Marmots and Yersinia pestis Strains in Two Plague Endemic Areas of Tien Shan Mountains

Abstract

The main purpose of this study was to clarify the role of gray marmots ( Marmota baibacina ) in the long-term maintenance of highly virulent strains of Yersinia pestis in two plague endemic foci of the Tien Shan Mountains in Kyrgyzstan. We present data from regular observations of populations of M. baibacina and small rodents cohabiting with marmots in the mountainous grasslands of the Sari-Dzhas (east of Issyk-Kul Lake) and the Upper-Naryn (south of Issyk-Kul Lake) natural foci. During 2012–2017, an abundance of marmots and their ectoparasites (fleas and ticks) was significantly higher in Upper-Naryn comparing to Sari-Dzhas, although there were no differences in a number and diversity of small rodents cohabiting with marmots. The plague bacterium was detected either in marmots or in their ectoparasites collected during 4 of 6 years of observation in Sari-Dzhas and during 2 of 4 years of observation in Upper-Naryn. Plague was found in three sectors situated closely to each other in Sari-Dzhas and in 1 of 8 repeatedly surveyed sectors in Upper-Naryn. During 6 years, we isolated 9 strains of Y. pestis from marmots, two from their fleas Oropsylla silantiewi , one from an unidentified tick, and one from the gray hamster ( Cricetulus migratorius ). All plague strains isolated from the rodents and their ectoparasites in this study were similar to Antiqua biovar specific for marmots. The results indicate that plague can circulate continuously in the Tien Shan Mountains in populations of gray marmots and their ectoparasites with a facultative involvement of other rodent species after significant changes in rodent communities that happened in Kyrgyzstan during the previous two decades. The simultaneous field survey of two natural foci of plague, Sari-Dzhas, and Upper-Naryn, would be important for further analysis of circulation of Y. pestis strains belonging to Antiqua biovar in the Tien Shan Mountains.

Alternative lifestyles: A plague persistence hypothesis

“…In the natural setting, Y. pestis L‐forms have been observed within the corpus of fleas (Bazanova et al, 1997; Konnov et al, 1986; Maevski et al, 1994). In field tick samples (Sariyeva et al, 2019) and have been recovered from ticks and mites weeks after experimental infection (Zykin et al, 1989). Further investigations have revealed L‐forms within live animals (Dunaev et al, 1982), in host carcasses (Dunayev et al, 1981; Zykin et al, 1989), and in soil protozoans (Domadarski et al, 1995).…”

Increasing risks for emerging infectious diseases within a rapidly changing High Asia

“…These outbreaks are linked to transfer from sympatric livestock (Dagleish et al 2007;Ostrowski et al 2011). Bubonic plague (Yersinia pestis) and anthrax (Bacillus anthracis) are also carried by wild ungulates and smaller prey taken by snow leopards, such as marmots (Marmota baibacina) (Sariyeva et al 2019). Marmots are hunted by people for their meat in large parts of the snow leopard range, and associated human deaths from plague transmission have been reported recently (Grewal 2020).…”

Eight Years of Collaboration on Biosafety and Biosecurity Issues Between Kazakhstan and Germany as Part of the German Biosecurity Programme and the G7 Global Partnership Against the Spread of Weapons and Materials of Mass Destruction

“…The Republic of Kazakhstan is a landlocked country in Central Asia dominated by continental climate. Totalling up to 2.7 million km 2 , the size of the country approximately is seven times the size of Germany and hosts a relatively small population of 18.6 million inhabitants. Historically, Kazakhstan served as the cradle of many consequential pathogens.…”

“…Its vast steppes and the hot and dry climate fuelled the evolution of plague (Yersinia pestis). Furthermore, diseases like Anthrax, Tularaemia and Brucellosis, to name but a few, are endemic to the region (1)(2)(3). There exists a vast amount of under-investigated potential natural foci for the vectors or reservoirs of some of these diseases.…”