Chukotka as a Portal for the Rabies Introduction into Kamchatka (Systematic Review)

Abstract

The aim of this review was to assess the peculiarities of distribution and epidemiological risk of rabies in the extreme northeast of Asia. The systematic review was prepared through synthesizing publications on rabies over 1860–2022 (n=22) and previously unpublished data for 2009–2023. From the late 19th century until the 1980s, rabies epizootics were consistently observed in Chukotka and Kamchatka. A correlation was found between the time of occurrence of rabies in those territories with a lag period of 1–2 years (r=0.349; p=0.054). In 2009–2023, 24 animal rabies cases were confirmed in Chukotka; rabies has not been registered in Kamchatka since 1981. Until 1982, 5 confirmed human rabies cases were described in Chukotka, as well as 4 lethal cases presumably due to rabies (Chukotka – 3, Kamchatka – 1). The similarity of the spatial distribution of epizootics in different periods of time was established. Rabies was detected mainly in the area of the permanent polar fox (Vulpes lagopus) habitation, in the coastal tundra from the mouth of the Kolyma River to the Anadyr Gulf. Outside this territory (the valleys of the Anadyr and Penzhina Rivers, the Kamchatka Peninsula), rabies was reported in red foxes (Vulpes vulpes). At present, the importance of the polar fox in the spread of rabies in Chukotka has decreased, while the significance of the red fox has increased substantially. Due to vaccination, rabies among dogs is recorded sporadically. Rabies virus isolates from Chukotka belong to the Arctic genetic lineage (Arctic-3 group), which has a circumpolar distribution. The possibility of independent circulation of the rabies virus in the Kamchatka Peninsula is doubtful because of the limited size of the red fox population. Based on the mapping, possible directions for the introduction of rabies to Kamchatka from Chukotka have been identified. Barrier oral rabies vaccination of foxes is recommended during the years of high abundance of red and polar foxes in Chukotka.