(Getty Images)
(Getty Images)

This summer’s series of torrential downpours in South Korea has brought an unusual and unsettling consequence to Seoul residents: more rats in the streets.

As sewers overflow and underground habitats are inundated, rodents have been driven above ground, prompting a spike in complaints across the city.

District offices in Gangnam and Gangdong report that public bulletin boards have been filling with sightings and requests for extermination. Local governments deployed high-tech rat traps and expanded disinfection patrols to contain infestations.

However, experts warn that these measures may be treating the symptoms rather than the cause. Climate change, they say, is the deeper force driving rodent populations upward.

Warmer temperatures mean more rats survive the winter and reproduce for longer periods of the year. Last fall, the average national temperature was 16.8 degrees Celsius, 2.7 degrees above the seasonal norm.

“Warmer winters are boosting rat survival rates and extending their breeding cycles, which accelerates population growth,” said Yang Young-chul, professor of environmental health and safety at Eulji University.

“Rats that usually stop breeding in cold weather are now reproducing more often, even in months when they would normally be dormant.”

Similar patterns are being observed globally. According to the journal Science Advances, 13 of 16 major cities studied, in countries including the United States and Japan, reported increases in rodent populations. In Washington, the number of rats has quadrupled over the past decade.

Managing the problem is challenging in densely populated urban environments. Cities lack natural predators that would normally help keep rodent populations in check. Efforts by health authorities to place poison bait are sometimes delayed or blocked by residents’ concerns, further complicating control measures.

The risks are more than a nuisance.

Rats are known to carry diseases such as hemorrhagic fever with renal syndrome, or HFRS, and leptospirosis, both of which can be fatal.

HFRS, transmitted through contact with rat urine or droppings, causes high fever and kidney failure and has a fatality rate of up to 15 percent. Leptospirosis, which also spreads through the excretions of rodents, can cause fever and muscle pain. In severe cases, it can be deadly. With no vaccines available for either disease, experts warn that prevention is critical.

City officials emphasize that public cooperation remains essential. Seoul City has asked citizens to notify their district office or health center if they encounter rats or signs of infestation.

As extreme weather events intensify and urban flooding becomes more frequent, experts caution that rat infestations may become an increasingly persistent feature of city life.


jychoi@heraldcorp.com