Toxocara species environmental contamination of public spaces in New York City

Human toxocariasis has been identified as an under-diagnosed parasitic zoonosis and health disparity of significant public health importance in the United States due to its high seropositivity among socioeconomically disadvantaged groups, and possible links to cognitive and developmental delays. Through microscopy and quantitative PCR, we detected that Toxocara eggs are widespread in New York City public spaces, with evidence of significant levels of contamination in all five boroughs. The Bronx had the highest contamination rate (66.7%), while Manhattan had the lowest contamination rate (29.6%). Moreover, infective eggs were only found in the Bronx playgrounds, with over 70% of eggs recovered in embryonic form and the highest egg burden (p = 0.0365). All other boroughs had eggs in the pre-infectious, unembronyated form. Toxocara cati, the cat roundworm, was the predominant species. These results suggest that feral or untreated cats in New York City represent a significant source of environmental contamination. These findings indicate that human toxocariasis has emerged as an important health disparity in New York City, with ongoing risk of acquiring Toxocara infection in public spaces, especially in poorer neighborhoods. There is a need for reducing environmental Toxocara contamination. Additional rigorous public health interventions should explore further approaches to interrupt transmission to humans.Author summary: Toxocara canis and Toxocara cati are helminth worms that infect dogs and cats, respectively. Infected dogs and cats will defecate thousands of Toxocara eggs into the environment. Humans are incidental hosts and are exposed when consuming contaminated soils via the fecal-oral route. After leaving the gastrointestinal tract, the Toxocara larvae will enter the vasculature and can migrate to any major organ system, including lungs, ocular, and central nervous system. Symptoms can range from mild muscle aches to severe asthma, blindness, and encephalitis. Humans are not definitive hosts of the parasite and cannot transmit Toxocara eggs to the environment or other humans. There is a need for research on the sanitary impact of Toxocara for both humans and animals, especially in large urban cities such as New York City. Poverty is also associated with higher rates of toxocariasis, with more contamination in poorer neighborhoods where animal control, deworming of pets, and less sanitary conditions exist. This study aims to understand further the disparity of lower socioeconomic areas having higher rates of contaminated parks and playgrounds, comparing the five boroughs of New York City.