Increased Rodent Sightings in Urban Areas Following Heatwave and Flooding, Concerns About the Spread of Infectious Diseases

Following the heatwave and flooding, sightings of rats have become frequent in urban areas, raising concerns about the potential spread of rodent-borne infectious diseases such as leptospirosis and hantavirus pulmonary syndrome.

Recently, reports of rat swarms appearing at bus stops and underground shopping malls have been flooding local district office complaint boards. In response to this situation, local governments are implementing various preventive measures.

Seongdong District of Seoul has installed eighty smart rat traps since last year, while Gwanak District has proactively responded by installing seven smart rat traps and rat poison at key points such as Seoul National University Station, Sillim Station, and Bongcheon Station on Line 2 of the subway.

The Risks and Symptoms of Rodent-Borne Infectious Diseases

As the rat population increases, the risk of spreading infectious diseases they carry also heightens.

According to data released by the Korea Disease Control and Prevention Agency on the 4th, major zoonotic diseases related to rats include leptospirosis and hantavirus pulmonary syndrome. These diseases are commonly transmitted through water or soil contaminated with rat urine, and special caution is required when working outdoors without boots or gloves, as pathogens can enter through skin wounds.

Common symptoms of these infectious diseases include fever, muscle pain, chills, headache, and abdominal pain, and inflammation may occur in the liver, kidneys, lungs, and meninges in some patients.

Even more serious is the potential progression to severe conditions such as sepsis, pulmonary hemorrhage, jaundice, and kidney failure, with fatality rates ranging from 5% to 15%.

Leptospirosis is an infection caused by contaminated water or mud originating from the urine of rodents or livestock, and human-to-human transmission is believed to be rare.

The incubation period varies from 2 to 30 days, and in Korea, there tends to be an increase in cases particularly between September and November following flooding or heavy rainfall.

In the past five years, the number of patients fluctuated, showing counts of 144 in 2020, 125 in 2021, 59 in 2022, 59 in 2023, and an estimated 70 in 2024.

Hantavirus pulmonary syndrome is an acute infectious disease transmitted to humans by viruses carried by infected rodents, which can progress through the incubation period to serious symptoms such as hypotension, shock, and hemorrhage.

After an incubation period of 12 weeks, symptoms such as high fever, chills, eye pain, muscle pain, headache, facial flushing, abdominal pain, and nausea may appear, with the possibility of subsequent progression to hypotension, shock, hemorrhage, and acute kidney failure. Major causes of death include shock, brain disease, acute respiratory failure, and pulmonary hemorrhage, with a fatality rate similar to that of leptospirosis, ranging from 5% to 15%.

While most patients recover, some may experience sequelae such as kidney function deterioration or cerebral hemorrhage, making early detection and treatment crucial.

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