Rickettsia raoultii, the predominant Rickettsia found in Mongolian Dermacentor nuttalli.

Since the year 2005, clinical patterns resembling tick-borne rickettsioses have been noticed in Mongolia. Epidemiological data regarding species of the aetiological agent, tick vector, prevalence, and distribution as well as incidence of human cases throughout Mongolia are still sparse to date. In order to identify Rickettsia species occurring in Mongolia, we investigated Dermacentor nuttalli (n=179) and Ixodes persulcatus (n=374) collected in 4 selected provinces. Rickettsia raoultii was the predominant Rickettsia (82% prevalence) found in D. nuttalli and was also detected in I. persulcatus (0.8%). The Rickettsia prevalence in D. nuttalli from different provinces varied between 70% and 97%. In addition, R. sibirica was identified in approximately 4% of D. nuttalli, but solely from Arkhanghai province. The results of this study extend the common knowledge about the geographic distribution of R. raoultii and its high prevalence in D. nuttalli. Although the pathogenicity of this Rickettsia is still unclear, it should be considered in Mongolian patients suspected of having tick-borne rickettsiosis.

Plague in Mongolia.

Mongolia is a country of Central Asia that occupies 1,564,116 km(2) and has a population of 2.7 million people. The geography of Mongolia is varied and has a continental climate. Plague, caused by the bacterium Yersinia pestis, is enzootic in wild rodent populations over large rural areas of Mongolia. Natural plague foci have occurred over 28.3% of Mongolia, and 47.1% of these foci are highly active. Highly active plague foci exist mainly in the western part of Mongolia. A total of 27% of all plague cultures were isolated from ectoparasites of 12 species of endemic mammals and 1 species of bird. Most plague cultures isolated from ectoparasites of mammals were from fleas (91.5%). The majority of cultures isolated from fleas were from marmot fleas (64.5% of all fleas). The marmot flea (Oropsylla silantiewi) is considered the primary vector of plague. Human cases of plague have been recorded in Mongolia since 1897 and more than 3000 plague cultures were isolated from natural foci. Plague foci occur between 50 degrees 00-43 degrees 00 longitude and 88 degrees 00-120 degrees 00 latitude and at altitudes between 640 and 3500 m.