[Investigation on infection sources of schistosomiasis in mountainous regions, Nanjian County, Yunnan Province].
OBJECTIVE
To understand the types of schisotsome infection sources and their roles in schistosomiasis transmission in mountainous endemic regions in Yunnan Province, so as to provide the evidence for implementing the comprehensive control measures based on infection source control.


METHODS
Two villages of typical mountainous regions in Nanjian County were chosen for field investigation. The Oncomelania hupensis snail status was surveyed by the methods of systematic and environmental sampling. The infections of schistosomiasis were surveyed in residents with the indirect haemagglutination and the hatching method, in livestock with the hatching method and in wild animals with the anatomical method and the hatching method. The distribution and pollution status of wild faeces were investigated in the snail environments nearby villages or with livestock frequent activities. The positives of schistosomiasis in wild faeces were tested with the hatching method. The pollution index of wild feces was calculated.


RESULTS
A total of 533.56 hm2 were investigated in two villages, and the area with snails was 16.52 hm2. The rate of frame with snails was 1.03%, the average density of snails was 0.07 snails/0.1 m2, and no positive snails were found. The positive rate of blood examinations of population was 1.61%, but no persons were positive with the hatching method. The infection rates were 0.90%, and 0.62% in cattle and equus, respectively, and there were no positives in other livestock. Totally 472 piles of wild feces of 6 species (human, cattle, equus, goat, pig and dog) distributed in the investigation areas, and among them, the densities of wild feces of cattle, equus, and dog were 7.2, 4.3 piles/hm2, and 2.1 piles/hm2 respectively, being relatively higher than others. The hatching positive rates of wild faeces of cattle, equus, and dog were 2.27% (3/132), 2.63% (2/76), and 3.70% (1/27), respectively. The relative pollution indexes of wild faeces of cattle, equus, and dog were 80.68%, 15.89%, and 3.43%, respectively.


CONCLUSIONS
After schistosomiasis transmission is controlled, the potential epidemic factors still remain in the mountainous endemic regions of schistosomiasis in Yunnan Province. The cattle are still the most infection source of schistosomiasis, but equus and dog as infection sources should be not neglected. We should extend the investigation and monitor scope of the infection sources, and carry out scientific and feasible control technique and management measures.
Yunnan Institute of Endemic Diseases Control and Prevention, Yunnan Province, Dali 671000, China.
Zong-Ti
ZT
Shao
Yunnan Institute of Endemic Diseases Control and Prevention, Yunnan Province, Dali 671000, China.
Xi-Guang
XG
Feng
Yunnan Institute of Endemic Diseases Control and Prevention, Yunnan Province, Dali 671000, China.
Meng-Tao
MT
Xiong
Yunnan Institute of Endemic Diseases Control and Prevention, Yunnan Province, Dali 671000, China.
Ming-Shou
MS
Wu
Yunnan Institute of Endemic Diseases Control and Prevention, Yunnan Province, Dali 671000, China.
Yun
Y
Zhang
Nanjian Prevention Station of Schistosomiasis, China.
Meng-Xian
MX
Yang
Nanjian Prevention Station of Schistosomiasis, China.
Ji-Mao
JM
Zuo
Yunnan Institute of Endemic Diseases Control and Prevention, Yunnan Province, Dali 671000, China.
Mei-Fen
MF
Shen
Yunnan Institute of Endemic Diseases Control and Prevention, Yunnan Province, Dali 671000, China.
Jia-Yu
JY
Sun
Nanjian Prevention Station of Schistosomiasis, China.
Zhi-Ying
ZY
Zhao
Nanjian Center for Animal Disease Prevention and Control, China.
Chun-Yuan
CY
Yi
Yunnan Institute of Endemic Diseases Control and Prevention, Yunnan Province, Dali 671000, China.
Xing-Qi
XQ
Dong
D000818:Animals; D002417:Cattle / Q000469:parasitology; D002681:China / Q000453:epidemiology; D004197:Disease Reservoirs / Q000469:parasitology*; D004285:Dogs / Q000469:parasitology; D005243:Feces / Q000469:parasitology; D006801:Humans; D012552:Schistosomiasis / Q000453:epidemiology* / Q000517:prevention & control; D012908:Snails / Q000469:parasitology