Discovery and vertical transmission analysis of Dabieshan Tick Virus in Haemaphysalis longicornis ticks from Chengde, China.

Introduction: Ticks are important blood-sucking ectoparasites that can transmit various pathogens, posing significant threats to the wellbeing of humans and livestock. Dabieshan tick virus (DBTV) was initially discovered in 2015 in Haemaphysalis longicornis ticks from the Dabieshan mountain region in Hubei Province, China. In recent years, DBTV has been discovered in various regions of China, including Shandong, Zhejiang, Liaoning, Hubei, Yunnan, and Guizhou Provinces. However, the researches on tick-borne transmission of DBTV are scarce. Methods: This study utilized the small RNA sequencing (sRNA-seq) method to identify tick-associated viruses in ticks collected from Chengde in Hebei Province and Yongcheng in Henan Province, leading to the discovery of a new DBTV strain in Hebei. The complete coding genome of DBTV Hebei strain was obtained through RNA-seq and Sanger sequencing. Furthermore, the transmission experiment of DBTV in H. longicornis was examined in laboratory for the first time. Results: DBTV was detected in newly molted adult H. longicornis ticks collected in Chengde, Hebei Province. Additionally, DBTV was also detected in both unfed nymphs and engorged females of H. longicornis collected from Chengde, with a positive rate of 20% and 56.25%, respectively. The complete coding genome of DBTV (OP682840 and OP716696) were obtained, and phylogenetic analysis revealed that the DBTV Hebei strain clustered with previously reported DBTV strains. Furthermore, this virus was observed in engorged females, eggs, and larvae of the subsequent generation. Discussion: It is necessary to expand the scope of DBTV investigation, particularly in northern China. This study demonstrated that DBTV can be transmitted from engorged females to larvae of the next generation. Moreover, the detection of DBTV in unfed nymphs and adults (which moulted from engorged nymphs) collected from the filed of Chengde suggests that H. longicornis serves as a potential transmission host and reservoir for DBTV through transstadial and transovarial transmission. However, there remains a lack of research on the isolation and pathogenicity of DBTV, highlighting the need for further studies to mitigate potential harm to the health of animals and humans.

Identification and a full genome analysis of novel camel hepatitis E virus strains obtained from Bactrian camels in Mongolia.

Hepatitis E virus (HEV) infects humans and a wide variety of other mammalian hosts. Recently, HEV strains belonging to genotype 8 (G8) within the Orthohepevirus A species of the Hepeviridae family, were identified in Bactrian camels (Camelus bactrianus) in China. The Bactrian camel (also known as the Mongolian camel) is native to the steppes of Central Asia. However, the HEV strains of Mongolian camels have not been examined. Among 200 serum samples from domestic Bactrian camels raised on 6 farms, in 6 soums in 3 provinces; 71 (35.5 %) were positive for anti-HEV IgG, with prevalence differing by farm (soum) (4.2-75.0 %); and 2 camels (1.0 %) that had been raised in Bogd, Bayankhongor Province, which had the highest seroprevalence among the six studied areas, were positive for HEV RNA. The two HEV strains (BcHEV-MNG140 and BcHEV-MNG146) obtained from the viremic camels in the present study shared 97.7 % nucleotide identity. They were closest to the reported G8 Chinese camel HEV strains but differed from them by 13.9-14.3 % over the entire genome, with a nucleotide difference of 24.0-26.5 % from the reported G1-G7 HEV strains. A phylogenetic tree indicated that the BcHEV-MNG140 and BcHEV-MNG146 strains were located upstream of a clade consisting of the Chinese camel HEV strains and formed a cluster with them, with a bootstrap value of 100 %, suggesting that they may represent a novel subtype within G8. These results indicate a high prevalence of HEV infection in Mongolian camels and suggest that the variability of camel HEV genomes is markedly high.

Evidence for camels (Camelus bactrianus) as the main intermediate host of Echinococcus granulosus sensu lato G6/G7 in Mongolia.

Cystic echinococcosis (CE), the parasitic disease caused by the larval stage of Echinococcus granulosus sensu lato (s.l.), is a global public health problem. In Mongolia, despite wide distribution of human CE, not enough information is available on the prevalence and molecular characterization of CE in livestock and its zoonotic linkage with human cases. We investigated the distribution of human CE cases and livestock population using statistical models to get insight into the zoonotic linkage. The incidence of human CE cases increased by a factor of 1.71 for one interquartile range increment in the density of the camel population. No significant association was observed with other livestock species. The samples collected from 96 camels and 15 goats in an endemic region showed a CE prevalence of 19.7% and 6.7%, respectively. All livestock CE were E. granulosus s.l. G6/G7 species of the E. granulosus s.l. complex. The genetic diversity was investigated using the haplotype network based on full cox1 gene analysis of the samples collected from livestock CE and nucleotide sequences previously reported from human CE and wild canids infection in Mongolia. Four haplotypes were identified within the livestock samples, two of which had not been previously reported. A common haplotype was identified among humans, camels, goats, and a wolf, all of which were within the same geographical area. A mixed infection of E. granulosus s.l. G6/G7 with different haplotypes in the intermediate host was identified. To the best of our knowledge, this is the most comprehensive description of the current epidemiological situation of CE in Mongolia with substantial evidence that camels might be the main intermediate host of E. granulosus s.l. G6/G7 in Mongolia. Moreover, our result presents the first report in the country to provide insight into the prevalence of E. granulosus s.l. G6/G7 in livestock.

Risk factors of brucellosis seropositivity in Bactrian camels of Mongolia.

BACKGROUND: More information on brucellosis epidemiology in Bactrian camels is needed due to their growing economic and livelihood importance for herders and renewed efforts in Mongolia to eliminate brucellosis through mass vaccination of ruminants excluding camels. Brucellosis prevalence in camels increased over the past two decades. Random multi-stage cluster surveys were done in the Eastern provinces of Dornod and Sukhbaatar in 2013 and 2014 and in the Southern & Western provinces of Dornogobi, Umnogobi and Khovd in 2014 and 2015. A total of 1822 camels, 1155 cattle, and 3023 small ruminant sera were collected and tested with the Rose Bengal Test. In addition, 195 vaginal swabs and 250 milk samples for bacteriological culture were taken from livestock with history of abortion. RESULTS: The overall apparent seroprevalence in camels was 2.3% (95% confidence interval 1.6-3.3). The main risk factor for camel seropositivity was being in an Eastern province when compared to Southern & Western provinces (odds ratio 13.2, 95% CI 5.3-32.4). Camel seroprevalences were stable over the two consecutive survey years, despite introduction of ruminant vaccination: 5.7% (95% CI 3.1-10.2%) and 5.8% (3.3-10.1%) in Eastern provinces and 0.4% (0.2-1.2%) and 0.5% (0.1-2.0%) in Southern & Western provinces. We isolated Brucella abortus from camels and cattle. Camel seropositivity was associated to keeping cattle together with camels. Monitoring of vaccination campaigns showed that coverage in cattle was insufficient because animals could not be adequately restrained. CONCLUSIONS: The present study reveals that brucellosis is present with important seroprevalence in Mongolian camels and was endemic in Eastern provinces. Camel herd seropositivity was most closely associated to infection in cattle. Longer term monitoring is needed to assess whether camel seroprevalance decreases with ongoing vaccination in Mongolia. This should be coupled with further confirmation on Brucella spp. isolates. To date, only Brucella abortus was isolated, but camels are also susceptible to Brucella melitensis. Clear verbal and written information on disease prevention in livestock and household members is important, particularly for remote camel herders who had only moderate knowledge on brucellosis epidemiology and preventive measures.