Definition

Visceral larva migrans is a human infection with certain parasites found in the intestines of dogs and cats.

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Alternative Names

Toxocariasis; Ocular larva migrans; Larva migrans visceralis

Causes, incidence, and risk factors

Visceral larva migrans (VLM) is caused by worms (parasites) that are found in the intestines of dogs and cats. The dog parasite is called Toxocara canis and the cat parasite is called Toxocara cati.

Eggs produced by these worms are in the feces of the infected animals. The feces mix with soil. Humans can get sick if they accidentally eat soil that has the eggs. This can be through eating fruit or vegetables that were in contact with infected soil and not washed thoroughly before eating. People can also become infected by eating raw liver of chicken, lamb, or cow.

Young children with pica are at high risk of getting VLM. Pica is a disorder involving eating inedible things such as dirt and paint. Most infections in the United States occur in children who play in areas with soil contaminated by dog or cat feces.

After the worm eggs are swallowed, they break open in the intestine. The worms travel throughout the body to various organs, such as the lungs, liver, and eyes. They may also travel to the brain and heart.

Symptoms

Mild infections may not cause symptoms.

Serious infections can cause the following symptoms:

• Abdominal pain
• Cough
• Fever
• Irritability
• Itchy skin (hives)
• Shortness of breath
• Wheezing

If the eyes are infected (called ocular larva migrans), loss of vision and crossed eyes (strabismus) can occur.

Signs and tests

If you have visceral larva migrans, you may have a high level of white blood cells.

People with this condition may also have signs of a swollen liver, rash, and lung or eye problems.

Tests may include:

• Complete blood count with differential
• Blood tests to detect antibodies to Toxocara

Treatment

This infection usually goes away on its own and may not require treatment. Some people need to take anti-parasitic drugs such as albendazole.

Expectations (prognosis)

Mild infections may go away without treatment. Severe infections involving the brain or heart can result in death, but this is rare.

Complications

• Blindness
• Decreased visual acuity (worsened eyesight)
• Encephalitis (infection of the brain)
• Heart arrhythmias
• Respiratory distress

Calling your health care provider

Contact your health care provider if you develop any of the following symptoms:

• Cough
• Difficulty breathing
• Eye problems
• Fever
• Rash

A full medical exam is needed to rule out visceral larva migrans. There are many conditions that cause similar symptoms.

Prevention

Prevention includes deworming dogs and cats and preventing dogs and cats from defecating in public areas. Children should be kept away from areas where dogs and cats may defecate.

It is very important to wash your hands thoroughly after touching soil or after touching cats or dogs. Teach your children to wash their hands thoroughly as well after being outdoors or after touching cats or dogs.

Do not eat raw liver of chicken, lamb, or cow.

References

Despommier DD, Hotez PJ. Tissue nematodes. In: Long SL, ed. Principles and Practice of Pediatric Infectious Diseases. 4th ed. Philadelphia, PA: Elsevier Saunders; 2012: chap 277.

Diemert DJ. Tissue nematode infections. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011: chap 366.

Nash TE. Visceral larvae migrans and other unusual helminth infections. In: Mandell GL, Bennett JE, Dolan R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Churchill-Livingstone; 2009:chap 291.

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