Necessity of a Surveillance System for Tick-borne Encephalitis.

Dear Editor:

With great interest, I have gone through the paper titled, “Prevalence of tick-borne encephalitis virus in ixodid ticks collected from the Republic of Korea during 2011–2012,” by Yun et al [1]. Yun et al [1] reported that the minimum infection rate (MIR) of tick-borne encephalitis (TBE) from a tick was 0.08%. The MIR from Haemaphysalis longicornis, a tick species that constitutes most collected ticks, was 0.06%. In another paper that also studied the MIR of severe fever with thrombocytopenia syndrome (SFTS) from H. longicornis reported a MIR of 0.46% [2]. In South Korea, the first case of a patient with SFTS was reported in 2013 [3]; the number then gradually increased to 79 cases in 2015 with the initiation of a surveillance protocol [4]. A simple comparison between the MIRs of TBE and those of SFTS from H. longicornis shows that the number of patients with TBE is one-eighth of the number of patients with SFTS. However, no additional cases were reported from 2011 after the legal designation of TBE as an infectious disease, up to October 2016. This may be due to a difference in transmission route or pathogenicity, but TBE is certainly under-reported in Korea because of its unfamiliarity. Therefore, TBE surveillance by health authorities should be strengthened and awareness among primary-care physicians by education and public relations about TBE should be increased.