers for Disease Control and Prevention: Division of Bacterial
and Mycotic Diseases
Cryptococcosis...Histoplasmosis
Disease Overview: Institutional Animal Care
and Use Committee, University of California, Santa Barbara.
Cryptococcosis and histoplasmosis are systemic fungal infections
caused by the organisms Cryptococcus neoformans and Histoplasma capsulatum.
Cases of infection are worldwide and sporadic. These organisms are found in
soil, pigeons, and starlings and are spread in bird feces. These systemic
fungi have a predilection for the lung and central nervous system. There is
an increased susceptibility in humans on steroid therapy and with disorders
of the reticuloendothelial system.
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