Zecken und durch Zecken übertragbare Krankheitserreger bei Rindern im Khentii Aimag, Mongolei

Ticks and tick-borne pathogens of cattle in Khentii District, Mongolia Ticks and tick-borne diseases affect the livestock industry worldwide. Recently, several studies were published which described the molecular detection of the tick-borne pathogens Babesia bovis, Babesia bigemina, Anaplasma marginale and Theileria orientalis in bovine blood samples collected from the provines Khentii, Uvs and Uvurkhangai in Mongolia (AbouLaila et al. 2010; Altangerel et al. 2011; Sivakumar et al. 2012; Ybanez et al. 2013). Theileria orientalis was also found in Dermacentor nuttalli ticks collected from the same regions. These findings were unexpected, as the known tick vectors (mainly Rhipicephalus spp.) are not known to exist in Mongolia. The aim of this study was therefore to screen Mongolian ticks and cattle for tickborne pathogens to investigate if known tick vectors now occur in Mongolia, or if local tick species may act as vectors for these pathogenes. An epidemiological study was conducted in the six Somons of Tsenkhermandal, Dschargaltchaan, Delgerchaan, Binder, Dadal und Bajan-Adarga in the Khentii district of Mongolia during May to July 2013. The selection of these Somons was based on previous publications which reported the causal agents of bovine babesiosis, theileriosis and anaplasmosis to occur in these regions. Ticks and blood samples were collected from 481 heads of cattle. Ticks were also collected from the vegetation and trapped rodents. All blood samples and ticks collected from the vegetation and rodents were screened by PCR followed by a Reverse Line Blot Hybridization Assay (RLB) for the presence of DNA from tick-borne pathogens. The results of selected RLB-positive samples were confirmed by sequencing. In total 2,318 ticks (778 males/1,540 females) were collected from cattle, 310 adult ticks (169 males/141 females) from the vegetation and 249 tick larvae were collected from 23 rodents. All ticks were identified as Dermacentor nuttalli. Known tick vectors of A. marginale, B. bovis and B. bigemina were not found in the study region. DNA from a previously uncharacterized Anaplasma sp (26/310; 8,4 %), Theileria orientalis (1/310; 0,3 %), Theileria equi (16/310; 5,2 %), Babesia caballi (5/310; 1,6 %), Rickettsia raoultii (252/310; 81,3 %), Borrelia afzelii (1/310; 0,3 %) Midichloria sp. (18/310; 5,8 %) and Neoerhlichia mikurensis (1/310; 0,3 %) was detected by RLB in adult ticks collected from the vegetation. Tick larvae were divided over 28 pools, in which DNA of Rickettsia raoultii (27/28; 96,4 %) and Midichloria (2/28; 7,1 %) was detected. The uncharacterized Anaplasma sp. was also detected in 153 (31,8 %) of 481 collected bovine blood samples by RLB. A phylogenetical analysis of this Anaplasma sp. showed a close relationship to Anaplasma ovis. Babesia bovis, Babesia bigemina and Anaplasma marginale could not be detected in the blood samples of cattle or ticks from Khentii district by RLB. None of the farmers reported the occurrence of diseases with clinical signs of bovine babesiosis, theileriosis or anaplasmosis. The variety of the found microorganisms and the results of recently published studies concerning tick-borne diseases in Mongolia emphasize the need for further monitoring of the Mongolian livestock and tick population for tick-borne pathogens to identify emerging diseases that may threaten the health of Mongolian livestock.