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

• Common Toxocariasis, NOS

What is Common Toxocariasis? (Definition/Background Information)

• Common Toxocariasis is a parasitic roundworm infection caused by Toxocara species. This type of toxocariasis infection is typically reported in adults
• The eggs of the parasite are often found in animal feces, or soil that has been contaminated by animal feces. When Toxocara eggs containing embryos are ingested and enter the gastrointestinal tract, they hatch. The released larvae then infect the intestinal wall and feed off the host cells
• The larvae/worm can also travel through blood within the human body, causing inflammatory reactions at various organ sites, resulting in associated symptoms
• The signs and symptoms of Common Toxocariasis are typically mild. It may include fever, abdominal pain, weakness, and lethargy
• Most infections are known to resolve spontaneously. However, if treatment is necessary, anti-parasitic drugs for Common Toxocariasis may be prescribed

Who gets Common Toxocariasis? (Age and Sex Distribution)

• Common Toxocariasis typically affects adults of both male and female genders
• The infection was originally reported in certain rural areas of Midi-Pyrénées region of France; but, is now seen in other parts of the world too

What are the Risk Factors for Common Toxocariasis? (Predisposing Factors)

The risk factors for Common Toxocariasis are as follow:

• 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

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 Common Toxocariasis? (Etiology)

Common Toxocariasis is caused by the parasitic roundworm of the genus Toxocara, and is generally characterized by mild symptoms.

• Toxocariasis is caused when Toxocara eggs containing embryos are ingested.  Once inside the host, the eggs hatch and give rise to larvae that infect the intestinal wall
• 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
• The larvae live inside the host, feeding-off the host cells by digesting them
• The larvae/worm can also move from one site to another within the human body via the bloodstream, causing inflammatory reactions at each site, resulting in symptoms of Common Toxocariasis

Occasionally, the term Common Toxocariasis is used synonymously with Covert Toxocariasis. However, the latter occurs primarily in children.

What are the Signs and Symptoms of Common Toxocariasis?

The signs and symptoms of Common Toxocariasis are typically mild and vague/unclear; the affected individuals may be asymptomatic as well. The following are some symptoms of the infection:

• Digestive problems, abdominal pain
• Eosinophilia: Increased eosinophils in blood, indicative of an infection
• Lethargy; chronic weakness
• Breathing difficulties
• Itching skin and skin rashes (infrequently noted)

How is Common Toxocariasis Diagnosed?

Common Toxocariasis is diagnosed with the aid of the following tools:

• A thorough physical examination and evaluation of complete medical history
• Blood test for measuring the level of eosinophils
• Tissue biopsy (if necessary) 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 Common Toxocariasis?

Common Toxocariasis does not often cause any complications. However, the infection may become chronic, and can cause excessive weakness in the affected individual.

How is Common Toxocariasis Treated?

Many cases of Common Toxocariasis are reported to resolve spontaneously without treatment. However, if the symptoms persist, anti-parasitic medication may be prescribed.

How can Common Toxocariasis be Prevented?

Prevention of Common Toxocariasis may be achieved 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 Common Toxocariasis? (Outcomes/Resolutions)

Common Toxocariasis often resolves spontaneously. However, there is a possibility for the infection to become chronic, without adequate treatment.

Additional and Relevant Useful Information for Common Toxocariasis:

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

Humans are paratenic hosts i.e., hosts who are not necessary for the parasite to complete its life cycle. However, such hosts may still contribute towards maintaining the life cycle of the parasite.