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Zoonoses:
Ringworm, Giardia and Toxoplasmosis
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Ringworm isn’t really a worm that forms under
your skin; it's actually a fungi in the group known
as dermatophytes. An infection of the dead layer of
the skin, hair and nails, ringworm often forms a C-shaped
‘ring’ which marks the boundary of the inflamed
skin.
In cats, this infection is usually caused by an organism
called Microsporum canis. Many cats, up to 20%, can
be infected with this well-adapted organism and show
no signs at all.
Ringworm infects the dead layer of skin, hair and nails.
The organisms get nutrients out of this dead tissue,
also called keratin. The fungus often grows on hair
follicles as well, often breaking the shaft of hair
in half as the infection spreads.
As the hair breaks off and is shed in a normal manner,
the organisms falls with it and can easily be transferred
to another animal in the house, your child, or you.
It makes the skin underneath the hair inflamed and often
dry, red, and scaly. |
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The most affected sites for ringworm include,
but are not limited to, the head, chest, forelegs and the
base of the tail. Lesions, although they may appear uncomfortable,
are typically not itchy. Spores can remain infective for up
to 24 months, and even after treatment is initiated, the affected
cat may remain contagious for 3 weeks!
So I just won’t touch my cat, right?
Wrong! Since the spores live on hair, the organisms are wherever
your cats' hair is. On the couch, your favorite blanket, the
carpet, the floor, anywhere! You don’t have to just
stop cuddling with Fluffy to develop ringworm yourself. Fungal
spores can still live many more months after they are shed
on bedding and carpets, however, cleaning with a mix of 1
cup bleach in 1 gallon of warm water, or steam cleaning a
carpet with water at least 110F will typically kill any remaining
spores.
Ok, so I know what it looks like, I know how NOT
to get it, but what if I do come across ringworm?
Bring your cat in to see us as soon as you notice is so we
can test the sites, and initiate treatment.
We test for ringworm a variety of ways. We first try using
a “Woods Lamp” (ultraviolet light) to see if the
affected hairs fluoresce. If they do not, however, it doesn’t
rule out ringworm as the culprit. We also like to run a fungal
culture on the hairs surrounding the lesion. The hairs are
plucked and placed on a culture media (gel) and watched for
growth and any color change in the gel (normal is yellow,
a positive result would change to red). Most cats will show
any positive signs in 10 days, however growth can still occur
in 14-21 days. If a cat develops small lesions, an anti-fungal
ointment is usually prescribed. For more severe cases, a combination
of anti-fungal baths and oral medication is prescribed.
Within 1-2 weeks of treatment, the lesions should stop growing,
and the skin underneath should begin to heal. Remember to
follow the prescription directions, and clean and vacuum your
living areas thoroughly to prevent against re-infection.
Giardia is an intestinal protozoal parasite called Giardia
intestinalis. Infection is the result of ingestion of this
parasite’s cysts.
Giardia is an important cause of diarrhea in both animals
and humans. Giardia is also known as the most common parasite
infection of man, sometimes being called “travelers
diarrhea” or “beaver fever.” The stool can
range from soft to watery and has a large amount of mucus
in it. The stool usually has a foul smell and sometimes blood
is seen as well.
Once ingested, the cysts transform into trophozoite form
and attach themselves to the wall of the intestine using their
flagella -hairlike structures that whip them back and forth-
and begin to feed. These trophozoites multiply in pairs and
some transform into a cyst stage, which are then shed in the
feces. When shed, the cysts can live for several months if
in the right environment. It can be cleaned with 1 cup of
bleach diluted in one gallon of warm water.
Once diagnosed using a fecal flotation test, direct smear,
or Giardia snap test, the condition is most often treated
with a drug called metronidazole or fenbendazole for 5-7 days.
Other symptoms of Giardia infection are vomiting, lethargy,
weight loss, dehydration and occasionally fever.
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