Ganbold et al.
Seroprevalence and risk factors of tick-borne encephalitis in Mongolia between 2016 and 2022
Parasite Epidemiol Control. 2023;22:e00318. doi:10.1016/j.parepi.2023.e00318

In Mongolia, the first TBE case was documented in 1989, and the virus circulates in 15 of 21 provinces. Most TBE cases have been notified in the Taiga-covered province Selenge. The main vector for TBE virus in Mongolia is Ixodes persulcatus, and both subtypes, the Far Eastern and the Siberian, have been isolated. Mongolia has about 3,400,000 inhabitants of which a third are nomadic.

A TBE seroprevalence study has been carried out from 2016 to 2022, and 993 sera were analyzed from people living in 21 provinces and the capital city Ulaanbaatar. In addition, the infection risk has been analyzed for various biographical zones and provinces.

20.2% of the analyzed sera were TBE IgG positive (in 15 provinces), and 8.1% were IgM positive. The highest seroprevalence rate was found in Selenge province (40%), while the prevalence was low in the Dornod province (steppe biogeographical zone; 0.5%). The seroprevalence was significantly higher in individuals aged 25–44 years than in those aged 60–75 years. Men were significantly more often affected (60%) than women. TBE was for the first time detected in the Bayan-Ulgii and Gobi-Altai provinces.

Mongolia has a high unemployment rate, and these individuals are more likely to spend time with outdoor activities like gold mining and ninja mining, working in forests and collecting wood, herding and hunting in TBE endemic areas with a high risk for tick bites.

The risk for TBE virus infections remains low in most regions of Mongolia but has increased in TBE endemic areas.

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