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Cryptosporidium is a protozoan parasite that can infect both humans and animals and cause cryptosporidiosis. We aimed to estimate the global prevalence of Cryptosporidium infection. In this study, Web of Science, Medline and PubMed were searched for relative articles, published between January 1, 1960 and January 1, 2018. Included articles were restricted to English language and that sample size of articles was not less than 50. Studies with no information on the study period, location, method of diagnosis, sample size and number of infected people were excluded. Studies about outbreak, laboratory report or immunocompromised population were excluded as well. The quality of the included publications was assessed. The prevalence of cryptosporidiosis was estimated by DerSimonian–Laird random-effects model, after converting by the Freeman–Tukey type double arcsine transformation. From 13,064 publications selected by literature search, 221 studies were included in the meta-analysis. The global pooled prevalence of Cryptosporidium infection was 7.6 % (95% CI: 6.9–8.5). The highest estimated prevalence of Cryptosporidium infection was in Mexico (69.6%, 95% CI 66.3–72.8), Nigeria (34.0%, 95% CI 12.4–60.0), Bangladesh (42.5%, 95% CI 36.1–49.0) and Republic of Korea (8.3%, 95% CI 4.4–13.2) among general residents, patients, school children and healthy population, respectively. The estimated prevalence was high in people from low-income country, people with gastrointestinal symptoms, people younger than 5 years old and residents not living in urban areas. These estimates indicate the substantial prevalence of Cryptosporidium infection in the world, which may provide a theoretical basis for the formulation of the prevention strategy about Cryptosporidium.

As a successful prevention strategy for controlling the highly contagious and pathogenic disease of spring viremia of carp (SVC), DNA vaccines reported in recent years could trigger protective responses against SVC with the means of injection. However, there remains many concerns and uncertainties related to DNA vaccination as well as injection is labor intensive, costly and not suitable to vaccinate large numbers of fish. Therefore, more efficient and safe prophylactic measures should be urgently investigated. In this research, single-walled carbon nanotubes (SWCNTs) as the candidate SWCNTs-pET32a-G subunit vaccine carrier were administrated via bath (1, 5, 10, 20, 40 mg L−1) or injection (1, 4, 8, 12, 20 μg) in common carp juvenile, and the different immune treatments to induce immunoprotective effect were analyzed. The results showed that SWCNTs-pET32a-G could enter fish body after immersion for 10 h, furthermore, compared to control groups, antibody levels, the non-specific immune parameters (complement activity, superoxide dismutase activity and alkaline phosphatase activity), and immune-related genes (especially the TNF-α and IFNg2b) in vaccinated groups were significantly enhanced in fish immunized with SWCNTs-subunit vaccine. In addition, as a promising carrier, SWCNTs can increase the immune protective effect of naked subunit vaccine by ca. 16% in bath immunization group and by ca. 23% in injection group. This study suggests that SWCNTs-vaccine may represent a potentially efficient immersion vaccine against viral pathogens of fish in the future.

Over the several decades, China has been incessantly optimizing control strategies in response to the varying epidemic situations of schistosomiasis. We evaluated continuously the changing prevalence under different control strategies of two villages, Sanlian and Guifan, in China through five phases lasting 37 years. We tested residents, calculated prevalence and discussed change causes. We found the prevalence in Sanlian did not differ significant from that of Guifan (p = 0.18) in 1981, but decreased to 2.66%, much lower than Guifan&rsquo, s 11.25%, in 1984 (p = 0). Besides, prevalence in Guifan increased to 21.25% in 1987, while in Sanlian it rose to 20.78% until 1989. Those data confirmed that praziquantel combined with snail control could better reduce the prevalence. From 1992 to 1994, the prevalence in the two villages displayed downtrends, which showed the World Bank Loan Project worked. From 1995 to 2004, repeated oscillations with no obvious change trend was seen. Since 2005, the prevalence in both villages has shown a significant downtrend (p &lt, 0.05), which suggests the integrated strategy is effective. We considered the control strategies were implemented suitably in the study area under changing social circumstances. Adjusting the strategy in consideration of social transformations is necessary and vital. The experience may be useful for policy making of other epidemic areas with an analogous situation.

Background Schistosomiasis remains an important public health issue in China and worldwide. Oncomelania hupensis is the unique intermediate host of schistosoma japonicum, and its change influences the distribution of S. japonica. The Three Gorges Dam (TGD) has substantially changed the ecology and environment in the Dongting Lake region. This study investigated the impact of water level and elevation on the survival and habitat of the snails. Methods Data were collected for 16 bottomlands around 4 hydrological stations, which included water, density of living snails (form the Anxiang Station for Schistosomiasis Control) and elevation (from Google Earth). Based on the elevation, sixteen bottomlands were divided into 3 groups. ARIMA models were built to predict the density of living snails in different elevation areas. Results Before closure of TGD, 7 out of 9 years had a water level beyond the warning level at least once at Anxiang hydrological station, compared with only 3 out of 10 years after closure of TGD. There were two severe droughts that happened in 2006 and 2011, with much fewer number of flooding per year compared with other study years. Overall, there was a correlation between water level changing and density of living snails variation in all the elevations areas. The density of living snails in all elevations areas was decreasing after the TGD was built. The relationship between number of flooding per year and the density of living snails was more pronounced in the medium and high elevation areas; the density of living snails kept decreasing from 2003 to 2014. In low elevation area however, the density of living snails decreased after 2003 first and turned to increase after 2011. Our ARIMA prediction models indicated that the snails would not disappear in the Dongting Lake region in the next 7 years. In the low elevation area, the density of living snails would increase slightly, and then stabilize after the year 2017. In the medium elevation region, the change of the density of living snails would be more obvious and would increase till the year 2020. In the high elevation area, the density of living snails would remain stable after the year 2015. Conclusion The TGD influenced water levels and reduced the risk of flooding and the density of living snails in the study region. Based on our prediction models, the density of living snails in all elevations tends to be stabilized. Control of S. japonica would continue to be an important task in the study area in the coming decade., Author Summary Oncomelania hupensis, an amphibious animal, is the unique intermediate host of schistosoma japonicum. Three Gorges Dam (TGD) is a tremendous hydrological project, and it influences the survival of animals downstream. It is studied for several reasons. First, schistosomiasis is still a world-wide parasitic disease which needs to be prevented and controlled. Second, TGD causes the change of water level, and it will impact the existence of snails, but how TGD causes the change of snails and even the epidemics of schistosomiasis is not revealed. In this study, the authors explore the association between TGD and snails. The time-series data contains over 10-year water level downstream TGD and 10-year density of living snails downstream TGD in Dongting Lake Region. These can help to find out the relationship between the change of water level and the change of density of living snails. After this exploration, we attempt to predict the density of living snails 7years later using ARIMA model.

Background Owing to the harmfulness and seriousness of Schistosomiasis japonica in China, the control and prevention of S. japonica transmission are imperative. As the unique intermediate host of this disease, Oncomelania hupensis plays an important role in the transmission. It has been reported that the snail population in Qiangliang Lake district, Dongting Lake Region has been naturally declining and is slowly becoming extinct. Considering the changes of environmental factors that may cause this phenomenon, we try to explore the relationship between circumstance elements and snails, and then search for the possible optimum scopes of environmental factors for snails. Methods Moisture content of soil, pH, temperature of soil and elevation were collected by corresponding apparatus in the study sites. The LISA statistic and GWR model were used to analyze the association between factors and mean snail density, and the values in high-high clustered areas and low-low clustered areas were extracted to find out the possible optimum ranges of these elements for snails. Results A total of 8,589 snail specimens were collected from 397 sampling sites in the study field. Besides the mean snail density, three environmental factors including water content, pH and temperature had high spatial autocorrelation. The spatial clustering suggested that the possible optimum scopes of moisture content, pH, temperature of the soil and elevation were 58.70 to 68.93%, 6.80 to 7.80, 22.73 to 24.23°C and 23.50 to 25.97 m, respectively. Moreover, the GWR model showed that the possible optimum ranges of these four factors were 36.58 to 61.08%, 6.541 to 6.89, 24.30 to 25.70°C and 23.50 to 29.44 m, respectively. Conclusion The results indicated the association between snails and environmental factors was not linear but U-shaped. Considering the results of two analysis methods, the possible optimum scopes of moisture content, pH, temperature of the soil and elevation were 58.70% to 68.93%, 6.6 to 7.0, 22.73°C to 24.23°C, and 23.5 m to 26.0 m, respectively. The findings in this research will help in making an effective strategy to control snails and provide a method to analyze other factors.

Experimental results on the study of pyridine molecules adsorbed on Ag films and Ag foils under atmospheric and ultra-high vacuum environments by the secondharmonic generation technique suggest that micro-scaled active sites existing in the evaporated Ag film play the key role for this kind of adsorption.