Schistosomiasis Transmission Research Articles

A Class of Nonautonomous Schistosomiasis Transmission Model with Incubation Period

A nonautonomous schistosomiasis model with latent period and saturated incidence is investigated. Further, we study the long-time behavior of the epidemic model. The weaker sufficient conditions for the permanence and extinction of infectious population of the model are obtained by constructing some auxiliary functions. Numerical simulations show agreement with the theoretical results.

Schistosomiasis mansoni in families of fishing workers of endemic area of Alagoas

Abstract Objective: To analyze the epidemiological and clinical aspects involved in the transmission and manifestation of schistosomiasis in a community of fishermen from the endemic area of Alagoas. Methods: Epidemiological, transversal, prospective, descriptive, quantitative study. The coproparasitological survey included 275 family units of fish workers and the epidemiological and clinical ones, those with a positive diagnosis for S. mansoni. Results: The prevalence of schistosomiasis was 13.9% (fishermen), 2.1% (shellfish) and 2.1% (family members). The occurrence of the infection varied according to gender, age, ethnicity and socioeconomic status. Exposure occurred near the home. Autochthonous and predominant low parasite burden, intestinal clinical presentation, abdominal pain and diarrhea were observed. There were no nutritional and pressure changes associated with parasitosis. Adherence to drug therapy and use of the schistosomicidal drug was feared. Conclusion: Fish workers are at high risk for contracting the disease with clinical hepatointestinal manifestation, which requires more intense health actions.

Role of ecological approaches to eliminating schistosomiasis in Eryuan County evaluated by system modelling

BackgroundSchistosomiasis was severely prevalent in Yunnan Province, and it is difficult to achieve its elimination by convention approaches due to complexity of the nature. We explored the comprehensive model to eliminate schistosomiasis in Eryuan County, Yunnan Province, the People’s Republic of China, through integration with the ecological protection programme in Erhai Lake, in order to promote an efficient elimination strategy. We expected that this model is able to be tailored to other local settings, which help achieve the goal of precisely eliminating the disease in Yunnan Province.MethodsEryuan County of Yunnan Province was chosen as the study area, where the data on environmental protection activities in Erhai Lake and on the schistosomiasis control programme were collected through different departments of Erhai County government since 2015. System modelling was performed using system dynamics software to establish a simulation model in order to evaluate the effectiveness of intervention activities.ResultsEcological approaches to control schistosomiasis in Eryuan County consist of three major components: (i) implementing precise interventions to stop schistosomiasis transmission by means of controlling the source of infection, blocking the biological transmission chains and cutting off the route of disease transmission; (ii) employing ecological approaches to improve the co-effectiveness of environmental protection and schistosomiasis prevention in the study area; and (iii) strengthening the professional skills of personnel involving in the schistosomiasis control programme. Simulation results showed that this strategy could speed up the progress of schistosomiasis control programme moving from the control stage to the elimination stage.ConclusionsEcological approaches implemented in schistosomiasis endemic areas of the Eryuan region are able to improve the co-effectiveness of environmental protection and schistosomiasis control, providing a new avenue for eliminating schistosomiasis thanks to the application of precise interventions.

Potential Biological Control of Schistosomiasis by Fishes in the Lower Senegal River Basin.

.More than 200 million people in sub-Saharan Africa are infected with schistosome parasites. Transmission of schistosomiasis occurs when people come into contact with larval schistosomes emitted from freshwater snails in the aquatic environment. Thus, controlling snails through augmenting or restoring their natural enemies, such as native predators and competitors, could offer sustainable control for this human disease. Fishes may reduce schistosomiasis transmission directly, by preying on snails or parasites, or indirectly, by competing with snails for food or by reducing availability of macrophyte habitat (i.e., aquatic plants) where snails feed and reproduce. To identify fishes that might serve as native biological control agents for schistosomiasis in the lower Senegal River basin—one of the highest transmission areas for human schistosomiasis globally—we surveyed the freshwater fish that inhabit shallow, nearshore habitats and conducted multivariate analyses with quantitative diet data for each of the fish species encountered. Ten of the 16 fish species we encountered exhibited diets that may result in direct (predation) and/or indirect (food competition and habitat removal) control of snails. Fish abundance was low, suggesting limited effects on schistosomiasis transmission by the contemporary fish community in the lower Senegal River basin in the wild. Here, we highlight some native species—such as tilapia, West African lungfish, and freshwater prawns—that could be aquacultured for local-scale biological control of schistosomiasis transmission.

Water Quality and Dynamic of Schistosomiasis Intermediate Host Snails in the Lake Areas, District of So-Ava, Southern Benin

Objectives: Urinary schistosomiasis is known to be endemic in the lake Nokoué areas of the District of So-Ava. For the past ten years, the National Control Programme for Communicable Diseases of the Ministry of Health has been making efforts to control schistosomiaisis morbidity through mass drug treatment with Praziquantel. This study aimed to assess the diversity and dynamic of potential snails known as schistosomiasis intermediate hosts. Methodology and Results: This study was carried out for 12 months (from July 2015 to June 2016) and consisted in the periodical analysis of the physical and chemical water parameters (temperature, oxygen concentration, pH, nitrite and nitrate rates. Salinity, total dissolved solids (TDS) and, biochemical oxygen demand) in relation with diversity, distribution and relative abundance of freshwater snails (Bulinus forskalii, B. globosus and B. truncatus). To this end, seven harvesting sites on Lake Nokoué were, reasonably selected for monthly hydrobiological and malacological data monitoring. The results showed a variable correlation between the dynamic of schistosomiasis intermediate host snailsm and several physico-chemical water parameters. Bulinus globosus was negatively influenced by salinity and nitrate rates while B. forskalii was negatively influenced by pH, Oxygen, TDS, salinity and nitrate rates. The three species of freshwater snails were strongly influenced by the water temperature. Conclusion: The results suggest a seasonal schistosome transmission induced by the seasonal dynamic of intermediate host snails. Water quality seems appropriate to the development of host snails from December to March and would be the strong period of schistosomiasis transmission. However, furthermore studies will need for well understanding the dynamic transmission necessary for developing adapted strategy control.

A delayed Schistosomiasis transmission model and its dynamics

A 6-dimension dynamical Schistosomiasis model incorporating 5 time delays is established in order to investigate the effects of time delays on the transmission mechanisms of Schistosomiasis. The stability behaviors at the endemic equilibrium are presented under different cases, which relate to the threshold value for disease breakout. The following results and available control strategies can be obtained from theoretical analyses and numerical simulations. (1) The incubation of egg hatching can postpone the outbreak of Schistosomiasis. Therefore it can be used as a new method for the control of Schistosomiasis spread that prolonging the incubation of egg hatching. (2) The time delays in miracidia and cercaria can extend the disease transmission cycle. Thus lengthening the incubation periods in miracidia and cercaria can be beneficial to Schistosomiasis prevention at the beginning. (3) The maturation periods of schistosome and sporocyst could give rise to Hopf bifurcations and periodic orbits, respectively, and the basic reproductive number decreases with respect to the maturation of sporocyst. Therefore, it is a reasonable strategy to control the spread of Schistosomiasis that prolonging the maturation duration of the sporocyst in snails. The consequences obtained motivate us that we can choose the right time to do the control laws, such as in winter (when lower temperature).

Spatial distribution and habitat suitability of Biomphalaria straminea, intermediate host of Schistosoma mansoni, in Guangdong, China

BackgroundBiomphalaria straminea is an invasive vector in China, posing a significant threat to public health. Understanding the factors affecting the establishment of this snail is crucial to improve our ability to manage its dispersal and potential risk of schistosomiasis transmission. This study sought to determine the spatial distribution of B. straminea in mainland China and whether environmental factors were divergent between places with and without B. straminea.MethodsA malacological survey of B. straminea was conducted in Guangdong Province, China. Snails were identified using anatomical keys. Water and sediment samples were taken, and their physicochemical properties were analyzed using national standard methods. Landscape and climatic variables were also collected for each site. We compared the environmental characteristics between sites with and without B. straminea using Mann-Whitney U test. We further used generalized linear mixed models to account for seasonal effects.ResultsB. straminea was found at six sites, including one in Dongguan and five in Shenzhen. Probability map found a hot spot of B. straminea distribution at Shenzhen and Hong Kong. Sites occupied by B. straminea were characterized by higher median altitude, mean annual precipitation and moderate temperature. Water with snails had higher median concentrations of total nitrogen, nitrate and nitrites, ammoniacal nitrogen, calcium, zinc and manganese but lower dissolved oxygen and magnesium. Sediments with snails had higher median copper, zinc and manganese. B. straminea was associated with maximum temperature of the warmest month (pMCMC < 0.001) and sediment zinc (pMCMC < 0.001).ConclusionsB. straminea is distributed in Shenzhen and its surrounding areas in Guangdong, China. Sites with and without B. straminea differed in the maximum temperature of the warmest month and sediment zinc. Surveillance should be continued to monitor the dispersal of this snail in China.

Schistosomiasis Burden and Its Association With Lower Measles Vaccine Responses in School Children From Rural Cameroon.

Background and Methods: Schistosomiasis is debilitating and reported to impair immune responsiveness of infected hosts. In Cameroon, mass drug administration (MDA) is used in schoolchildren to reduce transmission of S. haematobium and S. mansoni. The effects of MDA and the impact of schistosomiasis on the titers of antibodies in vaccinated children have been poorly studied. We therefore assessed the prevalence of schistosomiasis in schoolchildren, eight months after MDA, in two locations: Barombi Koto (BK), endemic for S. haematobium (N = 169) and Yoro (Y), endemic for S. mansoni (N = 356). Age, gender, residence time and frequency of contact with river water were assessed as risk factors for infection and morbidity in both localities. In 70 schoolchildren from BK and 83 from Y, ultrasound was used to assess morbidity according to the WHO guidelines. Evaluation of measles antibodies was performed in previously vaccinated schoolchildren (14 with S. haematobium and 12 egg-negative controls from BK and 47 with S. mansoni and12 egg-negative controls from Y).Principal Findings and conclusions: The prevalence of S. haematobium was 25. 4% in BK (43/169) and 34.8% for S. mansoni in Y (124/356), indicating the persistent transmission of schistosomiasis despite MDA. Older age (AOR 1.31; 95%CI 1.12–1.54) and higher frequencies of exposure to river water (AOR 1.99; 95%CI 1.03–3.86) were identified as risks for infection in BK whereas only older age (OR 1.15; 95%CI 1.04–1.27) was a risk for infection in Y. Bladder pathology (score 2 to 5) was observed in 29.2% (7/24) of egg-positive children in BK and liver pathology (pattern C) in 31.1% (19/61) of egg-positive children in Y. There was a positive correlation between S. haematobium egg burden and bladder pathology (AOR 1.01; 95% CI 0.99–1.02) and positive correlation between S. mansoni-driven liver pathology and female gender (AOR 3.01; 95% CI 0.88–10.26). Anti-measles antibodies in vaccinated children were significantly lower in S. mansoni-infected when compared to egg-negative controls (p = 0.001), which was not observed in the S. haematobium-infected group from BK. Our results demonstrate a questionable efficacy of MDA alone in halting schistosomiasis transmission and confirm a possible immunomodulatory effect of S. mansoni on response to vaccines.

Snail transmitters of schistosomiasis and other mollusks of medical and economic importance at the Simplício Queda Única Hydroelectric Plant, Southeast Brazil.

This paper presents the results of an extensive survey of freshwater mollusks in the Simplício Queda Única Hydroelectric Development area, Southeast Brazil. Mollusks were collected between 2008 and 2013. All specimens were examined for the presence of larval trematodes. In total, 12,507 specimens classified into 16 genera were obtained. Known snail vectors of schistosomiasis and fascioliasis and exotic species were identified, and new records are reported. No specimens parasitized by larval trematodes of medical interest were detected. However, the results reinforce the importance of surveillance in study areas vulnerable to the occurrence of schistosomiasis transmission.

Association of riverine prawns and intermediate host snails and correlation with human schistosomiasis in two river systems in south-eastern Côte d'Ivoire

The current emphasis of schistosomiasis control is placed on preventive chemotherapy using praziquantel. However, reinfection may occur rapidly in the absence of complementary interventions. Recent studies from Senegal suggest that predatory prawns might feed on intermediate host snails and thus impact on schistosomiasis transmission. We designed a study with four repeated cross-sectional surveys pertaining to prawns and snails, coupled with a single cross-sectional parasitological survey among humans. We assessed for potential associations between the presence/density of prawns and snails and correlation with Schistosoma infection in a composite sample of school-aged children and adults. The study was carried out between October 2015 and December 2016 in 24 villages located near the Agnéby and Mé coastal river systems in south-eastern Côte d'Ivoire. At each site, snails and prawns were collected, and in each village, 150 individuals were subjected to stool and urine examination for the diagnosis of Schistosoma mansoni and S. haematobium. We found peaks of relative abundance of intermediate host snails in the villages of the Agnéby River system, while predatory prawns were predominantly recorded in the Mé River system. A negative association was observed between intermediate host snail densities and riverine prawns; however, no pattern was found between this trend in the predator-prey relationship and the prevalence of human schistosomiasis.

Surveillance and risk assessment system of schistosomiasis epidemic focus in Hankou marshland of Wuhan City

To construct a monitoring and risk assessment system of schistosomiasis epidemic focus in marshland, so as to grasp the risk of schistosomiasis transmission, and to provide the technical support for targeted prevention and control measures. The crowd and the risk source of schistosomiasis in Hankou marshland in Wuhan City were monitored to grasp the risk factors of schistosomiasis. The risk level was evaluated by the three-dimensional risk matrix and three-dimensional visualization method. The total numbers of people on holidays and working days were 59 582 and 36 382 persontimes a day respectively in Hankou marshland. Fishing and swimming were the most common ways to contact the river water. The most majority of the people exposed to river water were male (73.9%), retirees (36.1%), local residents (69.7%) and people whose income was 1000 - 3000 yuan per month (52.1%), and the awareness of protection of them was low. In spring, the average density of living Oncomelania hupensis snails was 0.993/0.1 m2, the rat density was 7.72%, and the density of wild feces was 0.78/hm2. In autumn, the average density of living snails was 0.596 /0.1 m2, the rat density was 5.22%, and the density of wild feces was 0.32/hm2. The average density of living snails, the rat density and the density of wild feces were reduced by 39.9%, 32.4% and 59.0% respectively in autumn compared with those in spring. The risk assessment results of three-dimensional matrix showed that part 1 and part 2 were medium risk, part 3 was high risk and part 4 was maximum risk. The risk assessment results of the visualization method showed that the risk level increased from part 1 to part 4, which were basically consistent with the results of the risk matrix. There is a relatively large risk of schistosome infection in Hankou marshland in 2013. The surveillance and risk assessment system of epidemic focus is feasible and scientific.

Geographical and behavioral risks associated with Schistosoma haematobium infection in an area of complex transmission

BackgroundSchistosoma haematobium infection in endemic areas varies depending on the nature and complexity of the transmission networks present. Studies of micro-geographical transmission of S. haematobium infection indicate that discrepancy in prevalence between households is associated with diverse water contact behaviors and transmission that is restricted to particular sites harboring snail intermediate hosts. Detection of variations in the transmission sources with complex transmission networks of water bodies is required for optimization of malacological control. Longitudinal parasitological and malacological surveys were conducted to investigate geographical variations in transmission of urogenital schistosomiasis in Ikingwamanoti village, Shinyanga District, Tanzania.MethodsUrine samples were collected at baseline and follow-up time points from 282 school-aged children and examined microscopically for the presence of S. haematobium eggs. Malacological surveys involved collection of Bulinus nasutus every month from 30 sites. Snails were examined for patent infections. Global positioning system was used to map household distances from S. haematobium transmission sites, while water contact behavior was assessed using a questionnaire.ResultsSchistosoma haematobium infection was observed to be prevalent among older children (12–14 years) compared to younger groups prior to treatment, but no significant difference in infection prevalence was observed at one-year. Boys were highly infected than girls at both time points. No spatial influence was observed between children’s infection and the distance from child’s residence to the nearby snail habitats nor was any significant association observed between children’s reported water contact behavior with S. haematobium infection. However, malacological surveys with cercarial shedding combined with GPS data detected significant variation among different water sources in the transmission of S. haematobium with children living in households near to ponds with high B. nasutus populations having the highest prevalence of infection.ConclusionsInteraction between malacological surveys with cercarial shedding combined with GPS mapping in endemic settings can help detection of transmission sources even in areas with complex transmission networks. Subsequent studies are needed to determine whether the combination of GPS mapping and parasitology screens can aid the detection of transmission hotspots across varied transmission settings to enhance schistosomiasis control programmes.

Hubungan Perilaku Anak Sekolah Dasar dengan Kejadian Schistosomiasis di Kecamatan Lindu Kabupaten Sigi, Sulawesi Tengah

Schistosomiasis is a parasitic disease caused by infection of Schistosoma japonicum, S. haematobium, S. mansoni, S. mekongi, and S. intercalatum. It is transmitted to definitive host through cercaria contaminated water. In Indonesia, schistosomiasis was caused by S. japonicum which can be found in endemic areas at Lindu, Napu, and Bada highland. Schistosomiasis can infect all people regardless their age. If untreated, it leads to a chronic condition. Children who are infected will have a growth and cognitive problem and even death. The transmission of schistosomiasis cannot be separated from people behavior. This study aimed to identify the relationship between behavior of elementary student and schistosomiasis settle in Lindu, Sigi District, Central Sulawesi for eight months from March to December 2014. This was an observational study with a cross-sectional design. The data were collected by stool sampling and interview on elementary students. Stool samples were examined by Kato-Katz method. The chi-square analysis showed that there was no relationship between bathing habits, defecation habits, and using boots to schistosomiasis.

Identification of Biomphalaria sp. and other freshwater snails in the large-scale water transposition project in the Northeast of Brazil.

ABSTRACTThe wide eco-bio-social intervention generated by the SaoFrancisco River Integration Project (PISF) may contribute to the dispersion or introduction of schistosomiasis intermediate hosts in areas without prior recording. The objective was to characterize the limnic malacofauna and its distribution along watersheds involved in the PISF. A cross-sectional study based on the collection of mollusks from 33 water bodies, from Aurora, Brejo Santo, Jaguaretama, Jaguaribara, Jati e Mauriti municipalities in the Ceara (CE) State was developed. The conchological characteristics were used to identify snails at the genus level. The snails of the genus Biomphalaria were analyzed for the presence of Schistosoma mansoni cercariae and the molecular identification (only mollusks from Brejo Santo-CE) for differentiation between species. The following species were found: Biomphalaria sp.; Drepanotrema sp.; Melanoides sp.; Physa sp.; and Pomacea sp. Pomacea sp. (75.8%) and Biomphalaria sp. (72.7%) were the most prevalent species. All municipalities showed Biomphalaria sp. Biomphalaria straminea (Porcos Stream) and Biomphalaria kuhniana was identified in the Boi 1 and Cipo reservoirs (Brejo Santo). The evaluated municipalities under the influence of the PISF present areas with potential for schistosomiasis transmission. It is necessary to intensify control actions and health surveillance in these areas.

Assessment of schistosomiasis transmission risk after flood damage in Wuhan City

To assess the schistosomiasis transmission risk after flood damage in Wuhan City. Schistosomiasis epidemic villages in Wuhan City were selected by using probability proportional to size sampling (PPS). The field investigations of Oncomelania hupensis snails, the activity of people and cattle on marshland, water infectivity of schistosome, reservoir host infection and wild feces contamination were conducted. I-III levels of risk environments were assessed and treated with appropriate measures. A total of 90 schistosomiasis epidemic villages and 170 environments were monitored. Totally 9 811 snails were dissected but no Schistosoma japonicum infected snails were found. There were significant decreases in the density of snails and the survival rate of living snails after the flood (χ2 = 102.517, t = 4.724, both P < 0.01). Totally 289 pieces of wild feces were captured, and no eggs of S. japonicum were detected. A total of 11 surveillance and forecast sites were detected on water systems, and 221 sentinel mice were placed. After breeding, 219 sentinel mice survived (99.10%), and no schistosome infection was detected. In addition, 1 720 mouse traps were placed in 3 survey sites, and 66 Apodemus agrarius were captured, and no schistosome-infected ones were found. All of the environments were assessed as Grade III. Meanwhile, 5 key schistosomiasis control areas were determined, and no emergency happened after the implementation of comprehensive control interventions. The risk of schistosomiasis transmission remains low in Wuhan City after the flood, but the potential epidemic risk cannot be ignored.

Schistosomiasis Transmission Model and its Control in Anhui Province.

National Bureau of Statistics of China reports that the incidence of schistosomiasis has been increasing in recent years. To study dynamic behaviors of schistosomiasis transmission, based on practical experience of staff in Anhui Institute of Schistosomiasis, a mathematical schistosomiasis model with reinfection of recovered people is established in this paper. Metzler matrix theory and center manifold theorem are used to analyze stability of equilibria. Parameter estimation has been performed by combining model and monitoring data. It is found that the basic reproduction number is different every year. The most concern of Institute of Schistosomiasis is whether or when to kill snails every year. To answer this question, threshold value of snail density can be obtained. Once the snail density exceeds the threshold, the staff will need to kill snails. To find the best control measures, sensitivity analysis is used to find out sensitive parameters, and then control measures can be obtained by optimization control measures. The results show that combination of spraying molluscicide, publicity and education, improving the health facilities, and large-scale treatment of patient groups have the best effect. In additional, it is found that the number of patients does not change much when the reinfection rate of recovered people is very small. However, when the reinfection rate is slightly larger, the number of patients will suddenly increase to a large value.

Community knowledge, attitudes and practices related to schistosomiasis and associated healthcare-seeking behaviours in northern C\xf4te d\u2019Ivoire and southern Mauritania

BackgroundAmong parasitic infections, schistosomiasis ranks second after malaria in terms of worldwide morbidity. Despite efforts to contain transmission, more than 230 million people are infected, of which 85% live in Sub-Saharan Africa. While the epidemiologic characteristics of schistosomiasis have been extensively studied across endemic settings, social factors have been paid less attention. The current study assesses community knowledge of schistosomiasis causes, transmission, signs, symptoms and prevention, as well as healthcare-seeking behaviours in two West African settings, with the aim of strengthening schistosomiasis control interventions.MethodsFrom August 2014 to June 2015, we conducted two cross-sectional surveys in Korhogo, Côte d’Ivoire and Kaédi, Mauritania. We applied a questionnaire to collect quantitative data at the household level in Korhogo (n = 1456) and Kaédi (n = 1453). Focus group discussions (Korhogo: n = 32, Kaédi: n = 32) and participatory photography (photovoice) (Korhogo: n = 16, Kaédi: n = 16) were conducted within the communities to gather qualitative data. In addition, semi-structured interviews were used to discuss with key informants from control programmes, non-governmental organizations and health districts (Korhogo: n = 8, Kaédi: n = 7).ResultsThe study demonstrated that schistosomiasis is not well known by the communities; 64.1% claimed to know the causes of the disease, but the reality is different. This knowledge is more from cultural than biomedical source. It was observed that social construction of the disease is different from the biomedical definition. In Korhogo, schistosomiasis was often associated with several other diseases, notably stomach ulcer and gonorrhoea. The populations believe that schistosomiasis is caused by exposure to goat or dog urine in the environment. In Kaédi, schistosomiasis is considered as a disease transmitted by environmenal elements such as sunshine and dirty water. In both settings, the care-seeking pathways were found to be strongly influenced by local customs and self-medication acquired from the informal sector.ConclusionsThis study revealed that knowledge about the aetiology, transmission, symptoms, prevention and treatment of schistosomiasis among the populations in Korhogo and Kaédi is based on their local culture. Deep-rooted habits could therefore pose a significant obstacle to the elimination of schistosomiasis.

Potential role of rice cultivation and fish aquaculture in the transmission of schistosomiasis and the effect of pesticides and fertilizers used in rice cultivation on the snail Biomphalaria alexandrina and schistosome larval stages

Potential role of rice cultivation and fish aquaculture in the transmission of schistosomiasis and the effect of pesticides and fertilizers used in rice cultivation on the snail Biomphalaria alexandrina and schistosome larval stages

Risk Factors of Children Behavior in Schistosomythical Transfer in Two Villages of Lindu Regency, Sigi District, Central Sulawesi in 2017

Children of primary school are particularly vulnerable to schistosomiasis because 60-70% of them with age of 5-14 years do a lot of activity outside home. The impact of schistosomiasis in children are the lack of concentration in learning, anemia, and impaired growth. This study aimed to describe the behavior of children aged 7-12 years in Puro'o and Tomado Villages in preventing the transmission of schistosomiasis and to determine the correlation between age, sex behavior community in the prevention of schistosomiasis. The study was conducted in Tomado and Puro'o villages for 3 months from March to June 2016. This was a cross sectional study. The samples in this study were children aged 7-12 years, selected by stratified multistage random cluster sampling which was done in three phases: the first phase was the villages, the second phase was the primary school in the village, and the third stage was household selected by proportional random sampling. Data were collected through interview using a structured questionnaire and the observation was analyzed using chi-square test. Respondents who had less knowledge, mostly behave defecate/urinate (80%) in latrine/WC, handwashing behavior with soap after defecating/urinating (50%), wearing footwear outside the home (86.5%), and playing in the rice fields, marshes and lakes (67.3%). Analysis of the relationship between knowledge and child's behavior showed no significant relationship (p=0.114). As a conclusion, children aged 7-12 years in Tomado and Puro'o villages mostly had less supportive behavior in preventing the transmission of schistosomiasis and had moderate or less reliable knowledge.

Estimating the prevalence of schistosomiasis japonica in China: a serological approach

BackgroundThe prevalence of schistosomiasis japonica has decreased significantly, and the responses changing from control to elimination in Jiangsu Province, P.R. China. How to estimate the change in prevalence of schistosomiasis using only serological data will be important and useful.MethodsWe collected serum samples from 2011 to 2015 to build a serum bank from Dantu County of Jiangsu, China. Serum samples were detected by enzyme-linked immunosorbent assay (ELISA), the positive rate and optical density (OD) value were obtained. The Bayesian model including the prior information of sensitivity and specificity of ELISA was established, and the estimated infection rates were obtained for different years, genders and age groups.ResultsThere was no significant difference in the mean OD between different years and genders, but there was a significant difference between the different age groups. There were statistically significant differences in the positive rate for different years and age groups, but no significant difference at different genders. The estimated infection rate for the five years was 1.288, 1.456, 1.032, 1.485 and 1.358%, respectively. There was no significant difference between different years and between genders, but a significant difference between different age groups.ConclusionsThe risk of schistosomiasis transmission in this area still exists, and risk monitoring of schistosomiasis should be strengthened.