Time to set the agenda for schistosomiasis elimination

It is time to raise global awareness to the possibility of schistosomiasis elimination and to support endemic countries in their quest to determine the most appropriate approaches to eliminate this persistent and debilitating disease. The main interventions for schistosomiasis control are reviewed, including preventive chemotherapy using praziquantel, snail control, sanitation, safe water supplies, and behaviour change strategies supported by information, education and communication (IEC) materials. Differences in the biology and transmission of the three main Schistosoma species (i.e. Schistosoma haematobium, S. mansoni and S. japonicum), which impact on control interventions, are considered. Sensitive diagnostic procedures to ensure adequate surveillance in areas attaining low endemicity are required. The importance of capacity building is highlighted. To achieve elimination, an intersectoral approach is necessary, with advocacy and action from local communities and the health community to foster cooperative ventures with engineers, the private sector, governments and non-governmental organizations specialized in water supply and sanitation. Examples of successful schistosomiasis control programmes are reviewed to highlight what has been learnt in terms of strategy for control and elimination. These include St. Lucia and other Caribbean islands, Brazil and Venezuela for S. mansoni; Saudi Arabia and Egypt for both S. mansoni and S. haematobium; Morocco, Tunisia, Algeria, Mauritius and the Islamic Republic of Iran for S. haematobium; Japan and the People's Republic of China for S. japonicum. Additional targets for elimination or even eradication could be the two minor human schistosome species S. guineenisis and S. intercalatum, which have a restricted distribution in West and Central Africa. The examples show that elimination of schistosomiasis is an achievable and desirable goal requiring full integration of preventive chemotherapy with the tools of transmission control. An agenda for the elimination of schistosomiasis would aim to identify the gaps in knowledge, and define the tools, strategies and guidelines that will help national control programmes move towards elimination, including an internationally accepted mechanism that allows verification/confirmation of elimination.     

Morbidity control of schistosomiasis in China

After reviewing the schistosomiasis control program in China with focusing on the socio-economic impact on schistosomiasis endemicity, we introduce the promotion process of morbidity control strategy undertaken before and during the World Bank Loan Project (WBLP) on Schistosomiasis Control. We analyzed the data derived from case study of morbidity control for schistosomiasis, and evaluated the efficacy of chemotherapy. It is suggested that appropriate drug treatment declines worm burden and the intensity of infection as well as prevalence, but chemotherapy alone can hardly reduce the transmission because zoonotic Schistosoma japonicum infection has a great impact on the transmission of the disease. Therefore, the strategies in different (high, medium, and low) transmission areas during the maintenance stage were put forward in consideration of challenges in national control program in the future.     

Detection of circulating antigen in serum of mice infected with Schistosoma japonicum by immunomagnetic bead ELISA based on IgY

We developed a novel immunomagnetic bead ELISA based on IgY (egg yolk immunoglobulin) for detection of circulating antigen (CA) in sera of mice infected with Schistosoma japonicum. The assay involved the use of chicken polyclonal antibodies IgY against soluble egg antigens (SEA) of S. japonicum as a capture antibody and anti-SEA mouse monoclonal antibody NP28-5B labeled horseradish peroxidase (HRP) as a detecting antibody. Two groups of BALB/c mice infected with S. japonicum cercariae were used: lightly infected mice (infected with 10 S. japonicum cercariae) and heavily infected mice (infected with 30 S. japonicum cercariae). The CA was detectable as early as 4 and 5 weeks after infection in the sera of heavily and lightly infected mice, respectively. The CA levels rose rapidly and reached a peak in 8 weeks after infection and then remained a plateau for at least another 6 weeks in both groups. Moreover, the effect of praziquantel on the CA levels was also investigated. The heavily infected mice were treated with praziquantel and the CA levels in sera increased dramatically in the first week post-treatment and then decreased to the control level by 6 weeks after treatment. The novel assay appears to be sensitive for detection of schistosomal antigenemia and valuable to judge the efficacy of chemotherapy in murine schistosomiasis.     

Schistosomiasis control in the 21st century. Proceedings of the International Symposium on Schistosomiasis,Shanghai, July 4-6, 2001

A total of 120 papers were presented at the International Symposium on Schistosomiasis which was held in Shanghai, July 4-6, 2001 with the theme of Schistosomiasis Control in the 21st Century. In order to focus more attention on the new challenges in control programmes for schistosomiasis as well as show the priority of research areas in new century, we summarize the advances of control programmes and researches in nine areas, including (1) Status of schistosomiasis control programmes; (2) Progress in applied field research; (3) Biology and control approaches of snail hosts; (4) Novel approaches for schistosomiasis control; (5) Pathogenesis and morbidity of the disease; (6) Immunology and vaccine development; (7) Screening of population for chemotherapy in low transmission areas; (8) Sustainable intervention methods in different endemic settings; (9) Impact of animal schistosomiasis on agricultural development and importance of its control; (10) GIS/RS application and environmental changes.     

Mathematical modelling of schistosomiasis japonica: comparison of control strategies in the People's Republic of China

We present the first mathematical model on the transmission dynamics of Schistosoma japonicum. The work extends Barbour's classic model of schistosome transmission. It allows for the mammalian host heterogeneity characteristic of the S. japonicum life cycle, and solves the problem of under-specification of Barbour's model by the use of Chinese data we are collecting on human-bovine transmission in the Poyang Lake area of Jiangxi Province in China. The model predicts that in the lake/marshland areas of the Yangtze River basin: (1) once-yearly mass chemotherapy of humans is little better than twice-yearly mass chemotherapy in reducing human prevalence. Depending on the heterogeneity of prevalence within the population, targeted treatment of high prevalence groups, with lower overall coverage, can be more effective than mass treatment with higher overall coverage. Treatment confers a short term benefit only, with prevalence rising to endemic levels once chemotherapy programs are stopped; (2) depending on the relative contributions of bovines and humans, bovine treatment can benefit humans almost as much as human treatment. Like human treatment, bovine treatment confers a short-term benefit. A combination of human and bovine treatment will dramatically reduce human prevalence and maintains the reduction for a longer period of time than treatment of a single host, although human prevalence rises once treatment ceases; (3) assuming 75% coverage of bovines, a bovine vaccine which acts on worm fecundity must have about 75% efficacy to reduce the reproduction rate below one and ensure mid-term reduction and long-term elimination of the parasite. Such a vaccination program should be accompanied by an initial period of human treatment to instigate a short-term reduction in prevalence, following which the reduction is enhanced by vaccine effects; (4) if the bovine vaccine is only 45% efficacious (the level of current prototype vaccines) it will lower the endemic prevalence, but will not result in elimination. If it is accompanied by an initial period of human treatment and by a 45% improvement in human sanitation or a 30% reduction in contaminated water contact by humans, elimination is then possible.     

Use of landsat TM satellite surveillance data to measure the impact of the 1998 flood on snail intermediate host dispersal in the lower Yangtze River Basin

To assess the impact of the 1998 flood on snail distribution in the lower Yangtze River Basin, two study areas were selected, one in the Poyang Lake region, and the other along the Yangtze River in Jiangsu province. Using image analysis software, geocoded Landsat TM data were used to create TNDVI maps based on the formula TNDVI=Sqrt[(band4-band3/band4+band3)+0.5]. The images taken in the flood season were classified to produce a map depicting water and land. The images taken during springtime were processed and classified based on TNDVI. Composite images were created based on the time difference analysis, combining the flood season maps and spring vegetation maps to produce a map in which potential snail habitats were identified. When compared with ground survey data collected in the spring of 2000, the correspondence rate between potential snail habitats identified by image analysis of 1998-1999 Landsat TM data and ground survey data was over 90% in both regions. Results indicate that ecology based Landsat TM image analysis provides a new way to predict snail distribution under specific environmental conditions associated with the extent of the annual flood season.     

Efficacy of praziquantel and reinfection patterns in single and mixed infection foci for intestinal and urogenital schistosomiasis in Cameroon

The regular administration of the anthelminthic drug praziquantel (PZQ) to school-aged children (and other high-risk groups) is the cornerstone of schistosomiasis control. Whilst the performance of PZQ against single schistosome species infections is well-known, performance against mixed species infections is less so, as are patterns of re-infection following treatment. To address this, a study using a double treatment with PZQ, administered at 40 mg/kg spaced by 3 weeks, took place in two mixed intestinal-urogenital schistosomiasis foci in northern Cameroon (Bessoum and Ouro-Doukoudje) and in one single intestinal schistosomiasis infection focus (Makenene). A total of just under 1000 children were examined and the Schistosoma-infected children were re-examined at several parasitological follow-ups over a 1-year period posttreatment. Overall cure rates against Schistosoma spp. in the three settings were good, 83.3% (95% confidence interval (CI) = 77.9–87.7%) in Bessoum, 89.0% (95% CI = 79.1–94.6%) in Ouro Doukoudje, and 95.3% (95% CI = 89.5–98.0%) in Makenene. Interestingly, no case of mixed schistosome infection was found after treatment. Cure rates for S. mansoni varied from 99.5% to 100%, while that for S. haematobium were considerably lower, varying from 82.7% to 88.0%. Across transmission settings, patterns of re-infection for each schistosome species were different such that generalizations across foci were difficult. For example, at the 6-month follow-up, re-infection rates were higher for S. haematobium than for S. mansoni with re-infection rates for S. haematobium varying from 9.5% to 66.7%, while for S. mansoni, lower rates were observed, ranging between nil and 24.5%. At the 12-month follow-up, re-infection rates varied from 9.1% to 66.7% for S. haematobium and from nil to 27.6% for S. mansoni. Alongside these parasitological studies, concurrent malacological surveys took place to monitor the presence of intermediate host snails of schistosomiasis. In the two northern settings, three species of Bulinus (intermediate host snail of S. haematobium) were collected; i.e. Bulinus truncatus, B. globosus and B. senegalensis, however, Biomphalaria pfeifferi (intermediate host snail of S. mansoni) was much rarer despite repeated and intensive searching and was suggestive of limited local transmission potential of S. mansoni during this time. While this study highlights that performance of PZQ was satisfactory in this region, with somewhat greater impact upon intestinal than urogenital schistosomiasis, the dynamics of local transmission are shown, however, to be complex.     

A six-year follow-up of schoolchildren for urinary and intestinal schistosomiasis and soil-transmitted helminthiasis in Northern Tanzania

Two cross-sectional studies with a 6-year interval were undertaken in two primary schools in neighbouring villages in Mwanga District, Tanzania, to determine the prevalence of schistosome and soil-transmitted helminth infections before and 6 years after treatment. Within this interval, health-related interventions such as one mass treatment of the villagers, health education, improvement of sanitation and access to safe water were undertaken in the villages. In 1996, urinary schistosomiasis occurred in Kileo (n=284) and Kivulini (n=350) in 37.0 and 86.3% of the schoolchildren. Intestinal schistosomiasis was found in 22.9 and 43.5% of the children. The infection with soil-transmitted helminths ranged between 2.7 and 18.1% in both villages. After 6 years, the prevalence of urinary schistosomiasis in schoolchildren remained nearly constant in Kileo (33.5%; n=544), but dropped from 86.3% to 70.0% in Kivulini (n=514). In the latter village the proportion of children heavily infected with Schistosoma haematobium (> or = 50 eggs/10 ml urine) decreased from 53.8% to 34.4%. With the exception of hookworm infection, soil-transmitted helminthiasis and intestinal schistosomiasis were significantly less seen in 2002 compared to the baseline. The previous chemotherapy of schoolchildren and villagers in 1996 and 1998, respectively, might have led to a reduced transmission of schistosomiasis in the following years. However, the reduction of prevalence of soil-transmitted helminthiasis is more likely to be the result of health-related interventions.     

综合治理快速控制血吸虫病效果观察

目的探索血吸虫病快速控制方案。方法采用喷粉灭螺新技术、快速筛查化疗技术,并辅以环境改造和健康教育等组合措施作为快速控制血吸虫病的综合防治方案,在现场实施并观察其防治效果。结果依托新技术的综合防治方案实施后,2005-2008年连续4年无感染性钉螺,且未发现血吸虫急性感染病例;活螺密度由2004年的1.48只/0.1m^2下降至2008年的0.71只/0.1m^2;有螺面积由2004年的43.13hm^2下降至2008年的33.68hm^2;人畜查病阳性率均下降至0。结论实施喷粉灭螺和快速筛查化疗等新技术为核心的综合防治方案可以快速有效控制、乃至阻断血吸虫病的流行。     

1989～2009年广西玉林市血吸虫病监测及控制措施

目的总结和分析玉林市1989-2009年血吸虫病慌测结果,评价监测措施,为传播阻断后期血防成果巩固提供科学依据。方法回顾性收集并分析1989～2009年玉林市血吸虫病传播阻断达标后的监测和控制资料。结果21年间在原有螺区查螺1475．239hm^2．查出螺点2个．钉螺面积0．43hm2;毗邻螺区共查螺2024．865hm^2,未发现钉螺．灭螺15次．共计3．283hm^2;疫区居民血吸虫皮试阳性率为0．81％（72／8844）,血清学阳性率为0．35％（11／3171）;粪检1614人,未发现阳性;解剖野鼠4957只、家犬44条,粪检耕牛3923头,均未发现血吸虫虫卵阳性。结论玉林市维持在血吸虫病传播阻断状态．但螺情监测工作仍存在薄弱环节,需进一步加强．     

1989～2009年广西玉林市血吸虫病监测及控制措施

目的总结和分析玉林市1989-2009年血吸虫病慌测结果,评价监测措施,为传播阻断后期血防成果巩固提供科学依据。方法回顾性收集并分析1989～2009年玉林市血吸虫病传播阻断达标后的监测和控制资料。结果21年间在原有螺区查螺1475．239hm^2．查出螺点2个．钉螺面积0．43hm2;毗邻螺区共查螺2024．865hm^2,未发现钉螺．灭螺15次．共计3．283hm^2;疫区居民血吸虫皮试阳性率为0．81％（72／8844）,血清学阳性率为0．35％（11／3171）;粪检1614人,未发现阳性;解剖野鼠4957只、家犬44条,粪检耕牛3923头,均未发现血吸虫虫卵阳性。结论玉林市维持在血吸虫病传播阻断状态．但螺情监测工作仍存在薄弱环节,需进一步加强．     

2004~2013年铜陵县血吸虫病疫情趋势分析

【摘要】 目的  分析铜陵县血吸虫病疫情,为科学制定“十三五”血吸虫病防治规划提供依据。 方法  收集2004~2013年全县防治工作开展情况和人畜病情、螺情等疫情资料,进行综合分析。 结果  2004年以来,全县血吸虫病疫情呈现下降趋势。2013年底全县钉螺面积为2 476.17hm2,较2004年下降了23.05%;有螺环境数182个,较2004年下降了24.48%;人群病原学检查阳性率从2004年的7.55%下降至2012年以后查不出阳性;耕牛感染率从2004年的8.5%降至2011年以后查不出感染牛。2007年全县达疫情控制标准,2010年以后全县无急性血吸虫病疫情发生,2011年以后全县未发现感染性钉螺,2012年全县达血吸虫病传播控制标准。 结论  2004年以来,通过采取传染源控制为主的血吸虫病综合防治措施,铜陵县血吸虫病疫情降到历史最低水平,血吸虫病传播得到有效控制,但仍存在较大面积钉螺分布环境,疫情存在反弹风险,应继续加强血吸虫病防治工作。     

2007-2013年铜陵市血吸虫病疫情分析

目的 掌握铜陵市2007-2013年血吸虫病疫情变化情况和防治效果. 方法 收集2007-2013年铜陵市血吸虫病疫情资料,分析病情和螺情变化趋势. 结果 全市人群血吸虫血检阳性率和粪检阳性率分别从2007年的8.42％(5 427/64 436)和0.40％ (50/12 372),下降为3.20％(3 587/11 976)和0 (0/14 818);耕牛感染率从2.45％ (91/3 712)下降为0(0/700),并于2013年宰杀了全部耕牛.钉螺面积从2007年的3 107.37 hm2(1 hm2=10 000 m2),减少为2013年的2 775.09 hm2,2012年后未再发现感染性钉螺. 结论 通过实施以传染源控制为主的血吸虫病综合治理项目,铜陵市血吸虫病疫情显著下降,并呈低度流行态势.     

Praziquantel treatment of school children from single and mixed infection foci of intestinal and urogenital schistosomiasis along the Senegal River Basin: monitoring treatment success and re-infection patterns

Following major water development schemes in the 1980s, schistosomiasis has become a serious parasitic disease of children living in the Senegal River Basin. Both urogenital (Schistosoma haematobium) and intestinal (Schistosoma mansoni) schistosomiasis can be highly prevalent in school-aged children, with many individuals infected with both parasites. In order to investigate the transmission and re-infection dynamics of both parasite species, single and mixed infection foci at three villages (Nder and Temeye; S. mansoni and S. haematobium foci and Guia; S. haematobium focus) were studied. In each focus infected children were identified and selected for a 12-month study involving two treatments with praziquantel (40 mg/kg) three weeks apart at the beginning of the study and again 6 months into the study. Urine and stool samples were examined for schistosome eggs before and at 6 weeks and 6 months after chemotherapy. Prevalence and intensity of infection were recorded for each child at each time point. Before treatment, in all three villages, the prevalence and intensity of infection was extremely high for both S. mansoni (79–100%) and S. haematobium (81–97%). With the first round of chemotherapy sufficient cure rates (CRs) of both species were achieved in all villages (38–96%) with high egg reduction rates (ERRs) (97–99%). The data show that high and rapid re-infection rates occur, especially for S. mansoni, within a six-month period following treatment. Re-infection must be highly linked to ecological and seasonal factors. The persistence of S. mansoni in Nder could raise concern as levels of infection intensity remain high (geometric mean intensity at baseline 653 epg changed to 705 epg at 12 months) after four rounds of chemotherapy. This phenomenon could be explained by extremely rapid re-infection dynamics or a sub-optimal efficacy of praziquantel against S. mansoni in this village. High intensities in mixed infections may influence disease epidemiology and control warranting further studies. The disease situation in the SRB must be monitored closely and new treatment regimes should be designed and implemented to control schistosomiasis in the school-age population.     

A new surveillance and response tool: Risk map of infected Oncomelania hupensis detected by Loop-mediated isothermal amplification (LAMP) from pooled samples

Although schistosomiasis remains a serious health problem worldwide, significant achievements in schistosomiasis control has been made in the People's Republic of China. The disease has been eliminated in five out of 12 endemic provinces, and the prevalence in remaining endemic areas is very low and is heading toward elimination. A rapid and sensitive method for monitoring the distribution of infected Oncomelania hupensis is urgently required. We applied a loop-mediated isothermal amplification (LAMP) assay targeting 28S rDNA for the rapid and effective detection of Schistosoma japonicum DNA in infected and prepatent infected O. hupensis snails. The detection limit of the LAMP method was 100 fg of S. japonicum genomic DNA. To promote the application of the approach in the field, the LAMP assay was used to detect infection in pooled samples of field-collected snails. In the pooled sample detection, snails were collected from 28 endemic areas, and 50 snails from each area were pooled based on the maximum pool size estimation, crushed together and DNA was extracted from each pooled sample as template for the LAMP assay. Based on the formula for detection from pooled samples, the proportion of positive pooled samples and the positive proportion of O. hupensis detected by LAMP of Xima village reached 66.67% and 1.33%, while those of Heini, Hongjia, Yangjiang and Huangshan villages were 33.33% and 0.67%, and those of Tuanzhou and Suliao villages were 16.67% and 0.33%, respectively. The remaining 21 monitoring field sites gave negative results. A risk map for the transmission of schistosomiasis was constructed using ArcMap, based on the positive proportion of O. hupensis infected with S. japonicum, as detected by the LAMP assay, which will form a guide for surveillance and response strategies in high risk areas.     

Freshwater snail diversity in Benin (West Africa) with a focus on human schistosomiasis

The aim of this study was to conduct a large-scale freshwater snail survey in Benin to assess the malacological diversity and the larval trematode infections with a focus on Schistosoma genus. We conducted 82 freshwater snail surveys in 35 sites ranked in 4 types and belonging to 9 out of 12 departments. Among 19,200 collected snails, 11 species of freshwater snails were identified. Four species of human schistosome transmitting snails, Bulinus forskalii, B. globosus, B. truncatus and Biomphalaria pfeifferi and seven species of non-human schistosome transmitting snails. Although B. forskalii and B. globosus were the most largely distributed snails, none of the Bulinus snails were found naturally infected by schistosomes. B. pfeifferi was found naturally infected by S. mansoni only in one site with a 0.56% prevalence. The most risky areas were Borgou and the four coastal departments. Preliminary contempory information on human schistosomiasis was provided from three different sites. Schistosoma haematobium was found with 57.1%, 96% and 100% prevalences (two of which were new records for this species in Benin) while S. mansoni was restricted to one site (Toho-Todougba) with 74.3% prevalence. Our data showed that both schistosomiasis haematobium and mansoni prevalences increased during the last nineteen years in Toho-Todougba site.     

Relationship between the transmission of schistosomiasis japonica and the construction of the Three Gorge Reservoir

OBJECTIVE: To study the relationship between the changes of environment and the transmission of Schistosomiasis japonica after the construction of the Three Gorge Reservoir. METHODS: On the basis of the predictive data on changes of water level and sediment in the middle and lower reaches of the Yangtze River after the dam construction provided by the Yangtze River Committee on Water Conservancy, corresponding data were collected and analyzed. In order to understand the effects of changes of water level and sediment on Oncomelania hupensis, the intermediate host of Schistosoma japonicum, field surveys and ecologically intimated experiments were done. The prevalence status and factors related to transmission were investigated by epidemiology, medical geography and public health. RESULTS: Positive impact on control of schistosomiasis is that floods in the Yangtze River will occur less and will decrease the dispersal of snails and the chances of infection for humans and animals as well. Snail habitats' beach will be reduced in the flushed area along the Yangtze River. Exploitation of beach and elimination of snails will benefit from the beach's uplift in flushed area. The floods ahead of time in autumn will interfere with the development of snails. Negative impact is that the flushed beaches and migratory settlements at certain altitude may become snail habitats. So the reservoir area will be a potential transmission area of schistosomiasis due to dispersal of infectious resources and Oncomelania snails. The uprising of the water body level may cause the expending of the snail habitats in some places of Jianghan plain during the transition of spring to summer. The destruction of the embankments of the Dongting Lake will be put off by its delayed flush, which causes the beach in a situation of growing reed-grass or grass for a long time that benefits the reproduction of the snails. The chances for schistosome infection to humans and animals will be on the increase, because the water regression occurs ahead of time in the Dongting Lake beach in autumn. The distribution of snails will not be affected by the changes of water level in the lower reaches of the Yangtze River after the dam is built, but the flushed section in Anhui in the recent 80 years are suitable for the snails' development. The environmental changes due to dam construction will not obviously affect the development of snails and the transmission of schistosomiasis in the Poyang Lake area. CONCLUSION: The construction of the huge dam and the formation of the Three Gorge Reservoir on the Yangtze River may have both positive and negative impact on schistosomiasis transmission and control. Great effort must be made to decrease the negative impact to avoid or, at least, to decrease S. japonicum transmission.     

2000～2006年安徽省池州市贵池区血吸虫病疫情分析

目的分析池州市贵池区血吸虫病疫情变化,为更好地控制血吸虫病提供依据。方法收集贵池区2000～2006年的血吸虫病疫情监测资料,整理流行状况、人畜病情、螺情等相关材料,采用Cochran-Mantel-Haenszel χ^2检验和Spearman秩相关方法进行指标间关系的统计学分析。结果贵池区一、二类流行村数呈下降趋势,三、四类流行村数逐渐增加（χ^2=281.5,P〈0.01）;人群病情呈波动趋势（χ^2患病率=3705.6,P〈0.01;χ^2发病率=507.5,P〈0.01）;耕牛患病率呈整体下降趋势（χ^2患病率=118.5,P〈0.01）;螺情呈整体下降趋势,与其他指标间的相关性无统计学意义。结论贵池区7年间的血吸虫病疫情得到了一定控制,但仍需继续加强监测,以防止疫情突然反弹。     

Use of circulating cathodic antigen (CCA) dipsticks for detection of intestinal and urinary schistosomiasis

An evaluation of a commercially available antigen capture dipstick that detects schistosome circulating cathodic antigen (CCA) in urine was conducted in representative endemic areas for intestinal and urinary schistosomiasis in Uganda and Zanzibar, respectively. Under field-based conditions, the sensitivity (SS) and specificity (SP) of the dipstick was 83 and 81% for detection of Schistosoma mansoni infections while positive predictive (PPV) and negative predictive values (NPV) were 84%. Light egg-positive infections were sometimes CCA-negative while CCA-positives included egg-negative children. A positive association between faecal egg output and intensity of CCA test band was observed. Estimating prevalence of intestinal schistosomiasis by school with dipsticks was highly correlated (r=0.95) with Kato-Katz stool examinations, typically within +/-8.5%. In Zanzibar, however, dipsticks totally failed to detect S. haematobium despite examining children with egg-patent schistosomiasis. This was also later corroborated by further surveys in Niger and Burkina Faso. Laboratory testing of dipsticks with aqueous adult worm lysates from several reference species showed correct functioning, however, dipsticks failed to detect CCA in urine from S. haematobium-infected hamsters. While CCA dipsticks are a good alternative, or complement, to stool microscopy for field diagnosis of intestinal schistosomiasis, they have no proven value for field diagnosis of urinary schistosomiasis. At approximately 2.6 US dollars per dipstick, they are presently too expensive to be cost-effective for wide scale use in disease mapping surveys unless Lot Quality Assurance Sampling (LQAS) strategies are developed.     

2004～2007年广西壮族自治区血吸虫病疫情分析

目的了解近年广西壮族自治区（广西区）血吸虫病疫情变化情况,探讨今后的防治监测策略。方法根据广西区19个流行县（市）2004～2007年血防监测工作年报表,收集相关数据进行汇总、统计分析。结果4年内采用酶联免疫吸附试验（ELISA）筛查、粪便检查确诊,对26345名当地居民查病,未发现当地感染的血吸虫病人,但在393名外来人员中发现9例血吸虫病人;粪检当地耕牛14326头,解剖野鼠8566只,均未发现血吸虫阳性;累计在289个乡（镇）开展螺情监测,查螺面积12095.1hm^2,共发现2个残存螺点,面积4.6hm^2。结论广西区血吸虫病疫情稳定,但在监测中发现输入性病人和较大面积的残存螺点,提示今后应该继续加强监测工作。