Transmission efficiency of the plague pathogen (Y. pestis) by the flea, Xenopsylla skrjabini, to mice and great gerbils.
BACKGROUND
Plague, a zoonotic disease caused by Yersinia pestis, is characterized by its ability to persist in the plague natural foci. Junggar Basin plague focus was recently identified in China, with Rhombomys opimus (great gerbils) and Xenopsylla skrjabini as the main reservoir and vector for plague. No transmission efficiency data of X. skrjabini for Y. pestis is available till now.


METHODS
In this study, we estimated the median infectious dose (ID50) and the blockage rates of X. skrjabini with Y. pestis, by using artificial feeders. We then evaluated the flea transmission ability of Y. pestis to the mice and great gerbils via artificial bloodmeal feeding. Finally, we investigated the transmission of Y. pestis to mice with fleas fed by infected great gerbils.


RESULTS
ID50 of Y. pestis to X. skrjabini was estimated as 2.04 × 10(5) CFU (95% CI, 1.45 × 10(5) - 3.18 × 10(5) CFU), around 40 times higher than that of X. cheopis. Although fleas fed by higher bacteremia bloodmeal had higher infection rates for Y. pestis, they lived significantly shorter than their counterparts. X. skrjabini could get fully blocked as early as day 3 post of infection (7.1%, 3/42 fleas), and the overall blockage rate of X. cheopis was estimated as 14.9% (82/550 fleas) during the 14 days of investigation. For the fleas infected by artificial feeders, they seemed to transmit plague more efficiently to great gerbils than mice. Our single flea transmission experiments also revealed that, the transmission capacity of naturally infected fleas (fed by infected great gerbils) was significantly higher than that of artificially infected ones (fed by artificial feeders).


CONCLUSIONS
Our results indicated that ID50 of Y. pestis to X. skrjabini was higher than other fleas like X. cheopis, and its transmission efficiency to mice might be lower than other flea vectors in the artificial feeding modes. We also found different transmission potentials in the artificially infected fleas and the naturally infected ones. Further studies are needed to figure out the role of X. skrjabini in the plague epidemiological cycles in Junggar Basin plague focus.
The Center for Disease Control and Prevention of the Xinjiang Uygur Autonomous Region, Urumqi, 830002, China. xjsyzhang@163.com.
Yujiang
Y
Zhang
The Center for Disease Control and Prevention of the Xinjiang Uygur Autonomous Region, Urumqi, 830002, China. xjsydx@163.com.
Xiang
X
Dai
The Center for Disease Control and Prevention of the Xinjiang Uygur Autonomous Region, Urumqi, 830002, China. wqg801021@126.com.
Qiguo
Q
Wang
Qinghai Institute for Endemic Diseases Prevention and Control, Xining, 811602, China. mjy70315@163.com.
Hongjian
H
Chen
The Center for Disease Control and Prevention of the Xinjiang Uygur Autonomous Region, Urumqi, 830002, China. mww_1980@126.com.
Weiwei
W
Meng
Qinghai Institute for Endemic Diseases Prevention and Control, Xining, 811602, China. qhxnwkm@sina.com.
Kemei
K
Wu
The Center for Disease Control and Prevention of the Xinjiang Uygur Autonomous Region, Urumqi, 830002, China. lt7912@126.com.
Tao
T
Luo
The Center for Disease Control and Prevention of the Xinjiang Uygur Autonomous Region, Urumqi, 830002, China. wangxh6502@163.com.
Xinhui
X
Wang
The Center for Disease Control and Prevention of the Xinjiang Uygur Autonomous Region, Urumqi, 830002, China. azt6710@163.com.
Azhati
A
Rehemu
The Center for Disease Control and Prevention of the Xinjiang Uygur Autonomous Region, Urumqi, 830002, China. feizaopaogr@sina.com.
Rong
R
Guo
Qinghai Institute for Endemic Diseases Prevention and Control, Xining, 811602, China. yxt@qq.com.
Xiaotao
X
Yu
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China. ruifuyang@gamil.com.
Ruifu
R
Yang
The Center for Disease Control and Prevention of the Xinjiang Uygur Autonomous Region, Urumqi, 830002, China. chl2621215@126.com.
Hanli
H
Cao
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China. songyajun88@gmail.com.
Yajun
Y
Song
D000818:Animals; D002681:China; D004195:Disease Models, Animal; D005260:Female; D005849:Gerbillinae; D006801:Humans; D007303:Insect Vectors / Q000382:microbiology* / Q000502:physiology; D051379:Mice; D010930:Plague / Q000382:microbiology / Q000635:transmission*; D058260:Xenopsylla / Q000382:microbiology* / Q000502:physiology; D015010:Yersinia pestis / Q000502:physiology*; D015047:Zoonoses / Q000382:microbiology / Q000635:transmission*