It sounds like a sci-fi B movie, but the problem is real. Rats have long plagued Iran, and the problem worsens when springtime arrives: melting mountain snows flood the critters’ nests, and millions are flushed into the city’s streets and sewer network.
Tehran reportedly has more rats than its 12 million human inhabitants.
“It’s become a 24/7 war,” the head of Tehran municipality’s environmental agency, Mohammad Hadi Heydarzadeh, said on state television last month. “We use chemical poisons to kill the rats during the day and the snipers at night.”
Nearly 1 million rats are exterminated in Tehran every year, with city authorities launching multimillion dollar campaigns annually to curb the problem.
Authorities have employed over 45 tons of rat poison, but the rodents seem impervious, thriving despite chemical warfare: some reportedly weigh as much as 11 pounds.
Tehran city council environment adviser Ismail Kahram told Iranian news website Qudsonline that the rats, “seem to have had a genetic mutation, probably as a result of radiations and the chemical used on them.” “They are now bigger and look different”, he said, according to the International Business Times. “These are changes that normally take millions of years of evolution. They have jumped from 2 ounces to 11 pounds, and cats are now smaller than them.”
So Tehran has ramped up its attack. City officials told state media that 10 sniper teams armed with infrared scopes caught more than 2,500 rats recently, but Abu Dhabi’s The National called that number “a drop in the ocean.”
Dr David Baker, a veterinarian at Louisiana State University, told The Huffington Post it’s unlikely that a mutation caused the rats to super-size. “Nearly all genetic mutations identified across the field of biology are harmful and confer a disadvantage to the species rather than an advantage,” he said. “It’s not like in the movies.”
He conceded that there are several species of giant rats that can achieve the sizes described by Mr. Kahram. “During the Middle Ages, black rats in Europe reportedly grew large enough – and children were small enough – to carry off babies,” he said.
Genetic mutations aside, scientists have reported that certain rat populations are becoming poison-resistant. Last year, British researchers published findings estimating that 75% of west England’s rats were resistant to rodenticide. Last October, the BBC reported that preliminary research indicates all UK rats in could become poison-resistant within 10 years.
Rats flourish in warm weather. As snows on the nearby Alborz mountains start melting, water levels rise, forcing rats from their subterranean habitat. They migrate to roadside streams along Ali Asr, the Middle East’s longest street. The popular thoroughfare is home to restaurants and food stalls, and threads it’s way from North Tehran’s expensive neighborhoods to poorer southern suburbs, where the rat population is reportedly six times greater than the human population.
The government is considering ratcheting up the snipers to forty, but with a 6:1 ratio of vermin to humans, this war earns the monicker “quagmire”.