Toxocariasis (Visceral Larva Migrans)
What is Toxocariasis (Visceral Larva Migrans)?
Toxocariasis is a parasitic infection caused by roundworm larvae that normally live in dogs and cats. When humans accidentally ingest these parasite eggs, the larvae hatch and migrate through the body's tissues. This condition is also called visceral larva migrans because the larvae move through internal organs.
The infection happens most often in young children who play in contaminated soil or sandboxes. Dogs and cats shed roundworm eggs in their feces, and these eggs can survive in soil for months or years. When someone touches contaminated soil and then puts their hands in their mouth, they can swallow the eggs. The larvae then travel through the liver, lungs, and other organs, causing inflammation and tissue damage.
Most cases are mild and resolve on their own without treatment. However, heavy infections can cause serious symptoms, especially in children. Early detection through blood testing helps identify the infection and guide treatment decisions when needed.
Symptoms
- Fever that comes and goes
- Persistent cough or wheezing
- Enlarged liver that may be tender
- Abdominal pain and loss of appetite
- Skin rashes or itching
- Fatigue and general weakness
- Muscle aches
- Vision problems if larvae reach the eyes
Many people with toxocariasis have no symptoms at all, especially in mild infections. Symptoms typically appear when larvae migrate through organs and cause inflammation. Children are more likely to show symptoms than adults because they often ingest more parasite eggs.
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Causes and risk factors
Toxocariasis occurs when someone accidentally swallows roundworm eggs from dog or cat feces. The primary risk factor is contact with contaminated soil in areas where infected pets have defecated. Children between ages 2 and 7 are at highest risk because they play outside and often put their hands in their mouths. Eating dirt, a behavior called pica, significantly increases infection risk.
Pet owners face higher exposure risk, especially if their animals are not dewormed regularly. Puppies and kittens are the most common carriers of these roundworms. Playing in sandboxes, parks, or yards where animals roam freely increases the chance of contact with parasite eggs. Rural areas and communities with stray animal populations tend to have higher infection rates. Poor hand hygiene after outdoor play or contact with pets also contributes to transmission.
How it's diagnosed
Toxocariasis is diagnosed through a combination of blood tests, symptoms, and exposure history. Doctors look for elevated eosinophils, a type of white blood cell that increases during parasitic infections. A complete blood count showing eosinophilia, especially levels above 50% of total white blood cells, strongly suggests toxocariasis in the right clinical context. Rite Aid's testing panel measures eosinophil levels to help detect this condition.
Your doctor will also consider symptoms like liver enlargement, lung inflammation, and a history of pica or contact with puppies or kittens. Specialized antibody tests can confirm exposure to roundworm larvae, though these may not be available in all testing panels. Imaging studies like chest X-rays or liver ultrasounds may show organ involvement. Regular blood testing helps monitor eosinophil counts during treatment and recovery.
Treatment options
- Watchful waiting for mild cases without symptoms, as many infections resolve naturally
- Antiparasitic medications like albendazole or mebendazole for moderate to severe infections
- Corticosteroids to reduce inflammation in organs if symptoms are severe
- Regular deworming of household pets to prevent reinfection
- Improved hand hygiene, especially before meals and after outdoor play
- Covering sandboxes when not in use to keep animals out
- Teaching children not to eat dirt or put dirty objects in their mouths
- Removing pet feces from yards and play areas daily
- Monitoring eosinophil levels with blood tests during and after treatment
Concerned about Toxocariasis (Visceral Larva Migrans)? Get tested at Rite Aid.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
People get toxocariasis by accidentally swallowing roundworm eggs from dog or cat feces. This usually happens when children play in contaminated soil and then put their hands in their mouths. The eggs hatch in the intestines, and larvae migrate through the body's organs. Pet owners and children with pica are at highest risk.
Early signs include fever, fatigue, and loss of appetite. Many people notice a persistent cough or wheezing as larvae move through the lungs. Some develop abdominal pain or an enlarged liver. However, many mild infections cause no symptoms at all and go unnoticed.
Blood tests measure eosinophils, a type of white blood cell that increases during parasitic infections. Eosinophil levels above 50% of total white blood cells often indicate toxocariasis when combined with typical symptoms. Regular testing helps track infection severity and treatment response.
Yes, many mild cases of toxocariasis resolve on their own without medication. The larvae eventually die and are absorbed by the body. However, moderate to severe infections benefit from antiparasitic treatment to reduce symptoms and prevent complications. Your doctor will decide if treatment is needed based on symptoms and blood test results.
No, toxocariasis cannot spread directly from person to person. The infection requires ingestion of roundworm eggs from contaminated soil or surfaces. Humans are dead-end hosts, meaning the larvae cannot complete their life cycle and produce eggs in people. Only contact with infected animal feces poses a transmission risk.
Without treatment, mild infections typically resolve within several months as larvae die naturally. Symptoms may last weeks to months depending on infection severity. With antiparasitic medication, most people recover within a few weeks. Eosinophil levels usually return to normal within 6 to 12 months after the larvae are eliminated.
Most cases cause no lasting damage and resolve completely. However, severe infections can lead to complications like vision loss if larvae reach the eyes. Heavy infections may cause lung scarring or liver damage in rare cases. Early detection and treatment help prevent serious complications, especially in children.
Deworm your pets regularly, especially puppies and kittens. Teach children to wash their hands after playing outside and before eating. Remove pet feces from yards daily and cover sandboxes when not in use. Discourage children from eating dirt or putting dirty objects in their mouths.
Yes, it is wise to have your pets checked and dewormed by a veterinarian. Dogs and cats can carry roundworms without showing symptoms. Regular deworming prevents reinfection and protects other family members. Puppies and kittens should be dewormed multiple times in their first months of life.
See a doctor if you or your child has persistent fever, cough, abdominal pain, or vision changes after contact with puppies or kittens. Children who eat dirt and develop unexplained symptoms should be evaluated. Blood testing can check for elevated eosinophils. Early diagnosis helps prevent complications and guides treatment decisions.