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

• Central Nervous System Toxocariasis
• Cerebral Toxocariasis
• Toxocariasis of Central Nervous System

What is Neurotoxocariasis? (Definition/Background Information)

• Neurotoxocariasis is a type of parasitic infection known as toxocariasis, which is caused by the Toxocara species. This infection is transmitted from animals (commonly cats and dogs) to humans, making it a zoonotic infection
• Neurotoxocariasis occurs when an individual ingests the infective eggs of the roundworm, which then hatches inside their body, releasing larvae. The larvae then travel to the spinal cord or brain through blood, resulting in a set of neurological symptoms
• Both male and female adults are susceptible to this infection. Neurotoxocariasis may present walking difficulties, clumsiness, lack of concentration, and cognitive decline
• The infection is treated using anti-parasitic drugs with or without dexamethasone and steroids. If left untreated, severe complications, such as epilepsy, dementia, and encephalitis, may ensue, which can lead to a poor prognosis

Who gets Neurotoxocariasis? (Age and Sex Distribution)

• Neurotoxocariasis is a rare form of toxocariasis and it predominantly affects adults of both genders
• However, a few cases of this infection have been reported in children as well
• Most cases have been reported from Asia, Europe, and the Americas; very few cases are from Africa

What are the Risk Factors for Neurotoxocariasis? (Predisposing Factors)

The risk factors related to Neurotoxocariasis are as follows:

• 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 Neurotoxocariasis? (Etiology)

Neurotoxocariasis is caused when roundworms belonging to the genus Toxocara, migrate to the brain and spinal cord in the affected individual.

• 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
• The larvae/worm can also move from one site to another within the human body via the bloodstream
• When these parasites migrate to the brain and/or spinal cord, they cause an inflammatory reaction in these tissues, resulting in Neurotoxocariasis

What are the Signs and Symptoms of Neurotoxocariasis?

The type and severity of symptoms of Neurotoxocariasis may vary among the affected individuals. The following signs and symptoms have been reported:

• Headaches
• Nausea
• Clumsiness
• Walking difficulties; problems with gait
• Issues with memory and concentration

How is Neurotoxocariasis Diagnosed?

Neurotoxocariasis is diagnosed by the following methods:

• A thorough physical examination and complete medical history investigation
• Blood test for measuring the level of eosinophils (elevated levels are indicative of an infection)
• 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 Neurotoxocariasis?

If undiagnosed or left untreated, Neurotoxocariasis can lead to serious complications, such as

• Convulsions (epilepsy)
• Increased number of eosinophils in peripheral blood (eosinophilia)
• Inflammation of blood vessels in the brain and/or spinal cord
• Inflammation of brain (encephalitis)
• Idiopathic Parkinson’s disease
• Dementia

How is Neurotoxocariasis Treated?

Neurotoxocariasis is treated using the following medications:

• Using anti-parasitic drugs such as albendazole
• Using anti-parasitic drugs with simultaneous administration of dexamethasone, which increases plasma levels of the anti-parasitic drugs such as albendazole
• Use of corticosteroids

How can Neurotoxocariasis be Prevented?

Neurotoxocariasis 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 Neurotoxocariasis? (Outcomes/Resolutions)

• The prognosis for Neurotoxocariasis is indicated by the severity of symptoms, and whether treatment has been undertaken
• If complications arise, some or several functions associated with the brain and spinal cord may be impaired
• In some cases, residual weakness, spasms, and paralysis have been reported, even after the affected individual recovers from the infection

Additional and Relevant Useful Information for Neurotoxocariasis:

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