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. 2020 May 5;14(5):e0008249.
doi: 10.1371/journal.pntd.0008249. eCollection 2020 May.

Toxocara species environmental contamination of public spaces in New York City

Donna L Tyungu  1   2   3   4 , David McCormick  2 , Carla Lee Lau  4 , Michael Chang  3 , James R Murphy  3 , Peter J Hotez  2 , Rojelio Mejia  2 , Henry Pollack  4
Affiliations

Toxocara species environmental contamination of public spaces in New York City

Donna L Tyungu et al. PLoS Negl Trop Dis. .

Abstract

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.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1
Toxocara forms isolated in NYC specimens: a and b: Larvated ‘infective’ Toxocara eggs at 40x magnification, c: Unlarvated Toxocara egg at 40 x magnification, obtained in NYC study.
Fig 2
Fig 2. Geospatial results of Toxocara sampling across NYC.
Toxocara was found in those sites represented by either blue triangles (unembryonated egg(s)) red stars (embryonated egg(s)). Toxocara was not found at sites marked by black circles. The highest density of Toxocara geo-contamination was found in the Bronx, which was the only borough where infected larvae were found. Sampling ArcMap of NYC, created using ArcGIS 10.6.1.
Fig 3
Fig 3. qPCR results, parks that were qPCR-positive were contaminated with T. cati.
Calculated egg count was derived from dilutions of a known amount of Toxocara cati eggs and correlated to 40 –Ct (Spearman r = 0.999, p < 0.0001).
Fig 4
Fig 4. Association of positive Toxocara results with the median income of residents living in the ZIP codes of sampled sites.
The line represents the median income of families living in the zip code where Toxocara testing was performed. Results aggregated by borough. (Spearman r = -0.7, p = 0.233).
Fig 5
Fig 5. Toxocara eggs/park by borough.
Kruskal-Wallis P = 0.0365. Eggs were not equally distributed in the parks by borough. The Bronx* has the highest egg burden compared to the other boroughs.
See this image and copyright information in PMC

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References

    1. Borg OA, Woodruff AW. Prevalence of infective ova of Toxocara species in public places. British medical journal. 1973;4(5890):470–2. 10.1136/bmj.4.5890.470 - DOI - PMC - PubMed
    1. Holland CV. Knowledge gaps in the epidemiology of Toxocara: the enigma remains. Parasitology. 2015:1–14. Epub 2015/12/17. 10.1017/s0031182015001407 . - DOI - PubMed
    1. Strube C, Heuer L, Janecek E. Toxocara spp. infections in paratenic hosts. Veterinary parasitology. 2013;193(4):375–89. 10.1016/j.vetpar.2012.12.033 . - DOI - PubMed
    1. Ma G, Holland CV, Wang T, Hofmann A, Fan CK, Maizels RM, et al. Human toxocariasis. The Lancet Infectious diseases. 2018;18(1):e14–e24. 10.1016/S1473-3099(17)30331-6 . - DOI - PubMed
    1. Walsh MG, Haseeb MA. Reduced cognitive function in children with toxocariasis in a nationally representative sample of the United States. Int J Parasitol. 2012;42(13–14):1159–63. Epub 2012/11/06. 10.1016/j.ijpara.2012.10.002 . - DOI - PubMed

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Grants and funding

Acknowledgemets: This research was supported in part by the Committee of Interns and Residents Patient Care Trust Fund Research Project Grant funded from 2015-2017. Research funding support for RM was provided by the U.S. Department of Health and Human Services, Health Resources and Services Administration for Baylor College of Medicine Center of Excellence in Health Equity, Training and Research (Grant No: D34HP31024). Funding also provided by the Texas Children’s Hospital Center for Vaccine Development, and the National School of Tropical Medicine, Baylor College of Medicine. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.