Animals positive for Yersinia pestis in Armenia

Objective:  The objective of this study was to determine the species composition of mammals and parasites involved in the epizootic process of plague in Armenia and their geographic distribution. Introduction: Plague was first identified in Armenia in 1958 when  Y. pestis was isolated and cultured from the flea species  Ct. teres  collected from the burrows of common voles in the northwestern part of the country. In the process of digitalizing archived data, a statistical and spatial analysis of the species composition of mammals and parasites involved in the epizootic process of plague between 1958 and 2016 was performed. Methods:  The plague archives of the NCDCP were exploited. The geographic addresses from which strains of  Y. pestis  were isolated from mammals and their parasite species were analyzed and grouped into 38 administrative regions (Fig.1). For geostatistical analysis, databases were created using Microsoft Excel and converted into a ESRI Geodatabase (Fig.2). Results:  Data from the especially dangerous pathogen laboratories indicate that 9329  Y. pestis  strains were isolated in 27 of the 38 regions of the country with 7022 (75%) of the strains found in just four regions: Abovyan 2597 (28%), Sisian 1953 (21%), Martuni 1416 (15%) and Ashotsk 1056 (11%) (Fig.3). During this period, plague bacteria were isolated from 17 mammal species including 15 rodents,  Mustela nivalis  (weasel), and  Neomys fodien s (shrew) (Fig.4).  Y. pestis  was isolated from 22 species of fleas belonging to 11 genera along with two families of ticks. Of the 9329 bacterial isolates, 6540 (70.2%) came from fleas, 2646 (28.3%) came from mammals and 143 (1.5%) were from ticks (Fig.5). Conclusions:  In Armenia, the primary mammalian host for  Y. pestis  is the common vole  Microtus arvalis  from which 2600 isolates (27.9%) were taken. Flea species from which large numbers of plague bacteria have been isolated include  Ct. teres- 3758 (40.3%),  Ct. wladimiri- 1262 (13.5%) and  C. caspia- 667 (7.1%).