Larval parasites can be transmitted to humans, where they can migrate

[Guest guest]

http://www.cvm.uiuc.edu/petcolumns/showarticle.cfm?id=94

 

 

Pet Column for the week of November 23, 1998

 

Office of Public Engagement

2001 S. Lincoln Ave.

Urbana, Illinois 61802

Phone: 217/333-2907

 

By Sarah Probst

Information Specialist

University of Illinois

College of Veterinary Medicine

 

It's like something out of the movie Aliens, but it's science, not

fiction. Larval parasites can be transmitted to humans, where they can

" migrate " -or move-from the intestine to the eye, brain, or other internal

organs, possibly causing organ damage, blindness, and in rare

instances even death. Luckily, only a very small number of people get

these symptoms, and you can take steps to reduce the risks for your pet and for

you.

 

" Toxocara canis is one of the most common intestinal parasites of

dogs. This type of worm is one of a group known as ascarids, " says Dr. Allan

Paul, small animal Extension

veterinarian at the University of Illinois College of Veterinary

Medicine in Urbana.

 

" Almost every puppy is born with this parasite. Every puppy should be

dewormed at 2, 4, 6, and 8 weeks of age. The mother and her pups should be

dewormed at the same time, "

explains Dr. Paul. Kittens should be dewormed at 6, 8, and 10 weeks.

Kittens, unlike puppies, are not infected before birth but rather obtain the

infection through their mother's milk.

 

Puppies get the infection before birth through the placenta and after

birth via the mother's milk. Even if the mother has been dewormed, larvae

encapsulated in her liver, skeletal muscle, and kidneys are not killed. At day

42 in the dog's pregnancy, these larvae " wake

up " and migrate through the placenta and umbilical vein to the fetal

liver. Late in the pregnancy larvae move to the mammary glands, and by the fifth

day of nursing they infect the milk. Eggs are passed in the puppy's feces about

3 weeks after birth. Two weeks later

the egg of Toxcara canis may be capable of infecting humans.

 

Infected puppies typically have a rough coat, pot bellies, bad breath,

general failure to thrive, and sometimes vomiting and diarrhea. " Migrating

larvae may carry bacteria into the intestinal wall, the circulatory system, and

other organs through which they move. They can

also cause meningitis, encephalitis, and other central nervous system

disorders, " says Dr. Paul.

 

If two-week-old eggs are somehow ingested by humans (typically by

young children who eat dirt), the eggs hatch and larvae may migrate through

organs or to the eye or central nervous system. Such migration may cause organ

damage, blindness, or, if the central nervous system is involved, death. These

cases are very rare. One estimate indicates that about 2.8% of people in the

United States test positive for Toxocara infection. The vast majority of these,

however, do not experience symptoms or problems.

 

Wildlife can also harbor and distribute the infective stages of

migratory parasites. " Hygienic measures, such as thorough hand washing, should

especially be taken when working where

raccoons have been, " says Dr. Paul. Raccoons like to defecate on wood

piles. Cases have been reported of children being infected by sucking on wood

chips from an outdoor wood pile.

 

Several types of hookworms migrate in humans as well. People are

infected when larvae penetrate their skin. " The main problem of hookworm

infections in your pet is blood loss.

Because the hookworms damage the lining of the intestine when they

suck blood, bacterial infections may arise at feeding sites, " says Dr. Paul.

 

In humans, a type of hookworm called Ancyclostoma can cause cutaneous

larva migrans, also known as " plumber's itch. " The disease is described as a

creeping eruption, i.e., a trail of the larval migration in your skin.

" Electricians, plumbers and other workers who crawl beneath raised buildings,

sunbathers who recline on wet sand, and children typically become infected, "

according to the Centers for Disease Control and Prevention (CDC).

 

A publication from the CDC that urges veterinarians to educate pet

owners about intestinal parasites notes: " In the United States, the popularity

of pets together with high ascarid and

hookworm infection rates in dogs and cats, especially pups and

kittens, result in widespread contamination of soil with infective-stage

larvae. " Children's play habits and attraction to

pets put them at risk for parasite infection.

 

The best way to prevent ascarid and hookworm infection in you and your

pet is to deworm pets, especially young pups and kittens and their mothers.

These animals harbor large numbers of the parasites at an infective stage. To

prevent contaminating the environment,

always pick up your pet's feces whether your animal is infected or

not. Do not allow children to play in areas where infected pets or wildlife may

have been.

 

For further information or to discuss a deworming program for your

pet, contact your local veterinarian.

---------------

Office of Public Engagement

2001 S Lincoln Ave / Urbana, Illinois 61802-6199 / Phone: 217/333-2907

University of Illinois

Your comments about the site are welcome, but we cannot dispense

medical advice via the Internet. For permission to reprint individual

Pet Columns, please email Mandy Barth at mandyb.