Investigations On Novel Anaplasma Infections In Livestock And Ticks From Northern China

BackgroundAnaplasma is a kind of tick-borne agent which could infect both livestock and human. Ticks act as reservoir and vector of the bacteria. The disease caused by Anaplasmataceae are named as “Anaplasmosis”. The infections of domestic animals caused by Anaplasma and Ehrlichia are known at the 20 th century. The case of human infection of Anaplasma phagocytophilum which could cause human granulocytic anaplasmosis(HGA) was first reported in the USA in 1994. Since then, the prevalence of HGA greatly increased in America. Sporadic cases have also been reported in Europe and China. Another human anaplasmosis case is caused by Anaplasma ovis variant which is identified in a Cypriot patient in 2007.Since the beginning of the 1980 s, more than 30 emerging tick-borne agents have been identified in mainland China, including a several of species in the family Anaplasmataceae, which are E.chaffeensis, Ehrlichia sp. Tibet, E.canis, A.phagocytophilum, A.platys and Candidatus Neoehrlichia mikurensis. These emerging agents are known to be associated with 17 tick species. Their host reservoirs include sheep, goats, cattle, dogs, horses, hare, yaks, and rodents.The city of Beijing and Heilongjiang province are important natural foci of tick-borne agents in China. It had been reported for many times that livestock and ticks could infect with lots of agents in these areas. Moreover, cases of human infection of emerging tick-borne agents hand been reported for several times in above-mentioned regions.In recent years, a several of novel Anaplasma species had been discovered, but only one or two gene sequences were identified by using molecular biology methods among these Anaplasma species. Host, vector and human susceptibility, which is known as the three important factors of zoonotic agent, were also rarely mentioned in previous study. So it is also necessary to make further investigation and research on it. ObjectiveThe study was conducted to investigate the epidemic status of Anaplasma in vectors and host reservoirs in northern China and attempt to identify novel Anaplasma species. Vectors and host reservoirs of the novel Anaplasma species need to be cleared in order to discover potential natural foci. MethodFangshan district and Mudanjiang area were selected as the survey points to perform our investigations. We collected ticks and livestock whole blood samples from 2012 to 2015. The samples were extracted DNA templates and detected by using polymerase chain reaction(PCR) targeting Anaplasma specific genes. We used BLAST and Mega 5.0 to make sequence and phylogenetic analysis. ResultsCollection of ticks: Total of 311 Haemaphysalis longicornis(95 aduts, 156 nymphs, 60 larvae) were collected in Beijing Fangshan district during May 2012 to Septemer 2015. 628 ticks including 447 Ixodes persulcatus and 181 Haemaphysalis concinna were collected in Mudanjiang area in June 2014.Collection of livestock’s whole blood : Total of 153 goats’ whole blood samples were collected in Beijing Fangshan district and 550 domestic animals’ whole blood samples( 137 goats, 208 sheeps, 205 cattles) were collected in Mudanjiang area from 2012 to 2015.Investigation on Anaplasma capra in livestock: A novel Anaplasma species “Anaplasma capra” was identified in goats by amplifying Anaplasma 16 S r RNA and glt A gene. A.capra was identified in 67 goats(43.8%) at Beijing area. Another genotype of A.capra was identified in a cattle at Mudanjiang area. No infection was tested in goats and sheep at Mudanjiang area.Investigation on Anaplasma capra in ticks: A.capra was identified in 3 adults Haemaphysalis longicornis(3.2%) when amplified by PCR targeting glt A and rrs(16S r RNA) gene at Beijing area. No infection was tested in nymphs and larvae. The positive rate of adults is higher than nymphs and larvae. The difference of positive rate was statistically significant(P=0.035). 13 adults Ixodes persulcatus(2.9%) were tested as postive at Mudanjiang area. No infection was tested in the Haemaphysalis concinna.Investigation on “Anaplasma sp. Beijing” in livestock: A novel Anaplasma species was identified by using PCR to amplify rrs(16S r RNA), glt A and gro EL gene in goats at Beijing area. This novel Anaplasma species are temporally named as “Anaplasma sp. Beijing” in this study. “Anaplasma sp. Beijing” was identified in 3 goats(2.0%) at Beijing area and 1 sheep(0.5%) at Mudanjiang area. No infection was tested in cattle or goats at Mudanjiang area.Investigation on “Anaplasma sp. Beijing” in ticks: No infection was tested in Haemaphysalis longicornis at Beijing area. ConclusionBy the survey of Anaplasma in Beijing and Mudanjiang area, we identify a novel Anaplasma species ”A.capra” and find that goat and cattle are host reservoirs of A.capra. We confirm that Ixodes persulcatus as a vector could infect with A.capra in Northeast China and Haemaphysalis longicornis as a vector could infect with A.capra in North China.Molecular biology identification of “Anaplasma sp. Beijing” was performed by amplification and analyses of rrs(16S r RNA), glt A and gro EL gene sequences of this Anaplasma species. Goat and sheep were confirmed as host reservoir of “Anaplasma sp. Beijing”. This research is also helpful in finding potencial natural foci of this novel Anaplasma species.