Effect of integrated control intervention on soil-transmitted helminth infections in Jiangxi province in southeast China.

Soil transmitted helminths (STHs) burden was enormous in China several decades ago, however, rigorous control efforts have been successful with appreciable reduction in diseases burden. Here, we assessed provincial-level data derived from cross sectional surveys, executed in 1989, 2002 and 2014, on the prevalence of STHs among populations in Jiangxi province, China. This study, also, reported STHs integrated control intervention aimed at reducing STHs transmission and worm burden among population at county-level. The intervention strategies included mass drug administration (MDA), health education, improved water supply for drinking, improved sanitary facilities and environmental modification in Guixi municipality. The overall infection rate of STHs in Jiangxi province decreased from 77.7% (1989) to 6.3% (2014), while Ascaris lumbricoides, hookworm and Trichuris trichiura decreased from 71.1%, 17.6% and 17.0% (1989) to 0.9%, 4.7% and 1.0% (2014), respectively. STHs infection rates in female population were higher than male in the three surveys. Reduction in STHs prevalence was observed in all age groups, but the decline was less in higher age group. STHs prevalence in Guixi intervention region indicated remarkable reduction from 31.8% (2006) to 6.1% (2009) (χ2＝255.22, P＜0.01). A. lumbricoides, hookworm and T. trichiura infection rates decreased from 10.4%, 17.0% and 7.1% (2006) to 0.1%, 4.1% and 2.2%, respectively (2009) (X2A.l = 110.23, P<0.01; X2hk = 103.57, P < 0.01; X2T.t = 32.0, P < 0.01). A. lumbricoides infection rate declined the most of all STHs. Following control efforts with integrated control intervention strategies, STHs prevalence in Jiangxi province experienced remarkable trend in decline between 1989 and 2014. Consolidating control efforts with sustained integrated control strategies is, therefore, important to achieving STHs elimination in China.

[Progresses of alpine treeline formation mechanism.] / é«˜å±±æž—çº¿å½¢æˆæœºç†ç ”ç©¶è¿›å±•.

Alpine treelines represent one of the most distinct vegetation boundaries between canopy closed montane forest and treeless alpine vegetation. This transitional ecotone is highly sensitive to global and regional climate change and is considered as an ideal indicator of such changes. Treeline studies have evolved from morphological description to various hypotheses of treeline formation. Although individual hypothesis may provide reasonable explanation locally, a generalized hypothesis that is applicable on the global scale is still lacking. Temperature is considered the limited factor controlling the distribution of alpine treeline as low temperature restricts biochemical processes of tree growth. However, which particular biochemical processes are affected by low temperature remains unknown. This paper summarized the mechanisms of treeline formation with a focus on how low temperature affects photosynthesis characteristics, nutrient characteristics, non-structural carbohydrate (NSC) and antioxidant system. We also reviewed the key issues and future perspectives in treeline research.

[Effect of schistosomiasis control strategy based on infection source control of Poyang Lake region in Yongxiu County promotion zone].

OBJECTIVE: To evaluate the effect of schistosomiasis control strategy with emphasis on infection source control in the Yongxiu County promotion zone of Poyang Lake region. METHODS: The Wucheng Township of Yongxiu County was selected as the observation site, and the effect of the comprehensive control strategy was evaluated by using the method of field surveys combined with retrospective investigations. RESULTS: In 2010, there were 17 persons whose stool tests for schistosome infection were positive, and the number of calculated schistosomiasis patients was 2,331. The infection rate of cattle was 4.5%, and the area with infected Oncomelania hupensis snails was 10.00 hm². In 2011, the comprehensive control strategy was carried out, and in 2012, there were no cattle in the promotion zone. In 2013 and 2014, there were no schistosomiasis patients with positive stool tests. In 2014, no schistosome infected snails were found. CONCLUSION: The control strategy with emphasis on infection source control effectively controls the transmission of schistosomiasis in Yongxiu County promotion zone.

[Studies on impact of Water Conservancy Project of Poyang Lake on schistosomiasis transmission I: impact of water level regulation schemes of project on Oncomelania hupensis snail habitats].

OBJECTIVE: To investigate the impact of the Water Conservancy Project of Poyang Lake after operation on Oncomelania hupensis snail habitats in 10 counties (cities or districts) around Poyang Lake. METHODS: The data of the distribution, numbers, areas, elevation and slope, etc. of snail infested marshlands on upstream of the project site in Poyang Lake were investigated and collected. Accordingly, the status of the submerged and flooding areas of the marshlands were analyzed and calculated respectively in the case that the project ran by different water regulation schemes at 14, 13, 12 m and 11 m levels. RESULTS: In accordance with the regulation and storage preset programs at 14, 13, 12 and 11 m water levels, the number and its areas of submerged marshlands, from downstream to upstream in Poyang Lake, in turn decreased. Under the condition of the regulation at the 14 m water level, the numbers of completely submerged and partially submerged marshlands as well as the submerged areas were accounted for 32.9%, 51.4% and 60.3% of the whole marshlands, respectively. At the 13 m water level regulation, they were 9.8%, 46.8% and 1.9% respectively. At the 11 m level, only part of 4 marshlands were flooded, which were accounted for only 0.5% of the total number of marshlands and 0.2% of whole areas of the marshlands. CONCLUSIONS: The Water Conservancy Project of Poyang Lake may create a condition for eliminating snails through water flooding. If implementing regulation at the 14 m level for two or three consecutive years, 60.3% of snail habits could realize the snail-free objective. However, if implementing the 11 m or 10 m water level regulation, there will be little impact on areas of snail habitats and the snail distribution in the Poyang Lake region from the point of view of "marshlands flooding". The impacts on marshlands in different counties might differ due to the location and elevation.

[Assessment and analysis of risks of realizing schistosomiasis transmission control in Jiangxi Province].

OBJECTIVE: To evaluate the situation of realizing schistosomiasis transmission control in Jiangxi Province. METHODS: The situation of reaching the criteria of schistosomiasis transmission control was evaluated by using the method of field surveys combined with retrospective investigations. RESULTS: The schistosome infection in human was kept at a stable low level, and the infection rate in residents was below 1% in 90.24% (536/594) of whole epidemic controlled villages. There were 45 spots with schistosome infected Oncomelania hupensis snails in 38 pieces of marshland. The epidemic situation in livestock showed less optimistic than that in human, and the infection rate in bovine was higher than 1% in 19.87% (118/594) of the whole epidemic controlled villages. CONCLUSIONS: Currently, the prevalence of schistosomiasis is at a low level in 9 infection-controlled counties of Jiangxi Province. More favorable situation has emerged to the realization of schistosomiasis transmission control. However, it is necessary to strengthen the infectious sources control with emphasis on bovine so as to achieve the goal of transmission control in whole province in 2015.

[Prevalence and control of schistosomiasis in Jiangxi Province during 2002-2012].

OBJECTIVE: To analyze the status of prevalence and control of schistosomiasis in Jiangxi Province from 2002 to 2012. METHODS: Endemic status and control effectiveness during the period from 2002 to 2012 was analyzed by using a combination of field survey, data collection and retrospective investigation. RESULTS: From 2002 to 2012, schistosomiasis control made significant achievements in Jiangxi Province. The number of counties which have reached the criteria of transmission interruption of schistosomiasis increased from 19 in 2002 to 22 in 2012. The number of patients with schistosome infection decreased from 128 331 in 2002 to 73 102 in 2012. The positive rate of serological test and fecal examination in residents decreased from 12.2% and 4.2% in 2002 to 5.2% and 0.4% in 2012, respectively. Acute infection reduced from 146 cases in 2002 to 3 cases in 2012, but advanced cases increased by 42.4%. The positive rate of fecal examination in cattle reduced from 4.7% in 2002 to 1.3% in 2012. The density of living snails and infected snails significantly decreased to 0.083 5/0.1 a? and 0.000 037/0.1 m2 in 2012, respectively. However, the snail-ridden areas slightly increased. Jiangxi Province reached the criteria of endemic control for schistosomiasis in 2008. During 2002-2012, control activities were intensified. Examination and chemotherapy for human increased by 65.2% and 65.5%, while 23.4% and 251.1% for cattle. Mean while, area with snail control activities increased by 617.8%. An integrated strategy of infection source control was implemented in the Province. CONCLUSION: During 2002 to 2012, endemic index of schistosomiasis in Jiangxi showed a steady decline after 2005. Currently, schistosomiasis prevalence shows a low level. The endemic indicators of infection in human and livestock as well as Oncomelania snails have been kept stable at low level.

[The changes of hydrological regime in Poyang Lake after runs of Three Gorges Project and its impact on prevalence of schistosomiasis in the lake region].

OBJECTIVE: To clarify new features of hydrological regime in the Poyang Lake after runs of the Three Gorges Project and its impact on the prevalence of schistosomiasis in this region. METHODS: It is collected information of Three Gorges Project, average daily water level from 2002 to 2012 at Duchang hydrological station in Poyang Lake and the data of prevalence and control of schistosomiasis in 12 endemic counties along the lake. It was analyzed the trends of prevalence of schistosomiasis under the changed condition of hydrologic situation. RESULTS: Effects of impoundment of Three Gorges reservoir running on water level of Poyang Lake are mainly shown in: Water levels of the lake are suppressed throughout the year which was characterized by high water level in flood season dropped, lower water level appeared in the spring, water withdrew earlier and quicker in the fall and to an even lower level in dry season. After impoundment of Three Gorges Project, infection rate of Schistosomajaponica in human and in bovine decreased by 92.65% and 76.37% respectively in endemic areas around the lake. The density of Oncomelania snails decreased by 94.21%. Prevalent of schistosomiasis in this region showed a significant downward trend. CONCLUSIONS: After runs of the Three Gorges Project, regularized changes hydrologic conditions has taken place in Poyang Lake which is characterized by lower water level and thus might lead to lower density of Oncomelania snails on marshlands and reducing of prevalence of schistosomiasis. Significant strengthening of schistosomiasis control efforts might also contributed to the stable and low level of prevalence of schistosomiasis in the region.

[Retrospective investigation on changes of endemic situation before and after reaching criteria of schistosomiasis transmission controlled or interrupted in hilly endemic areas of Jiangxi Province].

OBJECTIVE: To investigate the changing rules of schistosomiasis endemic situation before and after reaching the criteria of schistosomiasis transmission controlled or interrupted in hilly endemic areas of Jiangxi Province, so as to provide the evidence for reformulating the criteria of schistosomiasis control and eradication in the future. METHODS: In the hilly areas of schistosomiasis endemic in Jiangxi Province, 2 counties where the transmission has been interrupted and 1 county where the transmission has been controlled were selected and investigated with the retrospective research method. The endemic detailed data were collected and recorded 10 years before reaching the criteria of transmission interrupted/controlled, and several years after reaching the criteria (ending in 2008), and then a database was established. The changing rules of endemic situation before and after reaching the criteria of transmission interrupted/controlled were analyzed and compared. RESULTS: After reaching the criteria of transmission controlled, in the 3 counties, Guangfen, Shangrao and Dean, the declined rates of areas with Oncomelania hupensis snails were 96.79%, 98.99%, and 99.77% respectively. The snail density maintained a lower level, and 95% of infected persons and cattle were cured. The average time from transmission controlled to the transmission interrupted was 17 years in Guangfen County and 26 years in Dean County. However, in Shangrao County, the snail situation rebounded due to the snail re-found and spread although the schistosomiasis morbidity of population/animals maintained stably. CONCLUSIONS: After reaching the criteria of transmission interrupted/controlled, the remained snails were easy to re-find and spread under some certain condition, which is one of main obstacles for reaching the criteria of transmission interrupted. In an isolated snail unit, if the snail area and snail density are controlled in a very low level, it is still difficult to transmit and spread schistosomiasis even if there exist infectious sources.

[Surveilance and response for Schistosomiasis japonica based on sentinel mice examination for cercariae-infested water in risk region, 2012].

OBJECTIVE: To monitor water body infestation in schistosomiasis high-risk areas with sentinel mouse technique. METHODS: A total of 72 surveillance sites from 47 counties were selected in Hunan, Hubei, Jiangxi, Anhui, Jiangsu, Yunnan, and Sichuan. The water infectivity of Schistosoma japonicum was determined in the surveillance sites by using sentinel mice during June-July and September, 2012. RESULTS: Among the 3,283 sentinel mice which were placed in 72 sites, 3,062 (93.3%) were recovered and dissected. Infected sentinel mice were found in six sites accounting for 8.3% (6/72) of the total surveillance sites, with an occurrence rate of sites with infected mice of 8.3% in June-July and 2.8% in September. 33 infected mice were discovered with a total infection rate of 1.08% (33/3,062). 1,085 adult worms were collected, with a mean worm burden of 32.9 worms per mouse in infected sentinel mice. 4 positive sites were in Hunan and 2 were in Jiangxi. Local acute schistosomiasis or suspected local acute cases which detected elsewhere were reported in 2 positive sites. Some follow-up activities were conducted in the 6 positive sites. CONCLUSION: Compared with those in 2010, the schistosomiasis risk areas are shrinking in 2012. However, some regions are still the schistosomiasis high-risk areas.

[Surveillance and forecast of Schistosoma japonicum-infected sentinel mice in key water regions of China in 2010].

OBJECTIVE: To explore the approach and tool for surveillance and forecast of schistosomiasis, so as to provide scientific evidence for improving the sensitivity of the surveillance and forecast system of schistosomiasis. METHODS: Two field detections were carried out in June and September by using the determination of sentinel mice in key high-risk water regions of 7 provinces of Hunan, Hubei, Jiangxi, Anhui, Jiangsu, Yunnan and Sichuan, and the sentinel mice were raised in laboratory and dissected for observation of schistosome infections. The database regarding schisosome infections in key water regions of China was established, and the tempo-spatial distribution and environmental features of the national surveillance and forecast sites with positive sentinel mice were analyzed. RESULTS: A total of 72 surveillance and forecast sites were detected in 34 counties (cities, districts) of 7 provinces. Of the 2 667 sentinel mice placed, 2 613 were recovered, with a recovery rate of 97.98%. Among the 72 sites detected, 17 were detected with positive sentinel mice, and the occurrence rate of positive sites was 23.61%. The occurrence rate was 17.24% (10/58) in June and 14.71% (10/68) in September, and no significant difference was observed between two batches (chi2 = 0.151, P = 0.698). Of the 2 436 sentinel mice dissected, 90 were positive, and 459 schistosome worms were collected, with a total infection rate of 3.69%, and the mean worm burdens of positive mice were 5.10 worms per mouse. The infection rate of sentinel mice was 2.82% (31/1 099) in June and 4.41% (58/1 337) in September, the infection rate of sentinel mice was significantly higher in September than that in Juen (chi2 = 14.681, P < 0.01), and the mean worm burdens of infected sentinel mice were 2.45 worms per mouse in June and 6.49 worms per mouse in September. The occurrence rates of the positive sites with infected snails detected in the study year, last year and without infected snails detected in recent 3 years were 29.63%, 41.67% and 12.12%, respectively, and no significant differences were detected (chi2 = 5.227, P = 0.071). The infection rates of sentinel mice in the aforementioned 3 settings were 9.38%, 3.98% and 0.59%, respectively, and there was significant difference observed (chi2 = 20.489, P < 0.01). CONCLUSIONS: The monitoring results of sentinel mice infections in key water regions can almost reflect the endemic situation of schistosomiasis in local areas. Notably, many infections are detected in settings without infected snails detected in recent years. The monitoring of sentinel mice infections could significantly improve the sensitivity of the surveillance and forecast system of schistosomiasis.

[A case-control study on risk factors for advanced schistosomiasis japonica].

OBJECTIVE: To investigate risk factors for the development of advanced schistosomiasis. METHODS: The case-control study was designed with a match of 1:1 and 1:2. Healthy persons and chronic schistosomiasis patients were used as control. Each group was composed of 213 cases. Items investigated included: history of schistosomiasis and treatment, exposure to the contaminated water, social-economical condition and nutritional status, other concomitant diseases. Cellular and humoral immunity, HBVMs and ABO blood groups were also detected. Statistical analysis was performed by 1:1 and 1:2 matched single and stepwise conditional logistic regression analysis with SAS software. RESULTS: By stepwise conditional logistic regression analysis, it was revealed that number of schistosomiasis examination (OR = 1.168-1.311), interval from first infection to last treatment(OR = 1.142), interval from first infection to this investigation (OR = 1.089), HBsAg+ (OR = 4.683-10.759), HBcAb+ (OR = 2.873), HBsAg+ + HBeAb+ + HBcAb+ (OR = 7.64) were risk factors of developing advanced schistosomiasis. The average living space and cellular immunity were lower in advanced schistosomiasis patients than others. No association was found between advanced schistosomiasis and ABO blood groups. CONCLUSION: The development of advanced schistosomiasis is associated with repeated infections, and delayed or incomplete treatment. Combined infection with hepatitis B, poor socio-economic conditions and impaired cellular immunity may increase the pathogenetic risk of schistosomiasis.