Toxocariasis

What is toxocariasis?

Toxocariasis is an infection caused by parasitic roundworms that ordinarily affect animals. The larvae of the roundworms commonly found in the intestines of dogs (Toxocara canis) and cats (Toxocara cati) cause the infection. The animals pass the worm eggs in their poop. If poop, soil or sand contaminated with the eggs get in your mouth, you can get the infection. Toxocariasis is a rare but serious condition.

Who does toxocariasis affect?

Toxocariasis can affect anyone, but young children and pet owners are more likely to be infected. The most severe cases develop in children who play in and eat dirt containing pet droppings.

How common is toxocariasis?

Studies show that about 5% of the U.S. population has Toxocara antibodies. This means that millions of Americans may have had exposure to the Toxocara parasite. However, most people don’t develop symptoms and wouldn’t have known they had the infection.

How does toxocariasis affect my body?

If you swallow dirt contaminated with animal poop that contains Toxocara eggs, you can get toxocariasis. After you swallow the eggs, larvae hatch in your intestines. The larvae push through your intestinal walls and spread through your bloodstream. The larvae can affect almost any tissue in your body. Your liver and lungs are most commonly affected. The larvae may live for months, and they can cause damage as they travel through your tissues. The larvae don’t mature into adulthood in humans.

Most cases of toxocariasis don’t cause symptoms. You’ll simply pass the worms along at some point when you poop. But if you’ve consumed a lot of Toxocara larvae, they may migrate to different parts of your body. There are two main types of the condition.

Visceral toxocariasis

Visceral toxocariasis occurs when Toxocara larvae travel to various organs in your body. This may include your lungs, liver and central nervous system. Another name for the infection is visceral larva migrans.

Ocular toxocariasis

Ocular toxocariasis occurs when Toxocara larvae travel to your eye. It can cause irreversible vision loss. Another name for the infection is ocular larva migrans.

What are the symptoms of toxocariasis?

Most people with toxocariasis don’t have symptoms and may not know they have the infection. If you develop symptoms of visceral toxocariasis, you may experience:

• Fever.
• Cough.
• Wheezing.
• Extreme tiredness (fatigue).
• Abdominal pain.
• Skin rash.
• Enlarged liver.
• Enlarged spleen.
• Pneumonia.

Ocular toxocariasis usually only affects one eye. Symptoms of ocular toxocariasis may include:

• Eye pain and redness.
• Retina scarring and damage.
• Vision problems.

What causes toxocariasis?

Toxocariasis infections from dogs are most common. Puppies can contract a _Toxocara _parasite (_T. canis_) from their mother before they’re born or from her milk. Toxocara larvae grow quickly in a puppy’s intestines. Within a few weeks of birth, the worms inside a puppy’s intestines can begin producing eggs. When the puppy poops, the eggs come out with it. Two to four weeks later, infectious larvae develop in the eggs.

When you or your child accidentally ingest dirt soiled with dog poop that contains Toxocara eggs, you can get the infection. Children often pick up the infection while playing in sandboxes. They can transfer the eggs from their hands to their mouth and may eat the contaminated sand. Adults may pick up the infection while gardening or working with dirt. Toxocariasis also affects children and adults who have a condition called pica. Pica is a condition where you crave nonfoods such as soil and dirt.

Rarely, you can develop toxocariasis by eating undercooked meat.

Is toxocariasis contagious?

Toxocariasis can’t spread from person to person like a cold or flu. Only animals can transmit the infection to humans through their poop.

How is toxocariasis diagnosed?

Your healthcare provider will perform a physical examination to diagnose toxocariasis. They may ask you about your symptoms and ask about possible exposure to Toxocara larvae. Your provider may request a blood test to check for evidence of toxocariasis. A blood test will check for Toxocara antibodies in your blood. Antibodies are proteins your immune system makes to help defend your body against infection.

How is toxocariasis treated?

You typically don’t need treatment for toxocariasis if you don’t have symptoms. The infection usually goes away on its own. If the infection is causing severe symptoms, don’t try any home remedies for intestinal parasites. Instead, make a call to your healthcare provider. They may recommend an antiparasitic drug such as albendazole or mebendazole. These medications will kill the worms.

Treatment guidelines for ocular toxocariasis may include measures to prevent permanent eye damage. Your healthcare provider may suggest the use of a corticosteroid. They may refer you to an eye specialist for treatment. You may need surgery to remove the worms or treat any problems with your vision.

How can I prevent toxocariasis?

You can prevent toxocariasis by taking some simple precautions. The most important thing you can do is practice good hand hygiene. Wash your hands with soap and water frequently, especially after touching animals and before eating. Other steps you can take to prevent the condition include:

Pets

Make sure you dog or cat sees their veterinarian for checkups regularly. Their veterinarian can recommend testing and provide treatment if your pet needs deworming.

Keep your pet’s living area clean. Wipe down their crate or wash their bedding at least once a week.

Either bury your furry friend’s poop or bag it and throw it in the garbage. Make sure to wash your hands after picking up your pet’s poop.

Children

Teach your children why it’s important to wash their hands. This is especially important after touching pets and playing outside.

Don’t let your children play near pet and other animal poop. Look around playgrounds, sandboxes and other areas that may have droppings. Cover sandboxes when not in use.

Teach your children why it’s dangerous to eat soil and dirt. Keep an eye on them while they’re playing if they have a habit or putting things in their mouths.

What can I expect if I have toxocariasis?

You may never know that you had toxocariasis. Most people don’t develop symptoms. But if you ingest significant amounts of _Toxocara _larvae, they can migrate to areas all over your body. Symptoms may range from a cough to pneumonia. Antiparasitic medications treat most cases of the condition. But if you develop ocular toxocariasis, you may experience permanent vision loss.

A note from Cleveland Clinic

Adding to the list of reasons to wash your hands often, toxocariasis is a condition that occurs when you ingest worm larvae from animal poop. The condition is usually harmless — you may never know you had it. But in some cases, it can cause serious symptoms and complications, including vision loss. So it’s important to see your healthcare provider right away if you develop any symptoms. And keep washing those hands!