目的 了解我国鄱阳湖血吸虫病流行区居民血吸虫感染及肝纤维化变化趋势,评估不同阶段不同防治策略的效果。 方法 以江西省鄱阳湖区庐山市新华村为观察点进行研究。1995—2001年为全民化疗阶段,每年对该村5岁及以上常住居民进行1次全民化疗;2002—2009年为目标人群化疗阶段,对该村5岁及以上常住居民进行血清学筛查,对血清抗血吸虫抗体阳性者给予化疗;2010—2019年为传染源控制阶段,采取“封洲禁牧、淘汰耕牛（肉牛）”等以传染源控制为主的综合防治措施。每年11或12月,采用改良加藤厚涂片法检查该村5岁及以上常住居民粪样中的血吸虫虫卵,其中1995—2003年实行1粪3检,2004—2007年2粪12检（每个受检者收集粪便2次,间隔3~5 d,每次制作6张涂片）,2008—2019年3粪27检（每个受检者收集粪便3次,间隔3~5 d,每次制作9张涂片）,对粪检阳性者给予吡喹酮顿服（40 mg/kg,口服）或二日疗法（总剂量60 mg/kg,分2日口服,每日3次）治疗。1995—1998、2000、2002、2007和2019年,对参与粪检的居民进行肝脏实质（肝纤维化）B超检查;肝实质分级以正常肾实质回声作为正常标准,分为0级、Ⅰ级、Ⅱ级和Ⅲ级等4个等级。计算各年居民血吸虫感染率、感染度（每克粪便虫卵数,EPG）、再感染率、血吸虫病肝实质异常率。居民血吸虫感染率、再感染率的年间比较采用χ²检验,各年感染率与感染度、居民当年感染率与次年再感染率、再感染者前后2年感染度之间的比较采用Pearson相关性分析;化疗前感染度的高低与次年是否存在再感染之间的关系采用Spearman相关性分析;血吸虫病肝实质异常率年间变化趋势的比较采用时间序列的趋势分析。 结果 1995—2019年,每年粪检人数为309~978人。全民化疗阶段,居民血吸虫感染率由1995年的17.89%（175/978）（95%CI：15.49%~20.29%）降至2001年的5.79%（50/864）（95%CI：4.23%~7.34%）,降幅为67.64%,感染率年间差异有统计学意义（χ² = 197.752,P < 0.01）;目标人群化疗阶段,居民感染率呈回升趋势,由2002年的5.13%（40/780）（95%CI：3.58%~6.68%）上升至2009年的7.97%（65/816）（95%CI：6.11%~9.83%）,年间差异有统计学意义（χ² = 39.823, P < 0.01）;传染源控制阶段,居民感染率逐年下降,由2010年的3.30%（28/849）（95%CI：2.10%~4.50%）降至2019年的0（0/475）。全民化疗阶段,感染者平均EPG为23.73~89.79,高峰出现在1995年（89.79）和1998年（85.33）;目标人群化疗阶段,感染者平均EPG维持在12.20~38.11;传染源控制阶段,感染者平均EPG除2016年为44.19外,其他年份均在20以下。各年度感染者平均EPG与感染率的变化较一致（r = 0.784,P < 0.01）。1996—2011年居民再感染率为4.29%~38.46%,年度间差异有统计学意义（χ² = 48.202,P < 0.01）,2012年以后虽然居民感染人数较少,但2017年出现再感染;居民感染率与再感染无相关性（r = 0.245,P > 0.05）,再感染者前后2年的感染度无相关性（r = 0.176,P > 0.05）;当年感染率≥ 10%,感染者EPG高低与次年是否再感染存在相关性（r = 0.516,P < 0.01）。B超检查结果显示,1995—1998、2000、2002、2007和2019年,居民血吸虫病肝实质异常率为34.90%（335/960）~57.15%（448/784）,中位值为50.36%。其中1995年最低,1998年最高;1997、1998、2000和2007年异常率均超过50%。居民血吸虫病肝实质Ⅰ级年间无明显变化趋势（R² = 0.032, F = 0.019,P > 0.05）,Ⅱ级和Ⅲ级呈逐年上升趋势（R² = 0.397、0.493,F = 7.367、7.774,P < 0.05）。1995、2007和2019年均接受B超检查的共204人,与1995年相比,2019年24.51%（50/204）的患者肝纤维化出现好转,29.90%（61/204）的患者肝纤维化继续发展;肝纤维化好转、发展与居民血吸虫感染度均无相关性（R² = 0.173、0.365,F = 1.233、2.174,P > 0.05）;1995—2019年,感染过血吸虫居民的肝纤维化发展率（54.24%,32/59）高于好转率（16.95%,10/59）（χ² = 17.892,P < 0.01）。 结论 以化疗为主的综合防治策略难以控制居民血吸虫感染,无论居民血吸虫感染率水平多低,再感染仍有可能发生;以传染源控制为主的综合防治策略可有效控制血吸虫病传播;血吸虫感染者肝脏损伤呈“慢性化”过程。

Objective This study investigated the changing trend in schistosome infection and liver fibrosis among residents in the Poyang Lake area, China, to evaluate the effectiveness of various control strategies at different phases. Methods The Xinhua Village of Lushan City, in Poyang Lake District, Jiangxi Province was set as the observation site for the study. The period of 1995—2019 was the mass chemotherapy phase, when permanent residents of the village over 5 years of age received chemotherapy yearly; the period of 2002—2009 was the targeting chemotherapy phase, when the villagers over 5 years of age were screened by serology, and those positives of serum antibody against were treated. In the infection source control phase covering 2010—2019, comprehensive measures including “closure of lake grass island and grazing prohibition/removing farm cattle (beef cattle)” were taken aiming at the control source of infection. In November or December every year, the modified Kato-Katz thick smear method was used to examine schistosome eggs in the fecal samples of villagers over than 5 years of age. From 1995 to 2003, fecal examination was performed with triplicate slide-reading/sample, while in 2004—2007, with two stool samples for 12 slide-reading (two fecal samples were collected from each participant at intervals of 3-5 days, and six slides were prepared from each sample); from 2008 to 2019, three samples for 27 slide-reading (three stool samples were collected from each participant at intervals of 3-5 days and nine slides were prepared from each sample). The fecal egg-positives were treated with praziquantel using either single oral dose once (40 mg/kg) or 2-day therapy (total dose 60 mg/kg, in three times a day for two days). In 1995—1998, 2000, 2002, 2007 and 2019, ultrasound scanning for liver parenchyma (liver fibrosis) was performed on residents who participated in stool examination. The liver parenchymal state was graded based on the renal parenchymal echo as the normal standard of reference. The four grades were grade 0, Ⅰ,Ⅱ and Ⅲ. The schistosome infection rate, infection intensity (eggs per gram feces, EPG), re-infection rate and liver parenchymal abnormality rate in residents were calculated for each year. The χ²-test was used for comparison of schistosome infection rates and re-infection rate between years. Pearson’s correlation analysis was used to compare the infection rate and infection intensity of each year, the infection rate in current year and next year, and the infection intensity of re-infected people in two years: previous and coming one. The association between the infection intensity before chemotherapy and the occurrence of re-infection in the following year was analyzed with Spearman’s correlation. Schistosomiasis liver parenchymal abnormality rates between years was compared through time series trend analysis. Results From 1995 to 2019, 309-978 villagers received fecal examination yearly. During the mass chemotherapy phase, the schistosome infection rate decreased from 17.89% (175/978) (95%CI: 15.49%-20.29%) in 1995 to 5.79% (50/864) (95%CI: 4.23%-7.34%) in 2001, with a decrease by 67.64%, and the difference between years was statistically significant (χ² = 197.752, P < 0.01). The infection rate in targeting chemotherapy phase showed increasing trend from 5.13% (40/780) (95%CI: 3.58%-6.68%) in 2002 to 7.97% (65/816) (95%CI: 6.11%-9.83%) in 2009, and the changes between years was statistically significant (χ² = 39.823, P < 0.01). In the infection source control phase, the infection rate declined year by year that from 3.30% (28/849) (95% CI: 2.10%-4.50%) in 2010 to 0 (0/475) in 2019. During the mass chemotherapy period, the average EPG in infected villagers was between 23.73 and 89.79, and peaked in 1995 (89.79) and 1998 (85.33). During the targeting chemotherapy phase, the average EPG in the infected maintained at 12.20-38.11. During the infection source control phase, the average EPG the infected was 44.19 in 2016, and that in all other years was lower than 20. Annually, the average EPG of the infected was in accordance with the change of infection rate (r = 0.784, P < 0.01). The re-infection rate in residents in 1996—2011 was 4.29%-38.46%, and the difference between years was statistically significant (χ² = 48.202, P < 0.01). The number of infected residents reduced after 2012, but re-infection occurred in 2017; the infection rate in villagers was uncorrelated with the re-infection (r = 0.245, P > 0.05); the infection intensity of re-infected villagers showed no correlation between two years of before and after; upon the EPG in infected villagers in that year was ≥ 10%, the infection intensity was correlated with re-infected occurrence in following year (r = 0.516, P < 0.01). Ultrasonography screening revealed that in 1995 to 1998, 2000, 2002, 2007 and 2019, the abnormality rate of liver parenchyma in residents ranging from 34.90% to 57.15%, with a median value of 50.36%, which was lowest in 1995, 34.90% (335/960), among them the lowest rate was found in 1995, the highest in 1998; the abnormality rate exceeded 50% in 1997, 1998, 2000 and 2007. No significant change in liver parenchyma grade Ⅰ was observed between years among residents with schistosomiasis (R² = 0.032, F = 0.019, P > 0.05); whereas grade Ⅱ and grade Ⅲ showed an increasing trend each year (R² = 0.397, 0.493; F = 7.367, 7.774; P < 0.05). Of the examinees with liver parenchyma abnormality, 204 received ultrasonography in 1995, 2007 and 2019. Compared to 1995, found in 2019, 24.51% (50/204) cases with liver fibrosis appeared improved; 29.90% (61/204) cases showed liver fibrosis remained in advancing; the fact of improvement or advancing of liver fibrosis was uncorrelated with the infection intensity (R² = 0.173, 0.365; F = 1.233, 2.174; P > 0.05). During 1995—2019, the participants with schistosome infection history showed the fibrosis advancing rate (54.24%, 32/59) higher than the improving rate (16.95%, 10/59) (χ² = 17.892, P < 0.01). Conclusion Comprehensive control strategy based mainly on chemotherapy is difficult to control schistosome infection in residents regardless of low infection rate in villagers, re-infection may still occur. The comprehensive strategy mainly based on controlling source of infection can effectively control schistosomiasis transmission. Hepatic lesion in people infected with schistosome showed chronic process.