Visceral larva migrans is an infection with the larval form of the parasite Toxocara canis (associated with dogs) or Toxocara cati (associated with cats), which can affect a person's eyes, lungs, liver, brain, and heart.
Alternative Names
Toxocariasis; Ocular larva migrans; Larva migrans visceralis
Causes, incidence, and risk factors
This infection is caused by ingestion of eggs from the dog and cat parasites called Toxocara canis and Toxocara cati , respectively. These worms inhabit the intestinal tract of infected dogs and cats, and their eggs appear in abundance in the feces of these animals. However, the parasites are not infectious until three weeks after they have been excreted -- so the major risk factor for this infection is not the animal feces but the soil into which the eggs have passed. Humans may ingest the eggs by eating unwashed raw vegetables. Young children with pica (eating inedible things such as dirt) are at highest risk, but this infection can also occur in adults. People can also become infected by eating raw liver. After ingestion, the eggs hatch into larvae in the gastrointestinal tract and are carried into the circulation and to various tissues -- primarily the lung, liver, and eyes. The brain, heart, and other organs can also be affected.
Signs and tests
Visceral larva migrans may be suspected in an individual with elevated white blood cell count (leukocytosis) and an elevated number of eosinophils (eosinophilia). An enlarged liver, rash, and lung or eye abnormalities may also be noted. The disease may be definitively diagnosed by detection of larvae in the affected tissue. A blood test for antibodies can also be used to detect infection.
Treatment
This infection is usually self-limiting and may not require therapy. Certain anti-parasitic drugs may also be used such as diethylcarbamazine, albendazole, or mebendazole.
Expectations (prognosis)
Prognosis is related to the site involved -- mild infections may resolve on their own or they may have additional complications. Certain severe infections involving the brain or heart can result in death, but this is rare.
Calling your health care provider
Notify your medical provider if you develop (or your child develops) fever, rash, difficulty breathing, cough, or eye-related symptoms. Although there are many conditions that may cause these symptoms, a full medical evaluation is needed.
Prevention
Deworming of dogs and cats and minimizing exposure of children to areas that may be contaminated with animal feces are important preventive measures. Hand washing after handling soil is also important.