DERMATOMYCOSIS

DERMATOMYCOSIS


A dermatomycosis is a highly contagious skin disease caused by fungi. It affects both people and animals. Other names for a dermatomycosis are tinea, ringworm, jock itch, and athlete’s foot. There are three groups of fungi that can cause dermatomycosis:


• Anthrophilic fungi use humans as their primary reservoir.

• Geophilic fungi live in the soil and cause ringworm in people and animals.

• Zoophilic fungi live on animals other than people, but can be transferred to people.

We will deal only with zoophilic fungi that are transmitted from animals to people.



MORBIDITY: +




MORTALITY: +




ETIOLOGY: FUNGAL


Two genera of zoophilic fungi, Microsporum and Trichophyton, are responsible for nearly all cases of dermatomycosis that are zoonotic. The spores of these fungi are able to survive in the environment, in protected areas, for 18 months or more. They rely on keratin, a protein found in the outer layer of the skin, hair, feathers, nails, and hooves, for survival. They thrive when on a person or animal, on shed hair, or on dead skin cells.



HOSTS


Dermatomycosis in animals is called ringworm. Cats, dogs, cows, horses, sheep, and rodents are the most common sources of zoonotic dermatomycoses. The following zoophilic fungi are responsible:


• Microsporum canis is carried by cats and dogs and causes the most common form of ringworm in these animals. It is transmissible to people (Figures 8 and 9).

• Trichophyton mentagrophytes causes ringworm in rodents, cats, dogs, horses, cattle, and pigs. It is transmissible to people (Figure 10).

• Trichophyton equinum is found on horses and rarely on people (Figure 11).

• Trichophyton verrucosum is carried primarily by cattle, but can be found on people, horses, and sheep (Figures 12 and 13).

• Microsporum nanum causes ringworm in pigs. It is rarely found on people.

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FIGURE 8 Microsporum infection in a human


(Courtesy Public Health Image Library, PHIL 3968, Centers for Disease Control and Prevention, Atlanta, 1959.)


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FIGURE 9 Microsporum canis in a cat: the alopecia and erythema of the lateral digit are typical of nail bed infections caused by M. canis


(From Medleau L, Hnilica KA: Small animal dermatology: a color atlas and therapeutic guide, ed 2, St Louis, 2006, Saunders.)


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FIGURE 10 Trichophyton infection in a dog


(Photograph by Annette Loeffler, with permission. From Gaudiano F, Curtis C: Veterinary dermatology: a manual for nurses and technicians, London, 2005, Elsevier.)


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FIGURE 11 Trichophyton infection in a horse. A, Ringworm: diffuse infection with Trichophyton in the girth and chest wall areas due to infection from contaminated girths and riding boots. B, Ringworm: generalized infection with Trichophyton in a 6-month-old foal


(From Pascoe RRR, Knottenbelt DC: Manual of equine dermatology, London, 1999, Saunders.)


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FIGURE 12 Trichophyton infection in a cow. Note irregularly ovoid, hairless areas with mild surface crusting


(Courtesy Dr. H. Denny Liggitt. From McGavin MD, Zachary JF: Pathologic basis of veterinary disease, ed 4, St Louis, 2006, Mosby.)


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FIGURE 13 Trichophyton infection in a human


(Courtesy Public Health Image Library, PHIL 2938, Centers for Disease Control and Prevention, Atlanta, 1964.)



TRANSMISSION


Not every person or animal that comes in contact with these fungi will develop clinical disease. Some animals and people will be carriers while remaining asymptomatic. Young animals and children are most often affected because their immune systems are not fully developed. The same is true for people with suppressed immune systems, such as people with HIV/AIDS, those receiving chemotherapy, and organ transplant recipients.


Animal dermatomycosis is transmitted by direct contact with an infected animal or with items contaminated with fungal spores. Grooming equipment, brushes, blankets, bedding, tack, carpeting, furniture, air filters, shed hair, or any other item that comes in contact with an infected animal can become contaminated with spores. Spores can survive in a boarding facility or any place an infected animal has visited, including veterinary facilities.


The incubation period varies in animals and people but is usually a few days to a few weeks.

Related posts:

  1. ABOUT THE DISEASES
  2. CAMPYLOBACTERIOSIS (VIBRIOSIS)
  3. MYCOBACTERIUM INFECTIONS (TUBERCULOSIS)
  4. PSITTACOSIS

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Oct 1, 2016 | Posted by in EXOTIC, WILD, ZOO | Comments Off on DERMATOMYCOSIS

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