Retrospective Evaluation of Implementation of Long-Term Forecast on Spatial Spread of Rabies in the Asian Part of Russia

Abstract

Objective: To evaluate the historical long-term forecast of the spatial spread of rabies in Siberia and Far East and to characterize modern approaches to spatial forecasting. The concept of spatial spread of rabies in the Asian part of Russia, developed in the 80s of the twentieth century, is subjected to critical analysis based on information on rabies registration for 1881–1980 and zoogeographic data. At that time, 5 rabies enzootic regions were identified, and the most probable directions of further exportation of infection suggested. At first, a review of published data on human and animal rabies cases for the period of 1985–2019 was undertaken (including reference publications). Data on cases of rabies among humans and animals were selected for which geographical coordinates could be determined. Mapping was performed using GIS (QGIS 3.12.0 software and “Natural Earth” and “OpenStreetMap” electronic maps). Comparison of maps for different time periods demonstrated that rabies incidence was recorded mainly within the previously identified risk areas. However, the occurrence of human disease in different regions did not always correspond to the intensity of epizootics and the predicted risk. Next, in an attempt to correct the prognosis of the spatiotemporal rabies spread, we reviewed publications that incorporated virus genetic data along with GIS technology and modeling application. The distribution of the three major rabies virus lineages (“steppe”, “Arctiс-like”, “Arctic”) corresponded to the regions that were previously identified. The spread of fox rabies (the “steppe” rabies virus lineage) in the north-east direction was described. In several instances, rabies outbreaks in southern Siberia and Far East were associated with cross-border movement of the virus from Kazakhstan, Mongolia and China. Data on the speed of the epizootic waves, pathways, and natural barriers for virus spread are discussed. The correction of the forecast for rabies virus circulation and spread is important for the development of control strategies in the region, including oral vaccination of wildlife virus reservoirs.

Reemergence of arctic-like rabies virus in a rabies-free area in the Amur river basin

“…In Russia, the nearest to the ARR rabies-enzootic territory is in the JAR, 200-300 km to the east, where the infection was historically present in lowland areas, including the Amur River valley [10,12,13,26] . During 2017-2018, animal rabies was documented in JAR [10] , just before the outbreak in ARR. Later, in 2018-2020, the fox rabies spread down the Amur River valley to Khabarovsk and Komsomolsk-na-Amure cities [Figure 3].…”

“…From 1983 to 2013, this region was considered rabies-free. Epizootic among foxes reemerged in 2014 because of an introduction of the Steppe genetic RABV lineage [10,21,27] . Thus, recent outbreaks in the Trans-Baikal Region of Russia and the ARR are disconnected and unrelated.…”

“…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] .…”

“…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.…”

“…Since then, the ARR has been considered rabies-free until 2017. In 2018, only rabies was registered again among wild animals, livestock, and dogs [10,13] . This study aimed to detect possible ways of incursion and features of the spatial spread of rabies in ARR, which was considered rabies-free for 45 years.…”