Seroprevalence of Severe Fever with Thrombocytopenia Syndrome in the Agricultural Population of Jeju Island, Korea, 2015–2017

Abstract

BackgroundSevere fever with thrombocytopenia syndrome (SFTS) is a tick-borne zoonotic disease that is caused by the SFTS virus (SFTSV), and exhibits an overall mortality rate of approximately 20.0% in Korea. Most cases of this disease have been reported in Korea, East China, and Japan, and it mostly affects outdoor workers and farmers. This study aimed to investigate the seroprevalence of SFTSV among healthy farmers on Jeju Island, Korea.Materials and MethodsIn this prospective cross-sectional study, we analyzed 421 blood samples obtained from 254 farmers (mean age, 59.9 years; 68.9% male) to determine the seroprevalence of SFTSV in 16 rural areas of the Jeju Special Self-Governing Province over a period of 3 years (January 2015–December 2017). We used an enzyme-linked immunosorbent assay to detect immunoglobulin (Ig) G antibodies against SFTSV in the collected samples.ResultsThe seroprevalence of the SFTSV IgG among farmers on Jeju Island was observed to be 2.4%. One subject showed seropositivity over the entire 3-year study period. The areas with the highest SFTSV IgG seropositivity rates were Seonheul-ri in Jocheon-eup, followed by Namwon-eup. Fruit farmers were at a higher risk of exposure to SFTSV than other farmers.ConclusionThe seroprevalence of SFTSV in the healthy agricultural population of Jeju Island was not high. However, personal hygiene management should be implemented for the agricultural population in the endemic areas. Surveillance of mild or asymptomatic infections is required in the endemic regions.

Neutralizing Antibodies to Severe Fever With Thrombocytopenia Syndrome Virus Among Survivors, Non-Survivors and Healthy Residents in South Korea

“…To investigate the levels of neutralizing antibodies to SFTSV, we collected 19 serum samples from 11 patients (non-surviving patients; n =6, mean age: 73.3 and surviving patients; n =5, mean age: 68.8), which were laboratory confirmed at Jeju National University from May 2013 to October 2019, Jeju, South Korea, and 7 serum samples from 5 healthy residents (mean age: 69.8) living in endemic areas who were positive for SFTSV IgG from November 2015 to April 2017 ( Yoo et al., 2019 ) ( Table 1 ). This study was approved by the Institutional Review Board (IRB) of Jeju National University Hospital.…”

“…Real-time RT-PCR showed that all the patients ( n =11) were positive for SFTSV, and 6 healthy residents were negative for SFTSV. Antibody detection was performed, and IgG was detected in the serum of all patients and 6 healthy residents ( Yoo et al., 2019 ).…”

“…In this study, we briefly investigated the levels of neutralizing antibodies to SFTSV in serum among surviving patients, non-surviving patients, and healthy residents living in endemic areas and who were positive for SFTSV IgG antibody in South Korea from 2013 to 2019 ( Yoo et al., 2019 ). We found that the titers of neutralizing antibodies to SFTSV maintained in surviving patients and healthy residents were higher than those detected in non-surviving patients.…”

Severe Fever with Thrombocytopenia Syndrome Virus in Ticks and SFTS Incidence in Humans, South Korea

“…cropland areas are associated with high risk for infection (2,3,6). Northeast Jeju Island, which includes SH, AW, and HD, has many farms and wetlands, and the IR of SFTSV in ticks peaked there in July, August, and September.…”

“…A previous study reported that the minimum infection rate of SFTSV in infected ticks was lower (0.37%) on Jeju Island than in other collection areas (1.97%) (4). However, 7%-14% SFTSV seropositivity was identified in domestic and wild animals (4-5), and 2%-5% SFTSV seropositivity was identified in a healthy population in South Korea (6). Therefore, our aim was to investigate the SFTSV infection rate (IR) in ticks in the region with the highest endemicity, Jeju Island, and to analyze the relationship between the geographic distribution of ticks and SFTSV and human cases of SFTS.…”