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Page 132 Botvinkin et al. One Health Implement Res 2023;3:125-34 https://dx.doi.org/10.20517/ohir.2023.19

had a similar landscape distribution in this area in the middle of the last century [12,13] .

Raccoon dogs were highly susceptible to experimental inoculation with the RABV strain isolated in the
Russian Far East in 1980 (presumably Acrtic-like-2), and all became ill even after a dose of 5 MICLD . At
50
[28]
the same time, some foxes did not become ill after a dose of 100 times more . In 2007, raccoon dogs
became ill during an outbreak of rabies caused by the Acrtic-like-2 rabies virus on a fur farm, but rabies was
not observed among foxes . In the last century, several human rabies cases were associated with raccoon
[16]
dog bites in adjacent territories of Russia and China [4,12,28,29] . Singular human rabies cases after fox bites began
[26]
[30]
to be registered in the Russian Far East only in 2002 and in China since 2016 . During recent years, fox
rabies has been detected repeatedly in the Amur River basin [9,10,25] . Comparison with data from 1949-1978
shows significant changes in ARR’s affected species composition. In the past, dogs (48.6%) and farm animals
(46.5%) dominated among the registered rabies cases, whereas cats and wild animals (wolf, raccoon dog)
accounted for 2.8% and 2.1%, respectively. Foxes were not found in the list of rabid animals in ARR during
that period .
[13]

Thus, the present rabies outbreak in the ARR confirms the increasing role of red foxes as a host of RABV in
Eastern Asia. The changes in the abundance of red foxes, raccoon dogs, and wolves in the Amur River basin
under the influence of human activity are suggested among the factors that contributed to the activity of
rabies epizootics, host shifts, and switches, introduction and re-introduction of the infection into rabies-free
territories. Intensive farming, irrigation, sown area expansion, and decreased hunting pressure led to an
[13]
increasing red fox population [10,13,21] . Simultaneously, the population of raccoon dogs in ARR decreased .
Perhaps we are currently witnessing an establishment of the Acrtic-like-2 RABV to red foxes. As suggested
by Yu et al., in the past, this genetic lineage of RV evolved in Asia predominantly in dogs, domestic animals,
[19]
and raccoon dogs .

Since the outbreak, the rabies vaccination of dogs, cats, and farm animals in the ARR has increased by five
times. Since 2019, oral vaccination of wild carnivores with the Rabistav live rabies vaccine made with the
PB-97 strain (Stavropol, Russia) has been performed. It would be premature to expect a quick and lasting
effect from these interventions. In 2021, rabies was diagnosed in foxes in Poland, where rabies had not been
detected in over 17 years. This finding occurred despite Europe’s intensive oral rabies vaccination program
since 1993. New animal rabies cases were located 100 km inside the vaccination belt .
[31]

The median distance from the first case to new cases during the observation period in the ARR was 77.6 km.
At the beginning of the fox rabies epidemic in Europe in the middle of the last century, the average speed of
epizootic spread was 30-60 km per year [32,33] . However, the rate of epizootic spread in the Russian Far East
can be much higher since the wolf population remains high in contrast with Europe. Using GPS tracking,
[34]
the maximum movement of a healthy wolf per day in the Trans-Baikal Territory was 97 km . Thus, wolves
can contribute to the long-distance introduction of the RABV along the Amur River valley. The regional
features of the spatial RABV spread described in the article may help improve rabies prophylaxis and
control in the Amur River basin.

CONCLUSION
An outbreak of rabies in the ARR, registered in 2018 for the first time since 1972, arose because of an
introduction of RABV that belongs to the Acrtic-like-2 lineage, documented broadly in eastern Asia. Rabies
was most likely introduced by wild carnivores from the adjacent territories of Russia or China, located
downstream of the Amur River. During the freezing period, the Amur floodplain can serve as an ecological
channel for the RABV spread. In 2018-2022, the epizootic expanded for about 200 km northwest within the