[Surveillance of schistosomiasis 34 years after transmission interruption in Songjiang District, Shanghai City]

OBJECTIVE

To analyze the surveillance data after schistosomiasis transmission interruption from 1985 to 2018, so as to provide scientific basis for the future prevention and control of schistosomiasis.

METHODS

The data pertaining to snail survey, surveillance of schistosomiasis in humans and livestock, and health education were collected and analyzed in Songjiang District after schistosomiasis transmission interruption from 1985 to 2018.

RESULTS

From 1985 to 2018, there were 8 townships, 68 villages and 1 462 settings with snails in Songjiang District, covering an area of 96.399 hm². There were 4 townships and 59 villages with snails newly identified in previously schistosomiasis non-endemic areas, with emerging snail habitats of 60.161 hm². A total of 26 148 snails were captured, and no infections were detected. The snail habitats were mainly distributed in the river course, ditches and farmlands, which accounted for 45.28%, 33.17% and 21.55% of total snail habitats, respectively. A total of 245 955 humans were subjected to the serological test, with a positive rate of 0.03%, and 37 humans were subjected to the parasitological test, with 3 positives detected. These three egg-positives were all imported chronic cases with schistosomiasis. A total of 9 109 livestock were detected using the serological test, and no infection was found. Most of the awareness rate of schistosomiasis control knowledge and the rate of correct behavior formation were over 80% in residents and students.

CONCLUSIONS

The achievements of schistosomiasis control are consolidated in Songjiang District; however, there are still risk factors of schistosomiasis transmission, including residual snails, snail diffusion and importation of external source of infection. The future surveillance of schistosomiasis should focus on snails and sources of infection.

[Historical Oncomelania hupensis snail environments in Baoshan District, Shanghai City]

OBJECTIVE

To understand the distribution and characteristics of historical Oncomelania hupensis snail environments in Baoshan District, Shanghai City, so as to provide the reference for adjusting and formulating the monitoring program of the snail situation in the future.

METHODS

A retrospective survey and a field survey were conducted to collect the information of historical O. hupensis snail environments and set up the database. The distribution and characteristics of them were analyzed.

RESULTS

There were 53 historical O. hupensis snail environments which distributed in three towns, and the accumulative area was 1 635 530 m² in Baoshan District, Shanghai City. Class I, II, III and IV accounted for 73.58%, 5.66%, 16.98% and 3.77% respectively. The complete transformation (Class I and Class II) was done in 42 places which covered the area of 1 622 043 m², in which Class I environments and Class II environments accounted for 79.25% and 99.18% of the total, respectively.

CONCLUSIONS

There has been a great change in the historical O. hupensis snail environments in Baoshan District, Shanghai City. The information of the field investigation should be enriched and updated at different times to guide the investigation of O. hupensis snails in the future.

[Risk analysis of imported schistosomiasis in Shanghai City from 2005 to 2015]

OBJECTIVE

To understand the risk situation of imported schistosomiasis and its main influencing factors in Shanghai City from 2005 to 2015.

METHODS

A retrospective survey was performed, and the database was established based on the data collection of imported schistosomiasis, Oncomelania hupensis snail situation and mobile population in Shanghai City from 2005 to 2015.

RESULTS

From 2005 to 2015, the mobile population in Shanghai City increased by 123.92%, which reached about 9 816 500, and 54.70% of them were located in the inner suburban districts. The accumulated areas with snails of 7.13 hm² were found in 16 towns of 4 outer suburbs (excluding Chongming District). A total of 23 cases of imported schistosomiasis were found in Shanghai City, and the number of the imported schistosomiasis cases was on the downward trend (rs = -0.782, P = 0.004). From 2005 to 2009, 11 out of 13 imported schistosomiasis cases (84.62%) were distributed in the inner suburban districts where no O. hupensis snails were found at the same time. From 2010 to 2015, 9 out of 10 imported schistosomiasis cases (90%) were distributed in the outer suburban districts where O. hupensis snails were found at the same time.

CONCLUSIONS

The number of imported schistosomiasis cases in Shanghai is on the downward trend. However, the threat of imported schistosomiasis to the prevention and control of schistosomiasis in Shanghai City should not be ignored.