Rats have been enjoying a close relationship with humans for hundreds, if not thousands, of years. Humans derive no benefits from having rats around, but rats get all sorts of perks. Most notably: food, shelter and water. Often this has little effect, but in some cases, rats go too far, and their impact on human populations becomes unbearable.
These 10 cities are among the most rat-plagued places on the planet, although rodent control efforts are (in most cases) always ongoing to try to keep the tally in check. But first up, let's visit one place where that's definitely not the case.
10: Deshnoke, India
In northwestern India, you'll find the city of Deshnoke, home to a place of worship called the Karni Mata Temple. What's interesting about this temple -- and what makes it a fitting addition to the list -- is that it's positively packed with rats. Some 20,000, in fact. Not only are they welcomed, they're worshipped.
It's considered lucky to have these holy rats patter across your feet, and even more of a blessing to eat or sip some cuisine they've sampled. But best of all? In a devilishly difficult game of "Where's Waldo?" the most auspicious accomplishment is spotting one of the temple's four or five white rats scampering amid the sea of brown.
In the next nine places we'll visit, rats are decidedly less welcome. First stop: Rat Island. Sounds promising, right?
9: Rat Island, the Aleutians
Rat Island, part of the Aleutian Islands, is just one example of an island habitat devastated by invasive rats. About 90 percent of the world's islands have been overrun by rodent stowaways, which can spell disaster for native species -- especially seabirds.
Happily, however, the name "Rat Island" is now technically a misnomer. Although rats enjoyed the run of the place starting in the 1780s when a shipwreck dropped some ashore, they were officially eradicated in 2010 after years of dedicated conservation efforts. Now birds are starting to reclaim this previously rat-infested stomping ground and slowly grow in numbers (as they are on other islands where eradication efforts have been successful). And not a moment too soon, considering rats cause about half of all island extinctions of bird and reptile species.
8: Paris, France
Rats show no respect for famed romantic locales, either. In 2008, Paris officials estimated the city's rat population had reached 8 million, and since only about 2 million people make their homes in Paris proper, that meant there were about four rats pounding the pavement for every Parisian.
In response, city officials encouraged residents and businesses to step up their rat-eradication efforts in a heavily advertised two-month campaign nicknamed "Le Smash" (or Le Service Municipal d'Actions de Salubrité et d'Hygiène), and to even "rat out" any neighbors who were slacking on rodent removal. Failure to act -- whether that be not calling a rat catcher, setting up traps, putting down poison, properly disposing of food or blocking building foundations -- led to steep fines.
7: London, England
Rats are also a big issue in London. Like the Seine in Paris, the River Thames has long been a major rat-magnet. But lately, rats have been thriving more than ever due to construction efforts for the 2012 Olympics and the aftereffects of the economic recession -- more abandoned properties mean more places for rats to roost undisturbed.
London's rats are also getting bigger than ever, at least partially thanks to increased littering -- especially of the fast-food variety -- by on-the-go Brits. Some big squeakers are reportedly growing up to double the usual size.
6: Atlanta, Ga.
Foreclosures triggered by the recession have made Atlanta a hotspot for rat populations. Urban poverty, along with the high foreclosure rate, mean many Atlantan homes stand abandoned, and rats are always ready to move in when no one is around to shoo them out. Even small cracks can serve as entry points, and rats will feast on anything from old boxes to overgrown hedges.
The problem has even spilled over into at least one airline serving the city's international airport. Although few follow-up details were made available by Delta Air Lines, a Delta plane was reportedly found littered with rodent pellets and urine by inspectors from the U.S. Food and Drug Administration.
5: New Orleans, La.
Many areas of New Orleans are plagued with rats, especially older residences prone to problematic cracks and other small holes through which rats can enter. Even when these holes are plugged, rats can still get in, eating through foam, caulk and wood.
And in one tragic 2009 case, rats did more than pester and frighten affected residents. A three-month-old baby's official cause of death was "exsanguination due to destruction of soft tissue secondary to murine activity." In layman's terms, the coroner believed she bled to death after rats repeatedly bit her.
4: Chicago, Ill.
Rats also have the run of Chicago, although the city receives some help at decreasing the rodent population from an unexpected source. That assistance comes from coyotes, which are allowed to roam the streets of Chicago as part of a study to see how coyotes behave in an urban environment.
Many of the coyotes you might glimpse loping down the streets of Chicago and the surrounding metropolitan area have been captured at one point or another, often as pups but also as adults, and then released with radio collars to track their whereabouts. Since rodents make up a large portion of a typical coyote's diet: Boom, dinner is served.
3: Baltimore, Md.
Baltimore's rat problem is bad enough that at one point, rats tunneled so intensely beneath a particular area of pavement that when garbage collectors drove over it, their truck sunk up to its axles. Rats in the vicinity took full advantage of the mishap and swarmed the truck, gorging on the garbage inside.
Baltimore also enjoys the dubious distinction of being a hotspot for rat-related research, beginning during World War II and continuing today, much of it carried out at Johns Hopkins University.
2: Boston, Ma
Like the ratty situations in London and Atlanta, Boston's rat problem may very well have been exacerbated by the recession. Improper trash storage and construction projects are another two commonly cited culprits. Regardless of the exact causes involved, the whole issue has Bostonians up in arms, especially considering the fact that between 1995 and 1997, Boston had a rodent-kill program in place that was wildly successful. But the money for that dried up, and rodents have since returned.
1: New York City, N.Y.
Incidents of unexpected rat appearances are frequently broadcast out of the Big Apple. Take the KFC/Taco Bell ratscapade of 2007. At a KFC/Taco Bell fast-food outlet located in Greenwich Village, a pack of rats drew big crowds and camera crews after they were discovered nonchalantly scurrying around the main eating area of the restaurant before it opened for the day. Word later got out that they regularly made themselves at home in the food prep area, too. Not pleasant information for frequent patrons, especially when news broke that the restaurant had several past rodent-related violations.
It's no wonder that with viral videos like that, some New Yorkers are worried negative coverage will hurt tourism. At least the city's in good company!