[The participation of birds in the circulation of the tick-borne encephalitis virus in the Asian part of Russia. 1. Natural foci in the Far East].

Virologic examinations of 811 samples of 70 species and of 81 ova from layings of 11 bird species, carried out in natural foci of tick-borne encephalitis (TBE) in the southern Maritime [correction of Primorye] Territory, yielded negative results; serologic examinations revealed a low level of the immune stratum to TBE virus even in the birds feeding on the soil or on grass and shrubberies, that is, belonging to the first and second ecologic groups (0.8 +/- 0.4%). A difference has been demonstrated between the shares of TBE immune samples in the first and second+third (birds feeding on trees but sometimes on soil) +fourth (feeding on trees, in air, out of forests, on animals) ecological groups of birds, as well as between the first+second and third+fourth groups.