[Surveillance and risk assessment system of schistosomiasis in Jiangsu Province. I. Distribution of surveillance site and effectiveness of the system].

OBJECTIVE: To establish the surveillance and risk assessment system of schistosomiasis in Jiangsu Province, so as to provide technical support for timely understanding of the risk of schistosomiasis transmission and implementation of targeted control measures. METHODS: The surveillance sites of schistosomiasis were assigned according to the epidemic status and endemic type of schistosomiasis as well as the characteristics of the water system, and the prevalence of Schistosoma japonicum in humans and domestic animals, and snail status were investigated. In addition, the quality control of serum detection of S. japonicum infections was performed. The prevalence of human and animal S. japonicum infections, snail status and missing diagnosis of serum detection were analyzed and compared among regions. RESULTS: A total of 27 surveillance sites of schistosomiasis were set up in 26 counties of 10 cities, Jiangsu Province, including 14 sites in transmission-interrupted villages and 13 sites in transmission-controlled villages, and 15 sites in marshland and lake regions, 9 sites in plain regions with water network and 3 sites in mountainous region. In the 27 surveillance sites, a total of 16 617 residents were screened for S. japonicum infection by using dipstick dye immunoassay (DDIA), and 326 were sero-positive, with a sero-prevalence of 1.96% (2.17% for men and 1.8% for women). Of the 326 individuals undergoing parasitological examination, 2 positive cases were detected in the marshland and lake region, with a S. japonicum human prevalence of 0.01%. Of the 762 floating population detected, 10 were positive for blood test, with a sero-prevalence of 1.31%, and no egg-positive individuals were detected. No infection was found in the 476 domestic animals. Of the 746 settings surveyed, a total of 240.7 hm2 snail area was detected, with a mean snail density of 0.06 snails/0.1 m2, and no infected snails were found. There were 780 quality-control sera detected in 26 surveillance sites of schistosomiasis, and the gross coincidence rate was 95.13%, with misdiagnosis rate of 1.28% and missing diagnosis rate of 19.23%. CONCLUSION: The surveillance sites of schistosomiasis show reasonable distribution in Jiangsu Province, and the endemic situation of schistosomiasis appears a low level in the whole province.

[Establishment and application of quality control system for detection of schistosomiasis in Jiangsu Province I ability of serological detection among county-level personnel].

OBJECTIVE: To evaluate the ability for serological screening of schistosomiasis among county-level personnel, so as to provide the evidence for establishing the quality control system of field detection of schistosomiasis. METHODS: The standard serum panel was prepared for the quality assessment of schistosomiasis diagnostic capability, and detected by county-level personnel in the endemic field simultaneously using single-blind method. The rates of coincidence, misdiagnosis and missed diagnosis were calculated compared with the standard results. RESULTS: Totally 780 samples of standard serum were detected in 26 counties, and showed 134 positive and 646 negative samples. The rates of coincidence, misdiagnosis and missed diagnosis were 95.13%, 1.28% and 19.23%, respectively, and there was a significant difference between the detection results and the standard results (chi2 = 11.6053, P = 0.0007). Among the 26 counties investigated, the misdiagnosis occurred in 5 counties (19.23%) and missed diagnosis occurred in 21 counties (80.77%). The misdiagnosis rate and missed diagnosis rate of serological screening of schistosomiasis were 0-2.08% and 16.67%-33.33% in beach, hilly, water net and marshland endemic areas, respectively, and no significant differences were found in the misdiagnosis rate and the missed diagnosis rate among various types of endemic areas (chi2 = 1.590 and 1.757, P = 0.6671 and 0.6244). The rates of misdiagnosis and the missed diagnosis were 1.14% and 1.39%, and 18.18% and 20.00% in the schistosomiasis transmission-controlled and the schistosomiasis transmission-interrupted areas, respectively, and no significant differences were found in the misdiagnosis rate and missed diagnosis rate between the schistosomiasis transmission-controlled and transmission-interrupted areas (chi2 = 0.008 and 0.001, P = 0.931 and 0.974). CONCLUSIONS: The missed diagnosis is a major cause for the reduction of quality of schistosomiasis detection at the county level in Jiangsu Province, and the coincidental detection of schistosomiasis with standard serum in the field is one of effective approaches for the control of the quality of schistosomiasis detection.

[Optimization of time of artificial population schistosome infected Oncomelania hupensis snails].

OBJECTIVE: To explore the optimizational time of artificial population schistosome infected Oncomelania hupensis snails. METHODS: Under laboratory conditions, the snails were infected with the miracidia of Schistosoma japonicum for 2 h, 3 h and 4 h respectively, and the death rates and the infection rates of the snails, and the quantities of cercariae of each group were observed 60-120 d after the infection, and all the data observed were analyzed to get the optimizational time of artificial population schistosome infected snails. RESULTS: Of the 3 h group, the snail infection rate was the highest and the mortality was the lowest among the 3 groups (P<0.05). The average number of cercariae of the 3 h group was higher than that of the 2 h group (P<0.05), while there was no statistical difference between the 3 h group and the 4h group (P>0.05). CONCLUSION: Under laboratory conditions, the optimizational time is 3 h in artificial population schistosome infected O. hupensis snails.