Assessment of transmission risk of human schistosomiasis japonica based on human population antibody level in Hubei Province

doi:10.12140/j.issn.1000-7423.2021.05.003

Abstract

Abstract:

Objective To understand the current status of the antibody level and changing trend in human schistosomiasis japonica in Hubei Province, thereby to assess the transmission risk. Methods Serum samples were collected from the seropositives of Schistosoma infection during mass screening in September to December yearly of 2016—2018, and the serum antibody titer was determined by indirect hemagglutination test. The antibody titer and basic information of the examinees were recorded. The disease screening and control progress in endemic areas (cities, districts) of Hubei Province were collected from the annual report data in 2016—2018. Four indicators were defined for assessment of transmission risk: the number of serum antibody-positives, sero-positive rate, proportion of high antibody titers in sero-positives, and the type of endemic area. The transmission risk was evaluated by county, and visualized by constructing a risk grade map using ArcGIS 10.5 software. Basic information on the people with positive serum antibody was analyzed with SPSS 26.0 software, to assess the distribution characteristics of key population. Results From 2016 to 2018, the number of participants in schistosomiasis antibody testing was 1 728 300, 1 531 611 and 1 498 039, respectively. In the three years, the numbers of seropositives reports with positive serum antibody were 41 154, 31 532 and 22 124, and the sero-positive rates 2.38%, 2.06%, and 1.48%, respectively, showing a decrease in both number and rate each year (χ ² = 3410.81, P < 0.01). In 2016 and 2017, the sero-positives were mostly reported from the transmission-controlled areas, accounting for 95.47% (39 290/41 154) and 63.68% (20 081/31 532) of the total seropositives (χ ² = 773.88, P < 0.01), respectively, while in 2018, the seropositives were mainly reported from the transmission-interrupted areas, accounting for 99.84% (22 088/22 124) of the total. From 2016 to 2018, the numbers of seropositives with antibody titer ≥ 1 ∶ 40 were 4 459, 4 498 and 2 482, respectively, accounting for 10.83%, 14.26%, and 11.22% of the total sero-positives, with significant difference between years (χ ² = 217.46, P < 0.01). The assessment of transmission risk by grading found five risk grade 1 areas in the province: Gong’an County, Shashi District, Jiangling County, Songzi City, and Qianjiang City. Ten risk grade 2 areas were identified: Yangxin County, Honghu City, Jiayu County, Jingzhou District, the Jingzhou Development Zone, Hannan District, Shishou City, Caidian District, Hanchuan City and Xiantao City. In addition, ten risk grade 3 areas were found, and the remaining 38 endemic areas were all risk grade 4 areas. Analysis on key population at schistosomiasis transmission risk indicated that among the population with serum antibody titer ≥ 1 : 40, males (62.43%, 7 141/11 439) and people of 44-65 years-old (71.09%, 8 132/11 439) composed the majority. Conclusion During 2016—2018, the number of seropositive cases of schistosomiasis in Hubei Province declined year by year. Currently, the transmission risk of schistosomiasis japonica was assessed mainly as grade 4, indicative of overall low risk in the endemic areas. However, prevention and control in areas of risk grade 1 and 2 remain to be strengthened, targeting the key population of males and those at the age of 44-65 years old.

Key words: Schistosomiasis japonica, Human, Transmission risk, Analysis and evaluation, Hubei Province

CLC Number:

R532.21

WU Jia-li, LI Bo, LIU Si, TU Zu-wu, TANG Li, TU Zhen, ZHOU Xiao-rong, SUN Ling-cong, XIAO Ying, ZHU Hong. Assessment of transmission risk of human schistosomiasis japonica based on human population antibody level in Hubei Province[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2021, 39(5): 578-584.

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References 18

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评分值 Score	血清抗体阳性数/例 No. of seropositive	血清抗体阳性率/% Seropositive rate/%	阳性血清抗体效价（≥ 1 ∶ 40）构成比/% Proportion of sero-positives with antibody titer ≥ 1 ∶ 40/%	流行区类型 Endemic area type
0	0	0	0
1	< 100	> 0~< 0.5%	> 0~< 5%	消除地区Eliminated areas
2	100~499	0.5%~< 1%	5%~< 10%	传播阻断地区Transmission interrupted areas
3	500~999	1%~< 2%	10%~< 20%	传播控制地区Transmission controlled areas
4	1 000~1 999	≥ 2%	≥ 20%
5	≥ 2 000

年份Year	< 100例 < 100 cases		100~499例 100-499 cases		500~999例 500-999 cases		1 000~1 999例 1 000-1 999 cases		≥ 2 000例 ≥ 2 000 cases		合计 Total
年份Year	报告县数No. county reported	报告例数No. case reported	报告县数No. county reported	报告例数No. case reported	报告县数No. count reported	报告例数No. case reported	报告县数No. county reported	报告例数No. case reported	报告县数No. county reported	报告例数No. case reported	报告县数No. county reported	报告例数No. case reported
2016	24	646	8	1 806	3	2 046	7	10 649	6	26 007	48	41 154
2017	22	618	9	1 696	4	3 036	7	9 850	4	16 332	46	31 532
2018	21	454	14	3 202	2	1 424	4	5 139	4	11 905	45	22 124

流行区类型Endemic area type	2016			2017			2018
	血清抗体阳性数No. seropositive case	血清抗体阳性率/%Seropositive rate/%		血清抗体阳性数No. seropositive case	血清抗体阳性率/%Seropositive rate/%		血清抗体阳性数No. seropositive case	血清抗体阳性率/%Seropositive rate/%
	血清抗体阳性数No. seropositive case	血清抗体阳性率/%Seropositive rate/%	消除 Eliminated areas	血清抗体阳性数No. seropositive case	血清抗体阳性率/%Seropositive rate/%	16	血清抗体阳性数No. seropositive case	血清抗体阳性率/%Seropositive rate/%	0.09	11	0.07	36	0.08
传播阻断Transmission interrupted areas	1 848	0.67	消除 Eliminated areas		11 440	1.95		22 088	1.52
传播阻断Transmission interrupted areas	传播控制Transmission control areas	39 290	2.74		20 081	2.16		-	-
合计Total	传播控制Transmission control areas	41 154	2.38		31 532	2.06		22 124	1.48

市 City	1级风险县（市、区） Risk grade 1 areas	2级风险县（市、区） Risk grade 2 areas	3级风险县（市、区） Risk grade 3 areas	4级风险县（市、区） Risk grade 4 areas
武汉Wuhan		汉南区、蔡甸区 Hannan District, Caidian District	东西湖区、黄陂区Dongxihu District, Huangpi District	省内其他流行区（38个） Other schistosomiasis endemic areas in Hubei Province (38)
黄石Huangshi		阳新县Yangxin County
宜昌Yichang			枝江市Zhijiang City
荆门Jingmen			京山县Jingshan County
孝感Xiaogan		汉川市Hanchuan City	云梦县Yunmeng County
荆州Jingzhou	沙市区、公安县、江陵县、松滋市Shashi District, Gongan County, Jiangling County, Songzi City	荆州区、荆州开发区、石首市、洪湖市Jingzhou District, Jingzhou Development Zone, Shishou City, Honghu City	监利县Jianli County
黄冈Huanggang			浠水县、武穴市 Xishui County, Wuxue City
咸宁Xianning		嘉鱼县Jiayu County	赤壁市Chibi City
仙桃Xiantao		仙桃市Xiantao City
潜江Qianjiang	潜江市Qianjiang City
天门Tianmen			天门市Tianmen City
襄阳Xiangyang
鄂州Ezhou