[Effect of calcium cyanamid synthetic drug on Schistosoma japonicum egg morphology].

OBJECTIVE: To study the morphological change of Schistosoma japonicum eggs processed by calcium cyanamide synthetic drug, so as to provide the basis for further study of the mechanism that calcium cyanamide synthetic drug to schistosome eggs. METHODS: The calcium cyanamide synthetic drug was added to the cattle feces containing schistosome eggs and mixed up, and then the cattle feces was stacked as original shape on the marshland. Blank controls were set at the same time. The cattle feces samples were collected and.the schistosome eggs were observed under a microscope on the 1st, 2nd, 3rd, 7th day after the experiment. RESULTS: By the effect of calcium cyanamide synthetic drug, the color of eggs was deepening gradually, the miracidia were atrophied, and the shells of eggs were thickened. The embryonic membrane of miracidia was no longer completed 3 days later, and the miracidia were deformed severely 7 days later. The atrophy of miracidia was not obvious in the blank controls. CONCLUSION: The schistosome miracidia and embryonic membrane can be damaged by the calcium cyanamide synthetic drug, and worse damaged with time extending.

[Effect of schistosomiasis control in towns reached criteria of infection controlled in Nanchang City].

OBJECTIVE: To evaluate the effect of schistosomiasis control in towns that had reached the criteria of infection controlled in Nanchang City. METHODS: The residents and livestock of 14 towns that had reached the criteria of infection controlled in Nanchang, Xinjian and Jinxian counties of Nanchang City were sampled to investigate the schistosomiasis endemic situation, Oncomelania hupensis snail status, and data of schistosomiasis control work. RESULTS: The positive rate of serum tests of the residents was 2.58%, and no positive stool samples were found. No cattle or sheep were positive in stool tests. Totally 1 635 snails were caught, and 1278 were alive with an average density of living snails of 0.051/0.1 M2, while no schistosome infected snails were found. All the surveyed administrative villages had the completed files of schistosomiasis control. Conclusion All the 14 towns that had reached the criteria of infection controlled of schistosomiasis have already reached the criteria of transmission controlled in Nanchang City.

[Current status of human Schistosoma japonicum infection and reinfection in marshland and lake regions of Xinjian County, Jiangxi Province, China].

OBJECTIVE: To understand the dynamics of human infection and reinfection of Schistosoma japonicum after chemotherapy in marshland and lake endemic regions so as to provide the evidence for developing a cost-effective control strategy. METHODS: From 2007 to 2011, the schistosome infection, intensities and reinfection of population were investigated and the results were analyzed dynamically in Caohui Village, a national schistosomiasis surveillance site in Changyi Township, Xinjian County, Jiangxi Province, China. RESULTS: The schistosome infection rate was 3.55% and the mean intensity was 1.56 in 2007, and the schistosome infection rate was 1.52% and the mean intensity was 1.60 in 2011. The reinfection rates were 2.70%, 9.09% and 2.47% in 2009, 2010, and 2011, respectively. CONCLUSION: The schistosomiasis endemic situation shows a downtrend in the village. However, the reinfection is still serious; therefore, we should strengthen the research of risk factors of reinfection and control them.

[Epidemic situation of acute schistosomiasis in Nanchang City of Jiangxi Province from 2005 to 2012].

OBJECTIVE: To understand the endemic regulation of acute schistosomiasis in Nanchang City of Jiangxi Province from 2005 to 2012 so as to provide the reference for policy-making of schistosomiasis control. METHODS: The data of acute schistosomiasis were collected and analyzed with the descriptive epidemiology method in Nanchang City from 2005 to 2012. RESULTS: A total of 52 acute schistosomiasis cases were reported in Nanchang City from 2005 to 2012. The morbidity of acute schistosomiasis was 0.003 46% in 2005, and it was 0 in 2012. The morbidity of acute schistosomiasis in different years was significant different (chi2 = 61.077, P < 0.01). The duration of incidence was from May to November, but the peak of the incidence was July. The sex ratio between males and females was 4.78:1 (43:9, chi2 = 22.231, P < 0.01). The ages of cases showed double humps, namely the 6-15 years' group and 30-40 years' group. Most of the acute cases were farmers (65.38%), students (25.00%), and fishermen (3.85%). Fishing and swimming were the main infection ways, with the infection rates of 63.46% and 26.92%, respectively. CONCLUSION: The susceptible populations are peasants and young students; therefore, we should strengthen health education for these high-risk groups.

[Effect of niclosamide spreading oil on killing schistosome cercariae].

Dechlorinated water (100 ml, 30 degrees C) was put into a plate (diameter 15 cm), and 1% niclosamide spreading oil 5 microl was added, then a ring of Schistosoma japonicum cercariae were picked up to the plate. The time of killing all the cercariae was observed at three time points (immediately, 24, 48 h), and the dechlorinated water was used as control. The results showed that schistosome cercariae were all killed in three minutes by 1% niclosamide spreading oil at the three time points. The cercaria-killing effects of each time point were not significantly different (F = 0.062, P > 0.05). The cercariae were alive in the control in 48 h.

[Influencing factors of changes of Oncomelania snail densities in Poyang Lake region, Nanchang City, 2011].

OBJECTIVE: To explore the influencing factors of the significant decrease of snail densities in Poyang Lake region, Nanchang City, 2011. METHODS: According to the elevation of the environment, 5 grasslands where there were high snail densities and their elevations were from 14 to 17 m were selected as study areas. The data of snails in the past three years and the hydrological information in the past five years were collected and analyzed. The current snail status was surveyed and the fishermen were interviewed. RESULTS: The snail density of Poyang Lake region in Jinxian County decreased by 91.2% in 2011 compared with that in 2009 (P < 0.01). In 2010, the water levels were 13.90 m in April and 16.07 m in May respectively in Xingzi Station, and the rainfalls were 312 mm in April and 356 mm in May in Poyang Lake region; in 2011, the water levels were 8.73 m in April and 10.31 m in May respectively in Xingzi Station, and the rainfalls were 90 mm in April and 145 mm in May respectively in Poyang Lake region, which were lower than those during the past five years. There was no any other apparently unusual phenomenon. CONCLUSION: The significant decrease of snail densities in Poyang Lake region in 2011 may be related to the long soaking time of marshland in 2010 and low rainfall in the first half of 2011.

[Study on an intervention model of "schools without infected students with schistosoma japonica" in heavy endemic areas].

OBJECTIVE: To study an intervention model of "schools without infected students with schistosoma japonica", to control and prevent students from schistosoma infection. METHODS: Twelve primary schools of four heavy endemic counties (districts) with schistosomiasis in the Poyang Lake areas were selected as the study fields, of which, ten schools were the experimental groups, and the other two schools were the control groups by cluster random sampling. All enrolment students were the target population. The baseline survey was carried out in 2005, and an intervention model, "information dissemination + behavior participation + behavior encouragement", was applied in the experiment groups in 2006 - 2008, then the effect of intervention was assessed. RESULTS: Before intervention (2005), the anti-schistosomiasis knowledge awareness rate of experimental and control groups were 14.75% (324/2196) and 16.58% (91/549), and the different was not significant (χ(2) = 1.14, P > 0.05); the rate of accurate attitude of anti-schistosomiasis were 14.71% (323/2196) and 11.84% (65/549) in experimental and control groups, and the difference was not significant (χ(2) = 2.98, P > 0.05); the rate of contacting infected water were 15.44% (18 988/122 976) and 15.03% (4622/30 744) in experimental and control group and the difference was not significant (χ(2) = 3.13, P > 0.05); and the infection rate of schistosomiasis of experiment control groups were 9.65% (212/2196) and 10.56% (58/549), the difference was not significant (χ(2) = 0.41, P > 0.05). After one year intervention (2006), the anti-schistosomiasis knowledge awareness rate of experimental and control groups were 97.79% (2032/2078) and 18.11% (98/541), and the different was significant (χ(2) = 1794.31, P < 0.01); the rate of accurate attitude of anti-schistosomiasis were 99.09% (2059/2078) and 13.49% (73/541) in experimental and control group, and the difference was significant (χ(2) = 2077.45, P < 0.01). After 1 - 3 years intervention (2006 - 2008), there were no any contactors with infected water and infectors with schistosome in students of the experiment group in successive 3 years. While in the control group of the same period, the rate contacting infected water were 16.12% (4884/30 296), 11.11% (3079/27 720) and 12.25% (3451/28 168); the infection rate of schistosomiasis were 8.87% (48/541), 7.47% (37/495) and 7.95% (40/503), respectively. CONCLUSION: The intervention model of health promotion, "information dissemination + behavior participation + behavior encouragement", can effectively control and prevent students from infecting schistosoma japonica in heavy endemic areas with schistosomiasis.

[Establishment and application of school-based health promotion and intervention model of schistosomiasis in lake-type endemic area].

OBJECTIVE: To establish an intervention model of school health promotion, and apply it in developing "schistosomiasis-free schools". METHODS: At the pilot stage, all students of Henghu primary school and Banshan primary school in Xinjian County of Jiangxi Province were selected as experiment group and control group, respectively. A baseline survey covered knowledge and attitude on schistosomiasis control, water contact behaviors and Schistosoma japonicum infection rate. Two health promotion intervention models, i.e. "information communication + training of protection skill + reward & punishment" (model A, 1993-1999) and "information communication + behavior participation + encouragement" (model B, 2000-2007), were implemented in Henghu school. The effect of two models was compared by infection rate. At the application stage, all students of 8 schools in Xinjian County, Nanchang County, and Jinxian County were chosen for evaluation of the effectiveness of Model B with same methods and index. RESULTS: Before intervention there was no significant statistical difference on the passed rate of anti-schistosomiasis knowledge, correct rate of anti-schistosomiasis attitude, frequency of infested water exposure and the infection rate between Henghu and Banshan schools (P > 0.05). In Henghu school, the intervention showed significant effect on the scores of knowledge and attitude after one year (P < 0.01), raised from 9.0% and 55.1% before intervention to 94.4% and 98.9% after intervention, respectively. The frequency of infested water exposure and the infection rate significantly decreased from 14.6% and 13.5% before intervention to 1.9% and 2.3%, respectively (P < 0.01). In 2-7 years after intervention, there were only one or two schistosomiasis cases each year. At the application stage, no schistosomiasis cases were found among Model B target population in two successive years after intervention. CONCLUSION: The practice of Model B can be extended to other schools in endemic area to develop "schistosomiasis-free schools".

[The second stage larvae of Ascaris lumbricoides].

OBJECTIVE: To induce the apoptosis of human alveolar epithelial cells (A549) by the extraction of the second stage larvae of Ascaris lumbricoides and investigate the extraction concentration and inducing time related to the apoptosis. METHODS: Following to the results of Microculture Tetrazolium Test (MTT), five concentrations of the extraction of the second stage larvae were chosen to induce the apoptosis of A549 cells. Meanwhile, control groups without the inducement were set up. For each group, observation was made at five time points since the start of inducement, to assess the existence of apoptosis and percentage of cells showing characteristics of apoptosis. HE stain and diphenylamine reaction methods were used to assess the cell apoptosis. Agarose gel electrophoresis of DNA and flow cytometry were also employed to confirm the apoptosis for some groups. RESULTS: Observations indicated that the apoptosis ratio of A549 cells induced by the extraction at different concentrations were significantly higher than that of the control cells (P < 0.05). At most time points of observation, the apoptosis ratio increased with the increase of concentration, indicating a positive correlation between them. For each concentration group, the apoptosis ratio increased as the inducing time prolonged until a peak appeared at 5 h of the inducement. CONCLUSION: The extraction of the second stage larvae of Ascaris lumbricoides can induce apoptosis of human alveolar epithelial cells in vitro with a concentration-dependent pattern. With regard to the relationship of apoptosis to the time of inducement, two trends were revealed and the relationship also influenced by the concentration of the larvae extraction.