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Retrospective descriptive epizootological study was conducted in the Amur Oblast (Russian Far East), where a rabies outbreak was reported in 2018. The aim of the study was to analyze probable routes of rabies introduction and features of its spatial and temporal spread in the territory that remained free from this infection from 1972 to 2018. In 2018–2021, altogether 1,416 animals were examined for the infection with the rabies virus. Forty-seven animal rabies cases were confirmed; the proportion of wild animals (Vulpes vulpes, Nyctereutes procyonoides, Canis lupus) amounted to 66%. The first cases were detected within 30 km from the state border with China. Nucleotide sequences of the nucleoprotein gene of three rabies virus isolates were determined and their belonging to the Arctic-like-2 genetic lineage was established. Genetically closest rabies virus isolates have been found in Heilongjiang Province (China, 2011, 2018) and Jewish Autonomous Oblast (Russia, 1980). GIS and open Earth remote sensing data were used to map the rabies cases. After 2018, the epizootic spread within the forest-steppe landscapes of the Zeya-Bureya Plain, where human and animal rabies cases had been earlier reported (until 1972). The front of the epizootic spread in a north-eastern direction at an average speed of 59 (16–302) km during one epizootic cycle. The introduction of the rabies virus was most likely along the Amur River valley from downstream regions of Russia and China that are rabies infected.

Rabies is endemic on the considerable part of the Russian Federation, and it is associated with current natural outbreaks of the infection. The highest animal morbidity rates are reported in the central and southern regions of the European part of Russia and in the southern part of Western Siberia. The Irkutsk Oblast is among the few regions of our country, which are rabies free for several decades. The research was aimed at the analysis of factors aiding to the maintenance of the rabies free status of the region. Retrospective study of archive and previously published reports on human and animal rabies cases in the Irkutsk Oblast starting from 1954 was performed. Epidemics of urban rabies ceased in the region in 1970s. Sporadic rabies cases in dogs, reported in 1976 and later, could be imported or could result from the infection from bats. Diagnostic errors were also possible. Rabies is reported in foxes in the Subjects bordering the Irkutsk Oblast: Krasnoyarsk Krai and Republic of Buryatia. It is supposed that in case of the infection introduction the forest-steppe agricultural areas near the Angara River are likely to be affected due to high population of foxes. Relative geographic isolation of the Irkutsk Oblast favors to the long animal rabies freedom of this territory. The vast area of mountain taiga with low fox population serves as an ecological barrier. In 2007–2009 and in 2019, barrier oral vaccination was carried out along the border with the Krasnoyarsk Krai and on the west coast of Baikal Lake. Measures for anti-rabies vaccination of dogs and cats were intensified. Active virological monitoring is performed on a regular basis. The paper demonstrates cartograms of fox and wolf population density along with designation of sites, where oral vaccination of wild carnivores was performed.

Rabies is one of the most pressing challenges for human and veterinary medicine. Lyssavirus genus comprises classical rabies virus and 13 other genotypes the most of which were isolated from bats. Updated information on taxonomy and phylogenetic and antigenic relationship of lyssaviruses are given in the review. The first phylogenetic group includes Rabies lyssavirus, Duvenhage lyssavirus, European bat lyssavirus type 1 and 2, Australian bat lyssavirus, Bokeloh bat lyssavirus, Aravan lyssavirus, Khujand lyssavirus and Irkut lyssavirus. The second phylogenetic group includes Lagos bat lyssavirus, Mokola lyssavirus and Shimoni bat lyssavirus. Cross serological neutralization within these two phylogenetic groups and limited cross neutralization between these two phylogenetic groups were revealed. West Caucasian bat lyssavirus is classified to the third phylogenetic group whereas Ikoma lyssavirus is classified to the fourth one. Lleida virus recently isolated from bats in Spain supposedly belongs to the fourth group. The most of rabies cases in humans and animals are caused by classical rabies virus (Rabies lyssavirus). Available anti-rabies vaccines protect from lyssaviruses of the first group but do not protect from viruses of other phylogenetic groups. That's why further investigations of recovered rabies isolates and new vaccine development are of great importance.