1.Analysis of epidemic trends and status of schistosomiasis in Jiangxi Province from 2002 to 2021
Yifeng LI ; Zongguang LI ; Tingting HE ; Jingzi XIE ; Shangbiao LYU ; Min YUAN ; Dandan LIN
Shanghai Journal of Preventive Medicine 2023;35(7):619-625
ObjectiveTo analyze the epidemic trends and current status in the prevalence of schistosomiasis in Jiangxi Province from 2002 to 2021, and to provide evidence for formulating and optimizing schistosomiasis control strategies in the province. MethodsEpidemiological data of schistosomiasis in Jiangxi Province from 2002 to 2021 were collected. The Joinpoint regression model was used to investigate the epidemic trends of schistosomiasis, and the annual average percent change (AAPC) was used to assess the changing trend of schistosomiasis infection in humans and bovines. SPSS 25.0 software was used to analyze the target achievement status, infection rate of schistosomiasis in humans and the areas with snails in 2021 to evaluate the differences among various districts and epidemic regions. ResultsBy 2021, 24 counties (61.50%) in the province had achieved the elimination goal, with hilly and marsh counties reaching 82.60% and 31.30%, respectively. The seropositive rate of schistosomiasis in human was 3.51% across the province. However, the seropositive rate in marshland areas (4.77%) was significantly higher than that in hilly areas (1.23 %) (χ2=3 827.51, P<0.001). The total area with snails in the province was 84 938.32 hm2, including 82 196.86 hm2 in marshland areas and 2 741.46 hm2 in hilly areas. From 2002 to 2021, the infection rate of schistosomiasis in the humans and bovines exhibited a declining trend, with AAPC values of -48.70 and -39.70, respectively. The decline rate in the hilly areas was higher than that in marshland areas. However, the area with snail showed an upward trend (AAPC=0.50), with a growth rate of 5.80% in hilly areas, which was greater than that in marshland areas (0.40%). ConclusionFrom 2002 to 2021, the infection rate of schistosomiasis in humans and bovines in Jiangxi Province continued to decline, while the areas with snails increased. The prevention focus should still be on the marshland endemic areas, and attention should also be given to the risk of schistosomiasis in hilly endemic areas. Therefore, it is necessary to continue implementing a comprehensive prevention and control strategy that emphasizes controlling the sources of infection and adopts tailored measures based on local conditions and precise policies.
2.Impact of drought on Oncomelania hupensis snails breeding in the Poyang Lake area
Fei HU ; Shangbiao LÜ ; Yifeng LI ; Zongguang LI ; Tingting HE ; Jingzi XIE ; Min YUAN ; Dandan LIN
Chinese Journal of Schistosomiasis Control 2024;36(4):370-375
Objective To examine the impact of arid climates on distribution of Oncomelania hupensis snails in the Poyang Lake area, so as to provide insights into precision control of O. hupensis snails in the Poyang Lake area. Methods O. hupensis snails-infested grass islands in Hukou County, Lianxi District and Lushan City in the northern Poyang Lake area, and Jinxian County, Nanchang County and Poyang County in the southern Poyang Lake area were selected as the study areas, and the occurrence of frames with living snails and the mean density of living snails were captured from snail surveys in the study areas in spring and autumn each year from 2006 to 2023. Five years 2007, 2011, 2013, 2019 and 2022 were selected as drought years, and the mean daily water levels were collected at the Xingzi hydrological station in the drought years, normal flow year (2012) and flood year (2020). The numbers of days with water levels ranging from the lower elevation (11 m) to the upper elevation (16 m) for snail survival and the numbers of days with water levels of 11 m and below were collected in the Poyang Lake area, and the changes of snail indicators were compared in different grass islands in the Poyang Lake area before and after drought. Results The numbers of days with water levels ranging from 11 to 16 m were 110, 88, 136 d and 125 d at the Xingzi hydrological station in four drought years 2007, 2011, 2013 and 2019, which were less than in the flow year and flood year, and the days with water levels of 11 m and below were 242, 277, 220 d and 198 d in four drought years 2007, 2011, 2013 and 2019, which were longer than in the flow year and flood year. A total of 416 snails-infested marshlands were surveyed in the Poyang Lake area from 2006 to 2021, and the survey marshlands accounted for 43.12% (307/712) and 46.98% (109/232) of total marshlands in the southern and northern Poyang Lake areas, respectively. The median occurrence of frames with living snails and mean density of living snails were 0.60% (interquartile range, 4.04%) and 0.010 1 snail/0.1 m2 (interquartile range, 0.076 1 snail/0.1 m2) in drought years, which were both lower than those [1.33% (5.19%) and 0.022 8 (0.098 9) snail/0.1 m2] in non-drought years (χ2= 42.170 and 44.911, both P values < 0.01). The proportion of grass islands with a continuous decline in snail indicators was higher in the southern Poyang Lake area than in the northern Poyang Lake area after the next year of drought (24.24% vs. 2.33%; χ2 = 10.633, P < 0.01), and the proportion of grass islands with rebounding snail indicators was higher in the northern Poyang Lake area than in the southern Poyang Lake area (53.49% vs. 15.76%; χ2 = 26.966, P < 0.01). A longitudinal analysis of snail indicators in marshlands with rebounding snail indicators after drought showed 1 to 5 years for return to pre-drought snail status, with a median of 2 (interquartile range, 1) years, and snail status was more likely to rebound if the occurrence of frames with living snails and the mean density of living snails were 2.11% and 0.025 5 snail/0.1 m2 and greater in snails-infested grass islands. Conclusions Drought causes a remarkable decline in O. hupensis snail indicators in the Poyang Lake area, with a more remarkable impact in the southern Poyang Lake area, and 1 to 5 years are required for return to pre-drought snail status.