Identifying host species driving transmission of schistosomiasis japonica, a multihost parasite system, in China.

Understanding disease transmission dynamics in multihost parasite systems is a research priority for control and potential elimination of many infectious diseases. In China, despite decades of multifaceted control efforts against schistosomiasis, the indirectly transmitted helminth Schistosoma japonicum remains endemic, partly because of the presence of zoonotic reservoirs. We used mathematical modeling and conceptual frameworks of multihost transmission ecology to assess the relative importance of various definitive host species for S. japonicum transmission in contrasting hilly and marshland areas of China. We examine whether directing control interventions against zoonotic reservoirs could further reduce incidence of infection in humans or even eliminate transmission. Results suggest that, under current control programs, infections in humans result from spillover of transmission among zoonotic reservoirs. Estimates of the basic reproduction number within each species suggest that bovines (water buffalo and cattle) maintained transmission in the marshland area and that the recent removal of bovines from this area could achieve local elimination of transmission. However, the sole use of antifecundity S. japonicum vaccines for bovines, at least at current efficacies, may not achieve elimination in areas of comparable endemicity where removal of bovines is not a feasible option. The results also suggest that rodents drive transmission in the hilly area. Therefore, although targeting bovines could further reduce and potentially interrupt transmission in marshland regions of China, elimination of S. japonicum could prove more challenging in areas where rodents might maintain transmission. In conclusion, we show how mathematical modeling can give important insights into multihost transmission of indirectly transmitted pathogens.

[Prevalence and Control of Parasitic Zoonoses].

At present, parasitic zoonoses in China are characterized by the reappearance of traditional parasitic zoonoses and constant emergence of new ones, which makes the prevention and control more difficult. In this review, we introduce the classification, epidemiological features, the endemic factors of the infection, as well as the principles and strategies for control, in the aim to provide hints on the control of such diseases in the future.

[Evaluation on the effect of comprehensive control strategy of schistosomiasis with emphasis on infection source control in Anhui province].

OBJECTIVE: To evaluate the effect of comprehensive control strategy of schistosomiasis with emphasis on infection source control in Anhui province. METHODS: Forty endemic villages in Guichi district, Chizhou city, Anhui province were selected as national pilot villages in the years from 2006 to 2008, and another 10 provincial pilot villages were respectively selected from 10 highly endemic villages in 7 cities in 2007. The comprehensive infection source control measures, including "replace cattle with machines", "raise livestock in pens", "improve the sanitary toilets", "supply safe water " and so on were carried out among the above pilot villages. At the end of 2008, 13 national pilot villages and 6 provincial pilot villages were selected to investigate the popularity of schistosomiasis, and the effect of the comprehensive control strategy in those villages were compared. RESULTS: After implementing the comprehensive control strategy, the infectious rate of schistosomiasis in national pilot villages decreased from 4.57% (487/10 659) to 1.76% (147/8370), with the reduction rate at 61.49%, whose difference showed statistical significance (χ(2) = 115.16, P < 0.01); and the density of infected snails decreased from 0.0067/0.1 m(2) to 0.0008/0.1 m(2), the infectious rate of snails decreased from 0.28% to 0.04%, whose reduction rates were 88.06% and 85.71% respectively. While as to the provincial pilot villages, the infectious rate of schistosomiasis decreased from 1.27% (54/4254) to 0.21% (14/6592), with the reduction rate at 83.46%, whose difference showed statistical significance (χ(2) = 94.57, P < 0.01); and the density of infected snails decreased from 0.0025/0.1 m(2) to 0.0003/0.1 m(2), the infection rate of snails decreased from 0.13% to 0.05%, whose reduction rates were 88.00% and 61.54% respectively. CONCLUSION: The comprehensive control strategy with emphasis on infection source control implemented in marshland and lake regions can effectively control the transmission of schistosomiasis.

Tuning the Energetic Performance of CL-20 by Surface Modification Using Tannic Acid and Energetic Coordination Polymers.

The energetic performance of hexanitrohexaazaisowurtzitane (CL-20) was modulated with two energetic coordination polymers (ECPs), [Cu(ANQ)2(NO3)2] and [Ni(CHZ)3](ClO4)2, in this study by a two-step method. First, tannic acid polymerized in situ on the surface of CL-20 crystals. Then, [Cu(ANQ)2(NO3)2] and [Ni(CHZ)3](ClO4)2 were hydrothermally formed on the surface of CL-20/TA, respectively. Explosion performance tests show that the impact sensitivity of the coated structure CL-20/TA/[Cu(ANQ)2(NO3)2] is 58% less than that of CL-20 with no energy decrease. On the other hand, CL-20/TA/[Ni(CHZ)3](ClO4)2 can be initiated by a low laser energy of 107.3 mJ (Nd:YAG, 1064 nm, 6.5 ns pulse width), whereas CL-20 cannot be initiated by even 4000 mJ laser energy. This study shows that it is feasible to modify the performance of CL-20 by introducing energetic CPs with certain properties, like high energy insensitive, laser-sensitive, etc., which could be a prospective method for designing high energy insensitive energetic materials in the future.

Contrasting reservoirs for Schistosoma japonicum between marshland and hilly regions in Anhui, China--a two-year longitudinal parasitological survey.

Schistosoma japonicum remains highly endemic in many counties in China and has recently re-emerged, to a large extent, in previously controlled areas. To test the hypothesis that small rodents and less agriculturally important domestic animals such as dogs and cats may play an important role in the transmission and potential re-emergence of this disease, an annual investigation of S. japonicum among humans, domestic animals and rodents, combined with detailed surveys of the snail intermediate host, was performed across 3 marshland villages and 3 hilly villages in Anhui province of China over 2 consecutive years. The highest infection prevalence and intensity observed across all mammals was in rodents in the hilly region; while in the marshland, bovines were suspected as the main reservoirs. However, relatively high infection prevalence levels were also found in dogs and cats in both regions. Such results may have implications for the current human- and bovine-oriented control policy for this medically and veterinarily important disease, particularly within the hilly regions of mainland China.

[Evaluation of recombinant 29,000 extra membranous protein for the immunodiagnosis of schistosomiasis japonica].

OBJECTIVE: To evaluate the recombinant membranous protein 29000 (rSj29) of Schistosoma japonicum in the immunodiagnosis of schistosomiasis by indirect ELISA. METHODS: 394 serum samples collected from two low-endemic villages in Anhui Province were tested by rSj29-ELISA and AWA-ELISA using adult worm antigen (AWA) of S. japonicum. Meanwhile all subjects were each tested by 9 examinations with 3 fecal samples by modified Kato-Katz method, and by indirect hemagglutination assay (IHA). RESULTS: It was found that the positive detection rates of stool examination, IHA, rSj29-ELISA and AWA-ELISA were 4.8% (19/394), 62.2% (245/394), 68.3% (269/394), and 89.9% (354/394), respectively. There was no statistical difference between rSj29-ELISA and IHA (chi2 = 3.2, P > 0.05) with the coincidence of 80.7% (318/394). The coincidence of IHA, rSj29-ELISA and AWA-ELISA with stool examination was 42.6% (168/394), 36.0% (142/394), and 15.0% (59/394), respectively. CONCLUSION: The indirect ELISA with rSj29 antigen shows similar effect as IHA for the diagnosis of schistosomiasis.

Surveillance-based evidence: elimination of schistosomiasis as a public health problem in the Peoples' Republic of China.

BACKGROUND: A steady progress on schistosomiasis control in the Peoples' Republic of China (P.R. China) was achieved and broadened into the twelve-year medium and long term national plan (MLNP) which marled the implementation of an integrated control strategy across all endemic areas in P.R. China in 2004. To understand the endemic trends of schistosomiasis to assess the effectiveness of an integrated strategy, we conducted an analysis of schistosomiasis surveillance data spanned from 2005 to 2015. METHODS: The schistosomiasis sentinel surveillance data from sentinel sites were collected and analyzed from 2005 to 2015. In these sentinel sites, residents aged 6 years or above were screened annually by indirect hemagglutination assay (IHA), while only antibody positives were followed by stool examination either Kato-katz method (KK) and/or hatching technique (HT). Domestic animals raised in sentinel sites were examined by HT for confirming the infection of schistosomes. Snail investigation was conducted each year through systematic sampling method combined with environmental sampling method. The snails collected from field were tested by microscopic dissection method. The infection rates of schistosomes in residents, domestic animals and snails, as well as the indicators reflecting the snails' distribution were calculated and analyzed. ANOVA analysis was used to examine the changes of the number of eggs per gram feces in population and Chi-square test was used to examine any change in proportions among groups. RESULTS: A total of 148 902 residents from sentinel sites attended this study and 631 676 blood samples were examined by IHA test during the 11 covered years. The annual average antibody positive rates presented a significant decrease trends, from 17.48% (95% CI: 17.20-17.75%) in 2005 to 5.93% (95% CI: 5.71-6.15%) (χ2 = 8890.47, P < 0.001) in 2015. During 2005-2015, the average infection rate of schistosomes in residents declined from 2.07% (95% CI: 1.96-2.17%) to 0.13% (95% CI: 0.09-0.16%), accompanied by significant decrease of infection intensity in population. In 2015, the stool positives were only found in farmers, fishermen and boatmen with infection rate of 0.16% (95% CI: 0.11-0.20%), 0.17% (95% CI: 0-0.50%) respectively. The infection rate of schistosomes in domestic animals dropped from 9.42% (538/5711, 95% CI: 8.66-10.18%) to 0.08% (2/2360, 95% CI: 0-0.20%) from 2005 to 2015. Infections were found in eight species of domestic animals at the beginning of surveillance while only two cattle were infected in 2015. Totally 98 ha of new snail habitats were found, while 94.90% (93/98) distributed in lake and marshland regions. The percentage of frames with snails decreased from 16.96% (56 884/33 5391, 95% CI: 16.83-17.09%) in 2005 to 4.28% (18 121/423 755, 95% CI: 4.22-4.34%) in 2014, with a slightly increase in 2015. Meanwhile, the infection rate of schistosomes in snails was decreased from 0.26% (663/256 531, 95% CI: 0.24-0.28%) to zero during 2005-2015. CONCLUSIONS: The infection rate of schistosomes declined significantly, providing evidence that the goal of the MLNP was achieved. Elimination of schistosomiasis as a public health problem defined as WHO was also reached in P.R. China nationwide. Surveillance-response system should be improved and strengthened to realize the final goal of schistosomiasis elimination.

Parasite genetic differentiation by habitat type and host species: molecular epidemiology of Schistosoma japonicum in hilly and marshland areas of Anhui Province, China.

Schistosoma japonicum, a parasite of significant public health importance in parts of China and Southeast Asia, is a true generalist pathogen with over 40 species of mammals suspected as definitive host reservoirs. In order to characterize levels of parasite gene flow across host species and identify the most important zoonotic reservoirs, S. japonicum larvae (miracidia) were sampled from a range of definitive host species in two contrasting habitat types within Anhui Province, China: a low-lying marshland region, and a hilly region, where animal reservoir populations may be predicted to differ substantially. Miracidia samples were genotyped using seven multiplexed microsatellite markers. Hierarchical F-statistics and clustering analyses revealed substantial geographical structuring of S. japonicum populations within Anhui, with strong parasite genetic differentiation between habitat types. Within most villages, there was very little or no parasite genetic differentiation among host species, suggesting frequent S. japonicum gene flow, and thus also transmission, across species. Moreover, the data provide novel molecular evidence that rodents and dogs are potentially very important infection reservoirs in hilly regions, in contrast to bovines in the marshland regions. The parasite genetic differentiation between habitat types might therefore be associated with contrasting host reservoirs. The high levels of parasite gene flow observed across host species in sympatric areas have important implications for S. japonicum control, particularly in hilly regions where control of infection among wild rodent populations could be challenging.

China's new strategy to block Schistosoma japonicum transmission: experiences and impact beyond schistosomiasis.

Despite sustained efforts for its control made over the past 50+ years, the re-emergence of schistosomiasis in China was noted around the turn of the new millennium. Consequently, a new integrated strategy was proposed to stop the contamination of schistosome eggs to the environment, which emphasizes health education, access to clean water and adequate sanitation, mechanization of agriculture and fencing of water buffaloes, along with chemotherapy. Validation of this integrated control strategy in four pilot counties in the provinces of Anhui, Hubei, Hunan and Jiangxi revealed significant reductions in the rate of Schistosoma japonicum infection in humans and intermediate host snails. Importantly, this strategy showed an impact on diseases beyond schistosomiasis, signified by concomitant reductions in the prevalence of soil-transmitted helminth infections. In view of China's new integrated strategy for transmission control of schistosomiasis showing an ancillary benefit on other helminthic diseases, we encourage others to investigate the scope and limits of integrated control of neglected tropical diseases.

[Infectious status of infection sources in the epidemic regions of Schistosomiasis japonica in China].

OBJECTIVE: To understand the infectious status of infection sources in some epidemic regions of Schistosomiasis japonica, and provide a scientific basis for further controlling infection sources in a comprehensive way. METHODS: Longshang village which lies in the area of hills and mountains and Yuye village which lies in the area of lakes and marshlands were chosen for field investigation. The study was targeted at snails and 1512 residents, while 197 samples of livestock were randomized (80 cattle, 46 pigs, 45 dogs, 18 cats, 8 sheep) and 32 wild animals (field rats) were screened in Anhui province between October to November in 2007. The infection rate and intensity of infection were calculated after pathogenic examination on the populations, livestock and wild animals (field rats). RESULTS: (1) The infection rate of snails in Longshang and Yuye village were 2.26%, 1.06% in 2007, and 0.55%, 0.72% in 2006 respectively. (2) Of the infection rate and geometric mean of egg per gram (EPG) of population, 3.8% and 0.14 (EPG) were in Longshang village and 3.4% and 0.13 (EPG) were in Yuye village. The positive rate of blood examination of the different sex in Longshang village was 17.5% (44/252) of the males, higher than that of the females 11.0% (25/227) (chi(2) = 4.026, P = 0.045), whereas, in Yuye village was 21.4% (66/309) of males and 19.4% (25/129) for the females, without significant differences (chi(2) = 0.217, P > 0.05). The positive rate of fecal examination of the different sex in Longshang village was 5.2% (14/268) of the men and 2.1% (5/236) of the women showing no statistical significance (chi(2) = 3.336, P > 0.05); whereas, in Yuye village was 5.7% (14/245) of the men and 1.2% (3/250) of the women (chi(2) = 7.603, P = 0.006). (3) The infection rate and the arithmetic mean of EPG of the cattle, 10.8% (8/74) and 135.00 (EPG) were in Longshang village, meanwhile, the infection rate of the bull was 9.1% (6/66) and 25.0% (2/8) for cow without statistical significance (chi(2) = 0.586, P = 0.444), whereas, the total number of cattle was 6 that had been examined and there was no positive case in Yuye village. Of 8 sheep examined in Yuye village, 6 was positive, with arithmetic mean of 254.82 (EPG), while there was no sheep in Longshang village. (4) Of the positive rate of the incubation for dog's feces and intensity of infection, 55.6% (24/36) and 20.00 (EPG) were in Yuye village whereas 23.81% (5/21) and 1.21 (EPG) were in Longshang village. (5) Of the infection rate of the field rats, 13.64% (3/22) in Longshang village whereas a total number of mouse was 10 that had been examined and there was no positive case in Yuye village. CONCLUSION: The farm cattle should be still the chief sources of infection in the regions of lakes and marshlands for schistosomiasis. Whereas, with the implementing in-depth of the strategy on controlling source of infection in a integrated way, high priorities should be given to the epidemiological factors of the animals such as sheep, dogs, field mouse and so on which are spreading schistosomiasis.

Effect of floods on the transmission of schistosomiasis in the Yangtze River valley, People's Republic of China.

The aim of the present study was to assess the effect of floods on the transmission of schistosomiasis in the Yangtze River valley, People's Republic of China. Retrospective analyses of malacologic, clinical and epidemiologic data, covering a 22-year period, were carried out to elucidate the dispersal patterns of intermediate host snails (Oncomelania hupensis), and acute and chronic infections with Schistosoma japonicum in humans in relation to floods. Potential O. hupensis habitats in years with floods were 2.6-2.7 times larger than in years when water levels were normal. Both the density and infection rate of O. hupensis dropped in the first two years after a flood, but significantly increased in the third year. The number of acute cases with schistosomiasis japonica was markedly higher in years characterized by floods; on average, 2.8 times more cases were observed when compared to years that the Yangtze River had normal water levels. In view of our findings, emergency responses are warranted as soon as possible after the occurrence of a flood in order to avoid or mitigate the reemergence and spread of human schistosomiasis in the People's Republic of China.

[A case-control study on the risk factors of cerebral schistosomiasis japonica].

OBJECTIVE: To explore the risk factors of cerebral schistosomiasis japonica. METHODS: A total of 37 confirmed cases, diagnosed during 1999-2004 in Anhui Province, were involved in the study as case group. Three controls for each case were selected from the general population either without schistosomiasis, with chronic schistosomiasis or with acute schistosomiasis. The relevant risk factors on the disease were analyzed. RESULTS: Four factors with labour intensity, physical, economical and nutritional conditions before illness between case group and normal control group, 7 factors including epilepsy history, hypersensitivity, intensity and times of infection between case group and acute schistosomiasis control group, 10 factors including intensity of infection, times of infection and treatment between case group and chronic schistosomiasis control group, all showed statistical significance (p < 0.05) . Five factors showed statistical significance (p < 0.05) between case group and the 3 control groups. CONCLUSION: The intensity of schistosome infection and treatment history are the main risk factors for cerebral schistosomiasis, and the physical and psychosocial conditions of the patients show some effect on the disease.

[Schistosomiasis transmission in areas where inhabitants migrated from outside embankment to new settlement].

OBJECTIVE: To observe the impact on the transmission of schistosomiasis in areas where the local inhabitants migrated from outside embankment to new settlements. METHODS: Two villages (Chenqiao and Qingjie) where the inhabitants had moved out and another 2 villages (Jiangzhou and Xiaohuang) disused for both inhabitants and cultivated land were selected for the investigation. Data on prevalence in human and domestic animals, and Oncomelania snail habitats, were collected. RESULTS: After moving from outside embankment to new settlements, the density of infested snails in Chenqiao and Qingjie decreased by 79.1% and 45.2% in 2005 compared with that in 2002, and the infection rate of snails decreased by 75.5% and 84.9%, respectively (P < 001). In Jiangzhou and Xiauhuang, the density of infested snails decreased by 100% and 74.9% in 2005 compared with that in 2002, and the infection rate of snails decreased by 100% and 40.0%, respectively (P > 0.05). In villages that only disused for inhabitants, the density and egg-positive rate of feces collected from the wild were higher than the other 2 villages. However, in villages disused for both inhabitants and cultivated land, the density and egg-positive rate of wild feces decreased gradually and no egg-positive feces was found in 2005. The prevalence of schistosomiasis in humans in villages disused only for inhabitants changed slightly from 2002 to 2005, but decreased gradually in villages disused for both inhabitants and cultivated land. Higher prevalence in cattle was found in villages disused only for inhabitants. Number of cattle reduced yearly and no cattle left in villages disused for both inhabitants and cultivated land in 2005. CONCLUSION: No significant change on the factors of schistosomiasis transmission has been found in villages disused only for inhabitants, but the transmission has been effectively controlled in villages disused for both inhabitants and cultivated land.

Spatio-temporal pattern of schistosomiasis in Anhui Province, East China: Potential effect of the Yangtze River - Huaihe River Water Transfer Project.

Anhui Province has been one of typical epidemic areas of schistosomiasis in East China as a wide range of large lake and marshland regions provide an ideal environment for growth and reproduction of the intermediate snail host. With the completion of the Yangtze River-Huaihe River Water Transfer Project (YHWTP), launched by the end of 2016, the epidemic areas are expected to expand and controlling schistosomiasis remains a challenge. Based on annual surveillance data at the county level in Anhui for the period 2006-2015, spatial and temporal cluster analyses were conducted to assess the pattern of risk through spatial (Local Moran's I and flexible scan statistic) and space-time scan statistic (Kulldorff). It was found that schistosomiasis sero-prevalence was dramatically reduced and maintained at a low level. Cluster results showed that spatial extent of schistosomiasis contracted, but snail distribution remained geographically stable across the study area. Clusters, both for schistosomiasis and snail presence, were common along the Yangtze River. Considering the effect of the ongoing YHWTP on the potential spread of schistosomiasis, Zongyang County and Anqing, which will be transected by the new water-transfer route, should be given a priority for strengthened surveillance and control. Attention should also be paid to Guichi since it is close to one of the planned inlets of the YHWTP.

Epidemiology of schistosomiasis in the People's Republic of China, 2004.

Results from the third nationwide cluster sampling survey on the epidemiology of schistosomiasis in the People's Republic of China, conducted by the Ministry of Health in 2004, are presented. A stratified cluster random sampling technique was used, and 239 villages were selected in 7 provinces where Schistosoma japonicum remains endemic. A total of 250,987 residents 6-65 years of age were included in the survey. Estimated prevalence rates in the provinces of Hunan, Hubei, Jiangxi, Anhui, Yunnan, Sichuan, and Jiangsu were 4.2%, 3.8%, 3.1%, 2.2%, 1.7%, 0.9%, and 0.3%, respectively. The highest prevalence rates were in the lake and marshland region (3.8%) and the lowest rates were in the plain region with waterway networks (0.06%). Extrapolation to all residents in schistosome-endemic areas indicated 726,112 infections. This indicates a reduction of 16.1% compared with a nationwide survey conducted in 1995. However, human infection rates increased by 3.9% in settings where transmission is ongoing.

[Effectiveness of routinely used assays for the diagnosis of schistosomiasis japonica in the field].

OBJECTIVE: To evaluate the effectiveness of routinely used assays for schistosomiasis diagnosis in the field. METHODS: From late November to early December 2005, 6-65 years old inhabitants from 3 endemic villages were examined by Kato-Katz technique (3 thick smears) and nylon bag sedimentation/hatching method. At the same time, dipstick dye immunoassay(DDIA), fast enzyme linked immunosorbent assay (F-ELISA), indirect haemagglutination test A (IHA-A) and B ( IHA-B) were carried out in parallel RESULTS: 1864 people were examined by stool examination with an average positive rate of 9.7%. The missing rate of DDIA was relatively stable in medium and heavily endemic areas of schistosomiasis. The missing rate of nylon bag sedimentation/hatching method was 25% and relatively stable when the number of eggs per gram of feces(EPG) was larger than 100. The average positive rate of DDIA, F-ELISA, IHA-A and IHA-B was 47.8%, 50.0%, 66.3% and 40.1% respectively. Using stool examination as the gold standard, the sensitivity of DDIA, F-ELISA, IHA-A and IHA-B was 75.3%, 65.8%, 85.6% and 76.0%; and the specificity was 55.1%, 51.7%, 35.7% and 63.6%, respectively. Among the four sero-diagnostics, the specificity, Youden index, positive likelihood rate and coincidence of IHA-B were the highest. CONCLUSION: Kato-Katz method is more stable and effective than nylon bag sedimentation/hatching method in medium and heavily endemic areas of schistosomiasis japonica. The sensitivity and specificity of these four diagnosis kits are lower than 90%.

[Potential impact of water transfer project from Yangtze River to Huaihe River on snail spread and schistosomiasis transmission].

OBJECTIVE: To investigate the possibility of spread of snails and transmission of schistosomiasis japonica due to the construction of water transfer project from Yangtze River to Huaihe River. METHODS: In order to understand the current endemic situation of schistosomiasis in the project area, the distribution of snails was surveyed by routine methods, level of anti-schistosome antibody in human sera was detected by indirect haemagglutination test (IHA), and the prevalence of schistosomiasis in cattle was detected by egg hatching method. The snail survival and reproduction were observed in Chaohu Lake area(experimental area) and a control area for one year. RESULTS: Snail density was high in two starting points, from where the water in Yangtze River will be directed to Huaihe River. In counties of Wuwei and Hexian, through which the project will be built, the positive rate of anti-schistosome antibody in residents was 22.11% (168/760) and 18.59% (37/199), schistosomiasis prevalence in cattle was 2.42% (9/371) and 0.2% (2/997), respectively. Schistosomiasis was also endemic in Juchao District of Chaohu City. Snails respectively from grassland and hilly area were collected and put in Chaohu Lake for breed and newborn snails were found one year later. During the egg-laying season, the survival rate of snails from grassland in 2 experiment areas and a control area was 11.3%-16.7%, 3.0%-20.8% and 4.7%-14.7% respectively (chi2 = 0.093, 0.760, P > 0.05; chi2 = 0.647, 0, P > 0.05), and that of snails from hilly area was 24.1%-44.4%, 37.8%-67.3% and 86.3%-93.1% respectively (chi2 = 9.575, 5.302, P < 0.05; chi2 = 56.863, 36.218, P < 0.05). There was no significant difference between the experimental area and the control area on the number of eggs in the ovaries of the same type female snails. CONCLUSION: The one-year observation reveals that the construction of the project might result in spread of snails and transmission of schistosomiasis japonica in the relevant areas.

[Observation on the change of anti-S. japonicum antibody level in population migrated from outside embankment to new town].

OBJECTIVE: To detect the change of the anti-S. japonicum antibody level after people migrated from outside embankment to newly established town. METHODS: Three pilot spots were established for the investigation: one spot that both inhabitancy and cultivation disuse (A), one spot that only inhabitancy disuse but farming continued (B) and the third one served as control (C). DIGFA and ELISA were used to detect the antibody level in the populations from 2002 to 2005. RESULTS: The positive rate of anti-S. japonicum antibody declined significantly from 6.63% to 3.52% by DIGFA and from 7.26% to 3.71% by ELISA at spot A (chi2=5.2625, P<0.05; chi2=6.3296, P<0.05, respectively). There was no significant difference on the positive rate of antibody in spots B and C. The average A450 value of ELISA in the three spots was statistically analyzed by One-Way ANOVA. It was only in spot B that the average A450 value declined from 0.182 in 2003 to 0.147 in 2005 (P<0.01). CONCLUSION: The anti-S. japonicum antibody level in human population has decreased at certain degree after they migrated from outside embankment to new town.

An economic evaluation of the national schistosomiasis control programme in China from 1992 to 2000.

The World Bank Loan Project, by far the largest effort in China for schistosomiasis control since control activities were initiated in the mid 1950s, was carried out for a 9-year period commencing in 1992 in the 8 provinces where Schistosoma japonicum remained endemic when the project started. To evaluate its impact, a retrospective economic evaluation was done in 2001. Six representative counties, i.e. Huarong in Hunan province, Qianjiang in Hubei province, Yugan in Jiangxi province, Tongling in Anhui province, Xichang in Sichuan province and Dali in Yunnan province, were selected for the study. The total financial input in these counties from 1992 to 2000 was RMB Yuan 90.334 million with the World Bank loan accounting for 40.9%. Control efforts resulted in reduction of human prevalence rates in the six counties from 0.7-9.0% in 1992 to 0.1-2.7% in 2000. With regard to S. japonicum infection in bovines, a high reduction was observed in Qianjiang, and smaller decreases were noted in four counties, while there was an increase in Dali. In general, the areas infested by the intermediate host snail fluctuated around the initial level. The net benefit-cost ratio was 6.20, which means that this project gained US$ 6.20 for every dollar spent. The correlation coefficients of the net benefit-cost ratio to the human and bovine infection rates at the beginning of the project were 0.55 and 0.66, respectively. It is conceivable that further progress in schistosomiasis control is an important feature for sustained growth of the local economy, particularly in areas where control of the disease has been most challenging.

Transmission of Schistosoma japonicum by humans and domestic animals in the Yangtze River valley, Anhui province, China.

The aim of the present work was to assess the relative contribution to transmission of Schistosoma japonicum by humans and domestic animals in two villages in the Yangtze River valley in Anhui province, China. A cross-sectional survey was conducted to determine the prevalence and intensity of S. japonicum in humans, cattle, water buffaloes, horses, pigs, goats, dogs and cats. Additionally, for each host species the number of individuals and the mean faecal excretion per day was determined. Results showed that both prevalence and intensity of infection varied significantly between species and between the two villages and neither of the variables gave an adequate picture of the potential transmission. Total daily egg excretion was significantly higher in Chenqiao village compared with Guanghui village. Whereas humans were the main contributors to transmission of schistosomiasis in Guanghui village (80.4%), water buffaloes accounted for nearly 90% and goats for more than 5% of the transmission in Chenqiao village. Hence, the present study suggests that schistosomiasis transmission might vary significantly within Chinese farm districts and successful control should rely on prior transmission index determinations on major potential contributors rather than routine data of prevalence and intensity of infection. Further studies should determine the value of adding other transmission variables like egg hatchability and faecal deposition habits.