Urban free-roaming cats in New York City pose rising zoonotic health risks with high parasite prevalence

New research reveals over half of free-roaming cats in NYC are carriers of zoonotic intestinal parasites, highlighting public health concerns amid trap-neuter-return programmes.

More than half of free-roaming cats sampled in New York City carried at least one zoonotic intestinal parasite, according to research published in PLOS One, adding to concern over the public health role of unmanaged urban cat colonies.

The study examined 87 cats enrolled in a trap-neuter-return programme and found that 57.5% were infected, with about one in five harbouring mixed infections. Toxocara spp., the roundworm most closely associated with human toxocariasis, was the dominant parasite, while hookworm was also detected. Antibodies to Toxoplasma gondii were present in a smaller share of blood samples, though no evidence was found of heartworm antigen or Cytauxzoon felis DNA.

The researchers said contamination risk was not evenly distributed. Young males shed far more Toxocara eggs than other cats, making them what the authors described as super-shedders. That matters because Toxocara eggs can persist in soil for years, and infection in people can cause visceral or ocular larva migrans, conditions that may affect the liver, lungs or eyes.

According to the authors, existing TNR schemes should be broadened to include targeted deworming, environmental clean-up and public education. Their argument fits a wider body of evidence that free-roaming cats remain an important reservoir for zoonotic parasites in cities.

Reference: Nguyen V-L, Gurtowski E, Chen J, Rosen M, Kafle P (2026) Zoonotic endoparasites and Toxoplasma gondii seropositivity in free-roaming cats (Felis catus) from New York City boroughs.
PLoS One 21(7): e0351437.
https://doi.org/10.1371/journal.pone.0351437