Yoshii et al.
Serologic evidence of Tick-borne encephalitis virus in a patient with suspected Lyme disease in Japan.
Am. J. Trop. Med. Hyg., in press
A retrospective seroepidemiological study has been carried out in a total of 158 samples from patients living throughout Japan, including Hokkaido, and of whom 81 had suffered from meningoencephalitis and had suspected Lyme disease. Sera from one patient with a history of tick bites on the island of Hokkaido in 2012 and severe encephalitis showed neutralizing TBE antibodies, but these sera were negative for JEV. The patient’s symptoms included fever, nausea, and vomiting 21 days after the tick bite, and after hospitalization a physician had initially diagnosed neuroborreliosis. This survey demonstrates that TBE cases may have been overseen in Japan. The same research team has recently published unrecognized subclinical TBE virus infections in members of the Japan Self Defense Force from the Northern Army (Yoshii et al., Emerg. Infect. Dis. 2017; 23: 1753-1754). Together with data showing that the TBE virus is circulating in animals on the island of Hokkaido (e.g. see snapshot week 23), these results indicate that TBE is underreported in Japan.