Toxocariasis is an infection caused by the parasitic roundworms commonly found in the intestine of dogs and cats. In most cases, toxocariasis infections are not serious. The most severe cases are rare. They are more likely to occur in young children who often play in outdoor sandboxes or dirt, or who eat dirt contaminated by dog or cat stool.


Infection occurs after swallowing infective roundworm eggs in soil or other contaminated surfaces.


Many people, especially adults infected by a small number of roundworm eggs, may not notice any symptoms. More serious cases may cause the following problems:

  • Ocular larva migrans (OLM). This is an eye disease that can cause blindness. OLM occurs when a microscopic worm enters the eye. It may cause inflammation and formation of a scar on the retina. This can result in permanent, partial loss of vision.

  • Visceral larva migrans (VLM). This is a disease that causes swelling of the body's organs or central nervous system. Symptoms of VLM, which are caused by the movement of the worms through the body, include fever, coughing, asthma, or pneumonia.


Your caregiver will examine you and perform blood tests. Other diagnositic tests may be performed.


  • People with mild illness caused by VLM do not require specific treatment because symptoms generally go away within a few weeks. For people with more severe or ongoing symptoms, treatment with antiparasitic drugs, usually in combination with anti-inflammatory medicines, is prescribed.

  • Treatment of OLM is more difficult. In addition to antiparasitic and anti-inflammatory drugs, surgery may be recommended to prevent progressive damage to the eye.


  • Have your veterinarian regularly treat your dogs and cats for worms. This is especially true for young animals.

  • Wash your hands well with soap and water after playing with your pets and after outdoor activities, especially before you eat. Teach children to always wash their hands after playing with dogs and cats and after playing outdoors.

  • Do not allow children to play in areas that are soiled with pet or other animal stool.

  • Clean your pet's living area at least once a week. Feces should be either buried or bagged and thrown away in the trash.

  • Teach children that it is dangerous to eat dirt or soil.


Take all medicines as directed by your caregiver.


  • You have a fever.

  • You develop coughing or wheezing.

  • You have abdominal pain.

  • You have a poor appetite.

  • You develop a rash.

  • You have swollen lymph glands.

  • You have vision problems.