Fleas and Rats in New York City

Rat Flea

Rat Flea

The Norway rat, Rattus norvegicus, is an invasive species with a world wide distribution. It is considered a native to East Asia and mistakenly linked to Norway (a misperception that won’t go away). It is presently the dominant rat species in New York City having displaced other species. Rats can harbor diseases and ectoparasites capable of transmitting disease to humans. What ectoparasites and diseases are present in the NYC rat population?  A survey of NYC rats and their parasites found 4 ectoparasites: 2 species of mites, the spined rat louse, Polyplax spinulosa and the rat flea, Xenopsylla cheopis.

The rat flea can transmit bubonic plague, Yersinia pestis, bartonellosis (caused by Bartonella Spp. bacteria) and murine typhus, Rickettsia typhi to human populations. The survey found that one third of the rats were infected with the rat flea. Survey for disease found only Bartonella and not bubonic plague nor murine typhus. These results indicate that the vector (rat flea) and a reservoir (Norwegian Rat) are both present in NYC. The plague bacteria, Yersinia pestis, is not which is good because NYC has large populations of both rats and people living in close proximity. In areas of the US where Y. pestis exists, the human population is sparse and infrequent contact between humans and infected rodents limits transmission.

M. J. Frye , C. Firth , M. Bhat , M. A. Firth , X. Che , D. Lee , S. H. Williams , W. I. Lipkin. 2015. Preliminary Survey of Ectoparasites and Associated Pathogens from Norway Rats in New York City. Journal Of Medical Entomology.
Journal of Medical Entomology Feb 2015,
DOI: 10.1093/jme/tjv014

About jjneal

Jonathan Neal is a retired Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
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6 Responses to Fleas and Rats in New York City

  1. Do rats only have rat fleas? Other fleas don’t infest them? I thought any flea would bite anything warm blooded … ?????

  2. jjneal says:

    Rats can have other flea species, they were not found in this survey.

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  6. Jordan says:

    Really informative post on rats here. I remember learning as a kid from the movie Ratatouille about rats – so it’s sometimes a little shocking to remember those little guys carry fleas and disease in real life! Thanks for sharing.

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