[Retrospective investigation on changes of endemic situation before and after reaching criteria of schistosomiasis transmission controlled or interrupted in hilly endemic areas of Jiangxi Province].
OBJECTIVE
To investigate the changing rules of schistosomiasis endemic situation before and after reaching the criteria of schistosomiasis transmission controlled or interrupted in hilly endemic areas of Jiangxi Province, so as to provide the evidence for reformulating the criteria of schistosomiasis control and eradication in the future.


METHODS
In the hilly areas of schistosomiasis endemic in Jiangxi Province, 2 counties where the transmission has been interrupted and 1 county where the transmission has been controlled were selected and investigated with the retrospective research method. The endemic detailed data were collected and recorded 10 years before reaching the criteria of transmission interrupted/controlled, and several years after reaching the criteria (ending in 2008), and then a database was established. The changing rules of endemic situation before and after reaching the criteria of transmission interrupted/controlled were analyzed and compared.


RESULTS
After reaching the criteria of transmission controlled, in the 3 counties, Guangfen, Shangrao and Dean, the declined rates of areas with Oncomelania hupensis snails were 96.79%, 98.99%, and 99.77% respectively. The snail density maintained a lower level, and 95% of infected persons and cattle were cured. The average time from transmission controlled to the transmission interrupted was 17 years in Guangfen County and 26 years in Dean County. However, in Shangrao County, the snail situation rebounded due to the snail re-found and spread although the schistosomiasis morbidity of population/animals maintained stably.


CONCLUSIONS
After reaching the criteria of transmission interrupted/controlled, the remained snails were easy to re-find and spread under some certain condition, which is one of main obstacles for reaching the criteria of transmission interrupted. In an isolated snail unit, if the snail area and snail density are controlled in a very low level, it is still difficult to transmit and spread schistosomiasis even if there exist infectious sources.
Jiangxi Provincial Institute of Parasitic Diseases, Nanchang 330046, China.
Dan-dan
DD
Lin
Jiangxi Provincial Institute of Parasitic Diseases, Nanchang 330046, China.
Shang-biao
SB
Lv
Jiangxi Provincial Institute of Parasitic Diseases, Nanchang 330046, China.
Xiao-nan
XN
Gu
Dean Station of Schistosomiasis Control, Jiangxi Province, China.
Hu
H
Ying
Shangrao Station of Schistosomiasis Control, Jiangxi Province, China.
Jian-fang
JF
Zeng
Guangfen Station of Schistosomiasis Control, Jiangxi Province, China.
Zao-fen
ZF
Zu
Jiangxi Provincial Institute of Parasitic Diseases, Nanchang 330046, China.
Hong-gen
HG
Chen
D000818:Animals; D002417:Cattle; D002681:China / Q000453:epidemiology; D019353:Endemic Diseases / Q000517:prevention & control*; D006801:Humans; D012189:Retrospective Studies; D012552:Schistosomiasis / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission