Since our earliest days, U.S. cities have gotten a bad rap. Thomas Jefferson referred to them as "pestilential to the morals, the health and the liberties of man," and that was a generous assessment.
One of the big problems in the cities is the rats. So many rats. Sewer rats, pizza rats, cities always have a ton of rats. And as the Daily Mail reports, those rats are, well...changing:
Scientists have uncovered a disturbing change in both mice and rats infesting America's biggest cities, making the rodents harder to kill than ever before.
Researchers at Rutgers University in New Jersey found the vast majority of smaller house mice and larger brown rats in New York, New Jersey, Pennsylvania and Washington DC have genetically mutated to become more resilient to poison.
Every public works director in every major U.S. city right now:
Now, many people might only be familiar with rat control in the form of the classic Victor snap-trap. You bait the trap, set the spring, and wait for old Mr. Rat to snap his way into rodent heaven.
But in fact the most popular way to kill rats, at least in the U.S. is through poison — specifically warfarin, which is a blood thinner and which is laced into rat bait, causing the rats to bleed out internally when they eat it. It works great.
Except, apparently, when they "mutate" to be more resistant to it. Because that's what has happened:
[F]ive out of every six rodents tested displayed at least one mutation in the Vkorc1 gene, which has been found to affect how well the poisons work.
This study of nearly 300 house mice and brown rats also confirmed that more than 69 percent of the rodents carried additional genetic mutations, which previous studies have proven make rodents immune to common exterminator poison.
Now, there's good news and bad news here. The good news is that, of the few hundred mice and rats surveyed in the study, rats were more sensitive to the poison than mice. So it's still at least somewhat easy to kill a rat by laying out a nice durable box of poison and letting him chow down.
Still, mice growing resistant to poison is not good either way. You want to be able to kill both of these filthy beasts if you can get the chance. And it turns out that mice are actually more durable regarding bait because they, um, eat it more often:
The researchers told the Philadelphia Inquirer that house mice were more likely to eat unfamiliar foods they come across, which leads to them consuming rodent bait more often.
The more exposure these tiny rodents have to fatal poisons, the more their DNA has a chance to develop a mutation, which protects them falling ill and dying.
Rats, meanwhile, are "playing catch-up," which means they're still more susceptible to poison bait — though presumably, at some point, in the future, they'll be more resistant to it.
This is a real problem for folks living in the big cities:
According to Census Bureau data cited by the researchers, 29 percent of all households in Philadelphia have spotted a rat in their home.
Fifteen percent of New Yorkers living in the borough of Manhattan have experienced rat problems in their apartments or homes, and one in five residents in Washington DC said the same.
Rodent scientists, we're begging you: Get back into the lab and figure out a way to kill more vermin, please!
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