Global Burden of Toxocariasis: A Common Neglected Infection of Poverty

Quantifying the neglected: Initial estimation of the global burden and economic impact of human toxocariasis

Toxocariasis is a parasitic zoonotic infection caused by Toxocara spp., ascarid nematodes of companion animals (dogs and cats) affecting people in both high-income and low/middle-income countries. Toxocariasis can manifest as several distinct syndromes. The most frequent, often termed common toxocariasis, is a self-limiting and mild febrile illness. Ocular and visceral larva migrans are severe disease manifestations affecting the eye and other internal organs, respectively, but their reported occurrence is rare. The vast majority of symptomatic cases are thought due to common toxocariasis, which has also been associated with cognitive impairment in children. Few studies to date have sought to quantity the health burden of toxocariasis in humans. In this study we provide a preliminary estimation using the Disability-Adjusted Life Year (DALY) approach. We estimate a total of 23,084 DALYs are lost annually in 28 selected countries due to common toxocariasis. Extrapolating based on a global average seroprevalence rate of 19%, we estimate 91,714 DALYs per year are lost across all countries due to toxocariasis, of which 40,912 are attributable to less severe forms, i.e. common toxocariasis, and 50,731 to cognitive impairment in children. Clinically diagnosed and reported ocular and visceral larva migrans represent a small proportion of estimated total health burden. We also found a positive correlation at national level between prevalence in cats or dogs and seroprevalence in humans, but no correlation between estimated soil contamination and seroprevalence in humans. Finally, we estimate the potential economic impact of toxocariasis in selected countries at 2.5 billion USD per annum, from costs of medical treatment and lost income. These preliminary estimates should serve as a call to action for further research and evidence-based measures to tackle toxocariasis.

Seroprevalence and Potential Risk Factors of Toxocariasis among General Population in Southwest Iran: Implications on the One Health Approach

Toxocariasis is one of the most common zoonotic diseases distributed worldwide. This study aimed to estimate the seroprevalence of anti-Toxocara immunoglobulin G (IgG) antibodies and the associated risk factors among general populations living in urban and rural areas of Abadan and Khorramshahr cities in Khuzestan Province, Southwest Iran. This cross-sectional study was conducted between March and September 2022. There were 363 participants (190 females and 173 males) aged from <20 to ≥60 years old. Anti-Toxocara IgG antibodies in serum samples were measured using a commercially available enzyme-linked immunosorbent assay (ELISA). A structured questionnaire was employed to collect information regarding sociodemographic status and probable risk factors associated with toxocariasis. It was found that the seroprevalence rate in males (15.0%, 95% CI = 10.47-21.11) was higher than in females (10.5%, 95% CI = 6.92-15.70). Moreover, we observed that the seroprevalence was higher in participants at younger ages compared to other age ranges (COR = 2.55, 95% CI = 0.92-7.12, p =0.073). The findings of the univariate analysis revealed that residency in rural areas (p  < 0.001), using unpurified water (p  < 0.001), contact with dog (p =0.002), contact with soil (p  < 0.001), consumption of improperly washed vegetables (p  < 0.001), and history of drinking untreated water (p  < 0.001) were risk factors associated with toxocariasis. Further comprehensive studies with a focus on humans and animals should be designed in different areas of the Province. The data represented by the current study are useful to health policymakers to consider precise surveillance and effective prevention measures to control this zoonotic infection among general populations.

Liver abscesses caused by visceral larva migrans: Aimless wanderer separated from the host

Visceral larva migrans (VLM) is a systemic zoonotic parasitic disease caused by migration of the second stage larva through viscera of humans. Despite being a foremost public health problem in low- and middle-income countries (LMICs) such as India, larva migrans remains an untended zoonosis. Here, we report two cases of VLM who presented with fever and abdominal pain for a prolonged duration. On further investigation, marked peripheral eosinophilia with multiple confluent necrotizing eosinophilic granulomas were identified on histopathological examination of the liver.

One Health approach on human seroprevalence of anti-Toxocara antibodies, Toxocara spp. eggs in dogs and sand samples between seashore mainland and island areas of southern Brazil

Toxocariasis, caused by Toxocara spp. nematodes, is among the top 5 neglected parasitic diseases worldwide; however, no comprehensive study to date has serologically compared infections in people and their dogs and environmentally contaminated soil or sand of mainland and island locations. Accordingly, this study aimed to assess the seroprevalence of anti-Toxocara antibodies in traditional human seashore populations, the presence of eggs in dogs' feces and hair, and the presence of eggs in environmental samples from islands compared to the adjacent mainland of southern Brazil. Overall, 212/328 (64.6%) people were positive for Toxocara spp. antibodies, including 125/190 (65.8%) island and 87/138 (63.0%) mainland residents. For dog samples, 12/115 (10.43%) were positive for the presence of Toxocara spp. eggs, all from dogs living in islands, and 22/104 (21.15%) dog hair samples contained eggs of Toxocara spp. Environmental contamination with Toxocara spp. eggs was observed in 50/130 (38.46%) samples from all sampled sites. No significant association was found between risk factors (age, sex, educational level, monthly income, owning dogs or cats, ingestion of treated water, and consumption of raw or uncooked meat) and Toxocara spp. seropositivity. The present study is the first concurrent report on people, their dogs, and environmental contamination of Toxocara spp. The high prevalence we observed in the seashore populations of both in island and mainland areas may be caused by exposure to contaminated sand and climatic factors favoring frequent exposure to Toxocara spp. In conclusion, seashore lifestyle and living conditions of both island and mainland areas may have predisposed higher contact with infected pets and contaminated soil, favoring the high prevalence of toxocariasis.

Toxocariasis-associated urinary system diseases: a systematic review of reported cases

BACKGROUND

Toxocariasis is a neglected tropical disease caused by Toxocara canis and Toxocara cati. Toxocara species can involve many organs, such as the brain, heart and lungs, however, the urinary system involvement of toxocariasis is largely unknown.

METHODS

We performed a systematic review to identify cases infected with urinary tract toxocariasis.

RESULTS

We identified seven cases that were eligible to be reviewed. Among the included citations, four studies reported bladder involvement and three reported kidney involvement. Fever, urinary, and abdominal presentations were amongst the most important clinical symptoms. Eosinophilic cystitis and nephrotic syndrome were the most common diagnoses.. The treatment regimen included a combination of anthelmintic drugs and steroids.

CONCLUSIONS

In cases of urinary tract presentations accompanied by eosinophilia or histopathologic findings suggestive of parasitic infection, toxocariasis should be included in the list of differential diagnoses, especially in endemic areas.

A One Health Approach for Guinea Worm Disease Control: Scope and Opportunities

Guinea worm disease (GWD) is a neglected tropical disease that was targeted for eradication several decades ago because of its limited geographical distribution, predictable seasonality, straightforward diagnosis, and exclusive infection of humans. However, a growing body of evidence challenges this last attribute and suggests that GWD can affect both humans and animal populations. The One Health approach emphasizes the relatedness of human, animal, and environmental health. We reviewed epidemiological evidence that could support the utility of a One Health approach for GWD control in the six countries that have reported human GWD cases since 2015-Angola, Cameroon, Chad, Ethiopia, Mali, and South Sudan. Human GWD cases have dramatically declined, but recent years have seen a gradual increase in human case counts, cases in new geographies, and a rapidly growing number of animal infections. Taken together, these suggest a need for an adjusted approach for eradicating GWD using a framework rooted in One Health, dedicated to improving disease surveillance and in animals; pinpointing the dominant routes of infection in animals; elucidating the disease burden in animals; determining transmission risk factors among animals and from animals to humans; and identifying practical ways to foster horizontal and multidisciplinary approaches.

Toxocara: Protecting pets and improving the lives of people

Toxocara sp. are zoonotic parasitic roundworms that cause infection and morbidity in both developed and developing countries. In humans, infection is thought to be most common in children, particularly those living in poverty, and usually results from consumption of soil contaminated with parasite eggs deposited by dog or cat faeces. Infection in humans results in different clinical manifestations, some more overt like visceral or ocular larva migrans and others more cryptic like neurocognitive delay. Despite its pervasiveness, toxocariasis has become a neglected infection. We review the dynamics of the human-animal interface in the context of this parasite, discuss the challenges in controlling transmission to humans, and cite key areas of research that could enable improved interventions. With political will and proper resource allocation, we propose that effective interventions are possible in the near term.

Pictorial Review of Thoracic Parasitic Diseases: A Radiologic Guide

Parasitoses are infectious diseases of global distribution, with predominance in areas of poor sanitation. Parasites cause damage through direct tissue injury and the inflammatory response generated by their migration and establishment in various organs. Thoracic involvement by parasitic disease can generate both specific and nonspecific clinical, laboratorial, and radiologic manifestations, which often makes their diagnosis challenging. The correct diagnosis is crucial for definition of treatment, which sometimes requires rapid intervention. Based on a literature review of the last few decades, this article aimed to characterize the main radiologic findings related to thoracic manifestations of parasitic diseases, correlating them with radiographic and tomographic images of patients with confirmed diagnosis of such pathologies. The included parasitic diseases are malaria, Chagas disease, toxoplasmosis, amoebiasis, ascariasis, toxocariasis, strongyloidiasis, dirofilariasis, cysticercosis, echinococcosis, schistosomiasis, and paragonimiasis.

Screening of Zoonotic Parasites in Playground Sandboxes of Public Parks from Subtropical Mexico

The pathological agents Toxoplasma gondii, Ancylostoma caninum, and Toxocara canis are widely distributed zoonotic parasites with high prevalence in tropical and subtropical regions of the world. The aim of the present study was to determine the presence of DNA from these parasites in sand samples from the sand playgrounds in the southeastern region of Mexico. Samples of sand were collected from 68 playgrounds in public parks in the city of Merida, Yucatan, which is the main urban area in the southeast of Mexico. The samples were examined using nested PCR to detect the SAG1 gene from Toxoplasma gondii, and endpoint PCR for the amplification of ITS-2 and rRNA-ITS2 genes from Toxocara canis and Ancylostoma caninum, respectively. The presence of T. gondii DNA was detected in 11.8% (8/68) samples, DNA from A. caninum and T. canis was not detected. Results indicate that playgrounds from the studied sandboxes are contaminated with T. gondii oocysts and may represent a risk of infection for people in contact with the sand, especially for preschoolers.

Toxocariasis in Carnivora from Argentinean Patagonia: Species molecular identification, hosts, and geographical distribution

Twenty four specimens of seven species belonging to the families Felidae, Mustelidae, and Canidae were obtained in Lanín and Nahuel Huapi National Parks from March 1996 to April 2016. Specimens were processed by necropsy in order to contribute to the knowledge of toxocariasis in wild carnivores of Argentinean Patagonia. The only Puma concolor and the seven Leopardus geoffroyi were positive for Toxocara cati. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the ITS-1 region from larval and adult DNA was carried out to confirm parasite species identification. This is the first molecular determination of T. cati from wild felids in Argentina and the study also fill gaps about the spatial distribution and hosts for Toxocara cati.

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Puma concolor and Leopardus geoffroyi were positive for Toxocara cati in Patagonia.

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Other five species of carnivores (Mustelidae and Canidae) were negative for T. cati.

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The species identity of ascarid specimens were confirmed by PCR-RFLP procedure.

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This is the first record of toxocariasis in wild Carnivora from Río Negro province.

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These are the southernmost record of T. cati. in South America for L. geoffroyi.

Soil-Transmitted Helminths in Tropical Australia and Asia

Soil-transmitted helminths (STH) infect 2 billion people worldwide including significant numbers in South-East Asia (SEA). In Australia, STH are of less concern; however, indigenous communities are endemic for STH, including Strongyloides stercoralis, as well as for serious clinical infections due to other helminths such as Toxocara spp. The zoonotic hookworm Ancylostoma ceylanicum is also present in Australia and SEA, and may contribute to human infections particularly among pet owners. High human immigration rates to Australia from SEA, which is highly endemic for STH Strongyloides and Toxocara, has resulted in a high prevalence of these helminthic infections in immigrant communities, particularly since such individuals are not screened for worm infections upon entry. In this review, we consider the current state of STH infections in Australia and SEA.

Toxocara malaysiensis infection in domestic cats in Vietnam--An emerging zoonotic issue?

Toxocara canis of canids is a parasitic nematode (ascaridoid) that infects humans and other hosts, causing different forms of toxocariasis. This species of Toxocara appears to be the most important cause of human disease, likely followed by Toxocara cati from felids. Although some studies from Malaysia and China have shown that cats can harbor another congener, T. malaysiensis, no information is available about this parasite for other countries. Moreover, the zoonotic potential of this parasite is unknown at this point. In the present study, we conducted the first investigation of domestic dogs and cats for Toxocara in Vietnam using molecular tools. Toxocara malaysiensis was identified as a common ascaridoid of domestic cats (in the absence of T. cati), and T. canis was commonly found in dogs. Together with findings from previous studies, the present results emphasize the need to explore the significance and zoonotic potential of T. malaysiensis in Vietnam and other countries where this parasite is endemic and prevalent in cats.