Abstract
Spotted fever group (SFG) rickettsiae cause infection in humans, domestic animals and wildlife. To date, no rickettsial agents have been reported in hard ticks from the long-tailed ground squirrel (Spermophilus undulatus). A total of 50 adult ticks and 48 nymphs were collected from S. undulatus in the border region of northwestern China. Tick species (identified according to morphological and molecular characteristics) included Dermacentor nuttalli, Dermacentor silvarum and Ixodes kaiseri. Based on the cytochrome c oxidase subunit I (COI) haplotype analysis, I. kaiseri from S. undulatus belongs to an ancestral. In addition, all tick samples were analyzed for the presence of rickettsiae by PCR amplification and sequencing of six genetic markers. Rickettsia raoultii and Rickettsia sibirica subsp. sibirica were shown to occur in adults and nymphs of D. nuttalli and D. silvarum. Rickettsia sibirica subsp. sibirica was also detected in an I. kaiseri adult. Dermacentor silvarum and I. kaiseri were found for the first time on S. undulatus. Rickettsia raoultii and R. sibirica subsp. sibirica were detected in two Dermacentor and one Ixodes species, respectively, suggesting that these rickettsiae circulate in the region of the China-Kazakhstan border by hard ticks infesting S. undulatus.
Highlights
The long-tailed ground squirrel (Spermophilus undulatus) has been listed as globally vulnerable by the International Union for Conservation of Nature (IUCN) since 2008 (Ramoslara et al 2014)
R. sibirica subsp. sibirica was found in nineteen D. nuttalli (8 nymphs and 11 adult ticks), 13 D. silvarum (6 nymphs and 7 adult ticks) and an adult I. kaiseri
R. raoultii was detected in D. nuttalli and D. silvarum from S. undulatus. These findings suggest that D. nuttalli, D. silvarum and I. kaiseri parasitizing S. undulatus may serve as reservoirs and carriers for R. raoultii and R. sibirica
Summary
The long-tailed ground squirrel (Spermophilus undulatus) has been listed as globally vulnerable by the International Union for Conservation of Nature (IUCN) since 2008 (Ramoslara et al 2014). This species is mainly distributed in Kazakhstan, Mongolia, Russia and northern China including Heilongjiang, Inner Mongolia and Xinjiang Uygur Autonomous Region (XUAR) (ZipcodeDev Team 2018). S. undulatus and its ectoparasites are reservoirs of Yersinia pestis, Francisella tularensis and tick-borne encephalitis virus (Zhao et al 2017; Wang and Yang 1983; Demina et al 2017). At that time no specimens of I. kaiseri were available from Asia for comparison
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