Introduction

What is toxocariasis?

Toxocariasis is an infection caused by a parasite called Toxocara, that spreads to humans from animals, commonly dogs or cats. This infection is also known as dog roundworm or cat roundworm, after the causative parasite.¹ The infection occurs when animals shed Toxocara eggs in their faeces, contaminating soil or sand. Humans can become infected if they accidentally ingest these eggs, often through contact with contaminated environments.²

There are two types of toxocariasis – ocular and visceral. Ocular toxocariasis affects the eye, leading to inflammation, retina damage or even vision loss. Visceral toxocariasis occurs when the parasite migrates to different organs of the body.¹

What are the symptoms of toxocariasis?

Most people with this infection do not display symptoms, and they may be unaware of the infection. However, people may experience some symptoms that vary according to the type of toxocariasis.²

The symptoms of visceral toxocariasis can include fever, cough, wheezing, fatigue, abdominal pain, skin rash, enlarged liver or spleen, as well as pneumonia.²

Ocular toxocariasis normally only affects one eye, and symptoms can include pain, redness, scarring, and retinal damage, which result in vision problems.²

Importance of understanding the risk factors

It is very important to know the risk factors and the causes of toxocariasis, as identifying vulnerable groups allows for the implementation of preventative measures. Children are particularly at risk, especially those who play outdoors and may put contaminated soil or sand in their mouths. This makes educational campaigns on handwashing and safe play habits especially important.³ Other preventive measures include promoting responsible pet ownership, including regular pet deworming and proper disposal of the faecal matter.⁴ Additionally, environmental controls, such as reducing soil contamination in playgrounds and public spaces, play a key role in limiting exposure.

For healthcare providers, awareness of risk factors aids in early identification, diagnosis, and treatment of infected individuals, improving health outcomes.³ Public awareness and education are also essential for developing effective public health strategies to control the spread of Toxocariasis within communities.⁴

Risk factors

There are several risk factors associated with Toxocariasis. To better understand them, they are divided into several groups: environmental, behavioural, demographic, and finally, immunosuppression factors.

Environmental factors

Exposure to contaminated soil and/or sand, for example, in playgrounds, gardens, or even beaches, is a key risk factor. Additionally, the ingestion of contaminated soil or sand is also a risk factor that is more common among younger individuals. Direct or indirect contact with infected animals or their faeces, such as owning pets, living near animals, or spending time in areas where animals defecate, also significantly increases the risk of infection.⁵

Behavioural factors

Certain behaviours elevate the likelihood of transmission. These include: 

• Geophagia (soil-eating), a practice common in some cultures or among children with pica, which increases the ingestion of parasite eggs
• Consumption of contaminated food – consuming raw or undercooked meat from animals that can act as hosts for Toxocara larvae can also pose a risk⁶
• Poor hygiene, particularly inadequate handwashing after playing outdoors, gardening, or handling pets and their waste, can easily lead to ingestion of eggs⁶

Demographic factors

Age is an important risk factor, as young children, especially those under the age of five, are most susceptible to contamination. Their exploratory behaviour, frequent contact with soil, and tendency to put objects in their mouths increase their exposure risk.^8,9 Other risk factors include living in areas with high animal populations and occupational exposure, such as farmers, veterinarians and animal shelter workers. Finally, travelling to regions with a high prevalence of Toxocara infections also increases the probability of exposure and contamination.

Immunosuppression factors

Immunocompromised individuals, such as those undergoing chemotherapy or with HIV/AIDS, have weakened immune systems, increasing susceptibility to severe infections.¹⁰

How to reduce the risk of toxocariasis?

Even though toxocariasis is a rare condition, there are simple preventative measures people can take to reduce the risk of infection. These include: 

• Regular hand washing, especially before eating 
• Wearing gloves when gardening reduces direct contact with infected soils 
• Teach young children not to eat soil or sand 
• Wash vegetables before consumption 
• Proper disposal of dog and cat faeces to prevent environmental contamination 
• Ensure regular deworming of pets 
• Prevent animals from defecating in areas where children play, such as sandboxes and playgrounds, and avoid letting children play in areas with visible animal waste

Summary

Toxocariasis is an infection caused by roundworms found in dogs and cats. These worms lay eggs in their faeces, which can contaminate soil or sand. If a person accidentally swallows these eggs, often through dirty hands or unwashed food, they can become infected. Most affected people are unaware of the infection due to the absence of symptom presentation. However, some may experience fever, coughing, stomach pain, or, in rare cases, vision problems if the worms reach the eyes.

Young children are most likely to get sick because they often play in the dirt and put their hands or objects in their mouths. People who live with pets should be extra careful to clean up after their animals. Farmers, veterinarians, and people who work at animal shelters might also be at higher risk.

To stay safe: 

• Always wash your hands well with soap and water after playing outside, gardening, or touching animals 
• Clean up after your pets promptly and dispose of their faeces properly 
• Avoid letting children play in areas where animals have defecated
• Teach children not to eat dirt or sand, and supervise their outdoor play

FAQs

What is toxocariasis?

Toxocariasis is an infection caused by roundworms carried by dogs and cats. These worms lay eggs in their waste matter, which can end up in the soil or sand. Accidental ingestion of these eggs can result in infection.

Who is most at risk of getting toxocariasis?

Young children are most at risk because they often play in the dirt and put things in their mouths. People who live with pets, work with animals (like farmers or veterinarians), and those who live in areas with high animal populations may also be at higher risk.

What are the symptoms of toxocariasis?

Many people who have Toxocariasis don't present any symptoms. However, some may experience fever, cough, tummy aches, or even have problems with their eyes.

How can I prevent toxocariasis?

• Wash your hands thoroughly with soap and water after playing outside, gardening, or touching animals
• Always clean up after your pets and dispose of their poop properly
• Avoid letting children play in areas where animals might have defecated
• Teach children not to eat dirt or sand

Can I get toxocariasis from petting my dog or cat?

No, you're more likely to get infected by accidentally swallowing the eggs from contaminated soil or sand.

Is toxocariasis contagious between people?

No, Toxocariasis is not contagious between people.

What should I do if I think I might have toxocariasis?

If you're concerned about possible symptoms, it's best to consult a healthcare professional for proper diagnosis and advice.

How is toxocariasis treated?

Treatment usually involves medication to help your body fight the infection.

Are there any long-term effects of toxocariasis?

Most cases of Toxocariasis resolve without any long-term problems. However, in some severe cases, there can be eye problems or damage to other organs.

How can I protect my pets from toxocariasis?

Regularly deworming your pets is the best way to prevent them from carrying and shedding Toxocara eggs.