[News Terms] Increase in 'Limebyeong' Patients, What Is the Reason?

Zoonotic Disease Transmitted by Ticks
Symptoms Include Skin Rash and Arthritis
Endemic in the US but Potential for Domestic Establishment

‘Lyme disease’ is a zoonotic infectious disease caused when ticks bite human skin and the Borrelia bacteria invade the body. It mainly occurs from May to November. In South Korea, it is classified as a third-class notifiable infectious disease, which includes 26 diseases such as Japanese encephalitis, malaria, and tetanus. Since Borrelia bacteria belong to the same genus as Treponema pallidum, which causes syphilis, Lyme disease is also referred to as the second AIDS.

The number of Lyme disease patients in South Korea decreased during the COVID-19 pandemic but has risen again. According to the Korea Disease Control and Prevention Agency (KDCA), the number of Lyme disease patients in South Korea was 23 in 2019, 18 in 2020, 8 in 2021, and 22 in 2022. Last year, there were 45 cases. By infection route, 36 were domestic infections, 8 were imported cases, and 1 had an unknown infection route.

Skin rash caused by Lyme disease and tick bite area [Photo by GOV.UK]

The KDCA is paying close attention to the recent increase in domestic cases. Among Lyme disease patients in South Korea over the past five years (2019?2023), 72.4% were infected domestically, which is significantly higher than the 56.4% recorded during the previous eight years (2011?2018). Considering this upward trend, there are concerns that the ticks transmitting Lyme disease have already become endemic in South Korea.

The KDCA stated, "Due to climatic factors such as temperature, humidity, and precipitation, it can be considered that the ticks transmitting Lyme disease have already become endemic domestically," and added, "With the expected increase in vectors due to climate change, the number of domestic cases and affected areas are likely to expand." In fact, the tick species that transmit Lyme disease, the Japanese tick and the deer tick, have been collected in all regions except Inje in Gangwon Province, Gwangju in Gyeonggi Province, Boseong in Jeollanam Province, and Jeju.

When infected with Lyme disease, symptoms progress in three stages. The first stage is a skin rash. A rash appears within one month after being bitten by a tick. This rash gradually enlarges. The size varies from a small coin-sized rash to one spreading across the back. Along with the rash, symptoms such as fever, pain, and fatigue occur.

The second stage occurs when the bacteria invade the nervous system and spread to muscles, bones, joints, and other areas, causing muscle pain and neuralgia. At the same time, dizziness, shortness of breath, and abnormalities in the electrocardiogram may appear. The third stage involves recurrent arthritis, usually appearing within two years after the tick bite. Symptoms such as facial paralysis, memory loss, and decreased concentration may also accompany this stage.

Justin Bieber, Avril Lavigne, Jimmy Walker
Photo by Reuters Yonhap News, Akyung DB

Lyme disease is usually cured if treated early with antibiotics. However, if diagnosis is delayed or complications occur, symptoms may become chronic despite antibiotic treatment, and in some cases, it can be fatal.

Lyme disease is endemic to the northeastern United States and was first identified in the city of Old Lyme, Connecticut, from which it takes its name. In 1975, a cluster of arthritis cases occurred among children playing near forests in this area, and during epidemiological investigations, tick bite marks were commonly found, revealing the cause of the disease. International celebrities such as American pop stars Justin Bieber and Avril Lavigne, as well as golfer Jimmy Walker, have publicly disclosed their battles with this disease.