Early Heat Brings Back Mosquitoes... Overseas Mosquitoes Also 'Stirring' Amid Endemic

Early Arrival of Mosquitoes [Image Source=Yonhap News]

Recently, as daytime temperatures across the country have exceeded 30 degrees Celsius, signaling an early heatwave, mosquito activity has also accelerated. With the number of mosquito-borne disease patients increasing accordingly, and the endemic (periodic outbreak of infectious diseases) approaching this year, overseas travel is expected to rise, leading to predictions of an increase in imported mosquito-borne disease cases.

With the heatwave arriving from mid-May, there is a possibility that the first confirmed case of Japanese encephalitis, transmitted by the small red house mosquito, will appear earlier than usual. Typically, the outbreak begins in late July when the heat intensifies and peaks in early September; last year, the first infected patient was reported in September. This year, as the small red house mosquito was detected earlier than usual, the Korea Disease Control and Prevention Agency (KDCA) issued a nationwide advisory 19 days earlier than last year, on March 23.

A KDCA official stated, “Although there were reports of an unusually early first patient this year, it was confirmed to be a misreport from a medical institution,” adding, “No first case of Japanese encephalitis has been reported yet.” In 2019, 34 people contracted Japanese encephalitis, which dropped to 7 in 2020, the first year of COVID-19, and slightly increased to 11 last year. Occasionally, it can lead to severe symptoms such as seizures, neck stiffness, and paralysis. Particularly, when it progresses to encephalitis, 30% of patients die, and even among survivors, 30-50% suffer from complications such as neurological and cognitive impairments. Vaccines for Japanese encephalitis have been developed, and children can receive free vaccinations according to the national immunization schedule. For adults, vaccination is recommended for high-risk groups such as residents near rice paddies or pig farms and those without prior vaccination history.

Malaria cases, which mainly occur between June and September, have reached 68 this year. This is nearly three times the number of malaria patients (23) during the same period last year. Although malaria is known to be prevalent in tropical climates such as Africa, it also occurs in South Korea. More than half of this year’s malaria patients, 37 individuals, were infected domestically. This is because the mosquito species that transmits Plasmodium vivax malaria inhabits the Incheon, northern Gyeonggi, and Gangwon regions. These mosquitoes are mainly active from 7 p.m. to 5 a.m. the following day. Since the 3rd of last month, the KDCA has started mosquito vector surveillance and monitoring in these areas. Malaria infection typically causes symptoms such as chills, fever, and loss of appetite, and early diagnosis is crucial for appropriate administration of treatment.

This year, with the end of the COVID-19 pandemic, international travel is expected to increase explosively, raising concerns about mosquito-borne diseases transmitted by overseas mosquitoes. Dengue fever, Zika virus, and chikungunya fever are representative examples. All present similar symptoms such as high fever, rash, and chills, but Zika virus can also cause conjunctivitis and bleeding. Vaccines for these viruses have not yet been developed.

Health authorities emphasize, “To prevent mosquito-borne infectious diseases, the most important thing is to avoid mosquito bites.” Until October, when tropical nights persist, it is advised to refrain from camping and fishing at night, and if unavoidable, to use mosquito repellents. If suspicious symptoms appear after traveling abroad, one should visit public health centers and medical institutions for testing and treatment.

This content was produced with the assistance of AI translation services.