Rats, Cities, People, and Pathogens:
A Systematic Review and Narrative Synthesis of Literature Regarding the Ecology of Rat-
Associated Zoonoses in Urban Centers
The article “Rats, Cities, People, and Pathogens: A Systematic Review and Narrative
Synthesis of Literature Regarding the Ecology of Rat-Associated Zoonoses in Urban Centers” by
Chelsea G. Himsworth, Kirbee L. Parsons, Claire Jardine, and David M. Patrick is about health
risks associated with zoonoses. The ecology of rat associated zoonoses (RAZ) is consociated
with the Urban Norway and black rats (Rattus norvegicus and Rattus rattus). These rats are the
generators of a number of pathogenic zoonotic diseases and they are responsible for increased
human deaths in many cities around world. Cities world-wide provide a stabilized environment
for rats which leads to close contact between the humans and the rats.
Understanding the zoonotic diseases transmitted by the rats is important for determining
the health risks linked with the different types of diseases the rats transmit. The knowledge of
zoonoses helps to gauge the presence and nature of the rat-associated health issues world-wide. It
helps in supervising the threats due to the rats in present and in future; this elevates the
awareness in health-care professionals about the risk factors and the misdiagnoses of these
diseases, and also develops effective rat control techniques and other health precautions to
prevent rat-to-human transmission. Urban Norway rats and black rats are the main source of
many pathogenic diseases; the pathogens include zoonotic bacteria such as the Leptospira
interrogans, Yersina pestis, Rickettsia typhi, Bartonella spp., Streptobacillus moniliformis,
viruses (Seoul hantavirus), and parasites called Angiostrongylus cantonensis.
Leptospira interrogans is a gram negative spirochete bacterium that is known as the most
widespread zoonotic pathogen in the world. This bacterium colonizes the kidneys of rats and
comes out through the urine, but there are no associated diseases in rats due to this pathogen.
This pathogen is carried in rats and is then spread to humans. Humans and rats get infected
(leptospirosis) by direct contact with the urine of rats or by contaminated water and soil. In
humans this disease is most common in the tropical countries in Southeast Asia, Indian
subcontinent, Latin America, and Caribbean. Along with the leptospirosis, Leptospira interrogan
is also related with febrile illness (progresses to Weil’s disease), Weil’s disease (a syndrome
characterized by jaundice, hemorrhage, and renal failure.), and pulmonary hemorrhage syndrome
which has the mortality rate as high as 50%.
Yersina pestis is a gram-negative bacillus bacterium which is an etiologic agent of the
