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detected south of the ARR, 30 km from the state border between Russia and China. In 2018-2022, the RABV
spread within the forest-steppe landscapes of the Zeya-Bureya Plain northwesterly; the maximum distance from
the first recorded event was 192.4 km (Me = 77.6). According to a phylogenetic analysis, the isolates from ARR
belonged to the Acrtic-like-2 RABV lineage and showed the maximum similarity to the isolates recovered in the
province of Heilongjiang (China, 2011, 2018) and the Jewish Autonomous Region (Russia, 1980).

Conclusion: Rabies was most likely introduced by wild carnivores from the adjacent territories of Russia or China,
located downstream of the Amur River.

Keywords: Rabies, Acrtic-like, re-emerging infection, transboundary outbreak

INTRODUCTION
Rabies is a zoonotic viral infection with an almost 100% case fatality rate, caused by rabies virus (RABV)
(order Mononegavirales, family Rhabdoviridae, genus Lyssavirus, species Lyssavirus rabies) and other
lyssaviruses. Preventive measures can significantly reduce the incidence. According to the Global Burden of
[1]
Disease Study, the number of human rabies cases globally halved between 1990-2019 . Many countries have
joined the implementation of the Global Strategic Plan to end human deaths from dog-mediated rabies by
[2,3]
2030 . Significant progress has been made in China: from 2007 to 2020, the annual number of human
rabies cases has dropped from 3,300 to 202 . Most of these cases were concentrated in the south of the
[4-6]
country. Rabies in humans was recorded sporadically in the northern provinces, where wild canids serve as
reservoirs of the RABV [4,7,8] . However, an uptick in human rabies cases has recently been reported in
northern China . This territory and neighboring territories of Russia and Mongolia lie in the Amur River
[5,9]
basin [Figure 1, Supplementary Table 1 and Figure 1].

Human and animal rabies has been historically common in Russia, part of the Amur River basin. Here,
rabies penetrates to the north through steppe and forest-steppe areas favorable for such rabies hosts as red
foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides). This phenomenon contrasts strikingly
with the vast territories of Siberia covered by conifer taiga forests, where host populations are scarce, and
rabies has been recorded extremely rarely [10,11] . In the 1980s, wildlife rabies foci were described in the Russian
Far East in lowland areas along the Amur River and around Khanka Lake, where raccoon dog was
recognized as a reservoir of RABV [12,13] . Despite wildlife rabies, the infection mediated by domestic dogs
predominated as the cause of human disease (> 80% of human rabies cases). Only rare human deaths after
[12]
wolf and raccoon dog bites were reported in the Russian Far East during the previous century . RABV
variants of the so-called Arctic-like lineage prevail in the adjacent territories of Russia [14,15] and China [16-19] .
The similarity of landscapes, genetic lineages, and natural hosts of RABV led to the conclusion about the
transboundary nature of rabies outbreaks in the Amur River basin [12,16,19] .

Since the 1980s, the number of human and animal rabies cases and area of rabies-enzootic territories in the
Russian Far East have gradually decreased. The area between Lake Baikal and the Jewish Autonomous
Region (JAR) became rabies-free. At that time, dog and cat vaccination was enhanced, but the real reasons
for rabies disappearance in the rabies-enzootic territories remain unclear. However, in 2014, rabies
reemerged in all regions of Russia located to the East of Baikal Lake [10,20,21] . The situation in the Amur Region
of Russia (ARR) is the most striking illustration of these processes. In 1912, the specialized medical facility
(Pasteur Station) was opened in Blagoveshchensk for human post-exposure rabies prophylaxis. Until 1957,
34 human deaths were recorded, mainly after dog bites. In 1972, the last several rabies cases in cattle bitten
by wolves were documented . Since then, the ARR has been considered rabies-free until 2017. In 2018,
[13]
only rabies was registered again among wild animals, livestock, and dogs [10,13] .