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,