What are the other Names for this Condition? (Also known as/Synonyms)

• Larva Migrans Visceralis
• Systemic Toxocariasis
• VLM (Visceral Larva Migrans)

What is Visceral Larva Migrans? (Definition/Background Information)

• Visceral Larva Migrans (VLM) is a type of toxocariasis that occurs because of migration of the Toxocara larva within an affected individual, from one location to another in the body. The migrating larva move to different tissues and organs, provoking a body reaction/response, which results in the associated symptoms
• Toxocariasis is a parasitic infection in humans caused by roundworms belonging to the genus Toxocara. This infection is transmitted from animals (commonly cats and dogs) to humans, making it a zoonotic infection
• The infection occurs when a human ingests the parasite. This mostly occurs via contamination of one’s hands or food (prior to eating) with the feces of an infected animal. The infection can occur from ingestion of undercooked or raw meat/poultry that is infected
• The signs and symptoms of Visceral Larva Migrans may vary from one individual to another, depending upon the number of larvae present in his/her body system and their specific location. The symptoms of VLM may include coughing, abdominal pain, and enlarged liver 
• The treatment of Visceral Larva Migrans primarily involves the use of anti-parasitic drugs to eliminate the parasite from the body. Surgical intervention may be required to physically remove larvae from the affected organs or tissues
• Delay in treatment or untreated infection can lead to complications, such as organ damage, cardiac arrest, blindness and epilepsy, among others. Nevertheless, the infection can be cured with prompt and adequate treatment

Who gets Visceral Larva Migrans? (Age and Sex Distribution)

• Visceral Larva Migrans is reported globally, with most of the cases being reported in individuals living in poverty and poor economic status
• In the United States, about 14% of the population is reported to be seropositive (testing positive for the presence of Toxocara sp.)
• African-Americans are reported to show an increased susceptibility to VLM

What are the Risk Factors for Visceral Larva Migrans? (Predisposing Factors)

The risk factors for Visceral Larva Migrans may include:

• Having a cat or dog, especially puppies and kittens: Young animals have a weaker immune system and decreased ability to fight infections and foreign pathogens. Toxocara can also be passed through milk from a lactating dog or cat to its offspring
• Owning a household pet that has not been treated for worms
• Breeding animals inside the house/household
• Young children who frequently play outdoors: Children may come into contact with animal feces or soil contaminated by animal feces, which may then infect them via the oral route (mouth). Toys dropped to the ground may be inadvertently placed in the mouth
• Ingesting raw or undercooked meat infected with larvae of Toxocara; including meat of certain birds, rabbits, etc. The liver and other tissues of these animals are host to the parasite
• Consuming raw milk of cows and buffaloes
• Children with Pica, which is a disorder characterized by eating things/materials considered inedible

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Visceral Larva Migrans? (Etiology)

Visceral Larva Migrans is caused by the parasitic roundworm belonging to the genus Toxocara.

• Eggs of Toxocara species are often found in animal feces, or soil that has been contaminated by animal feces
• However, it may take between 2-4 weeks under ideal conditions (such as temperature and humidity) to become infective
• When Toxocara eggs containing embryos are ingested and enter the human gut, they hatch. The released larvae then infect the intestinal wall
• The larvae live inside the host, feeding-off the host cells by digesting them
• Visceral Larva Migrans (VLM) occurs when the Toxocara parasite larvae travel or migrate to multiple tissues (through the bloodstream), such as to the liver, lung, muscle, brain, and heart, causing inflammatory reactions at each site, resulting in a set of associated symptoms

What are the Signs and Symptoms of Visceral Larva Migrans?

The signs and symptoms of Visceral Larva Migrans depend on the site of migration/area of infection, as well as the “parasitic burden”. It is a term used to describe (roughly) the number of eggs or larvae an individual has in his/her system or body.

The severity of symptoms may vary among the affected individuals, with some being asymptomatic. Young children, who are unable to articulate symptoms experienced, may be more severely affected. The following are some reported signs and symptoms of VLM:

• Fever and headaches
• Eosinophilia: Increased eosinophils in blood, indicative of an infection
• Abdominal pain or discomfort
• Coughing
• Weakness or tiredness
• Muscle pain
• Enlarged liver
• Vision abnormalities
• Confusion and memory-related problems

How is Visceral Larva Migrans Diagnosed?

Visceral Larva Migrans is diagnosed with the aid of the following tools:

• A thorough physical examination and complete medical history investigation
• Blood test for measuring the level of eosinophils
• Tissue biopsy to check for the presence of roundworm larvae; although, this test is not definitive. It is difficult to establish a diagnosis on the morphology of the parasite alone
• Confirmation of the presence of parasitic infection in the serum/intra-ocular fluids/cerebrospinal fluid, through antibody detection using enzyme-linked immunosorbent assay (ELISA)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Visceral Larva Migrans?

Visceral Larva Migrans does not often cause any serious complications. However, complications may arise based on the location of the infecting roundworms in the body. The rare but potential complications may include:

• Bowel dysfunction
• Infection of the lungs (pneumonia)
• Damage to the infected organ, which over time, can cause organ failure
• Convulsions (epilepsy)
• Heart attack

How is Visceral Larva Migrans Treated?

The treatment for Visceral Larva Migrans typically includes:

• The use of anti-parasitic drugs, such as albendazole
• Surgical removal of the infection, when symptoms are severe and/or persistent

How can Visceral Larva Migrans be Prevented?

It is possible to prevent Visceral Larva Migrans by adhering to the following practices:

• Washing hands, especially after being outdoors, gardening, or handling animals or playing with pets, prior to eating or performing other related activities
• Frequently deworming household animals including cats and dogs
• Having thoroughly cooking food (especially meat)
• Clearing/disposing pet feces in a timely and appropriate manner
• Supervising young children while they play outdoors; ensuring that children avoid the ingestion of soil or dirt

What is the Prognosis of Visceral Larva Migrans? (Outcomes/Resolutions)

• Most cases of Visceral Larva Migrans subside without causing any serious infection. Also, with treatment, the infection typically clears in a matter of few days or weeks
• A delay in diagnosis and treatment may cause severe damage of infected tissue and interfere with the function of several organs. This may lead to organ failure
• In some rare instances, mostly due to a lack of treatment, some cases are fatal

Additional and Relevant Useful Information for Visceral Larva Migrans:

The life cycle of Toxocara is as follows:

• The parasite eggs are passed through the feces of an infected animal
• The eggs become embryonated in the environment (outside the animal), if conditions, such as humidity and temperature, are ideal
• Once embryonated, the eggs are infective, and hatch once ingested by an animal or human
• The larvae infect the intestinal wall in the small intestine
• The roundworm develops into an adult, once it infects the small intestine and is able to lay eggs that are passed through the feces
• The cycle repeats when eggs are ingested by another animal or host