3.1 Surveillance results of schistosomiasis
3.1.1 Surveillance results on population
From 2005 to 2016, a total of 3 569 509 serological tests were conducted for schistosomiasis screening and 24 978 blood samples were determined as antibody positives in the five PLADs (Table 1). The annual positive rate of serological tests was 0.56–0.90%, with a slight fluctuation from 2005 to 2010, and a sustained downward trend from 2011.
Totally 45 997 stool examination were performed during the twelve years in five PLADs and 221 stool positives were detected (Table 1). Among the stool positives, Zhejiang, Shanghai and Fujian PLADs accounted for 87.33% (193/221), 11.31% (25/221) and 1.36% (3/221), respectively, while no stool positive cases were found in Guangdong or Guangxi PLADs. All stool positives were imported cases who got infection from other endemic areas.
Table 1. Surveillance results of schistosomiasis on human beings in five PLADs during 2005–2016
Year
|
Serological tests
|
|
Stool examination
|
No. serum samples examined
|
No. antibody positives
|
Positive rate
(%, 95% CI)
|
|
No. fecal examinations
|
No. stool positives
|
2005
|
428 800
|
3479
|
0.81 (0.78–0.84)
|
|
4565
|
44
|
2006
|
475 182
|
2681
|
0.56 (0.54–0.59)
|
|
4740
|
36
|
2007
|
476 201
|
3348
|
0.70 (0.68–0.73)
|
|
5876
|
27
|
2008
|
391 047
|
2647
|
0.68 (0.65–0.70)
|
|
3549
|
17
|
2009
|
339 583
|
3062
|
0.90 (0.87–0.93)
|
|
4145
|
21
|
2010
|
345 645
|
3057
|
0.88 (0.85–0.92)
|
|
3993
|
12
|
2011
|
240 121
|
1488
|
0.62 (0.59–0.65)
|
|
5167
|
12
|
2012
|
223 487
|
1332
|
0.60 (0.56–0.63)
|
|
3720
|
9
|
2013
|
221 765
|
1324
|
0.60 (0.57–0.63)
|
|
2570
|
14
|
2014
|
150 182
|
973
|
0.65 (0.61–0.69)
|
|
3520
|
10
|
2015
|
143 617
|
842
|
0.59 (0.55–0.63)
|
|
2563
|
8
|
2016
|
133 879
|
745
|
0.56 (0.52–0.60)
|
|
1589
|
11
|
Total
|
3 569 509
|
24 978
|
-
|
|
45 997
|
221
|
No.; Number of.
3.1.2 Surveillance results on cattle
From 2005 to 2016, a total of 82 858 serological tests were conducted for surveillance on cattle in the five PLADs and 19 serological positives were found in Zhejiang Province, with 11 and 8 positive in 2014 and 2015, respectively (Table 2). Meanwhile, a total of 42 645 stool examination were performed, and no infected cattle was detected.
Table 2. Surveillance data of cattle in the five PLADs from 2005 to 2016.
Year
|
No. serological
tests
|
No. positive serological tests
|
No. stool examinations
|
No. positive stool examinations
|
2005
|
12 869
|
0
|
4812
|
0
|
2006
|
8846
|
0
|
4231
|
0
|
2007
|
8827
|
0
|
4027
|
0
|
2008
|
7525
|
0
|
2700
|
0
|
2009
|
7601
|
0
|
2593
|
0
|
2010
|
5730
|
0
|
2362
|
0
|
2011
|
6706
|
0
|
3109
|
0
|
2012
|
6068
|
0
|
2882
|
0
|
2013
|
5917
|
0
|
3031
|
0
|
2014
|
4878
|
11
|
3299
|
0
|
2015
|
4859
|
8
|
4368
|
0
|
2016
|
3032
|
0
|
5231
|
0
|
Total
|
82 858
|
19
|
42 645
|
0
|
No.: Number of.
3.1.3 Data on snail survey
Snail surveys were conducted in 126 837.75 hm2 of areas from 2005 to 2016 in the five PLADs. The area infested with living Oncomelania hupensis presented a descending trend, decreased from 112.70 hm2 in 2005 to 52.81 hm2 in 2016 (Table 3). Among the five PLADs, Guangdong maintained the status without snails’ infestation since 1992. The area of snail habitats in Zhejiang Province always accounted for the largest percentage, but presented a decrease trend from 80.72 hm2 in 2005 to 44.41 hm2 in 2016. However, no infected snail was found through dissection method in the five PLADs.
During the twelve years, 11.98 hm2 of new snail habitats (environments with no snails initially) were found in Zhejiang (6.53 hm2), Shanghai (4.19 hm2) and Guangxi (1.26 hm2). In addition, snail infestation reoccurred in 247.55 hm2 of former snail habitats since 2011, mainly distributed in Zhejiang (224.62 hm2), Guangxi (11.48 hm2), Fujian (10.73 hm2) and Shanghai (0.72 hm2).
Mollusciciding and extended mollusciciding were implemented among areas with snails. During the 12 years, mollusciciding were done with the area of 2111.89 hm2 and environmental modifications were done among some appropriate environments with the area of 139.45 hm2.
Table 3. Results of snail survey in the five PLADs during 2005–2016
Year
|
Areas conducted snail survey (hm2)
|
Areas with living snails (hm2)
|
Area of new snail habitats (hm2)
|
Area with recurrent snails (hm2)
|
Areas with mollusciciding
(hm2)
|
Areas with environmental modification
(hm2)
|
2005
|
13 181.83
|
112.70
|
1.26
|
*
|
261.58
|
9.06
|
2006
|
11 190.36
|
116.12
|
0.00
|
*
|
306.71
|
26.36
|
2007
|
11 059.95
|
126.90
|
4.66
|
*
|
239.83
|
23.34
|
2008
|
11 243.00
|
95.90
|
0.00
|
*
|
184.40
|
24.02
|
2009
|
10 735.92
|
100.26
|
0.00
|
*
|
110.07
|
15.12
|
2010
|
11 059.37
|
71.06
|
0.60
|
*
|
117.55
|
5.16
|
2011
|
10 046.77
|
58.52
|
0.82
|
51.74
|
118.06
|
4.64
|
2012
|
9161.18
|
79.15
|
0.61
|
61.52
|
320.61
|
2.77
|
2013
|
9326.08
|
62.52
|
0.43
|
35.64
|
123.77
|
16.33
|
2014
|
9441.76
|
48.46
|
1.18
|
28.90
|
123.29
|
3.43
|
2015
|
9833.01
|
47.52
|
0.43
|
32.60
|
103.23
|
3.88
|
2016
|
10 558.53
|
52.81
|
1.99
|
37.15
|
102.79
|
5.34
|
Total
|
126 837.75
|
-
|
11.98
|
247.55
|
2111.89
|
139.45
|
*The data couldn’t be got
3.2 Comprehensive assessments of surveillance capacity
3.2.1 Capacity for testing skills and snail detection.
Totally fifteen disease prevention and control agencies attended the assessment on testing skills and snails detection. For IHA, all professionals from the 15 agencies could perform and judge the results of five serum samples accurately, the accuracy rate was 100% (75/75). For MHT, the average accuracy rate was 89.3% (67/75, 95% CI: 82.2–96.5%), while eight wrong judgment results were all occurred in four CDC laboratories at county level.
For snail identification, all agencies preformed excellent capacity to identify the snails’ living status with the accuracy rate of 100% (150/150) (Fig. 2). The average accuracy rate of identifying infection status of snails was 98.1% (103/105, 95% CI: 95.4–100.8%). And two wrong judgment results occurred in one CDC at county level.
3.2.2 Questionnaires survey on basic knowledge of schistosomiasis
Total of 108 medical staffs in fifteen disease prevention and control agencies attended the questionnaire survey (Table 4). The results showed that the average accuracy rate of all respondents was 98.0% (529/540, 95% CI: 96.8–99.2%). Among five PLADs, respondents from Guangdong and Guangxi PLADs answered all questions correctly. The wrong-answered questions were mainly about knowledge on national comprehensive schistosomiasis control strategies and diagnosis of schistosomiasis.
Table 4. Scores of questionnaires on schistosomiasis control knowledge among professionals from 15 institutions in 5 provinces and 10 counties.
Province
|
Level of each
agency
|
No. respondents
|
No. questions
|
No. correct answers
|
Accuracy rate (%)
|
Guangdong
|
Province
|
9
|
45
|
45
|
100.0
|
|
Qingcheng
|
9
|
45
|
45
|
100.0
|
|
Qujiang
|
9
|
45
|
45
|
100.0
|
|
Subtotal
|
27
|
135
|
135
|
100.0
|
Shanghai
|
Municipality
|
3
|
15
|
15
|
100.0
|
|
Pudong
|
9
|
45
|
45
|
100.0
|
|
Songjiang
|
9
|
45
|
39
|
86.7
|
|
Subtotal
|
18
|
90
|
84
|
93.3
|
Fujian
|
Province
|
3
|
15
|
14
|
93.3
|
|
Xiapu
|
9
|
45
|
45
|
100.0
|
|
Fuqing
|
9
|
45
|
44
|
97.8
|
|
Subtotal
|
21
|
105
|
103
|
98.1
|
Guangxi
|
Autonomous region
|
3
|
15
|
15
|
100.0
|
|
Jingxi
|
9
|
45
|
45
|
100.0
|
|
Yizhou
|
9
|
45
|
45
|
100.0
|
|
Subtotal
|
21
|
105
|
105
|
100.0
|
Zhejiang
|
Province
|
3
|
15
|
15
|
100.0
|
|
Jiahsan
|
9
|
45
|
45
|
100.0
|
|
Changshan
|
9
|
45
|
42
|
93.3
|
|
Subtotal
|
21
|
105
|
102
|
97.2
|
Total
|
|
108
|
540
|
529
|
98.0
|
No.: Number of.
3.2.3 The total scores of the surveillanceassessment
Based on the results of testing skills and snail detection and questionnaire surveys, except for Fujian scored 29 points, the scores of the other four PLADs were all 30 points (Table 5). In ten counties, the scores ranged from 26 to 30 points.Table 5. Comprehensive assessment scores of schistosomiasis surveillance capabilities in five provinces and ten counties.
Province
|
Level of each
agency
|
Diagnostic skills
|
Snail identification
|
Questionnaire survey
|
Total
|
Guangdong
|
Province
|
10
|
10
|
10
|
30
|
|
Qingcheng
|
9
|
10
|
10
|
29
|
|
Qujiang
|
10
|
10
|
10
|
30
|
Shanghai
|
Municipality
|
10
|
10
|
10
|
30
|
|
Pudong
|
10
|
9
|
10
|
29
|
|
Songjiang
|
6
|
10
|
4
|
20
|
Fujian
|
Province
|
10
|
10
|
9
|
29
|
|
Xiapu
|
10
|
10
|
10
|
30
|
|
Fuqing
|
10
|
10
|
9
|
29
|
Guangxi
|
Autonomous region
|
10
|
10
|
10
|
30
|
|
Jingxi
|
10
|
10
|
10
|
30
|
|
Yizhou
|
10
|
10
|
10
|
30
|
Zhejiang
|
Province
|
10
|
10
|
10
|
30
|
|
Jiahsan
|
8
|
10
|
10
|
28
|
|
Changshan
|
9
|
10
|
7
|
26
|