Health related behaviors among HIV-infected people who are successfully linked to care: an institutional-based cross-sectional study.

BACKGROUND: By the end of October 2019, there were 958 thousand people were reported living with HIV/AIDS in China. Unhealthy lifestyle factors, such as smoking, drinking alcohol, using illicit drugs and no physical activity have been found to mitigate the positive impact of antiretroviral therapy (ART) on viral load and HIV-related quality of life. Moreover, risky sexual behavior among HIV-positive persons places their partners at risk for HIV transmission and other sexually transmitted infections. The aim of the study is to determine the prevalence of unhealthy behavior of people living with HIV/AIDS and related influencing factors, particularly those that are closely connected with HIV infection and ART effects. METHODS: An institutional based cross-sectional study design was used to collect data from people living with HIV/AIDS (PLWHA) in Beijing and Yunnan Province. The following information was included in the questionnaire survey: social-demographic characteristics, health behavior information, sexual risk behaviors. Binary logistic regression model was conducted to analyze the influencing factors of unhealthy general health behaviors and risky sexual behaviors. RESULTS: In total, 2575 PLWHA were included in the study and 78.3% (2017/2575) were male. For the general health behaviors, 34.2% (987/2544) smoke; 33.8% (870/2575) drank alcohol and 2.3% (49/2134) reported the use of illicit drugs in the previous 6 months. From the sexual behaviors perspective, 59.0% (1519/2575) had sex in the previous 6 months. Among people who had sex, 92.0% (1398/1519) had fixed sexual partners. Among those with no fixed sexual partner, 38.0% (46/121) had more than three partners. Among men who had sex, 34.7% (448/1292) reported having sex with men in the previous 6 months and 16.7% (75/448) of these had group sexual activity. Among participants, 72.2% (1053/1458) used condoms every time they had sex while 6.4% (94/1458) of people never used condom. Male people living with HIV/AIDS were more likely to have sexual risk behaviors (adjusted odds ratio [OR] = 2.208, 95% confidence interval [CI]: 1.147-4.252) and unhealthy general health behaviors (adjusted OR = 2.029, 95% CI: 1.480-2.783). The odds of higher risk sexual behaviors was 1.546 times (95% CI: 1.302-1.827, P = 0.001) greater among participants who drank alcohol compared with their non-drinking counterparts. CONCLUSIONS: PLWHA is a group that is vulnerable to problematic health behaviors, especially for men who were more likely to drink alcohol, have more sexual partners, more sexual risk behaviors including group sexual activity, not using condoms and using drugs. Therefore, interventions focusing on gender-specific risk behaviors reduction for people living with HIV/AIDS are now necessary to control the spread of HIV infection and improve the efficacy of antiviral treatment.

Family support, discrimination, and quality of life among ART-treated HIV-infected patients: a two-year study in China.

BACKGROUND: By September 2016, approximately 653,865 people in China were living with HIV/AIDS (PLWHA) and 492,725 people were receiving antiretroviral therapy (ART). PLWHA frequently experience discrimination in all domains of their personal and social lives. The World Health Organization includes discrimination in its list of social determinants of health factors that have been linked to poor physical and psychological health. This paper identifies the family support enjoyed and discrimination faced by people infected with HIV and examines the effect they have on patients' quality of life (QOL) as they undergo ART in China. METHODS: We conducted this observational cohort study of ART-treated patients with HIV in Guangxi Province using a questionnaire survey at baseline, 6, 12, and 24 months, starting in 2010. Descriptive analysis was used to describe the demographic characteristics (e.g., age, sex, educational level, marital status, and employment status) of participants. Generalized estimating equations (GEE) were employed to examine the relationships between family support, discrimination, and QOL. RESULTS: In the study, 90.4% (n = 281) of patients received family support at baseline, here defined as the initiation of ART, 91.8% (n = 244) received family support 6 months into ART, 95.5% (n = 220) at 12 months, and 94.3% (n = 230) at 24 months. The proportion of patients who did not feel discriminated against by their families was 87.2% (n = 274) at baseline, 90.4% (n = 229) 6 months into ART, 90.0% (n = 210) at 12 months, and 94.5% (n = 219) at 24 months. Patients' overall QOL scores were positively associated with having received family support (OR = 2.74, P = 0.040, 95% CI: 1.68-4.47), not feeling discriminated against by their families (OR = 1.3, P = 0.041, 95% CI: 1.07-1.59) or discrimination from patients themselves, including never experiencing fear of abandonment by family (OR = 2.05, P = 0.025, 95% CI: 1.49-2.82). CONCLUSIONS: Family support along with no or minimal discrimination was found to contribute to QOL among people infected with HIV. Their overall QOL tended to improve significantly as ART continued. This suggests that strategies meant to improve and strengthen family support, care for PLWHA, and promote HIV screening among high-risk populations should be explored by both policy makers and researchers.

[Analysis of schistosomiasis prevalence in endemic areas using retrospective space-time permutation scan statistics].

Objective: To analyze the characteristics of schistosomasis prevalence by using the spatial epidemiological method, and test the application of retrospective space-time permutation scan statistics in determining mountainous and lake-type endemic areas of schistosomiasis. Methods: The data of schistosomasis in humans, cattle and snails in Jiangxi Province during 2009-2014 and in Yunnan Province during 2004-2013 were collected and analyzed. The temporal and spatial distribution of schistosomiasis endemic areas in the two provinces was analyzed with retrospective space-time permutation scan statistics. Results: The prevalence of schistosomiasis in residents and Oncomelania snails showed a trend of decline in Jiangxi, from 0.21% and 0.03% in 2009 to 0.01% and zero in 2014. A similar trend was found in cattle, from 1.25% in 2012 to 0.12% in 2014. The average annual percentage change (APC) in residents was-47.36%(P < 0.05). The space-time permutation clustering analysis revealed a temporal and spatial clustering of schistosomiasis prevalence from 2009 to 2014 in residents, cattle, and snails, with 3,2 and 1 clustering areas, respectively, all distributed in Poyang Lake Region. A similar declining trend of schistosomiasis prevalence was found in residents, snails and cattle in Yunnan during 2004-2013, from 2.49%,0.70% and 3.76% in 2004 to no infection in residents and snails and 0.02% in cattle in 2013. The APC in residents was-49.17%(P < 0.05). There was a temporal and spatial clustering of schistosomiasis prevalence during 2004-2013 in residents, cattle, and snails, with 2,2 and 6 clustering areas, respectively. Conclusion: A declining trend of schistosomiasis prevalence is shown in lake-type endemic areas in Jiangxi during 2009-2014 and in mountainous endemic areas in Yunnan during 2004-2013. The retrospective space-time permutation scan statistics reveal a clustering of schistosomiasis in humans, cattle, and snails, suggesting its applicability in analyzing the temporal and spatial distribution of schistosomiasis.

Integrated control programmes for schistosomiasis and other helminth infections in P.R. China.

The prevalence of human schistosomiasis and soil-transmitted helminthiasis (STH) has decreased significantly in the People's Republic of China (P.R. China), particularly after 2005 when the national control programmes were reinforced by forming of integrated control strategies. Furthermore, social-economic development also contributed to the decrease of schistosome and soil-transmitted helminth infections. The prevalence of the zoonotic helminthiasis, including clonorchiasis and echinococcosis, on the other hand, is either underestimated or has in fact increased due to changes in social and environmental factors. In comparison with the control strategies in force and their effects on those four kinds of helminthiasis, the challenges and control priorities for the potential transfer from control to elimination of each disease is reviewed, to provide evidence for policy-makers to act upon.

Schistosomiasis japonica: modelling as a tool to explore transmission patterns.

Modelling is an important tool for the exploration of Schistosoma japonicum transmission patterns. It provides a general theoretical framework for decision-makers and lends itself specifically to assessing the progress of the national control programme by following the outcome of surveys. The challenge of keeping up with the many changes of social, ecological and environmental factors involved in control activities is greatly facilitated by modelling that can also indicate which activities are critical and which are less important. This review examines the application of modelling tools in the epidemiological study of schistosomiasis japonica during the last 20 years and explores the application of enhanced models for surveillance and response. Updated and timely information for decision-makers in the national elimination programme is provided but, in spite of the new modelling techniques introduced, many questions remain. Issues on application of modelling are discussed with the view to improve the current situation with respect to schistosomiasis japonica.

Establishing and applying a schistosomiasis early warning index (SEWI) in the lower Yangtze River Region of Jiangsu Province, China.

BACKGROUND: China has made remarkable progress in schistosomiasis control over the past decades. Transmission control has replaced morbidity control as the country moves towards the goal of elimination and the current challenge is to find a sensitive measure capable of gauging transmission risk in low-prevalence areas. The study aims to develop a Schistosomiasis Early Warning Index (SEWI) and demonstrate its use in Jiangsu Province along the lower Yangtze River. METHODOLOGY/PRINCIPAL FINDINGS: The Delphi approach, a structured communication technique, was used to develop the SEWI. Two rounds of interviews with 30 public health experts specialized in schistosomiasis control were conducted using 40 indicators that reflected different aspects of schistosomiasis transmission and control. The necessity, feasibility, and sensitivity of each indicator were assessed and the weight value of each indicator determined based on these experts' judgment. The system included 3 first-order indicators, 7 second-order indicators, and 30 third-order indicators. The 3 first-order indicators were endemic status, control measures, social and environmental factors, with the weight values 0.366, 0.343 and 0.291, respectively. For the 7 second-order indicators, the highest weight value was for control measures for snails (0.175) and the lowest for transmission route (0.110). We estimated and mapped the SEWI for endemic areas at the county scale in Jiangsu Province finding that the majority of the endemic areas were characterized as medium transmission risk (SEWI risk values between 0.3 and 0.6), while areas where transmission interruption had been officially declared showed SEWI values <0.30. A few isolated areas (e.g. endemic islands in the Yangtze River) produced SEWI values >0.60. These estimates are largely in agreement with the endemicity levels based on recent epidemiological surveys. CONCLUSIONS/SIGNIFICANCE: The SEWI should be useful for estimation of schistosomiasis transmission surveillance, particularly with reference to the elimination of the disease in China.

Field comparison of circulating antibody assays versus circulating antigen assays for the detection of schistosomiasis japonica in endemic areas of China.

BACKGROUND: Schistosomiasis remains a serious public health problem in affected countries, and routine, highly sensitive and cost-effective diagnostic methods are lacking. We evaluated two immunodiagnostic techniques for the detection of Schistosoma japonicum infections: circulating antibody and circulating antigen assays. METHODS: A total of 1864 individuals (between 6 and 72 years old) residing in five administrative villages in Hubei province were screened by serum examination with an indirect hemagglutination assay (IHA). The positive individuals (titer ≥20 in IHA) were reconfirmed by stool examination with the Kato-Katz method (three slides from a single stool specimen). Samples of good serum quality and a volume above 0.5 ml were selected for further testing with two immunodiagnostic antibody (DDIA and ELISA) and two antigen (ELISA) assays. RESULTS: The average antibody positive rate in the five villages was 12.7%, while the average parasitological prevalence was 1.50%; 25 of the 28 egg-positive samples were also circulating antigen-positive. Significant differences were observed between the prevalence according to the Kato-Katz method and all three immunodiagnostic antibody assays (P-value <0.0001). Similar differences were observed between the Kato-Katz method and the two immunodiagnostic antigen assays (P-value <0.0001) and between the antigen and antibody assays (P-value <0.0001). CONCLUSION: Both circulating antibody and circulating antigen assays had acceptable performance characteristics. Immunodiagnostic techniques to detect circulating antigens have potential to be deployed for schistosomiasis japonica screening in the endemic areas.

[Risk assessment for malaria elimination in P. R. China].

OBJECTIVE: To identify the risk area in China during the malaria elimination process, and provide the evidence for promotion of the national malaria elimination programme and implementation of elimination strategy. METHODS: Data collection was conducted in 24 endemic provinces in 2010, including data of transmission capacity, potential risk of malaria transmission and the capacity of health professional team at county level. Quantitative assessment of the malaria transmission risk as well as the capacity of health facilities were conducted based on the calculation of malaria transmission risk index (MTI) and health facilities capacity index (CI). ArcGIS 10.0 was used to develop the risk map based on the outcome of quantitative assessment. RESULTS: The data of transmission capacity, potential risk of transmission and the capacity of health professional team were collected from 2147 counties in 24 provinces. Based on MTI and CI calculated for each county, statistic results showed that about 40% of the counties were under the average level of both MTI and CI. The relationship among potential risk of transmission, the capacity of health professional team and malaria incidence were analyzed in three dimensions, and four types were categorized among 2147 counties. Type I (super-high risk area) counties (20) distributed in Yunnan (9), Guangxi (5), Henan (1), Hunan (1), Hebei (1), Sichuan (1), Chongqing (1), and Tibet (1). 17 counties were classified into type II (high risk area) area, distributed in Yunnan (3), Guangxi (2), Guizhou (2), Shaanxi (2), Guangdong (1), Jiangxi (1), Hubei (1), Sichuan (1), Gansu (1), Hebei (1), Fujian (1) and Tibet (1). A total of 170 type III (moderate risk area) counties distributed in 19 provinces including Yunnan (15), Guizhou (14), Hebei (14), Sichuan (13), Shanxi (10), Guangxi (9), Hunan (9), Anhui (9), Jiangsu (9), Shaanxi (9), Shandong (9), Chongqing (8), Gansu (8), Jiangxi (7), Henan (7), Fujian (6), Guangdong (5), Hubei (5), and Zhejiang (4). 1940 type IV (low risk area) counties distributed in 24 provinces. CONCLUSION: The distribution of four types of risk area for malaria elimination is identified in China.

[Determination of key interventions for the transition from control to elimination of malaria in China].

OBJECTIVE: To determine the key interventions transferring from the control to elimination of malaria in China so as to provide the basic information for achieving malaria elimination. METHODS: Based on the data collected from the document entitled of The National Annual Report on Schistosomiasis, Malaria and Echinococcosis, published by the National Institute of Parasitic Diseases of Chinese Center for Disease Control and Prevention, the malaria incidence and intervention data were selected only in the typical endemic provinces during the period of 2004-2010. The correlation between the incidence and interventions in the target provinces was analyzed based on the Panel Data Regression Model, and the key interventions were determined. RESULTS: Four provinces namely Anhui, Yunnan, Hainan and Henan were targeted with 87.56% of the national malaria figures from 2004 to 2010. When Y was given as vivax malaria incidence, X1 as the log of the number of historical cases receiving radical treatment in the pre-transmission stage (RTPT) (F = 14.53, P < 0.01, R2 = 0.72), X2 as the log of risk population receiving RTPR (F = 15.90, P < 0.01, R2 = 0.71) and X3 as the number of technicians trained in microscopy (F = 11.53, P < 0.01, R2 = 0.61), three space-fixed effect models were established respectively, and X1, X2, as well as X3 had negative effects on Y value. When Y was given as falciparum malaria incidence, X1 as the accumulated technicians trained in microscopy (F = 11.06, P < 0.01, R2 = 0.87), X2 as the log of technicians trained in entomology (F = 15.28, P < 0.01, R2 = 0.89) , two two-way (space and time) fixed effect models were established respectively, and both X1 and X2 had negative effects on Y value. CONCLUSION: RTPT among historical patients and at-risk populations as well as microscopy training influences the variation of vivax malaria incidence, while the significant interventions of microscopy training and vector control training indicate that the integrated measures with strengthened capacity in diagnosis and vector control are of importance in the control of falciparum malaria transmission.

[Establishment and application of rapid assessment system of environment with high transmission risk of schistosomiasis in marshland and lake regions. I. Establishment of an index system with Delphi method].

OBJECTIVE: To establish an index system for rapid assessment of environment with high transmission risk of schistosomiasis in marshland and lake regions. METHODS: The alternative indices were established preliminarily by the documentary method, and then the Delphi method was used two rounds to select the indices and establish the index system. The degree of familiar and authority of the experts as well as the weights of all indices were assessed. RESULTS: A total of 3 primary indices namely morbidity in domestic animals, morbidity in humans and Oncomelania snail status were established, among which the weight of morbidity in domestic animals (0.68) was the highest. Totally 16 secondary indices were established, among which the combinative weights of the positive rate of wild feces (0.09), the infection rate of livestock (0.09), the infection rate of humans (0.07), the number of cases with acute schistosomiasis (0.07), the area with infected snails (0.07), and the density of infected snails (0.07) were the highest. The coefficients of familiar degree and authority degree of the experts of the primary indices were 0.79-0.85 and 0.88-0.91, and those of the secondary indices were 0.68-0.86 and 0.77-0.91, respectively. CONCLUSIONS: The index system for rapid assessment of environment with high transmission risk of schistosomiasis in marshland and lake regions is established preliminarily. Using this system, we can assess the key endemic indices of humans, domestic animals and snails to understand the endemic situation in the investigated sites.

[Relationship between schistosome serum test positive rate of residents and positive rate of Oncomelania snails in a national schistosomiasis surveillance site of Jiangling County].

OBJECTIVE: To explore the relationship between schistosome serum test positive rate of residents and positive rate of Oncomelania snails in a national schistosomiasis surveillance site of Jiangling County. METHODS: According to the national schistosomiasis monitoring scheme, the data of surveillance including the schistosome serum test positive rates of residents and positive rates of Oncomelania snails from 2005 to 2011 were collected and analyzed statistically. RESULTS: From 2005 to 2011, the schistosome serum test positive rates of residents were 26.09%, 11.84%, 10.37%, 10.09%, 12.08%,9.61%, and 6.00%, respectively; the schistosome positive rates of Oncomelania snails were 0.36%, 0.08%, 0.15%, 0.129%, 0.067%, 0.091%, and 0.045%, respectively. There was a significant positive correlation between them (r = 0.929, P < 0.01). CONCLUSION: There is a positive correlation between schistosome serum test positive rate of residents and positive rate of Oncomelania snails. Therefore, we should strengthen the snail control.

[Study on assessing system for endemicity of schistosomiasis].

OBJECTIVE: To establish a scientific, objective and operational assessing system for schistosomiasis endemicity, so as to provide a scientific evidence for revising the current Criteria for Control and Elimination of Schistosomiasis in China (GB 15976-2006). METHODS: A questionnaire was designed based on reference review and 20 scientists working in the field of schistosomiasis control, research or management were investigated by using the Delphi method. The importance of each index reflecting the endemicity of schistosomiasis was scored by each scientist. The assessing system for endemicity of schistosomiasis was established and the normalized weight and combined weight were calculated. RESULTS: The assessing system included three indices in the first grade and seven indices in the second grade. Among the indices in the first grade, the normalized weights of infection status of human beings, infection status of livestock, and Oncomelania snail's status were 0.360 2, 0.335 2, and 0.304 6, respectively. Among the indices in the second grade, the prevalence of livestock showed the highest combined weight of 0.335 2 while the infection rate of snails showed the lowest score of 0.093 3. CONCLUSIONS: The indexes of the assessing system for the endemicity of schistosomiasis established are reasonable, comprehensive, and authoritative, which provide the scientific evidence for revising the currently available Criteria for Control and Elimination of Schistosomiasis in China.

Transmission risks of schistosomiasis japonica: extraction from back-propagation artificial neural network and logistic regression model.

BACKGROUND: The transmission of schistosomiasis japonica in a local setting is still poorly understood in the lake regions of the People's Republic of China (P. R. China), and its transmission patterns are closely related to human, social and economic factors. METHODOLOGY/PRINCIPAL FINDINGS: We aimed to apply the integrated approach of artificial neural network (ANN) and logistic regression model in assessment of transmission risks of Schistosoma japonicum with epidemiological data collected from 2339 villagers from 1247 households in six villages of Jiangling County, P.R. China. By using the back-propagation (BP) of the ANN model, 16 factors out of 27 factors were screened, and the top five factors ranked by the absolute value of mean impact value (MIV) were mainly related to human behavior, i.e. integration of water contact history and infection history, family with past infection, history of water contact, infection history, and infection times. The top five factors screened by the logistic regression model were mainly related to the social economics, i.e. village level, economic conditions of family, age group, education level, and infection times. The risk of human infection with S. japonicum is higher in the population who are at age 15 or younger, or with lower education, or with the higher infection rate of the village, or with poor family, and in the population with more than one time to be infected. CONCLUSION/SIGNIFICANCE: Both BP artificial neural network and logistic regression model established in a small scale suggested that individual behavior and socioeconomic status are the most important risk factors in the transmission of schistosomiasis japonica. It was reviewed that the young population (≤15) in higher-risk areas was the main target to be intervened for the disease transmission control.

[Establishment of policy indicators of adaptation to the impact of climate change on the transmission of schistosomiasis and malaria in China].

OBJECTIVE: To set up a framework of indicators for schistosomiasis and malaria to guide the formulation and evaluation of vector-borne disease control policies focusing on adaptation to the negative impact of climate change. METHODS: A 2-level indicator framework was set up on the basis of literature review, and Delphi method was applied to a total of 22 and 19 experts working on schistosomiasis and malaria, respectively. The result was analyzed to calculate the weight of various indicators. RESULTS: A total of 41 questionnaires was delivered, and 38 with valid response (92.7%). The system included 4 indicators at first level, i.e. surveillance, scientific research, disease control and intervention, and adaptation capacity building, with 25 indicators for schistosomiasis and 21 for malaria at the second level. Among indicators at the first level, disease surveillance ranked first with a weight of 0.32. Among the indicators at the second level, vector monitoring scored the highest in terms of both schistosomiasis and malaria. CONCLUSION: The indicators set up by Delphi method are practical,universal and effective ones using in the field, which is also useful to technically support the establishment of adaptation to climate change in the field of public health.

[Evaluation of the comprehensive schistosomiasis control measures with emphasis on infection source of replacing cattle with machine].

OBJECTIVE: To evaluate the effect of comprehensive measures with an emphasis on schistosomiasis infection source control by replacing cattle with machine. METHODS: In 2011, 2 villages from each of Jingzhou District, Jianli County and Jiangling County, Hubei Province, were selected as intervention group where the comprehensive measures were implemented, while 2 villages from Shishou City served as control with routine control activities. A cluster random sampling was carried out in the 8 villages with more than 300 people in each village were sampled. Stool examination using modified Kato-Katz was applied for identification of the infected persons and hatching test for cattle survey. The systemic sampling was applied for snail survey, fecal specimens from the field were examined by hatching test. Each sample was examined three times. Data were collected for the analysis of control effect between intervention and control groups in 2007 (baseline), 2009 (before implementation of comprehensive measures) and 2011 (post-intervention). RESULTS: In intervention villages, the overall prevalence in human reduced significantly from 3.6% (135/3 772) in 2007 and 2.0% (63/3 116) in 2009 to 0.9% (21/2 396) in 2011 (chi2 = 43.411, chi2 = 11.840, P < 0.05). Until 2011, there were no cattle in intervention group; the prevalence decreased by 52.6% in human and about 100% in cattle from 2010 to 2011. In control group, the infection rate in residents in 2007, 2009 and 2011 was 4.5% (64/1 410), 2.6% (34/1 294) and 1.8% (24/1,320), respectively (chi2 = 16.178, P < 0.05), and 5.1% (8/158) in 2007, 1.6% (3/187) in 2009 and 1.6% (3/189) in 2011 in cattle, respectively (chi2 = 3.387, P > 0.05). The infection rate in human and cattle fell by 25.0% and 5.9% from 2010 to 2011, respectively. There was a significant difference in human infection rate between the intervention and control groups after intervention (chi2 = 6.309, P < 0.05). No infected snails were detected in intervention and control groups. No positive feces from the field was found in the intervention group, 7.5% positive rate was recorded in the control. CONCLUSION: The comprehensive measures focused on infection source control by replacing cattle with machine can effectively control Schistosoma japonicum transmission, with a significant decrease of the prevalence in human and cattle.

[Retrospective investigation on national endemic situation of schistosomiasis. II. Analysis of changes of endemic situation in transmission-controlled counties].

OBJECTIVE: To summarize and analyze the process of the changes of schistosomiasis infection and Oncomelania snails in schistosomiasis transmission-controlled areas to explore the rules of the impact of changes of snail indexes on human infection before and after the stage of transmission control, so as to provide the evidence for editing snail indexes in the schistosomiasis controlled criterion and a more scientific, standardized control assessment and evaluation. METHODS: Twenty-one schistosomiasis transmission-controlled or transmission-interrupted counties in lake endemic areas and hilly endemic areas in 8 provinces were selected and investigated retrospectively to collect schistosomiasis epidemiological information 10 years before these counties reached the criterion of transmission control and the subsequent years until 2008 or 2009. A " Standard county schistosomiasis epidemic survey data review software" was developed to establish a national epidemic retrospectively database; the trends of changes of snail status, infected snail status and human infection status were analyzed in different years. The trends and rules of the changes of snail areas, emerging snail areas, living snail densities, infected snail densities, snail infection rates and human infection rates were analyzed and compared before and after the counties reached the schistosomiasis transmission-controlled criterion in different types of endemic areas. RESULTS: Before the transmission control, the human infection rate presented a declining trend in endemic areas. In lake endemic areas, the human infection rate declined to below 5% 4 years before the transmission control; in hilly endemic areas, the human infection rate declined to below 3% 8 years before the transmission control, and the human infection rates of the lake and hilly endemic areas declined to 2.10% and 1.45%, respectively, at the year of transmission control. However, 3 to 4 years after transmission control, the disease began to rebound, especially in lake endemic areas. The snail areas and snail densities declined year by year 10 years before the transmission control in the lake and hilly endemic areas, and the proportion of snail areas occupying the historic snail areas declined the lowest, being 2.75% and 0.55%, respectively, at the year of transmission control. The average densities of living snails kept a low level from 3-4 years before the transmission control to 9-10 years after the transmission control, and then rebounded. The new snail areas appeared 6-7 years after the transmission control and the snail areas and densities of living snails rebounded 9-12 years after the transmission control. CONCLUSIONS: The snail status can maintain a relatively low level during about 10 years after the transmission control in the lake and hilly schistosomiasis endemic areas, but the schistosomiasis status rebounded 5 years after the transmission control. While the comprehensive measures mainly including infectious source controlled are implemented, the snail surveillance and control should be still strengthened, and it is recommended that "the proportion of snail areas decreased" and "the control of infected snails" would be the indicators of the criterion of schistosomiasis transmission control.

[Retrospective investigation on national endemic situation of schistosomiasis I analysis of changes of endemic situation in transmission-interrupted counties].

OBJECTIVE: To analyze the changing rules of schistosomiasis endemic situation in the area of transmission that has been interrupted before and after they reach the criteria of transmission interruption, so as to offer the basis of amending to the criteria of schistosomiasis transmission interruption and a more scientific, standardized assessment and evaluation of the effects of schistosomiasis control in the future. METHODS: Nineteen counties of transmission that has been interrupted in 9 provinces nationwide were selected and investigated with the retrospective research method to collect and record the endemic detailed data 10 years before they reach the criteria of transmission interruption and several years later (ended in 2008 or 2009) and then a database was established. The changing rules of various disease indices in different endemic areas before and after reaching the criteria of transmission interruption were analyzed and compared. RESULTS: The average time from the transmission control to the transmission interruption was 17 years in the 17 counties. After reaching the criteria of transmission interruption, the infection rates of people turned down to a minimum level in various endemic areas, the infection rates in a few numbers of lake endemic areas and hilly endemic areas increased slightly after the transmission interruption 4-9 years later, but all of them were below 1%. The densities of living Oncomelania snails in lake endemic areas and water-network endemic areas were high and the changes were great each year, and the densities of living snails were much lower in hilly endemic areas than in the above two types of areas and they came to the lowest 4 years before and after the transmission interruption. The infected snails appeared occasionally in lake endemic areas, and they recurred 6 years and 10 years after the transmission interruption in water-network endemic areas and hilly endemic areas, respectively. The continued time without infected snails found before reaching transmission interruption was 2.71 +/- 1.10 years averagely in transmission-interrupted counties with endemic stable, and was 3. 80 +/- 1.43 years in lake endemic areas. CONCLUSIONS: It is possible to maintain a low level of population schistosome infection, and the endemic rebound is shown as snail rebound after the endemic areas reach the criteria of transmission interruption, The infected snails could be the comprehensive index reflecting the control achievement and the risk of schistosomiasis transmission. So the persistent control of infected snails is the fundament of schistosomiasis transmission interruption. It is suggested that in our current social and economic development and science and technology capacity conditions, the status of no infected snails found continuously for 5 years would be one of the criteria of schistosomiasis transmission interruption.

[Retrospective investigation on national endemic situation of schistosomiasis. III. Changes of endemic situation in endemic rebounded counties after transmission of schistosomiasis under control or interruption].

OBJECTIVE: To analyze the changes of schistosomiasis endemic situation before and after reaching the criteria of schistosomiasis transmission control or transmission interruption in endemic rebounded areas, so as to offer the information for modifying the criteria of schistosomiasis control and elimination, and consolidating achievements of schistosomiasis control in People's Republic of China. METHODS: Twelve counties with endemic rebound were selected from seven endemic provinces and investigated with the retrospective research method. The data including the epidemic information and relative materials 10 years before the counties reached the criteria of transmission control and several years later (until 2008 or 2009) were collected. The changes of epidemic situation of these counties before and after the transmission was under control or interrupted, and the factors causing the endemic rebound were analyzed. RESULTS: Counties consolidated the endemic situations with an average time of 5 +/- 3 years after the transmission control, with endemic rebound normally caused by single factor. The ratio of Oncomelania snail areas to historically accumulative snail areas increased over 10% in hilly endemic regions and lake endemic regions in 7 and 12 years separately, while it was stabilized in a low level in water-network endemic areas. The rebound peak time of infected snail densities was consistent with or later than that of densities of living snails. The prevalence of schistosome infection in humans in lake endemic regions rebounded 2 years after transmission under control. The transmission interruption counties consolidated the endemic situations with an average time of 7 +/- 4 years. The human prevalence of schistosome infection decreased to a very low level after the counties reaching the criteria of transmission interruption. The snail areas increased to over 2% of historically accumulative snail areas 3-6 years after transmission interruption in lake, water-network endemic areas successively, while densities of living snails and infected snails were increased at the same year or 2-3 years later. CONCLUSIONS: The endemic rebound in regions after the transmission under control or interrupted is caused by biological, natural and social factors and mainly presents as the rebound of snail status. The modification of criteria for schistosomiasis control and elimination should consider the influence of variation of snails, snail areas and density of infected snails on endemic situations in different endemic areas comprehensively. Sensitive and valid surveillance and forewarning system should be established to strengthen the monitoring and consolidating endemic situation in endemic areas after the transmission under control or interrupted.

[Application of artificial neural networks in infectious diseases].

With the development of information technology, artificial neural networks has been applied to many research fields. Due to the special features such as nonlinearity, self-adaptation, and parallel processing, artificial neural networks are applied in medicine and biology. This review summarizes the application of artificial neural networks in the relative factors, prediction and diagnosis of infectious diseases in recent years.

[Risk factors of schistosomiasis transmission in marshland and lake regions in midstream of Yangtze River].

OBJECTIVE: To study the risk factors of schistosomiasis related to household economic condition and individual behavior in marshland and lake regions, so as to provide evidences for schistosomiasis control. METHODS: Six villages were sampled with the stratified cluster sampling method, 2 339 villagers from 1 247 households were surveyed by a questionnaire and meanwhile their sera were assayed for schistosomiasis by IHA. The Logistic regression was used to analyze the relationship between the results of serological examinations and risk factors. RESULTS: The Logistic regression model fitted well (R2 = 0.598 4) and it indicated that there existed a regressive relationship between the antibody positive rate and the endemic situation of village, family economic status, age, education level and infection history of schistosomiasis. CONCLUSION: Suitable measures should be made in according to the local economic situation, endemic type and population to control the transmission of schistosomiasis effectively.