Abstract
BackgroundThe oriental rat flea (Xenopsylla cheopis), which infests several mammals, primarily rats (Rattus spp.), is the most notorious vector of human plague. In this study, we measured the genetic differentiation among populations of fleas from the Asian house rat (Rattus tanezumi) and the brown rat (R. norvegicus) using microsatellite markers in order to investigate the extent of host-switching in this parasite.ResultsWe developed 11 polymorphic microsatellite loci for our study, nine of which showed high potential for inbreeding. AMOVA showed that the majority (84.07%, P < 0.001) of the variation was derived from within populations, followed by variation among groups (14.96%, P < 0.001); in contrast, variation within groups of populations was nearly absent (0.97%, P > 0.05). Analyses of the pairwise fixation index revealed that most of the ten allopatric population pairs but none of the five sympatric population pairs were significantly differentiated. Moreover, based on genetic structure clustering analysis, there was obvious differentiation between allopatric populations but not between sympatric population pairs.ConclusionsThese results indicate the presence of frequent migrations of the oriental rat flea between the sympatric Asian house rat and brown rat, causing a high rate of gene flow and limited genetic differentiation. We suggest that there is no clear boundary limiting the migration of oriental rat fleas between the two hosts, and thus both rat species should be monitored equally for the purposes of plague prevention and control.
Highlights
The oriental rat flea (Xenopsylla cheopis), which infests several mammals, primarily rats (Rattus spp.), is the most notorious vector of human plague
There have been three major historical plague pandemics that caused a total of 200 million deaths: the first occurred in the area around the Mediterranean Sea in the 6th century, the second occurred in Europe in the 14th century, and the third started in China during the middle of the 19th century and from there spread worldwide [1]
While it is widely accepted that flea switching among different sympatric hosts increases plague prevalence, little is known about the extent of switching among hosts
Summary
The oriental rat flea (Xenopsylla cheopis), which infests several mammals, primarily rats (Rattus spp.), is the most notorious vector of human plague. We measured the genetic differentiation among populations of fleas from the Asian house rat (Rattus tanezumi) and the brown rat (R. norvegicus) using microsatellite markers in order to investigate the extent of host-switching in this parasite. Yunnan accounted for approximately 60% of the total human-related plague cases in China from 1986 to 2005 [6]. The main hosts of oriental rat fleas in the province were Asian house rat (Rattus tanezumi) and brown rat (R. norvegicus) [8] and the fleas as well as plague were distributed almost all over the province [5].
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