哺乳动物卵母细胞不对称分裂的研究进展

哺乳动物卵母细胞成熟过程需要进行两次连续的不对称分裂,最终形成体积差异巨大的子细胞:大体积的卵母细胞和两种体积较小的极体。不对称分裂现象是哺乳动物卵母细胞减数分裂的典型特征,不对称分裂后的卵母细胞是高度极化的细胞。精卵结合后,细胞重新恢复了对称分裂,但是在卵母细胞减数分裂过程中形成的极性特征却得以保留并影响早期胚胎的极性。本文对近年来在哺乳动物卵母细胞不对称分裂方面的相关研究展开综述,从细胞质不对称分裂和细胞核不对称分裂两个方面对染色体、细胞骨架在哺乳动物卵母细胞不对称分裂中的作用、细胞器在哺乳动物卵母细胞成熟过程中的重组分配、染色体非随机分离等过程进行介绍,旨在从细胞和分子水平阐述哺乳动物卵母细胞不对称分裂的主要机制。

Spatiotemporal heterogeneity of schistosomiasis in China's Mainland:Evidence from a multi-stage continuous downscaling sentinel monitoring

Objective:To determine the spatiotemporal distribution of Schistosoma(S.)japonicum infections in humans,livestock,and Oncomelania(O.)hupensis across the endemic foci of China.Methods:Based on multi-stage continuous downscaling of sentinel monitoring,county-based schistosomiasis surveillance data were captured from the national schistosomiasis surveillance sites of China from 2005 to 2019.The data included S.japonicum infections in humans,livestock,and O.hupensis.The spatiotemporal trends for schistosomiasis were detected using a Joinpoint regression model,with a standard deviational ellipse(SDE)tool,which determined the central tendency and dispersion in the spatial distribution of schistosomiasis.Further,more spatiotemporal clusters of S.japonicum infections in humans,livestock,and O.hupensis were evaluated by the Poisson model.Results:The prevalence of S.japonicum human infections decreased from 2.06%to zero based on data of the national schistosomiasis surveillance sites of China from 2005 to 2019,with a reduction from 9.42%to zero for the prevalence of S.japonicum infections in livestock,and from 0.26%to zero for the prevalence of S.japonicum infections in O.hupensis.Analysis using an SDE tool showed that schistosomiasis-affected regions were reduced yearly from 2005 to 2014 in the endemic provinces of Hunan,Hubei,Jiangxi,and Anhui,as well as in the Poyang and Dongting Lake regions.Poisson model revealed 11 clusters of S.japonicum human infections,six clusters of S.japonicum infections in livestock,and nine clusters of S.japonicum infections in O.hupensis.The clusters of human infection were highly consistent with clusters of S.japonicum infections in livestock and O.hupensis.They were in the 5 provinces of Hunan,Hubei,Jiangxi,Anhui,and Jiangsu,as well as along the middle and lower reaches of the Yangtze River.Humans,livestock,and O.hupensis infections with S.japonicum were mainly concentrated in the north of the Hunan Province,south of the Hubei Province,north of the Jiangxi Province,and southwestern portion of Anhui Province.In the 2 mountainous provinces of Sichuan and Yunnan,human,livestock,and O.hupensis infections with S.japonicum were mainly concentrated in the northwestern portion of the Yunnan Province,the Daliangshan area in the south of Sichuan Province,and the hilly regions in the middle of Sichuan Province.Conclusions:A remarkable decline in the disease prevalence of S.japonicum infection was observed in endemic schistosomiasis in China between 2005 and 2019.However,there remains a long-term risk of transmission in local areas,with the highest-risk areas primarily in Poyang Lake and Dongting Lake regions,requiring to focus on vigilance against the rebound of the epidemic.Development of high-sensitivity detection methods and integrating the transmission links such as human and livestock infection,wild animal infection,and O.hupensis into the surveillance-response system will ensure the elimination of schistosomiasis in China by 2030.

Chromosome-level genome assembly of Oncomelania hupensis: the intermediate snail host of Schistosoma japonicum

Background Schistosoma japonicum is a parasitic flatworm that causes human schistosomiasis, which is a significant cause of morbidity in China, the Philippines and Indonesia.Oncomelania hupensis (Gastropoda: Pomatiopsidae) is the unique intermediate host ofS. japonicum. A complete genome sequence ofO. hupensis will enable the fundamental understanding of snail biology as well as its co-evolution with theS. japonicum parasite. Assembling a high-quality reference genome ofO. hupehensis will provide data for further research on the snail biology and controlling the spread ofS. japonicum.Methods The draft genome was de novo assembly using the long-read sequencing technology (PacBio Sequel II) and corrected with Illumina sequencing data. Then, using Hi-C sequencing data, the genome was assembled at the chromosomal level. CAFE was used to do analysis of contraction and expansion of the gene family and CodeML module in PAML was used for positive selection analysis in protein coding sequences.Results A total length of 1.46 Gb high-qualityO. hupensis genome with 17 unique full-length chromosomes (2n = 34) of the individual including a contig N50 of 1.35 Mb and a scaffold N50 of 75.08 Mb. Additionally, 95.03% of these contig sequences were anchored in 17 chromosomes. After scanning the assembled genome, a total of 30,604 protein-coding genes were predicted. Among them, 86.67% were functionally annotated. Further phylogenetic analysis revealed thatO. hupensis was separated from a common ancestor ofPomacea canaliculata andBellamya purificata approximately 170 million years ago. Comparing the genome ofO. hupensis with its most recent common ancestor, it showed 266 significantly expanded and 58 significantly contracted gene families (P < 0.05). Functional enrichment of the expanded gene families indicated that they were mainly involved with intracellular, DNA-mediated transposition, DNA integration and transposase activity.Conclusions Integrated use of multiple sequencing technologies, we have successfully constructed the genome at the chromosomal-level ofO. hupensis. These data will not only provide the compressive genomic information, but also benefit future work on population genetics of this snail as well as evolutional studies betweenS. japonicum and the snail host.

Impact factors of Blastocystis hominis infection in persons living with human immunodeficiency virus:a large-scale,multi-center observational study from China

Background Blastocystis hominis(Bh)is zoonotic parasitic pathogen with a high prevalent globally,causing opportunistic infections and diarrhea disease.Human immunodeficiency virus(HIV)infection disrupts the immune system by depleting CD4^(+)T lymphocyte(CD4^(+)T)cell counts,thereby increasing Bh infection risk among persons living with HIV(PLWH).However,the precise association between Bh infection risk and HIV-related biological markers and treatment processes remains poorly understood.Hence,the purpose of the study was to explore the association between Bh infection risk and CD4^(+)T cell counts,HIV viral load(VL),and duration of interruption in antiviral therapy among PLWH.Methods A large-scale multi-center cross-sectional study was conducted in China from June 2020 to December 2022.The genetic presence of Bh in fecal samples was detected by real-time fluorescence quantitative polymerase chain reaction,the CD4^(+)T cell counts in venous blood was measured using flowcytometry,and the HIV VL in serum was quantified using fluorescence-based instruments.Restricted cubic spline(RCS)was applied to assess the non-linear association between Bh infection risk and CD4^(+)T cell counts,HIV VL,and duration of interruption in highly active antiretroviral therapy(HARRT).Results A total of 1245 PLWH were enrolled in the study,the average age of PLWH was 43 years[interquartile range(IQR):33,52],with 452(36.3%)being female,50.4%(n=628)had no immunosuppression(CD4^(+)T cell counts>500 cells/μl),and 78.1%(n=972)achieved full virological suppression(HIV VL<50 copies/ml).Approximately 10.5%(n=131)of PLWH had interruption.The prevalence of Bh was found to be 4.9%[95%confidence interval(CI):3.8-6.4%]among PLWH.Significant nonlinear associations were observed between the Bh infection risk and CD4^(+)T cell counts(Pfor nonlinearity<0.001,L-shaped),HIV VL(Pfor nonlinearity<0.001,inverted U-shaped),and duration of interruption in HARRT(Pfor nonlinearity<0.001,inverted U-shaped).Conclusions The study revealed that VL was a better predictor of Bh infection than CD4^(+)T cell counts.It is crucial to consider the simultaneous surveillance of HIV VL and CD4^(+)T cell counts in PLWH in the regions with high level of socioeconomic development.The integrated approach can offer more comprehensive and accurate understanding in the aspects of Bh infection and other opportunistic infections,the efficacy of therapeutic drugs,and the assessment of preventive and control strategies.

Surveillance-based evidence:elimination of schistosomiasis as a public health problem in the Peoples’Republic of China

Background:A steady progress on schistosomiasis control in the Peoples’Republic of China(P.R.China)was achieved and broadened into the twelve-year medium and long term national plan(MLNP)which marled the implementation of an integrated control strategy across all endemic areas in P.R.China in 2004.To understand the endemic trends of schistosomiasis to assess the effectiveness of an integrated strategy,we conducted an analysis of schistosomiasis surveillance data spanned from 2005 to 2015.Methods:The schistosomiasis sentinel surveillance data from sentinel sites were collected and analyzed from 2005 to 2015.In these sentinel sites,residents aged 6 years or above were screened annually by indirect hemagglutination assay(IHA),while only antibody positives were followed by stool examination either Kato-katz method(KK)and/or hatching technique(HT).Domestic animals raised in sentinel sites were examined by HT for confirming the infection of schistosomes.Snail investigation was conducted each year through systematic sampling method combined with environmental sampling method.The snails collected from field were tested by microscopic dissection method.The infection rates of schistosomes in residents,domestic animals and snails,as well as the indicators reflecting the snails’distribution were calculated and analyzed.ANOVA analysis was used to examine the changes of the number of eggs per gram feces in population and Chi-square test was used to examine any change in proportions among groups.Results:A total of 148902 residents from sentinel sites attended this study and 631676 blood samples were examined by IHA test during the 11 covered years.The annual average antibody positive rates presented a significant decrease trends,from 17.48%(95%CI:17.20–17.75%)in 2005 to 5.93%(95%CI:5.71–6.15%)(χ2=8890.47,P<0.001)in 2015.During 2005–2015,the average infection rate of schistosomes in residents declined from 2.07%(95%CI:1.96–2.17%)to 0.13%(95%CI:0.09–0.16%),accompanied by significant decrease of infection intensity in population.In 2015,the stool positives were only found in farmers,fishermen and boatmen with infection rate of 0.16%(95%CI:0.11–0.20%),0.17%(95%CI:0–0.50%)respectively.The infection rate of schistosomes in domestic animals dropped from 9.42%(538/5711,95%CI:8.66–10.18%)to 0.08%(2/2360,95%CI:0–0.20%)from 2005 to 2015.Infections were found in eight species of domestic animals at the beginning of surveillance while only two cattle were infected in 2015.Totally 98 ha of new snail habitats were found,while 94.90%(93/98)distributed in lake and marshland regions.The percentage of frames with snails decreased from 16.96%(56884/335391,95%CI:16.83–17.09%)in 2005 to 4.28%(18121/423755,95%CI:4.22–4.34%)in 2014,with a slightly increase in 2015.Meanwhile,the infection rate of schistosomes in snails was decreased from 0.26%(663/256531,95%CI:0.24–0.28%)to zero during 2005–2015.Conclusions:The infection rate of schistosomes declined significantly,providing evidence that the goal of the MLNP was achieved.Elimination of schistosomiasis as a public health problem defined as WHO was also reached in P.R.China nationwide.Surveillance-response system should be improved and strengthened to realize the final goal of schistosomiasis elimination.

Infestation risk of the intermediate snail host of Schistosomajaponicum in the Yangtze River Basin: improved results by spatial reassessment and a random forest approach

Background:Oncomelania hupensis is only intermediate snail host of Schistosomajaponicum,and distribution of 0.hupensis is an important indicator for the surveillance of schistosomiasis.This study explored the feasibility of a random forest algorithm weighted by spatial distance for risk prediction of schistosomiasis distribution in the Yangtze River Basin in China,with the aim to produce an improved precision reference for the national schistosomiasis control programme by reducing the number of snail survey sites without losing predictive accuracy.Methods:The snail presence and absence records were collected from Anhui,Hunan,Hubei,Jiangxi and Jiangsu provinces in 2018.A machine learning of random forest algorithm based on a set of environmental and climatic variables was developed to predict the breeding sites of the 0.hupensis intermediated snail host of S.japonicum.Different spatial sizes of a hexagonal grid system were compared to estimate the need for required snail sampling sites.The predictive accuracy related to geographic distances between snail sampling sites was estimated by calculating Kappa and the area under the curve(AUC).Results:The highest accuracy(AUC=0.889 and Kappa=0.618)was achieved at the 5 km distance weight.The five factors with the strongest correlation to 0.hupensis infestation probability were:(1)distance to lake(48.9%),(2)distance to river(36.6%),(3)isothermality(29.5%),(4)mean daily difference in temperature(28.1%),and(5)altitude(26.0%).The risk map showed that areas characterized by snail infestation were mainly located along the Yangtze River,with the highest probability in the dividing,slow-flowing river arms in the middle and lower reaches of the Yangtze River in Anhui,followed by areas near the shores of China's two main lakes,the Dongting Lake in Hunan and Hubei and the Poyang Lake in Jiangxi.Conelusions:Applying the machine learning of random forest algorithm made it feasible to precisely predict snail infestation probability,an approach that could improve the sensitivity of the Chinese schistosome surveillance.system.Redesign of the snail surveillance system by spatial bias correction of 0.hupensis infestation in the Yangtze River Basin to reduce the number of sites required to investigate from 2369 to 1747.

Antibiotic resistance and molecular characterization of diarrheagenic Escherichia coli and non-typhoidal Salmonella strains isolated from infections in Southwest China

Background:Bacterial diarrhea is one of the most common causes for medical consultations,mortality and morbidity in the world.Diarrheagenic Escherichia coli(DEC)and non-typhoidal Salmonella(NTS)are major intestinal pathogens in developing countries,and the indiscriminate use of antibiotics has greatly contributed to resistant strains.Hence,the aim of the present study is to identify the antimicrobial resistance patterns and the molecular characteristics of DEC and NTS in southwest,China.Methods:1121 diarrheal patients and 319 non-diarrheal subjects across all age groups were recruited from four sentinel hospitals from June 2014 to July 2015 in Kunming City,Yunnan Province.Each stool specimen was collected to detect DEC and NTS with standard microbiological and molecular methods.Antimicrobial resistance testing was performed with the Kirby-Bauer disk diffusion method,and the standards for antimicrobial susceptibility testing complied with the Clinical and Laboratory Standards Institute(CLSI).Molecular characterization of strains was carried out using pulsed-field gel electrophoresis(PFGE).A structured questionnaire was used to record basic epidemiological data(e.g.sex,age,residence,season,etc.).Data were analyzed using Chi-square or Fisher’s exact test.Results:DEC was detected in 127(11.33%)diarrhea cases and 9(2.82%)non-diarrheal cases(χ^(2)=20.69,P<0.001,OR=4.36,95%CI:2.19-8.65),and the prevalence of NTS isolated from diarrhea cases was higher than that of non-diarrheal cases across all age groups(n=42,3.75%,n=1,0.31%,χ^(2)=10.10,P=0.002,OR=12.38,95%CI:1.70-90.29).The rates of resistance to ten antibiotics of DEC and NTS showed significant differences(χ^(2)=386.77,P<0.001;χ^(2)=191.16,P<0.001).The rates of resistance to Amoxicillin and Clavulafiate(AMC),Cephalothin(CEP),Gentamicin(GEN)and Sulfamethoxazole-Trimethoprim(SXT)of DEC isolated from diarrhea cases were higher than those of NTS isolated from diarrhea patients(37.01%vs 14.29%,χ^(2)=7.57,P=0.006;29.92%vs 11.90%,χ^(2)=5.40,P=0.02;37.01%vs 11.90%,χ^(2)=5.80,P=0.016;62.20%vs 26.19%,χ^(2)=16.44,P<0.001;respectively).Ciprofloxacin(CIP)was the most sensitive antibiotic for DEC and NTS strains isolated from diarrhea cases.Resistance rates of DEC isolates from cases and controls to more than three kinds antimicrobials(multidrug resistance,MDR)showed no significant differences(81.10%vs 88.89%,P=0.33).Pulsotype patterns of DEC strains were highly diverse;however,the pulsotype pattern of NTS strains was closely related to the serotype.The pattern of S.enteritidis was highly similar,but the S.enterica Typhimurium strain was discrete.Conclusions:Antibiotic resistance of Enterobacteriaceae is of great concern.The societal effects of antibiotic use justify strict monitoring to combat increases in antimicrobial resistance.Molecular epidemiology and systematic epidemiological investigation can provide accurate evidence for tracking the infection source.

HIV and intestinal parasite co-infections among a Chinese population: an immunological profile

Background:Parasite infections often result in a switch of the human body’s predominant immune reaction from T-helper 1(Th1)-type to Th2-type.Hence,parasite infections are widely expected to accelerate the progression of human immunodeficiency virus(HIV)infections to acquired immunodeficiency syndrome(AIDS).In the People’s Republic of China,both parasitic diseases and AIDS are epidemic in certain rural areas,and co-infections are relatively common.However,no population-based studies have yet investigated the frequency of HIV and parasite co-infections,and its effects on immune responses.We studied(1)the immune status of an HIV-infected population,and(2)the effect of co-infection of HIV and intestinal parasites on selected parameters of the human immune system.Methods:A total of 309 HIV-infected individuals were recruited and compared to an age-matched and sex-matched control group of 315 local HIV-negative individuals.Questionnaires were administered to all participants to obtain information on sociodemographic characteristics,sanitation habits,family income,and recent clinical manifestations.Two consecutive stool samples and 10 ml samples of venous blood were also collected from each individual for the diagnosis of parasite infections and quantitative measurements of selected cytokines and CD4+T-lymphocytes,respectively.Results:During the study period,79 HIV-infected individuals were not under highly active antiretroviral therapy(HAART)and were thus included in our analysis;the prevalence of intestinal helminth infections was 6.3%and that of protozoa was 22.8%.The most common protozoan infections were Blastocystis hominis(B.hominis)(13.9%)and Cryptosporidium spp.(10.1%).The prevalence of Cryptosporidium spp.in HIV-infected individuals was significantly higher than that in HIV negative individuals(P<0.05).Compared to the non-co-infected population,no significant difference was found for any of the measured immunological indicators(P>0.05).However,the following trends were observed:IFN-γlevels were lower,but the IL-4 level was higher,in the population co-infected with HIV and helminths.In the population co-infected with HIV and B.hominis,the IL-2 level was higher.The population co-infected with HIV and Cryptosporidium spp.had markedly lower CD4+T-lymphocyte counts.Conclusion:According to the immunologic profile, co-infection with helminths is disadvantageous to HIV-infected individuals. It was associated with a shift in the Th1/Th2 balance in the same direction as that caused by the virus itself, which might indicate an acceleration of the progress from an HIV infection to AIDS. Co-infection with Cryptosporidium spp. was not associated with a significant change in immune factors but co-infection with Cryptosporidium spp. was associated with a reduced level of CD4 + T-lymphocytes, confirming the opportunistic nature of such infections. Co-infection with B. hominis, on the other hand, was associated with an antagonistic shift in the immunological profile compared to an HIV infection.

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

Background:Schistosomiasis 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.Methods:Eryuan 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.Results:Ecological 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.Conclusions:Ecological 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.

Change patterns of oncomelanid snail burden in areas within the Yangtze River drainage after the three gorges dam operated

Background:An"integrated control"strategy has been implemented within seven provinces at highest risk for schistosomiasis along Yangtze River in Peoples'Republic of China(P.R.China)since 2004.Since O ncom elania hupensis is the only intermediate host of the blood fluke(Schistosom a japonicum),controlling the distribution of snails is considered an essential and effeaive way to reduce the risk of schistosomiasis infection.The study aimed to determine the snail area burden and annual trend among provinces with potential risk for schistosomiasis along the Yangtze River,above and below the Three Gorges Dam(TGD).Methods:This retrospective study utilized data previously collected from the National Parasitic Diseases Control Information Management System(NPDCIMS)on annual snail surveys from 2009 to 2017.Descriptive statistics were performed for analyzing the snail burden by provinces,counties,type of environmental location and year,and mapping was conducted to present the snails distribution.Results:From 2009 to 2017,the total snail infested area decreased by 4.22%,from 372253 hm^2 to 356553 hm^2 within the seven high risk provinces.The majority of snails were found in the marshland and lake regions,outside of control embankments.The total snail burden trend remained relatively stable in upstream regions above the TGD from 2010 to 2015,while the trend decreased within downstream regions during this period.In 2016 and 2017,the total snail burden trend increased in both upstream and downstream provinces,however,upstream saw a larger increase.From 2009 to 2017,there were a total of 5990 hm^2 of newly developed snail areas in the seven study provinces and the majority were concentrated in regions below the TGD,accounting for 5610 hm^2(93.70%).Conclusions:There has been a decline in total snail counts from 2009 to 2017.Meanwhile,new snail breeding areas were formed mainly within provinces downstream the TGD due to spread of snails,indicated that the oncomelanid snail would be difficult to completely eliminate.We suggest that the national schistosomiasis integrated control strategy,including mollusciding and environmental modification,will need to be enhanced significantly going forward to achieve a greater reduaion in snail burden and ultimately to achieve elimination.

Small-scale spatial analysis of intermediate and definitive hosts of Angiostrongylus cantonensis

Background:Angiostrongyliasis is a food-borne parasitic zoonosis.Human infection is caused by infection with the third-stage larvae of Angiostrongylus cantonensis.The life cycle of A.cantonensis involves rodents as definitive hosts and molluscs as intermediate hosts.This study aims to investigate on the infection status and characteristics of spatial distribution of these hosts,which are key components in the strategy for the prevention and control of angiostrongyliasis.Methods:Three villages from Nanao Island,Guangdong Province,China,were chosen as study area by stratified random sampling.The density and natural infection of Pomacea canaliculata and various rat species were surveyed every three months from December 2015 to September 2016,with spatial correlations of the positive P.canaliculata and the infection rates analysed by ArcGIS,scan statistics,ordinary least squares(OLS)and geographically weighted regression(GWR)models.Results:A total of 2192 P.canaliculata specimens were collected from the field,of which 1190 were randomly chosen to be examined for third-stage larvae of A.cantonensis.Seventy-two Angiostrongylus-infected snails were found,which represents a larval infection rate of 6.1%(72/1190).In total,110 rats including 85 Rattus norvegicus,10 R.flavipectus,one R.losea and 14 Suncus murinus were captured,and 32 individuals were positive(for adult worms),representing an infection rate of 29.1%of the definitive hosts(32/110).Worms were only found in R.norvegicus and R.flavipectus,representing a prevalence of 36.5%(31/85)and 10%(1/10),respectively in these species,but none in R.losea and S.murinus,despite testing as many as 32 of the latter species.Statistically,spatial correlation and spatial clusters in the spatial distribution of positive P.canaliculata and positive rats existed.Most of the spatial variability of the host infection rates came from spatial autocorrelation.Nine spatial clusters with respect to positive P.canaliculata were identified,but only two correlated to infection rates.The results show that corrected Akaike information criterion,R2,R2 adjusted andσ2 in the GWR model were superior to those in the OLS model.Conclusions:P.canaliculata and rats were widely distributed in Nanao Island and positive infection has also been found in the hosts,demonstrating that there was a risk of angiostrongyliasis in this region of China.The distribution of positive P.canaliculata and rats exhibited spatial correlation,and the GWR model had advantage over the OLS model in the spatial analysis of hosts of A.cantonensis.

Identification of the high-risk area for schistosomiasis transmission in China based on information value and machine learning:a newly data-driven modeling attempt

Background:Schistosomiasis control is striving forward to transmission interruption and even elimination,evidence-lead control is of vital importance to eliminate the hidden dan gers of schistosomiasis.This study attempts to ide ntify high risk areas of schistosomiasis in China by using in formation value and machine learni ng.

Surveillance on schistosomiasis in five provincial-level administrative divisions of the People's Republic of China in the post-elimination era

Background:The People's Republic of China(P.R.China)has made significant progress on schistosomiasis control.Among the 12 provincial-level administrative divisions(PLADs)with schistosomiasis endemic in P.R.China,Guangdong,Shanghai,Fujian,Guangxi and Zhejiang PLADs(following as five PLADs)had successively eliminated schistosomiasis during 1985-1995.However,consolidation of the schistosomiasis elimination in these five PLADs remains challenging.In the current study,we sought to understand the epidemic situation in these post-elimination areas and their surveillance capabilities on schistosomiasis.Methods:Annual data reflecting the interventions and surveillance on human beings,cattle and snails based on county level from 2005 to 2016 were collected through the national schistosomiasis reporting system and the data were analyzed to understand the epidemic status of schistosomiasis in the five PLADs.A standardized score sheet was designed to assess the surveillance capacity for schistosomiasis of selected disease control agencies in five PLADs and ten counties.Assessment on surveillance capacity including schistosomiasis diagnostic skills,identification of snails'living and infection status and knowledge about schistosomiasis and its control were made.Descriptive analysis was used to analyze the epidemic status and evaluation results on surveillance capacities.Results:The assessments showed that no local cases in humans and cattle or infected snail were found in these five PLADs since 2005.However,from 2005 to 2016,a total of 221 imported cases were detected in Zhejiang,Shanghai and Fujian,and 11.98 hm^2 of new snail habitats were found in Zhejiang,Shanghai and Guangxi.In addition,snail infestation reoccurred in 247.55 hm^2 of former snail habitats since 2011.For the surveillance capacity assessment,the accuracy rate of IHA and MHT were 100 and 89.3%,respectively.All participants could judge the living status of snails accurately and 98.1%on the infection status of snails.The accuracy rate of the questionnaire survey was 98.0%.Conclusions:Elimination of schistosomiasis was consolidated successfully in five PLADs of P.R.China due to effective and strong post-elimination surveillance.Comprehensive consolidation strategies should be focused on the elimination of residual snails and the prevention of imported infection sources to consolidate the achievements of schistosomiasis control.

Efficacy of the combination of modern medicine and traditional Chinese medicine in pulmonary fibrosis arising as a sequelae in convalescent COVID-19 patients: a randomized multicenter trial

Background:The coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)has led to a significant number of mortalities worldwide.COVID-19 poses a serious threat to human life.The clinical manifestations of COVID-19 are diverse and severe and 20%of infected patients are reported to be in a critical condition.A loss in lung function and pulmonary fibrosis are the main manifestations of patients with the severe form of the disease.The lung function is affected,even after recovery,thereby greatly affecting the psychology and well-being of patients,and significantly reducing their quality of life.

The genetic variation of Angiostrongylus cantonensis in the People’s Republic of China

Background:The People’s Republic of China(P.R.China)is the presumptive home range of the rat lungworm Angiostrongylus cantonensis,a major aetiological agent of human eosinophilic meningitis.We present a study of the genetic variation of A.cantonensis in P.R.China.Our aim was to deepen the current knowledge pertaining to its origin and global spread from a molecular perspective.Methods:Adult A.cantonensis were collected in the frame of a national survey and identified based on morphological criteria.Polymerase chain reaction(PCR)was employed to amplify the target DNA sequences(cytochrome c oxidase subunit I(cox1),nicotinamide adenine dinucleotide dehydrogenase subunit 1(nad1)and internal transcribed spacer(ITS)).The PCR product of cox1 was directly submitted to sequencing,while clone sequencing was used for nad1 and ITS.The identity of the samples was verified by comparing the sequences to those of accepted A.cantonensis specimens.The specific composition of substitutions in each gene was analysed,and the genotypes were compared based on the complete cox1,nad1 and ITS genes.Results:We characterised the complete mitochondrial genes cox1 and nad1 of 130 specimens and obtained 357 nuclear sequences containing two complete ITS(ITS1 and ITS2)and 5.8S rRNA of the same samples.All specimens were genetically confirmed as A.cantonensis.Two major groups(i.e.I and II)were identified according to the phylogeny of cox1 sequences.Group I could be further categorised into six distinct clades.Almost half of the specimens(47.7%)belong to the clade Ia and 22.3%to the group II.The former was widely distributed across the study region.A variable number of repeat units in three microsatellites was observed,resulting in considerable length variation in ITS.Intragenomic variation of ITS sequences was found in a large proportion of the samples.Genotyping showed a striking difference between mitochondrial DNA and ITS.Conclusions:Our results demonstrate that A.cantonensis is the only rat lungworm species in P.R.China and shows high genetic diversity.Results of diversity and genotyping of A.cantonensis can be impacted by the sequencing strategy and biomarker.Although ITS may be a valuable marker for interspecific identification,it is not suitable for studying the intraspecific variation of A.cantonensis due to its high intragenomic variation and current challenges for direct sequencing.

Assessment of the Transmission Risk of Schistosomiasis after Flooding-North Poyang Lake,Jiangxi Province,China,2020

What is already known about this topic?Over 90%of Oncomelania snails,the only intermediate host of Schistosoma japonicum,are distributed in the middle and low reaches of Yangtze River.Flooding can extend the distribution of Oncomelania snails and hence accelerate the transmission of schistosomiasis.What is added by this report?Although the dispersal of Oncomelania snails was negligible in north Poyang Lake after flooding in 2020,2 samples of cattle feces with Schistosoma egg and 2 infected snails samples were indeed found.All four risk sites were distributed in Lushan County.Cattle feces were observed in the six out of seven field sites in Lushan County.What are the implications for public health practice?The present national control strategy focusing on control of infection source should be reinforced in Lushan and other schistosomiasis endemic areas.Overlaps of infected snails and cattle feces with Schistosoma egg were not observed,which called for intensive surveillance in Lushan County.

The Potential Distribution Prediction of Oncomelania hupensis Based on Newly Emerging and Reemergent Habitats-China,2015−2019

What is already known about this topic?Oncomelania hupensis(O.hupensis)is the only intermediate host of Schistosoma japonica.The distribution of O.hupensis is affected by a series of climate,geographical,sand ocioeconomic factors,which reflect the risk areas of schistosomiasis.What is added by this report?There were certain geographical aggregations in the potential high distribution areas of O.hupensis,which were mainly distributed in Poyang Lake area,Dongting Lake area,and the middle and the lower reaches of the Yangtze River.What are the implications for public health practice?Monitoring and forecasting the distribution of O.hupensis is conducive to improving the early warning capabilities of the potential risk of schistosomiasis transmission and progressively promoting the elimination of schistosomiasis nationwide.

Molluscicidal effectiveness of Luo-Wei,a novel plant-derived molluscicide,against Oncomelania hupensis,Biomphalaria alexandrina and Bulinus truncatus

Background:Control of snail intermediate hosts has been proved to be a fast and efficient approach for interrupting the transmission of schistosomiasis.Some plant extracts have shown obvious molluscicidal activity,and a new compound Luo-Wei,also named tea-seed distilled saponin(TDS),was developed based on the saponins extracted from Camellia oleifera seeds.We aimed to test the molluscicidal activity of 4%TDS against the intermediate host snails in China and Egypt,and evaluate its environmental safety to non-target organisms.Methods:In the laboratory,Oncomelania hupensis,Biomphalaria alexandrina and Bulinus truncatus were exposed to 4%TDS,and the median lethal concentration(LC5o)was estimated at 24,48 and 72 h.In the field,snail mortalities were assessed 1,2,3 and 7 d post-immersion with 2.5 g/m34%TDS and 1,3,7 and 15 d post-spraying with 5 g/m24%TDS.in addition,the acute toxicity of 4%TDS to Japanese quail(Coturnixjaponica),zebrafish(Brachydanio rerio)and freshwater shrimp(Macrobrachium nipponense)was assessed by estimations of LC5o or median lethal dose(LD5o).Results:In the laboratory,the LC5o values of 4%TDS for O.hupensis were 0.701,0.371 and 0.33 mg/L at 24,48 and 72 h,respectively,and 4%TDS showed a 0.33 mg/L 24 h LC5o against B.alexandrina,and a 1.396 mg/L 24 h LCs0 against B.truncatus.Across all study regions,the pooled mortalities of O.hupensis were 72,86,94 and 98%at 1,2,3 and 7 d,following field immersion of 4%TDS at a dose of 2.5 g/m3,and were 69,77,85 and 88%at 1,3,7 and 15 d,following field spraying at 5 g/m2,respectively.4%TDS had moderate toxicity to Japanese quail(7 d LD5o>60 mg/kg)and to shrimp(96 h LCs0=6.28 mg/L;95%CI:3.53-11.2 mg/L),whereas its toxicity to zebrafish was high(96 h LCso--0.15 mg/L;95%CI:0.14-0.17 mg/L).Conclusions:4%TDS is active against O.hupensis,B.alexandrina and B.truncatus under laboratory and field conditions,and it may be a candidate molluscicide of plant origin.

Could China’s journey of malaria elimination extend to Africa?

World Health Organization (WHO) certified China malaria-free on June 30, 2021, which brightens the goal of global malaria elimination efforts. China contributed its unique innovations to the global community: Artemisinin, discovered by Tu Youyou, has saved millions of lives globally;the “1-3-7” norm developed in 2012, has been adapted in the local contexts of countries in the Southeast Asia and Africa. How to the targets of Global Technical Strategy for Malaria (GTS) 2016−2030. By looking into the malaria control phase, towards elimination phase from 1960 to 2011 in sub-Saharan Africa and China, we found that the gap in malaria burden will widen unless the interventions in Africa are enhanced. It is imperative to identify the key China–Africa cooperation areas on malaria control and elimination, so that synergized efforts could be pooled together to help African countries achieve the elimination goal. The practices from China malaria control and elimination efforts could be leveraged to fast-track malaria elimination efforts in Africa, which makes it possible that the China’s journey of malaria elimination extends to Africa.

Synthesis of 2-aminothiazoles via rhodium-catalyzed carbenoid insertion/annulation of sulfoxonium ylides with thioureas

Sulfoxonium ylides as carbene precursors couple smoothly with thioureas in the presence of 5 mol% of rhodium(Ⅱ) acetate dimmer via carbenoid insertion to afford the corresponding 2-aminothiazoles with high chemoselectivity,providing a facile and efficient approach to access a variety of 2-aminothiazole derivatives with good functional groups tolerance.