The urban environment is an ideal habitat for many pest species, and some cities have significantly higher rates of infestations than others. High food sources, shelter options, and human activity concentrations lead to an optimal environment for pests to flourish. Climate, population density, and the age of local infrastructure are all environmental factors that directly affect pest prevalence.
Warmer cities are havens for larger pest populations year-round, and aging sewage systems and buildings offer unlimited opportunities for entry and harborage. Waste management practices are also critical. For example, delays in garbage collection and poor sanitation provide ample food for rodents, cockroaches, and other pests. These elements bring insight into why pest control issues differ significantly from city to city, with some urban areas facing high demand for an Exterminator in Southlake to eradicate their pest problem.
Which Is The Most Infested City In The World?
Mumbai, India, on pest control indices and public health reports, is the worst infested city in the world. The city has a perfect storm of conditions for massive pest populations: tropical climate with high humidity levels, extremely high population density (in some cases, over 20,000 people per square kilometer), decaying infrastructure, and wealth inequality that directly impacts sanitation services.
According to a World Health Organization study, the number of rats in Mumbai exceeds the human population by a ratio of 3:1, with around 60 percent of residents claiming pest problems on a regular basis. The city’s monsoon season, when they get a lot of rain each year, compounds all of this by forcing pests into buildings and flooding areas for mosquitos to breed.
Top 10 Most Infested Cities In the World
Here are the 10 most infested cities in the world.
| City | Estimated Infestation Statistics |
| Mumbai, India | 88% of buildings report pest issues; 3:1 rat-to-human ratio |
| New York City, USA | 2.2 million rats; 18% of households report rodent sightings |
| London, UK | 100+ million rats; 1.3 million homes with cockroach infestations |
| São Paulo, Brazil | 1.5 rats per person; 70% of sewage areas heavily infested |
| Tokyo, Japan | 5 million rats; 22% of food establishments report pest issues |
| Bangkok, Thailand | 65% of markets show rodent activity; 8 million rat population |
| Paris, France | 6 million rats; 1 in 5 buildings report persistent rodent problems |
| Chicago, USA | 1.5 million rats; ranked #1 in US rat sightings for 6 consecutive years |
| Sydney, Australia | 500+ million rodents; 38% of properties report pest problems |
| Mexico City, Mexico | 40 million rats; 55% of public areas show pest evidence |
- Asian Cities
Mumbai and Bangkok are the two representatives on this list in Asia. Mumbai’s problems arise from an extreme population density within some of its areas, with over 20,000 residents per square kilometer, but with an inadequate waste management infrastructure. 88% of buildings in Mumbai complain of pest problems, which persist. Bangkok’s canaled nature and food markets have compounded the situation, with studies showing 65 percent of food markets displaying significant rodent activity.
- North American Contenders
New York has different termite challenges than Chicago. The city’s polygamous 2.2 million estimated rats love the subterranean sprawl of its networks. Pest sightings increase by 40% from 2020–2024 For the last six years, the Windy City has held the dubious title of America’s “rattiest city” from pest control companies, as roughly 1.5 million rats have called the city’s aging sewer systems and the foundations of its buildings home.
- European Representatives
Both London and Paris contend with vast rat populations. There are 100+ million rats living in London’s Victorian-era sewage system. Paris has been plagued with the same problem, with around 6 million rats in total — which is about twice the number of humans that currently live in the French capital. Every 5th building in Paris has a chronic rodent problem, despite the city’s efforts to control the vermin.
