Overview

Toxocariasis is a non-contagious zoonotic infection caused when humans accidentally ingest the eggs of the larvae of Toxocara canis (dog roundworm) or Toxocara cati (cat roundworm) from contaminated food or water.¹ The condition is transmitted by direct contact with infected animals' faeces. When someone consumes undercooked meat from infected paratenic hosts, contaminated raw vegetables and food from contaminated soil, the likelihood of contracting the roundworm infestation is high. Toxocariasis is a noxious zoonotic infection in children. The true disease burden of toxocariasis is fairly accurate hence, it is critical to raise the perception of toxocariasis through direct public health interventions and ultimately reduce Toxocara-induced morbidity in the vulnerable demographics.²

The clinical signs presented have been used to categorise Toxocariasis.⁵

Even though Toxocara infects about 1,4 billion people worldwide, the vast majority of the infected individuals may be asymptomatic. Despite the lack of symptoms or mild clinical signs, the infection underpins important health and socioeconomic consequences, particularly in underprivileged, tropical, and subtropical areas. Children, particularly those playing in contaminated soil, and individuals with close contact with dogs or cats, are at higher risk. People in regions with poor sanitation, hygiene and who own pets, particularly in low and middle-income countries.

Most cases of Toxocariasis are mild; severe cases like OLM or neurotoxocariasis can lead to blindness and neurological conditions. Consequently, preventive measures include practicing good hygiene, regular deworming of pets, preventing children from playing in contaminated soil or sandboxes and proper disposal of pet faeces.

How is toxocariasis diagnosed?

Diagnosis involves serological assays like enzyme-linked immunosorbent assay (ELISA), but these tests often lack specificity, complicating clinical differentiation from other eosinophilic diseases.⁶ ELISA to detect antibodies against Toxocara, along with clinical history and imaging techniques (e.g., ultrasound, MRI) to identify larval migration. Chronic could be undiagnosed due to non-specific symptoms, such as eosinophilia and fatigue, further complicating disease management. A rare form of Toxocariosis -Neurotoxocariasis,  is increasingly causally associated with epileptic disorders, particularly in endemic regions global epidemiological data regarding the relationship between seropositivity and toxocarosis is limited.⁵

Prevention and control strategies

Toxocariasis prevention is multifaceted, requiring public education, improved sanitation, and regular deworming of pets. Interventions targeting environmental contamination, such as safe disposal of pet faeces and soil hygiene, are essential. Community health initiatives,  strengthening veterinary services delivery, particularly in endemic regions, can significantly reduce transmission rates by promoting awareness and access to healthcare resources.⁷ Preventive measures, including routine deworming with effective antihelmintic regimens, public education, and improved hygiene practices, are critical to mitigate the dual impact of toxocariasis and associated parasitic infections.⁵ Advances in immunological research and community interventions provide a roadmap for addressing these overlapping disease burdens. Advances include DNA vaccines, immunodiagnostics, and therapeutic use of probiotics, which represent promising interventions.¹ Treatment is primarily with benzimidazole derivatives, but their efficacy remains limited in severe cases involving CNS or ocular manifestations.³

Impacts of Toxocariasis on Global Health

As one of the neglected zoonotic diseases, a considerable challenge is posed to global health as a marker of Health Inequalities. Although endemic to developed and developing nations, it is more prevalent in developing tropical and subtropical nations due to limited sanitation and Veterinary services.⁵ In the low-income climes, exposure to contaminated soil or infected pets is common. Often times because the condition is asymptomatic or mild, cases are underreported, leading to paucity of epidemiological data and surveillance programs.⁵ Moreover, the infection has a modulating role in immune responses which complicates co-morbid conditions such as asthma, atopy, and even tuberculosis, further burdening healthcare systems.⁸ The immunomodulatory effects of toxocariasis are of critical concern, as the infection induces regulatory imbalances such as increased IgE levels, altered eosinophil counts, and suppressed IL-10, which impair the host's immune response to concurrent infections, including tuberculosis (TB).⁸ This dual burden exacerbates disease outcomes, complicating treatment due to overlapping symptoms and reduced efficacy of antiparasitic and antibacterial therapies. Co-infections with toxocariasis and helminthiases are commonly linked to atopic disorders, such as asthma, through shared pathways of immune hypersensitivity.⁷

Toxocariasis precipitates significant economic burdens on global public health systems, particularly in its endemic regions. The economic costs are triggered by its widespread occurrence, underdiagnosis, and misdiagnosis, as well as the medical care required for severe complications like blindness, neurological disorders, and organ damage. Epidemiological studies of toxocariasis have highlighted the high seroprevalence rates in disadvantaged populations, particularly in children, due to poor sanitation and exposure to contaminated environments.⁹

In regions like Latin America, toxocariasis contributes to significant public health expenditures due to the costs associated with diagnostics, treatment, and long-term care for complications such as visceral and ocular larva migrans. Efforts to control the disease, including public health education, environmental sanitation, and routine deworming programs, are resource-intensive but critical to reducing transmission rates.⁷

The disease's indirect economic cost arises from its comorbidity with other conditions such as asthma, atopic disorders, and developmental delays in children. Misdiagnosis and delayed treatment often escalate associated healthcare spending.¹⁰

Economic losses are worsened by reduced productivity among affected individuals, especially in rural and agricultural communities. Proactive measures, such as enforcing pet hygiene laws and integrating One Health approaches, could reduce costs and simultaneously improving both human and animal health.⁵

FAQs

What is the role of Pets in Toxocariasis transmission?

Dogs and cats act as well-characterised hosts for Toxocara. Infected animals shed eggs in their faeces, contaminating the environment. Regular deworming of pets can significantly reduce transmission risks.¹¹

Are there vaccines for toxocariasis?

Currently, there are no vaccines available for toxocariasis. Research into vaccine development and novel immunotherapies is ongoing.⁴

How is toxocariasis treated?

Treatment utilises anthelmintics like albendazole or mebendazole. Corticosteroids may be prescribed for severe inflammation or ocular involvement. Supportive care depends on the severity and organs affected. The efficacy of the benzimidazole derivatives has been reported to be limited in severe CNS and ocular toxocariasis.³

What are the long-term health implications of untreated toxocariasis?

Asymptomatic and Untreated toxocariasis, caused by the migration of Toxocara larvae in humans, engenders health complications and developmental difficulties, specifically in children from endemic regions. Furthermore, the disease has been causally linked with cognitive deficits, reduced academic performance, and behavioural challenges due to central nervous system involvement. In regions with poor sanitation, such as northeast Argentina, the prevalence of toxocariasis among children reached 67%, with significant associations to risk factors like geophagia and proximity to animals. Untreated cases showed persistent high IgG levels, indicating sustained or recurrent exposure to the parasite

Toxocariasis presents a huge global burden, with a seroprevalence of 19% worldwide and peaks in low-income, humid regions. Such conditions foster transmission through soil contamination and contact with infected animals. Affected children often belong to socioeconomically disadvantaged groups, further compounding health disparities.¹⁰ In urban environments, predictive models suggest high probabilities of infection in areas with inadequate education and poverty, with New York City highlighting localised risks in underserved communities.¹² Surveillance studies in South Korea emphasise the need for continuous monitoring of children’s play areas, underscoring that even managed environments can face re-contamination.¹³

Summary

Addressing Toxocariasis as a marker of health disparity requires a collaborative effort that include robust surveillance, enhanced diagnostic techniques, and integrative public health strategies. Global health systems should integrate innovative diagnostics and vaccines, prioritise interventions to reduce the disease's burden, particularly among vulnerable populations in endemic regions. Such efforts will not only control toxocariasis but also alleviate its compounding impact on other health conditions, fostering better health equity worldwide. Additionally, the need for improved diagnostics and the absence of a vaccine contribute to the ongoing financial strain on healthcare systems.