Abstract:

Objective To analyze schistosomiasis surveillance Results among transient population in Hangzhou City from 2004 to 2023, and to investigate the epidemiological characteristics of schistosomiasis cases. Methods Schistosomiasis surveillance data among transient population in Hangzhou City from 2004 to 2023 were retrieved from the annual schistosomiasis surveillance reports, historical materials compilation and annual summary of schistosomiasis control in Hangzhou Municipal Center for Disease Control and Prevention, and data pertaining to schistosomiasis epidemics were captured from the Notifiable Disease Report Information Management System of Chinese Center for Disease Control and Prevention, epidemiological case investigation forms and investigation reports of confirmed schistosomiasis cases. Schistosomiasis surveillance was performed among transient population from endemic foci by means of active and passive approaches. The number of transient population monitored for schistosomiasis, number of seropositives, number of transient population receiving stool examinations, number of transient population receiving urine tests and number of transient population positive for urine tests, and the gender, age, occupation, place of origin, clinical symptoms and signs, history of exposure to infested water, place of infection, and local work, living and healthcare-seeking behaviors of confirmed schistosomiasis cases were collected. All data were analyzed statistically using the SPSS 26.0 software and R 4.1.0 package, and the temporal, spatial and population distribution, place of infection, and clinical diagnosis and treatment of schistosomiasis patients were analyzed using a descriptive epidemiological method. Results The mean seroprevalence of schistosomiasis was 0.51% (1 188/234 415) among transient population in Hangzhou City from 2004 to 2023, with the highest in 2004 (1.37%, 115/8 366) and the lowest in 2023 (0.01%, 1/8 160), and the seroprevalence of schistosomiasis appeared a tendency towards a decline over years from 2004 to 2023 (Z = ‒4.190, P < 0.05). There were 40 confirmed schistosomiasis cases, and all were imported cases (34 domestically imported cases and 6 overseas imported cases), including 8 case with acute schistosomiasis, 26 cases with chronic schistosomiasis, 3 cases with schistosomiasis haematobia, 2 cases with schistosomiasis intercalate and 1 case with schistosomiasis mansoni. Man was the predominant gender (85.0%, 34/40) and the occupation mainly included students, labors and farmers (65.0%, 26/40). The schistosomiasis patients detected from 2019 to 2023 were all overseas imported, and were concentrated in Lin’an District (3 cases) and Xihu District (2 cases), and the 34 domestically imported cases mainly acquired infections in Jiangxi Province (41.2%, 14/34), Anhui Province (29.4%, 10/34) and Hubei Province (20.6%, 7/34). Of the 6 overseas imported cases, 5 cases were foreign students with African nationality and another case was a labor with Anhui household registration that worked in Africa, and the place of acquiring infections included Equatorial Guinea (2), Guinea (1), Zambia (1), Nigeria (1) and Zimbabwe (1). Acute schistosomiasis japonica was mainly reported during the period between July and September (7/8), and the symptoms mainly included fever (8/8) and eosinophilia (7/8), 35.5% (11/31) of cases were misdiagnosed or missed, accounting for 4/11, 2/11, and 5/11 of the provincial, municipal, and county-level medical institutions, respectively. Conclusion The seroprevalence of schistosomiasis is low among transient population in Hangzhou City, with schistosomiasis cases shifting from domestic importation to overseas importation and location of case reporting shifting from concentrated areas of migrant labors to universities with a concentration of African students. In addition, misdiagnosis or missed diagnosis remains in medical institutions at all levels.

Key words: Schistosomiasis, Transient population, Surveillance, Epidemiological characteristics