When common parasites of dogs and cats infect humans, the
illness is called toxocariasis (or visceral larva migrans).
Toxocariasis usually affects kids under age 10. Especially at risk
are those who like to put things in their mouths, or those whose
families have pet dogs or cats.
Signs and Symptoms
Many kids won't have symptoms, but if they do, they can
include fever, cough or wheezing, abdominal pain, enlarged liver or
spleen, poor appetite, a rash that sometimes looks like hives, and
enlarged lymph nodes ("swollen glands").
Toxocariasis also may affect the eyes, causing decreased vision,
swelling around the eyes, or a cross-eyed appearance. Untreated
toxocariasis can cause retinal damage and decreased vision.
Most cases go undiagnosed and do not cause problems. Some
toxocariasis cases are diagnosed during a routine eye exam or an
X-ray study done for some other reason.
Transmission
Toxocariasis is an infection caused by the larvae of parasitic
worms -
Toxocara canis
and
Toxocara cati -
that usually live in the intestines of dogs and cats. Eggs from the
worms pass into the feces of dogs and cats and can contaminate pet
areas around the home where kids play. The eggs can be swallowed by
children, especially those who:
- are 1 to 4 years old
- often put things in their mouths
- don't often wash their hands
After entering the body, the eggs hatch into larvae that
penetrate through walls of the digestive tract and may migrate to a
child's liver, lungs, eyes, and elsewhere.
Experts in the United States estimate that about 20% of dogs
pass
Toxocara
eggs into their stool. In Great Britain, 24% of soil samples taken
from public parks contained the eggs. Toxocariasis cannot be spread
from person to person.
Prevention
To help prevent kids from being exposed to toxocariasis:
- keep them away from areas where dogs or cats play
- wash your toddler's hands frequently
- reminding older kids to wash their hands often, especially
after playing with a pet dog or cat
- discouraging toddlers from putting dirty hands in their
mouth
- keeping pets away from the sandbox and covering the sandbox
when it's not being used
- taking household pets to the veterinarian to be dewormed,
especially puppies younger than 6 months old
Diagnosis and Treatment
A doctor can usually diagnose a case of toxocariasis by physical
exam and blood tests. Doctors may not prescribe any medication to
treat a child with mild symptoms. Severe toxocariasis involving the
lungs, eye, or other important organs may be treated with
antiparasitic drugs to kill the larvae. For severe lung
toxocariasis, doctors sometimes also prescribe anti-inflammatory
drugs.
A child with severe toxocariasis should be given medicine as
prescribed by your doctor. Prevent reinfection by deworming your
pets and keeping kids away from areas where pets defecate (poop).
Remind your kids to wash their hands often during the day,
especially after playing with pets.
When to Call the Doctor
Call your doctor if your child has any of the symptoms of
toxocariasis, including:
- fever
- rash
- cough or wheezing
- abdominal pain
- poor appetite
- vision problems
Reviewed by:
Joel Klein, MD
Date reviewed: November 2008
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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