Malaria Transmission Potential in the Three Gorges Reservoir of the Yangtze River, China

Objective To define and evaluate the malaria transmission potential in the Yangtze River, following construction of the Three Gorges Reservoir. Methods Six villages, namely, Kaixian, Fengjie, Wanzhou, Fuling, Yubei, and Zigui were selected for investigating the malaria transmission potential in the reservoir. Transmission potential was estimated by mathematical modeling and evaluation of the local malaria situation. Factors that influenced the transmission potential were analyzed using Poisson regression analysis in combination with Grey Systematic Theory （based on evaluation by the Delphi method）. Results Indirect fluorescent antibody data and the incidence of malaria in the local population were consistent with the malaria transmission potential calculated for the area. Multivariate Poisson regression analysis showed a statistically significant association between the riparian zone and the man‐biting rate. Conclusion The risk of a malaria epidemic can be forecasted using the malaria transmission potential parameters investigated here which was closely correlated with the riparian zone.

Age-related Infection with Cryptosporidium Species and Genotype in Pigs in China

Objective Pigs, as hosts of zoonotic Cryptosporidium species/genotypes, are domestic animals with public health significance. The present study was to characterize the infection rate and species/genotype of Cryptosporidium in pre-weaned and post-weaned pigs from Shanghai and Shaoxing, China. Methods A total of 208 fecal samples （42 from pre-weaned piglets, and 166 from post-weaned pigs） were examined by nested PCR of the 185 rRNA gene and analyzed by phylogenetic DNA fragment sequencing of secondary PCR products. Results Infection was detected in 79 samples （19/42 pre-weaned piglets, and 60/166 post-weaned pigs）. C. suis （14/79） and Cryptosporidium pig genotype II （65/79） were identified; piglets were more susceptible to the former （13/14） and post-weaned pigs to the latter （59/65）. Conclusion Infection of Cryptosporidium spp. in pigs was age-specific; piglets were more susceptible to C. suis while pigs were more susceptible to Cryptosporidium pig genotype II. These findings combined with the isolation of the two Cryptosporidium from water suggest that pigs may be a source of zoonotic Cryptosporidium water pollution. Improvements in pig feeding practices, sewage discharge, feces disposal and field worker protection are therefore important to prevent potential public health problems.

Study of Infection of Echinococcus granulosus in Yak in Spring and Its Potential Role in Transmission of Cystic Echinococcosis in Rangtang County of Sichuan,China

Dear Editor, Cystic echinococcosis （CE）, caused by Echinococcus granulosus in larval stage, is considered as one of the most dangerous parasitic zoonosis in the world. The obligate 2-host parasitic cycle of Echinococcus granulosus is predominantly synanthropic. Dogs are the usual definitive hosts, and lots of mammalian species can be intermediate hosts, including domestic livestock and human[I2]. In the Tibetan plateau, China, the population is mainly Tibetans primarily engaged in livestock husbandry and CE is therefore a health problem for both people and animal in Tibetan communities. The reported infection rate of Echinococcus gronulosus in slaughtered yak in slaughterhouses is usually very high, being about 50% or higher as reported, and the liver and lungs are the main affected organs[34].

A direct,sensitive and high-throughput genus and species-specific molecular assay for large-scale malaria screening

Background:Infectious disease diagnostics often requires sensitive molecular assays that identify at both genus and species levels.For large scale screening,such as malaria screening for elimination,diagnostic assay can be a challenge,as both the throughput and cost of the assay must be considered.The requirement of nucleic acid extraction hampers the throughput of most molecular assays.Co-amplification of multiple species or multiplex identification either can result in missed diagnosis or are too costly for large-scale screening.A genus-and species-specific diagnostic assay with simplified procedure,high sensitivity and throughput is still needed.This study aimed to develop a sensitive and high-throughput approach for large-scale infectious disease screening.Methods:We developed multi-section Capture and Ligation Probe PCR(mCLIP-PCR)for the direct detection of RNA without extraction and reverse transcription.Multiple tailed sandwich hybridization probes were used to bind at genus-and species-specific sections of the target RNA to cooperatively capture the target onto a 96-well plate.After enzymatic ligation of the bound probes,a single-stranded DNA formed at each section with distinct tail sequence at the ends.They were separately PCR-amplified with primers corresponding to tail sequences for genus or species identification.We applied the method to the active screening ofPlasmodium infections of 4,580 asymptomatic dried blood spot samples collected in malaria endemic areas and compared the results with standard qPCR using linear regression.Results:With multi-section cooperative capture but separate amplification strategy,we accurately identified genusPlasmodium and speciesP.falciparum andP.vivax without RNA extraction,with favorable sensitivities among the published reports.In the active screening,our method identified all 53 positive infections including two mixed infections,and twoP.vivax infections that were missed by standard qPCR.Conclusions:mCLIP-PCR provides a sensitive and high-throughput approach to large-scale infectious disease screening with low cost and labor,making it a valuable tool for malaria elimination in endemic region.

Spatio-temporal disparities of Clonorchis sinensis infection in animal hosts in China:a systematic review and meta-analysis

Background Clonorchis sinensis,one of the most important food-borne zoonotic trematodes,remains prevalent in China.Understanding its infection status in animals is crucial for controlling human clonorchiasis.Here we conducted a systematic review and meta-analysis to focus on the spatio-temporal disparities ofC.sinensis infection in animals in China.Methods Data onC.sinensis prevalence in snails,the second intermediate hosts,or animal reservoirs in China were extracted from electronic databases including PubMed,Embase,Web of Science,Chinese Wanfang database,CNKI,VIP,and China Biomedical Literature database.A random-effects meta-analysis model was utilized to estimate the pooled prevalence in each of the above animal hosts.Subgroup analysis and multivariable meta-regression were performed to explore potential sources of heterogeneity across studies and compare the temporal disparity of infection rates between high and low epidemic areas.Scatter plots were used to depict the biogeographical characteristics of regions reportingC.sinensis infection in animals.Results The overall pooled prevalence ofC.sinensis was 0.9%(95%CI:0.6-1.2%)in snails,14.2%(12.7-15.7%)in the second intermediate host,and 14.3%(11.4-17.6%)in animal reservoirs.Prevalence in low epidemic areas(with human prevalence<1%)decreased from 0.6%(0.2-1.2%)before 1990 to 0.0%(0.0-3.6%)after 2010 in snails(P=0.0499),from 20.3%(15.6-25.3%)to 8.8%(5.6-12.6%)in the second intermediate hosts(P=0.0002),and from 18.3%(12.7-24.7%)to 4.7%(1.0-10.4%)in animal reservoirs.However,no similar decrease in prevalence was observed in high epidemic areas(with human prevalence≥1.0%).C.sinensis infections were predominantly reported in areas with altitudes below 2346 m and annual cumulative precipitation above 345 mm and were mostly concentrated in eastern China.Conclusions There are spatio-temporal disparities in the animal infections ofC.sinensis in different areas of China.Animal infections are primarily concentrated in regions with low altitude and high precipitation.The results suggest that implementing One Health-based comprehensive measures targeting both humans and animals,especially in high epidemic areas,is essential for successful eradication ofC.sinensis in China.

Knowledge of, attitudes towards, and practice relating to schistosomiasis in two subtypes of a mountainous region of the People’s Republic of China

Background:Schistosomiasis japonica is still endemic in the People’s Republic of China(P.R.China)in five provinces of lake and marshland regions and in two provinces of mountainous regions.Studies elucidated that individual and community perception,attitudes towards schistosomiasis,and hygiene behaviors were crucial factors for preventing schistosomiasis.This study sought to assess the knowledge of,attitudes towards,and practices(KAP)relating to schistosomiasis in two subtypes of a mountainous region in Eryuan County,Yunnan Province,P.R.China.The study’s aim is to make suggestions for establishing more specific and effective control measures for disease transmission and interruption in two subtypes of a mountainous region with low-level infection rates.Methods:A cross-sectional study of 3,000 inhabitants was carried out in the Yongle(plateau basin)and Xinzhuang(plateau canyon)communities of Eryuan County,Yunnan Province in November and December 2011.Stratified cluster random sampling was undertaken using a uniform set of quantitative questionnaires administered by trained assistants.This was further supported with qualitative data from in-depth interviews(IDIs)conducted with ten farmers and ten students.All participants were examined for schistosomiasis using both a serological test(indirect hemagglutination assay[IHA])and a stool examination(Kato-Katz).Results:The total schistosomiasis knowledge rate in Yongle(83.4%)was significantly lower than that in Xinzhuang(95.5%).In both communities,among the respondents aged 15 years or below,more than one third didn’t know the name,endemic areas,and animal reservoirs of schistosomiasis.The majority of respondents in Eryuan acquired their schistosomiasis knowledge from doctors,followed by handouts and hearing from others.The infection rate was once the highest in Yongle,but is now the highest in Xinzhuang,where there are more risk factors for schistosomiasis,such as frequently grazing cattle,digging vegetables or cutting grass in the field,as well as raising cattle by free grazing.Conclusion:In short,Eryuan County’s overall knowledge rate of schistosomiasis was found to be high.Due to various dominating risk factors,different control strategies should be designed keeping in mind the two different subtypes of endemic areas for schistosomiasis in mountainous regions,namely plateau basins and plateau canyons.

Inferring the potential risks of H7N9 infection by spatiotemporally characterizing bird migration and poultry distribution in eastern China

Background:In view of the rapid geographic spread and the increasing number of confirmed cases of novel influenza A(H7N9)virus infections in eastern China,we developed a diffusion model to spatiotemporally characterize the impacts of bird migration and poultry distribution on the geographic spread of H7N9 infection.Methods:Three types of infection risks were estimated for 12 weeks,from February 4 to April 28,2013,including(i)the risk caused by bird migration,(ii)the risk caused by poultry distribution,and(iii)the integrated risk caused by both bird migration and poultry distribution.To achieve this,we first developed a method for estimating the likelihood of bird migration based on available environmental and meteorological data.Then,we adopted a computational mobility model to estimate poultry distribution based on annual poultry production and consumption of each province/municipality.Finally,the spatiotemporal risk maps were created based on the integrated impacts of both bird migration and poultry distribution.Results:In the study of risk estimation caused by bird migration,the likelihood matrix was estimated based on the 7-day temperature,from February 4 to April 28,2013.It was found the estimated migrant birds mainly appear in the southeastern provinces of Zhejiang,Shanghai and Jiangsu during Weeks 1 to 4,and Week 6,followed by appearing in central eastern provinces of Shandong,Hebei,Beijing,and Tianjin during Weeks 7 to 9,and finally in northeastern provinces of Liaoning,Jilin,and Heilongjiang during Weeks 10 to 12.In the study of risk caused by poultry distribution,poultry distribution matrix was created to show the probability of poultry distribution.In spite of the fact that the majority of the initial infections were reported in Shanghai and Jiangsu,the relative risk of H7N9 infection estimated based on the poultry distribution model predicted that Jiangsu may have a slightly higher likelihood of H7N9 infection than those in Zhejiang and Shanghai,if we only take the probability of poultry distribution into consideration.In the study of integrated risk caused by both bird migration and poultry distribution,the higher risk in southeastern provinces occurred during the first 8 weeks,and that in central eastern provinces appeared during Weeks 8 to 12,and that in northeastern provinces since Week 12.Therefore,it is necessary to regulate the poultry markets as long as the poultry-to-poultry transmission is not so well understood.Conclusion:With reference to the reported infection cases,the demonstrated risk mapping results will provide guidance in active surveillance and control of human H7N9 infections by taking intensive intervention in poultry markets.

Distribution of the intermediate hosts of Echinococcus multilocularis in Shiqu County, Sichuan, China

Background The rodentia and lagomorpha animals are the intermediate hosts of Echinococcus multilocularis, their distribution and infection of this parasite may facilitate the infection of definitive hosts such as dogs. The aim of this study was to determine the distribution of the intermediate hosts of Echinococcus multilocularis in Shiqu County, Sichuan, China. Methods A systematic sampling method was used to investigate the density of burrows of rodents and lagomorphs at 97 pasture sites in winter and summer pastureland and remote sensing （RS） techno（ogy was used to correlate their densities to the distribution of these animals in different landscape types. Results Based on the densities of Ochotona curzoniae, Microtus fuscus （dependent variable） and their burrow densities （independent variable） in survey points, regression equations were fitted respectively （Ochotona curzoniae, P 〈0.0001, R2=0.8705; Microtus fuscus, P 〈0.0001,R2=0.9736）. Their burrow density in summer pastureland was higher than in winter pastureiand （F=36.65, P 〈0.0001）. The burrow densities of Ochotona curzoniae and Microtus fuscus in bareland and half-bareland are higher than in grassland （F=7.73, P〈0.001）. Conclusions The regression relationship between the densities of Ochotona curzoniae and Microtus fuscus and their burrow densities indicate that the burrow densities could reflect the animal densities and that the burrow density was greater in summer pastureland than in winter pastureland. The main distribution areas of the intermediate hosts were in bareland and half-bareland.

Assessing stool quantities generated by three specific Kato-Katz thick smear templates employed in different settings

Background:The Kato-Katz technique is recommended for the diagnosis of helminth infections in epidemiological surveys,drug efficacy studies and monitoring of control interventions.We assessed the comparability of the average amount of faeces generated by three Kato-Katz templates included in test kits from two different providers.Methods:Nine hundred Kato-Katz thick smear preparations were done;300 per kit.Empty slides,slides plus Kato-Katz template filled with stool and slides plus stool after careful removal of the template were weighed to the nearest 0.1 mg.The average amount of stool that was generated on the slide was calculated for each template,stratified by standard categories of stool consistency(i.e.mushy,soft,sausage-shaped,hard and clumpy).Results:The average amount of stool generated on slides was 40.7 mg(95%confidence interval(CI):40.0–41.4 mg),40.3 mg(95%CI:39.7–40.9 mg)and 42.8 mg(95%CI:42.2–43.3 mg)for the standard Vestergaard Frandsen template,and two different templates from the Chinese Center for Disease Control and Prevention(China CDC),respectively.Mushy stool resulted in considerably lower average weights when the Vestergaard Frandsen(37.0 mg;95%CI:34.9–39.0 mg)or new China CDC templates(37.4 mg;95%CI:35.9–38.9 mg)were used,compared to the old China CDC template(42.2 mg;95%CI:40.7–43.7 mg)and compared to other stool consistency categories.Conclusion:The average amount of stool generated by three specific Kato-Katz templates was similar(40.3–42.8 mg).Since the multiplication factor is somewhat arbitrary and small changes only have little effect on infection intensity categories,it is suggested that the standard multiplication factor of 24 should be kept for the calculation of eggs per gram of faeces for all investigated templates.

Co-infection of HIV and parasites in China: Results from an epidemiological survey in rural areas of Fuyang city, Anhui province, China

The aim of this study was to investigate epidemiological characteristics of co-infection of HIV and intestinal parasites in a HIV/AIDS highly endemic area in China.A cross-sectional survey was carried out in two villages where HIV/AIDS prevalence in residents was over 1%.Stool samples of all residents in the two targeted villages were examined for the presence of intestinal parasites.Blood examination was performed for the HIV infection detection and anemia test.A questionnaire survey was carried out in all residents participating in the study.A total of 769 individuals were enrolled in the investigation,720 of whom were involved in stool examination of intestinal parasites.The infection rates of parasites in the residents of the targeted villages were as follows:0.56%for Ascaris lumbricoides,4.03%for Hookworm,0.28%for Trichuris trichiura,0.42%for Clonorchis sinensis,21.39%for Blastocystis hominis,3.89%for Giardia lamblia,1.67%for Entamoeba spp.,4.44%for Cryptosporidium spp.,and no infection for Strongyloides stercoralis.The overall infection rate of intestinal worms was 4.72%,intestinal parasite infection rate was 24.31%,the anemia prevalence rate was 34.68%,the co-infection rate of HIV and intestinal helminthes 2.17%,the co-infection rate of HIV and intestinal protozoa 28.26%,of which the co-infection rates of HIV and Blastocystis hominis,and HIV and Cryptosporidium spp.were 19.57%and 13.04%,respectively.A significant difference of Cryptosporidium spp.infection rate was found between HIV-positive group(13.04%)and HIV-negative group(4.70%)(P<0.05).Higher prevalence of anemia(34.68%)occurred in the study villages,particularly in children(>50%)and women(>39%).It was concluded that the infection rate of intestinal protozoa in the residents was higher than that of intestinal helminthes in the local setting,and a same pattern appeared in the co-infection rate of HIV and parasites.An interestingfinding is that the infection rate of Cryptosporidium spp.among the HIV-positives was significantly higher than that in the HIV-negatives,and children and women had higher anemia prevalence.

Ebola wreaks havoc in Sierra Leone

Background:Ebola virus disease has taken a toll on more than 8,000 lives in West Africa in 2014.The most affected countries are Guinea,Liberia,and Sierra Leone.The number of people infected by Ebola in Sierra Leone surpassed that of Liberia in the last month in this year and almost half of human cases are distributed in this country.Discussion:The ignorance on Ebola among people,including health workers at the early stage,plaid an important role in spread of Ebola virus disease.Subsequently,Ebola ravages urban settings for the first time and takes a huge toll on the lives.The government and international partners do make efforts to control the epidemic,however,lack of synergy make them lip service.Summary:The leading role of government in the response to the epidemic should be emphasized.Basic information of Ebola should be quickly spread among communities by health education programme and social mobilization should be a basic measure for Ebola control.

Research priorities in modeling the transmission risks of H7N9 bird flu

The epidemic of H7N9 bird flu in eastern China in early 2013 has caused much attention from researchers as well as public health workers.The issue on modeling the transmission risks is very interesting topic.In this article,this issue is debated and discussed in order to promote further researches on prediction and prevention of avian influenza viruses supported by better interdisciplinary datasets from the surveillance and response system.