Baasandavga et al.
A case series of fatal meningoencephalitis in Mongolia: epidemiological and molecular characteristics of tick-borne encephalitis virus
Western Pacific Surveillance and Response 2019, 10; 1,
doi 10.5365/wpsar.2018.9.1.003

In Mongolia, fatal TBE cases have been registered since 2005. A descriptive epidemiological study of 14 fatal TBE cases from 2008 to 2017 has been carried out. All patients had been bitten by ticks in the provinces Bulgan and Selenge. All patients were men, and the median age was 45 ± 12.6 years. The incubation time was 16 ± 11.4 days, and the fatalities occurred 8.1 ± 5.2 days after clinical symptoms developed. The most common clinical symptoms were fever (85.7%), paralysis (85.7%), headache (78.6%) and vomiting (71.5%). The case fatality rate in Bulgan province was 18.2 to 50% and in Selenge province was 5.7 to 10%. From one fatal human case and from Ixodes persulcatus ticks collected in Selenge province, TBE virus RNA specific for the glycoprotein E gene could be amplified. Phylogenetic analyses showed that the isolated viruses belonged to the Far Eastern subtype. Since 2005, vaccination and educational campaigns have been administered throughout the affected areas of Mongolia, but human TBE cases and fatalities continue to increase.

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