OBJECTIVE: To construct a schistosomiasis transmission risk assessment system in Wuhan City and preliminary evaluate its application effect, so as to promote the rational allocation of schistosomiasis control resources and accelerate the progress towards schistosomiasis elimination. METHODS: The schistosomiasis risk assessment indicators were collected through referring schistosomiasis surveillance data of Wuhan City from 2014 to 2020, literature review and expert interviews. Indicators within each criterion and sub-criterion were screened using the Delphi method, and a hierarchical structure model was created based on analytic hierarchy process. Quantitative assignment of each indicator was conducted according to relative importance, and the weight and combination weight of each criterion were calculated in each analytic hierarchy framework to create a schistosomiasis transmission risk assessment system, which was used for the schistosomiasis transmission risk assessment in 12 national schistosomiasis surveillance sites in Wuhan City. RESULTS: A three-level schistosomiasis transmission risk assessment system was preliminarily constructed, which included a target layer, 5 criterion layers and 21 sub-criterion layers. Of all indicators in the criterion layer, transmission route had the highest weight (0.433), followed by source of Schistosoma japonicum infection (0.294); and among all indicators in the sub-criterion layer, S. japonicum infection in Oncomelania hupensis and sentinel mice had the highest combination weight (0.125), followed by prevalence of S. japonicum infection in humans (0.091) and bovines (0.053), snail control by chemical treatment (0.049), positive rate of inquiry examinations (0.048), allocation of schistosomiasis control professionals (0.045), and areas of submerged snail-infested settings (0.041). Of the 12 national schistosomiasis surveillance sites in Wuhan City, there were 5 sites with weights of > 0.8, 4 sites with weights of 0.6 to 0.8, and 3 sites with weights of < 0.6 in 2020. CONCLUSIONS A schistosomiasis transmission risk assessment system has been constructed based on analytic hierarchy process in Wuhan City, which may provide a evidence-based basis for health resource allocation and decision-making for schistosomiasis control.
Animals ; Humans ; Cattle ; Mice ; Analytic Hierarchy Process ; Schistosomiasis/prevention & control* ; Schistosomiasis japonica/epidemiology* ; Snails ; Risk Assessment

OBJECTIVE: To evaluate the diagnostic efficacy of indirect haemagglutination assay (IHA) for detection of Schistosoma japonicum infections among boatmen and fishermen in Dongting Lake region, so as to provide insights into improving the schistosomiasis surveillance program among boatmen and fishermen. METHODS: The boatmen and fishermen were detected for S. japonicum infections using IHA and Kato-Katz technique or miracidium hatching test nylon gauze simultaneously at schistosomiasis testing sites in the anchor sites for boatmen and fishermen in the Dongting Lake region during the period from 2014 to 2016, and using IHA for serological screening followed by parasitological testing of seropositives during the period from 2017 to 2019. The sensitivity and specificity of IHA were evaluated for detection of S. japonicum infections among boatmen and fishermen, with the 2014-2016 parasitological testing results as a gold standard. In addition, the seroprevalence of S. japonicum infections was compared among boatmen and fishermen with different characteristics and among years. RESULTS: A total of 306 schistosomiasis testing sites were assigned for boatmen and fishermen, and a total of 143 360 person-time boatmen and fishermen were tested for S. japonicum infections in the Dongting Lake region from 2014 to 2019. The sensitivity and specificity of IHA were 69.9%, 97.3% and 96.1% (χ² = 74.6, P < 0.05), and 70.9%, 74.5% and 71.9% for detection of S. japonicum infections from 2014 to 2016 (χ² = 29.4, P < 0.05), respectively. The seroprevalence of S. japonicum infections reduced from 30.3% in 2014 to 1.8% in 2019 among boatmen and fishermen, appearing an overall tendency towards a decline (Z = 1 552.4, P < 0.05). In addition, male, individuals at ages of 45 to 60 years, full-time boatmen and fishermen were more likely to be seropositive for S. japonicum infections (all P values < 0.05). CONCLUSIONS The seroprevalence of S. japonicum infections appeared a tendency towards a decline among boatmen and fishermen in the Dongting Lake region year by year from 2014 to 2019. IHA presented a high efficacy for screening of S. japonicum infections among boatmen and fishermen in the Dongting Lake region.
Animals ; China/epidemiology* ; Hemagglutination ; Humans ; Lakes ; Male ; Middle Aged ; Prevalence ; Schistosoma japonicum ; Schistosomiasis/epidemiology* ; Schistosomiasis japonica/prevention & control* ; Seroepidemiologic Studies

OBJECTIVETo study the dynamics of the reinfection of Schistosoma japonicum and related risk factors among the people in schistosomiasis endemic areas in China.

METHODSLiterature retrieval was conducted by using databases of PubMed, CNKI,VIP and Wanfang to collected all the data about the human re-infection of Schistosoma japonicum and related risk factors in the endemic areas in China. And a Mata-analysis was conducted on the literatures met the inclusion standards.

RESULTSEighteen studies involving 12 604 people for infection survey and 3 128 people for re-infection survey were included in the analysis. The overall infection rate was 20.8%, and the overall re-infection rate was 21.0% . The difference had no statistical significance (Z = 1.12, P = 0.26). The re-infection related factors included baseline infection intensity (OR = 3.58, 95% CI: 1.56-8.22); the index of contaminated water OR = 2.37, 95% CI: 1.08-5.22); distance from house to river-side (OR = 1.72, 95% CI: 0.41-7.30) and age (OR = 0.48, 95% CI: 0.19-1.23).

CONCLUSIONThe baseline infection intensity, the index of contaminated water and distance from house to river-side were the risk factors related to the re-infection of Schistosoma japonicum and age was a protective factor.

Animals ; Asian Continental Ancestry Group ; China ; Humans ; Risk Factors ; Schistosoma japonicum ; Schistosomiasis japonica ; epidemiology ; parasitology

OBJECTIVETo analyze the impact of water transfer project from the Yangtze River to the Huaihe River on schistosomiasis transmission, and to evaluate the risk of the disease input to the potential endemic area in Anhui Province, namely the Chaohu Lake region.

METHODSFrom 2008 to 2012, 1 fixed and 3 mobile surveillance sites in the Chaohu Lake area were selected, and the schistosomiasis infection situation of 615 local residents in the fix surveillance site was investigated in autumn of 2008 and 2012, while the schistosomiasis infection situation of 1603 mobile population in the 3 mobile surveillance sites were investigated in autumn of 2008 to 2012. All people were screened by indirect hemagglutination assay (IHA), and the positive ones were then examined by sedimentation method. 303 local livestock and livestock from schistosomiasis endemic areas were examined by stool hatching method in autumn of 2008 to 2012. From 2008 to 2012, the distribution of Oncomelania snails was investigated in risk areas and suspicious areas, and the snail spreading pattern was conducted through salvaging floaters in rivers connected with the Yangtze River. In addition, the Oncomelania snails were raised in the cages on the beaches of the Chaohu Lake, a control area, from 2007 to 2010, and their survival and reproduction capacity was observed.

RESULTSIn 2008 and 2012, 301 and 314 local residents were detected by IHA, but there were no positive found. From 2008 to 2012, a total of 1603 mobile population were examined by IHA, and the positive rate of antibody was 3.1% (49/1603); 75 individuals were examined by sedimentation method, and the positive rate was 36.00% (27/75). A total of 303 livestock were examined by stool hatching method, but no one showed positive. A total of 1630 km(2) in risk areas and 3551 km(2) in suspicious areas were surveyed, but there were no Oncomelania snails found. A total of 457.6 kg floating debris were investigated, and 11 Oncomelania snails were found. From 2007 to 2010, the survival rate of Oncomelania snails in two trail areas in the Chaohu Lake and in the control area was 88% (86/98), 51% (45/89), 30% (25/71), 24% (20/84) and 92% (85/92), 54% (50/92), 23% (12/52), 17% (13/79) and 96% (85/89), 52% (44/85), 26% (18/69), 18% (14/76), respectively, there were no statistical significance between the trial areas and the control area (χ1(2) = 3.78, P > 0.01; χ2(2) = 0.27, P > 0.01; χ3(2) = 2.51, P > 0.01; χ4(2) = 1.50, P > 0.01), and filial generation snails were found in each observation area from 2008 to 2010, the number was 156-312.

CONCLUSIONThe imported infectious sources of schistosomiasis have been found in the Chaohu Lake region, the possibility of imported exogenous Oncomelania snails spreading into the Lake and surviving and reproducing there is high. The risk of schistosomiasis input to the potential endemic area in Anhui Province is predicted to be high.

Animals ; Cross-Sectional Studies ; Environmental Monitoring ; Humans ; Lakes ; parasitology ; Risk Assessment ; Rivers ; parasitology ; Schistosomiasis japonica ; epidemiology ; prevention & control ; transmission ; Snails ; parasitology

Schistosomiasis is a kind of common disease around the riverside or lakeside areas, especially popular in rural areas, and causes huge economic loss. Based on existing schistosomiasis dynamic models and data, a new method of working out coefficients, and an improved model were provided in our study. The improved model can be applied to the study of the characteristics of transmission of schistosomiasis, and the effect of new control methods for schistosomiasis was evaluated.
Animals ; Cattle ; China ; Computer Simulation ; Humans ; Models, Theoretical ; Numerical Analysis, Computer-Assisted ; Schistosoma japonicum ; isolation & purification ; Schistosomiasis japonica ; epidemiology ; prevention & control ; transmission ; Snails ; parasitology

OBJECTIVETo 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.

METHODSLongshang 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.

CONCLUSIONThe 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.

Animals ; Animals, Wild ; parasitology ; Cats ; Cattle ; China ; epidemiology ; Dogs ; Feces ; parasitology ; Female ; Humans ; Male ; Mice ; Parasite Egg Count ; Rats ; Schistosomiasis japonica ; epidemiology ; parasitology ; Sheep ; Swine

OBJECTIVETo use a mathematical model and computer simulation to study transmission dynamics and control of schistosomiasis in mountainous regions of Sichuan.

METHODSBased on studies of schistosomiasis japonica transmission in 20 villages in mountainous regions of Sichuan, a mathematical model was developed to characterize the impact of local environmental factors on transmission intensity. The model integrated site-specific factors and was calibrated to field epidemiological data from 3 subset villages. The dichotomic method was then used to predict different control measures.

RESULTSThe study showed high variations in prevalence of infection and infection intensity across villages, ranging between 3%-73%, 0.1-100 epg (eggs per gram stool), respectively. Important factors including occupation of local residents, exposure to contaminated water, microclimatic characteristics were integrated in the model. The predictions of dichotomic models showed that continuing chemotherapy (coverage between 50%-60%) could reduce infection intensities to 30%-80%, but could not change local transmission potential; therefore, the termination of chemotherapy would be followed by bouncing back of transmission. Sustaining targeted environmental interventions through snail and parasite oval control at certain coverage (30%-50%, respectively) could reduce the transmission to relatively stable levels. The model predictions showed that an integrated control (e.g., including both chemotherapy and environmental interventions) could suppress the transmission to an undetectable level even interruption of transmission between 5-10 years.

CONCLUSIONThe study demonstrated the feasibility of using a dynamic model, calibrated to local data, to gain insights into complicated processes underlying the transmission and informing site-specific control strategies.

Adolescent ; Adult ; Animals ; Child ; Child, Preschool ; China ; Environment ; Humans ; Middle Aged ; Models, Theoretical ; Schistosoma japonicum ; Schistosomiasis japonica ; epidemiology ; prevention & control ; transmission ; Snails ; parasitology

OBJECTIVETo evaluate the practical value and the advantages of globe geographical positioning with wireless communication monitoring and supervision system in the field survey.

METHODSSpots which were randomly sampled by the National Ministry of Health for the investigation were chosen in the endemic areas for schistosomiasis in Jiangsu, Jiangxi, Anhui, Hunan, Hubei, Sichuan and Yunnan provinces. Portable GPS CEC9680 was used for collecting relevant waypoints and track, recording on-the-spot geographical positions. The positioning data package was sent back synchronously in the form of short message of SMS to the monitoring service center, and the moving routes of the terminal receiver monitored were displayed on the GIS map to achieve real-time supervision and staff scheduling.

RESULTSWith globe geographical positioning with wireless communication monitoring and supervision system, accurate positioning of 12 spots in the provinces of Jiangsu and 3 trial spots for schistosomiasis control with comprehensive treatment designated by the State Council has been established with real-time communicating recording, and monitoring systems.

CONCLUSIONThe globe geographical positioning with wireless communication monitoring and supervision system has provided a technical platform for the survey of schistosomiasis and other infectious diseases.

Animals ; China ; Environmental Monitoring ; methods ; Epidemiological Monitoring ; Geographic Information Systems ; Humans ; Schistosomiasis ; epidemiology ; prevention & control ; Schistosomiasis japonica ; prevention & control

OBJECTIVETo investigate the changes in natural ecology and social environment after the construction of the dam in the Three Gorges Reservoir area, and to understand the social behavior status and education backgrounds of the local residents, and to analyze the potential impact of these factors on schistosomiasis spreading.

METHODSData of nature and social economy after the construction of the dam in the Three Gorge area were collected, and a cross-sectional study with questionnaire survey on information including social demographic characteristics, people's production and life style, knowledge about schistosomiasis was conducted among natives, emigrations.

RESULTSAfter the construction of the dam, as the stream became slower, the water-level fluctuating zone on the bank of the reservoir was formed. The main source of drinking water and daily life activity are mainly depends on the river supplying (accounting about 68.7% and 75.8%, respectively); due to the needs of farming, washing cloths and vegetables, 45.6% of resident had a close contact with river water. People with away-from-home employment among emigrations were increased from 5.7% to 18.7%. The proportion of using hygienic lavatory was 88.6%. The main source of water for drinking and daily life among emigrations was tap water (85.4% and 87.0%). The residents had no awareness about the health hazard for schistosomiasis, with less health information

CONCLUSIONThe natural environment of reservoir areas and the life style are risk factors for the spread of schistosomiasis. The improved sanitation condition and the economy construction after the construction of the dam is propitious to keeping away from the introduction of schistosomiasis. However, people with away-from-home employment among emigrations are still at risk of schistosomiasis.

Animals ; China ; Fresh Water ; Humans ; Life Style ; Rain ; Schistosoma japonicum ; Schistosomiasis japonica ; epidemiology ; transmission ; Social Behavior ; Surveys and Questionnaires ; Water Movements ; Water Pollution ; Workplace

OBJECTIVETo clarify the change of vegetation types and its relationship between the density of alive-snails in the areas of "breaking dikes or opening sluice for water store" in Jicheng.

METHODSSynthesized false color images of Jicheng before and after 1998 (1994 and 2003) were classified without supervision and results were compared. Vegetation types were identified on the spot.

RESULTSNormalized difference vegetation index (NDVI) of snail habitats before 1998 were between 126 and 183 in Jicheng, whose vegetation types were mainly paddy, cotton and cabbage. NDVI of snail habitats in Jicheng after 1998 were between 152 and 193 whose vegetation types were mainly poplar forest, bulrush and grass. Areas of snail habitats increased from 64.64% to 66.47%. Snail habitats were mostly composed of mixed vegetation types and mono-typed vegetation was hardly found. According to the density of alive-snails orders from high to low were poplar forest and bulrush, poplar forest and grass, bulrush.

CONCLUSIONVegetation types would not be identified by unsupervised classification only. Poplar forest, bulrush and grass were closedly related to the density of alive-snails.

Animals ; Breeding ; China ; epidemiology ; Disease Vectors ; Ecology ; Environmental Monitoring ; Epidemiological Monitoring ; Fresh Water ; Plants ; Satellite Communications ; instrumentation ; Schistosoma japonicum ; isolation & purification ; Schistosomiasis japonica ; epidemiology ; transmission ; Snails ; growth & development ; parasitology ; physiology