[Study on the epidemiological significance related to community-structural difference of the rat plague host and vectors in Western Yunnan, China].
OBJECTIVE
To study the epidemiological significance of community-structural difference regarding both small mammal and flea communities on Rattus flavipectus in Dehong and Baoshan areas, Yunnan province, during 1982 to 1996.


METHODS
Methodologies as cluster analysis, communities dominated constitution and species diversity were used for data analysis.


RESULTS
75 490 small mammals of 27 species could be divided into three types: I. Ruili habitat-communities dominated by R. flavipectus (54.41%) and Suncus murinus (33.37%); II. Longchuan and Yingjiang habitat-communities dominated by R. flavipectus (62.99%), S. murinus (23.25%) and Mus musculus (10.06%); III. Baoshan habitat-community dominated by R. flavipectus (48.07%), S. murinus (19.56%) and Crocidura attenuats (14.37%). The captured 61 122 fleas of 11 species on R. flavipectus could be divided into three types: i. Ruili habitat-communities dominated by Xenopsylla cheopis (83.51%) and Lentistivslius ferinus (13.86%); ii. Longchuan and Yingjiang habitats X. cheopis (74.42%) and L. segnis (22.94%); iii. Baoshan habitat-communities dominated by L. segnis (70.62%) and X. cheopis (22.70%). There had been 1471 strains of Y. pestis isolated from the hosts of 7 species and vectors of 5 species in Dehong areas for the ten year period. 36 strains of Y. pestis were isolated from host of one species and vectors of 2 species in Baoshan area for ten years. The constitution ratio of R. flavipectus and X. cheopis was higher in Dehong area with average as 58.70% and 78.97% respectively. However, the diversities of species among host and vector communities were low, with average as 1.010 and 0.625. On the contrary, the constitution ratios of R. flavipectus and X. cheopis were lower in Baoshan area, with an average as 48.07% and 22.70% respectively but the diversities of species among host and vector community were higher with the averages as 1.471 and 0.829 respectively. The main dominative flea species from 'group ii' to 'group iii' in the flea community had changed from X. cheopis to L. segnis.


CONCLUSIONS
The species diversity index of host and vector community was higher in Baoshan area, while the constitution ratio of main host and vector community was lower. This findings seemed to be the important factor of the decrease of plague prevalence in Baoshan area.
Yunnan Institute for Endemic Disease Control and Prevention, Dali 671000, China.
Ai-Guo
AG
Wu
Tian-Yuan
TY
Li
Jian-Meng
JM
Feng
Xing-Qi
XQ
Dong
D000818:Animals; D002681:China / Q000453:epidemiology; D007303:Insect Vectors / Q000145:classification / Q000235:genetics / Q000382:microbiology; D010802:Phylogeny; D010930:Plague / Q000453:epidemiology* / Q000382:microbiology; D051381:Rats; D005423:Siphonaptera / Q000145:classification / Q000235:genetics / Q000382:microbiology; D015010:Yersinia pestis / Q000472:pathogenicity