Mutant sewer rats spreading through major US cities as scientists discover disturbing DNA changes

Daily Mail UK ^ | June 24, 2026 | CHRIS MELORE, US DEPUTY SCIENCE EDITOR

[Red Badger]

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.

Specifically, five 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.

The changes were significantly greater in the smaller house mouse, which typically measures between two and four inches in length and can squeeze through the tightest space to get inside homes.

Meanwhile, the brown rat, also known as the sewer rat or Norway rat, which can grow up to 10 inches long, was found to be much more susceptible to common pesticides as they displayed fewer of the mutations.

Rutgers postdoctoral researcher and lead study author Jin-Jia Yu said in a statement: 'Genetic mutation is not that special in these creatures. But we found that the house mouse shows a lot of genetic mutations related to rodenticide resistance.'

In large urban areas, rodent infestations have been a continuous public health threat for decades, as scientists consider them a major source of disease transmission from animals to humans, passing on illnesses such as hantavirus, salmonella and plague.

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TOPICS: Health/Medicine; Outdoors; Pets/Animals; Weird Stuff
KEYWORDS: blackplague; hantavirus; helixmakemineadouble; mice; rats; rodents; salmonella

[Salman]

Hey! It’s just natural selection.

[Bikkuri]

New Yorkers turning into real live rats?

[mass55th]

Two-legged, mutant RATS can be found all over the United States.

[null and void]

Are they Rodents Of Unusual Size? 🤨

Rodents of Unusual Size? I think they don't exist.

[DennisR]

DemocRATS? Yeah.

[Carry_Okie]

Yeah, I used to live in a boat on the estuary in Oakland, CA.

I’ve seen big Norwegian browns.

[Presbyterian Reporter]

“”””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.””””

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And the Democrats are gleeful that they have more voters.

[MCF]

Yes, we know the rats are mutating. They’re becoming Democrat Socialists

[KarlInOhio]

Specifically, five 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.

I spent the last few years building up an immunity to Iocane powder.

[KarlInOhio]

Specifically, five 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.

I spent the last few years building up an immunity to Iocane powder.

[Mouton]

20 gage verses rats. 20 gage undefeated.

[The Duke]

NOTE TO SELF: Invest in the pellet gun factory.

[Clay Moore]

He not rat, he Siberian hamster.

[piasa]

We could send our surplus of Florida pythons to these cities annually to eat rodents in the warm season…

[redinIllinois]

.

[Carry_Okie]

Who knows, maybe they'll get there on their own. Hell, the homeless could eat them, or get eaten by them. Now that's a win-win proposition. /s