Visceral larva migrans

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


Visceral larva migrans is caused by worms (parasites) that infect 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, allowing the infection to spread to humans. Humans may get sick if they eat food that grew in the infected soil. People can also become infected by eating raw liver.

Young children with pica (a disorder involving eating inedible things such as dirt and paint) are at highest risk, but this infection can also occur in adults. Outbreaks have occurred in the U.S. in children who play in areas with soil contaminated by dog or cat feces.

After a person swallows the contaminated soil, the worm eggs break open in the gastrointestinal tract and are carried throughout the body to various organs, such as the lungs, liver, and eyes. The brain, heart, and other organs can also be affected.


Mild infections may not cause symptoms.

More serious infections may cause the following symptoms:

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

Exams and Tests

If you have visceral larva migrans, you may have a higher-than-normal 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


This infection usually goes away on its own and may not require treatment. However, some people may need anti-parasitic drugs such as albendazole.

Outlook (Prognosis)

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

Possible Complications

When to Contact a Medical Professional

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 includes de-worming dogs and cats, preventing dogs and cats from defecating in public areas, and keeping children away from areas where dogs and cats may defecate. It is very important to carefully wash your hands after touching soil.

Alternative Names

Toxocariasis; Ocular larva migrans; Larva migrans visceralis


Kazura JW. Nematode infections. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 378.

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. Orlando, FL: Saunders Elsevier; 2009:chap 291.

Updated: 4/10/2012

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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