What is Toxocariasis?

Toxocariasis is a type of parasitic infection that occurs when a person accidentally swallows traces of cat or dog feces that contain roundworm eggs. Ingested roundworm larvae spread throughout the human gastrointestinal tract, which can lead to abdominal pain and nausea. In severe cases, larvae can cause more widespread problems in the lungs, eyes, or brain. Most infections are considered mild and do not require medical treatment. If toxocariasis causes organ damage or vision problems, however, a physician can administer medications to eradicate the parasite and prevent further complications.

Dogs can carry a roundworm parasite known as Toxocara canis, while cats carry Toxocara cati. Either of these roundworms can lead to toxocariasis in humans if feces is swallowed. The condition is most commonly seen in young children who do not wash their hands after playing in contaminated soil. Eating unwashed garden vegetables or undercooked meat from animals raised with dogs or cats can also lead to infection. Symptoms tend to appear one to three weeks after ingestion when the eggs begin to mature and hatch in the gastrointestinal tract.

Doctors recognize three distinct types of toxocariasis infection. Most cases in children are called covert, meaning that symptoms are mild and short-lasting. An individual with covert toxocariasis may experience slight abdominal pain, a cough, or a headache. Visceral larva migrans occurs when eggs hatch and spread throughout the body, leading to inflammation of the lungs, skin, heart, or even the brain. Larvae can occasionally spread to the eyes in a condition called ocular larva migrans, which can cause blurred vision and redness.

If an individual notices possible signs of toxocariasis in herself or her child, she should visit a physician immediately to receive a proper diagnosis. A doctor can take a blood sample to check for an increased white blood cell level and the presence of parasites. If visceral or ocular larva migrans is suspected, the physician may take computerized tomography scans of the internal organs to analyze the extent of damage.

Treatment for toxocariasis depends on the type of infection and the severity of symptoms. Most cases of covert toxocariasis are not treated medically; the larvae are naturally expelled in bowel movements over a few weeks. If roundworm larvae spread, however, a physician can prescribe drugs called anthelmintics that seek out and destroy parasites in the bloodstream. Anti-inflammatory medications can help relieve other symptoms related to infection. In rare cases where parasites cause significant eye or organ damage, surgery may be needed to repair or remove affected body parts.