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