Reinfection rate and endoscopic changes after successful eradication of Helicobacter pylori

AIM:To determine the long-term outcomes regarding reinfection with Helicobacter pylori(H.pylori)and endoscopic changes after successful H.pylori eradication. METHODS:From June 1994 to January 2007,186 patients(M:F=98:88;mean age 50.0±11.4 years), in whom H.pylori had been successfully eradicated, were enrolled.The mean duration of follow up was 41.2±24.0 mo. RESULTS:H.pylori reinfection occurred in 58 patients (31.2%).The average annual reinfection rate was 9.1% per patient year.No recurrence of peptic ulcer was detected at the follow up endoscopy.There were no significant differences between the H.pylori eradication regimens for the reinfection rate and no significant differences in endoscopic findings between the H.pylorirecurred group and the H.pylori-cured group.CONCLUSION:The reinfection rate in Korea is 9.1% which represents a decreasing trend.There was no relationship between H.pylori infection status and changes in endoscopic findings.There was also no recurrence or aggravation of ulcers.

Prevention of hepatitis B virus reinfection after orthotopic liver transplantation

BACKGROUND: Hepatitis B virus reinfection is an impor-tant problem after liver transplantation. The aim of thisstudy was to discuss the prevention of hepatitis B virus rein-fection following orthotopic liver transplantation.METHODS: Sixty-eight cases of chronic fulminant hepatitisB, end-stage liver cirrhosis, and liver carcinoma complicat-ed with HBV cirrhosis were given anti-viral drugs beforeand after transplantation to prevent hepatitis B virus rein-fection. Lamivudine was administered in 2 patients, lami-vudine + hepatitis B immunoglobulin ( HBIG ) in 63, andadefovir + HBIG in 3. The measurement of serum HBV,HBV DNA, liver biopsy immunohistochemistry and clini-cal study were performed.RESULTS: In 1 of the 2 patients who developed reinfectionafter lamivudine administration, serum HBsAg, HBeAb,HBcAb, HBV DNA were positive and liver biopsy immu-nohistochemistry showed HBsAg phenotype. In 2 of 63 pa-tients who developed reinfection after use of lamivudine +HBIG, serum HBsAg, HBeAb, HBcAb were positive andliver biopsy immunohistochemistry showed HBsAg pheno-type. Serum HBV DNA was positive in one of them.Three patients developed no reinfection with HBV after useof adefovir.CONCLUSIONS: Orthotopic liver transplantation is effectivein the treatment of HBV-infected diseases. Lamivudine +HBIG or adefovir + HBIG could effectively prevent hepatitisB virus reinfection.

High rate of Helicobacter pylori reinfection in Lithuanianpeptic ulcer patients

AIM: To evaluate the frequency of Helicobacter pylori(H. pylori) reinfection in peptic ulcer patients during 9 years after H. pylori eradication.METHODS: We invited 117 peptic ulcer patients in whom eradication of H. pylori was confirmed 1 year after eradication treatment both by histology and by rapid urease test. In total, 57 patients were available for the study procedures: 34(59.6%) male, 23(40.4%) female; mean age 52.3 ± 13.0 years. There were 45(78.9%) patients with duodenal ulcer and 12(21.1%) with gastric ulcer. H. pylori was diagnosed by a rapid urease test and histology if endoscopy was performed. If endoscopy was refused, H. pylori was diagnosed by the C14-urea breath test and serology. H. pylori was established if at least one of the tests was positive.RESULTS: The mean follow-up was 8.9 ± 1.0 years(range, 6-12). H. pylori was established in 15 patients. In 2 H. pylori-negative patients, H. pylori was established during the follow-up period and eradicated. Therefore, we consider that reinfection occurred in 17 patients. In the per protocol analysis, reinfection was established in 17 of 57(29.8%; 95%CI: 19.2-42.2) patients during the follow-up period. The annual rate of infection was 3.36%. If all non-responders were considered H. pylori-negative, reinfection would be 14.5%(17/117), the annual ratebeing 1.63%. The mean age of patients with reinfection was 51.8 ± 14.0 years, and without reinfection was 52.5 ± 13.0 years, P > 0.05; the mean body mass index of patients with reinfection was 27.2 ± 4.1 kg/m2, and without reinfection was 25.7 ± 4.2 kg/m2, P > 0.05. There were no differences in the reinfection rates according the location of the peptic ulcer, the eradication regimen used, and smoking status.CONCLUSION: The reinfection rate of H. pylori is relatively high in Lithuania and probably related to the high prevalence of H. pylori, what may reflect differences in the socioeconomic status between Western and Eastern European countries.

Reinfection risk of novel coronavirus(COVID-19):A systematic review of current evidence

BACKGROUND There is recently a concern regarding the reinfection and reactivation of previously reCoVered coronavirus disease 2019(CoVID-19)patients.AIM To summarize the recent findings and reports of CoVID-19 reinfection in patients previously reCoVered from the disease.METHODS This study was a systematic review of current evidence conducted in August 2020.The authors studied the probable reinfection risk of novel coronavirus(CoVID-19).We performed a systematic search using the keywords in online databases.The investigation adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)checklist to ensure the reliability and validity of this study and results.RESULTS We reviewed 31 studies.Eight studies described reCoVered patients with reinfection.Only one study reported reinfected patients who died.In 26 studies,there was no information about the status of the patients.Several studies indicated that reinfection is not probable and that post-infection immunity is at least temporary and short.CONCLUSION Based on our review,we concluded that a positive polymerase chain reaction retest could be due to several reasons and should not always be considered as reinfection or reactivation of the disease.Most relevant studies in positive retest patients have shown relative and probably temporary immunity after the reCoVery of the disease.

Hepatitis B virus reinfection after liver transplan- tation: related risk factors and perspective

BACKGROUND: In recent years, liver transplantation (LT) has been acknowledged as an acceptable option for patients with hepatitis B virus (HBV) related end-stage liver diseases. However, HBV reinfection is an important event affecting the long-term survival of recipients. This paper was to review the risk factors related to HBV reinfection after LT. DATA SOURCES: English literature was reviewed based on MEDLINE focusing on the potential factors related to HBV reinfection after LT. RESULTS: HBV reinfection attributes to the unfavorable prognosis after LT. Many related factors may be responsible for it, including recipent factors (ethnical background, preoperative HBV replication status, extrahepatic HBV existence status), donor factors (compromised donor liver, HLA-A, -B compatibilities), perioperative treatment (use of antiviral agents, drug resistance, virus mutation, immu-nosuppressants protocol, blood transfusion) and others. CONCLUSIONS: The successful management of HBV reinfection will only be achieved by perfect clarification of its mechanism. The new strategies include new antiviral agents, gene therapy and immune intervention, reliable use of the compromised donor livers, and so on.

Elevated levels of fructosamine are independently associated with SARS-CoV-2 reinfection:A 12-mo follow-up study

BACKGROUND The association between blood levels of fructosamine(FMN)and recurrent coronavirus disease 2019(COVID-19)is currently unclear.AIM To investigate a prospective relationship between blood levels of FMN and severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)reinfection.METHODS A total of 146 Chinese hospitalized patients infected with SARS-CoV-2 were consecutively collectively recruited and followed from January 2020 to May 2021.Diagnosis of COVID-19 and SARS-CoV-2 reinfection was based on the diagnostic criteria and treatment protocol in China.The levels of FMN were determined in blood and divided into tertiles based on their distribution in the cohort of COVID-19 patients.Multivariate-adjusted hazard ratios(HRs)with 95%confidence intervals(CIs)were estimated for SARS-CoV-2 reinfection across the tertiles of FMN levels.A Cox regression model was used to generate the HR for SARS-CoV-2 reinfection in the participants in the top tertile of FMN levels compared with those at the bottom.Disease-free survival was used as the time variable,and relapse was used as the state variable,adjusted for age,gender,influencing factors such as diabetes mellitus,hypertension,and corticosteroid therapy,and clinical indexes such as acute liver failure,acute kidney failure,white blood cell(WBC)count,C-reactive protein,prognostic nutritional index(PNI),and blood lipids.Kaplan-Meier analysis with log-rank tests was used to compare the survival rate between patients with elevated FMN levels(FMN>1.93 mmol/L,the top tertile)and those with nonelevated levels.RESULTS Clinical data for the 146 patients with confirmed COVID-19[age 49(39-55)years;49%males]were analyzed.Eleven patients had SARS-CoV-2 reinfection.The SARS-CoV-2 reinfection rate in patients with elevated FMN levels was significantly higher than that in patients with nonelevated FMN(17%vs 3%;P=0.008)at the end of the 12-mo follow-up.After adjustments for gender,age,diabetes mellitus,hypertension,corticosteroid therapy,WBC count,PNI,indexes of liver and renal function,and blood lipids,patients with nonelevated FMN levels had a lower risk of SARS-CoV-2 reinfection than those with elevated FMN levels(HR=6.249,95%CI:1.377-28.351;P=0.018).Kaplan-Meier analysis showed that the cumulative survival rate of patients infected with SARSCoV-2 was higher in patients with nonelevated FMN levels than in those with elevated FMN levels(97%vs 83%;log rank P=0.002).CONCLUSION Elevated levels of FMN are independently associated with SARS-CoV-2 reinfection,which highlights that patients with elevated FMN should be cautiously monitored after hospital discharge.

Co-dynamics of COVID-19 and TB with COVID-19 vaccination and exogenous reinfection for TB:An optimal control application

COVID-19 and Tuberculosis(TB)are among the major global public health problems and diseases with major socioeconomic impacts.The dynamics of these diseases are spread throughout the world with clinical similarities which makes them difficult to be mitigated.In this study,we formulate and analyze a mathematical model containing several epidemiological characteristics of the co-dynamics of COVID-19 and TB.Sufficient conditions are derived for the stability of both COVID-19 and TB sub-models equilibria.Under certain conditions,the TB sub-model could undergo the phenomenon of backward bifurcation whenever its associated reproduction number is less than one.The equilibria of the full TBCOVID-19 model are locally asymptotically stable,but not globally,due to the possible occurrence of backward bifurcation.The incorporation of exogenous reinfection into our model causes effects by allowing the occurrence of backward bifurcation for the basic reproduction number R_(0)<1 and the exogenous reinfection rate greater than a threshold(η>η*).The analytical results show that reducing R_(0)<1 may not be sufficient to eliminate the disease from the community.The optimal control strategies were proposed to minimize the disease burden and related costs.The existence of optimal controls and their characterization are established using Pontryagin's Minimum Principle.Moreover,different numerical simulations of the control induced model are carried out to observe the effects of the control strategies.It reveals the usefulness of the optimization strategies in reducing COVID-19 infection and the co-infection of both diseases in the community.

Backward bifurcation,basic reinfection number and robustness of an SEIRE epidemic model with reinfection

Recent evidences show that individuals who recovered from COVID-19 can be reinfected.However,this phenomenon has rarely been studied using mathematical models.In this paper,we propose an SEIRE epidemic model to describe the spread of the epidemic with reinfection.We obtain the important thresholds R_(0)(the basic reproduction number)and R_(c)(a threshold less than one).Our investigations show that when R_(0)>1,the system has an endemic equilibrium,which is globally asymptotically stable.When R_(c)<R_(0)<1,the epidemic system exhibits bistable dynamics.That is,the system has backward bifurcation and the disease cannot be eradicated.In order to eradicate the disease,we must ensure that the basic reproduction number R_(0) is less than R_(c).The basic reinfection number is obtained to measure the reinfection force,which turns out to be a new tipping point for disease dynamics.We also give definition of robustness,a new concept to measure the dificulty of completely eliminating the disease for a bistable epidemic system.Numerical simulations are carried out to verify the conclusions.

SARS-CoV-2 reinfection in two patients who have recovered from COVID-19

Dear Editor,The duration of immune protection against SAR-CoV-2 reinfection in patients who have recovered from COVID-19 is a critical unanswered question.To determine the long-term clinical and virologic outcome in patients who have recovered from COVID-19,we prospectively followed 220 patients with COVID-19 admitted to Renmin Hospital of Wuhan University between 15 January and 15 February 2020 who recovered and were followed up until 15 July 2020.

Reinfection rates among patients previously infected by SARS-CoV-2:systematic review and meta-analysis

Background:Asymptomatic or symptomatic infection with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)can be followed by reinfection.The protection conferred by prior infection among coronavirus disease 2019(COVID-19)patients is unclear.We assessed the incidence of SARS-CoV-2 reinfection and the protection effect of previous infection against reinfection.Methods:We searched PubMed,EMBASE,Cochrane,Scopus,Web of Science,and ClinicalTrials.gov for publications up until the end date of May 1,2021.The reinfection rate of recovered patients and the protection against reinfection were analyzed using meta-analysis.Results:Overall,19 studies of 1096 reinfection patients were included.The pooled reinfection rate was 0.65%(95%confidence interval[CI]0.39-0.98%).The symptomatic reinfection rate was a bit lower(0.37%[95%CI 0.11-0.78%],I^(2)=99%).The reinfection rate was much higher in high-risk populations(1.59%[95%CI 0.30-3.88%],I^(2)=90%).The protection against reinfection and symptomatic reinfection was similar(87.02%[95%CI 83.22-89.96%]and 87.17%[95%CI 83.09-90.26%],respectively).Conclusions:The rate of reinfection with SARS-CoV-2 is relatively low.The protection against SARS-CoV-2 after natural infection is comparable to that estimated for vaccine efficacy.These data may help guide public health measures and vaccination strategies in response to the COVID-19 pandemic.High-quality clinical studies are needed to establish the relevant risk factors in recovered patients.

Reinfection of urogenital schistosomiasis in pre-school children in a highly endemic district in Northern Zimbabwe:a 12 months compliance study

Background:In light of the shift to aiming for schistosomiasis elimination,the following are needed:data on reinfection patterns,participation,and sample submission adherence of all high-risk age groups to intervention strategies.This study was conducted to assess prevalence,reinfections along with consecutive participation,sample submission adherence,and effect of treatment on schistosomiasis prevalence in children aged five years and below in an endemic district in Zimbabwe,over one year.Methods:The study was conducted from February 2016-February 2017 in Madziwa area,Shamva district.Following community mobilisation,mothers brought their children aged 5 years and below for recruitment at baseline and also urine sample collection at baseline,3,6,9 and 12 months follow up surveys.At each time point,urine was tested for urogenital schistosomiasis by urine filtration and children found positive received treatment.Schistosoma haematobium prevalence,reinfections as well as children participation,and urine sample submission at each visit were assessed at each time point for one year.Results:Of the 535 children recruited from the five communities,169(31.6%)participated consecutively at all survey points.The highest mean number of samples submitted was 2.9 among communities and survey points.S.haematobium prevalence significantly reduced from 13.3%at baseline to 2.8%at 12 months for all participants and from 24.9%at baseline to 1.8%at 12 months(P<0.001)for participants coming at all-time points.Among the communities,the highest baseline prevalence was found in Chihuri for both the participants coming consecutively(38.5%,10/26)and all participants(20.4%,21/103).Reinfections were significantly high at 9 months follow up survey(P=0.021)and in Mupfure(P=0.003).New infections significantly decreased over time(P<0.001).Logistic regression analysis showed that the risk of acquiring schistosomiasis was high in some communities(P<0.05).Conclusions:S.haematobium infections and reinfections are seasonal and depend on micro-geographical settings.The risk of being infected with schistosomes in pre-school aged children increases with increasing age.Sustained treatment of infected individuals in a community reduces prevalence overtime.Participation compliance at consecutive visits and sample submission adherence are important for effective operational control interventions.

Reinfection and Breakthrough Infection of SARS-CoV-2:An Emerging Challenge That Is Threatening Our World

The pandemic of coronavirus disease 2019 has threatened humans for more than one and a half years.In particular,viral mutation like delta strain has led to third-or fourth-wave transmission among the countries in Asia,Europe,and North America.Although large-scale vaccination has been carried out in many countries,the incidence of reinfection and vaccine-past breakthrough infection is becoming an emerging challenge to humans worldwide.The related mechanisms underlying the reinfection and breakthrough infection remain unknown.In this review,we summarized the challenge and related reasons for severe acute respiratory syndrome coronavirus 2 reinfection and breakthrough infection.Simultaneously,we addressed some critical contents of the study in future.

Is Helicobacter pylori infection associated with glycemic control in diabetics?

AIM:To investigate whether Helicobacter pylori(H.pylori) infection is associated with glycemic control and whether hyperglycemia is modified by eradication therapy.METHODS:The databases of Pub Med,Cochrane Library,Chinese Bio Medicine Web Base and Chinese Science and Technology Journals were searched from inception to June 2014.Studies examining the association between H.pylori infection and glycemic control and/or the effect of eradication treatment on glycemic control in diabetic humans were eligible for inclusion.Meta-analyses were conducted using the Review Manager software version 5.2.The outcome measures are presented as weighed mean differences(WMDs) with 95% confidence intervals(CIs).Statistical heterogeneity was assessed by the Cochran Q test and the I2 statistic.RESULTS:A total of 21 relevant publications were identified.A meta-analysis of 11 studies with 513 patients with diabetes mellitus(DM) showed significantly lower glycosylated hemoglobin(Hb A1c) levels in the H.pylori-negative than H.pylori-positive DM participants(WMD = 0.43,95%CI:0.07-0.79;P = 0.02).In children and adolescents with type 1 DM(T1DM),there was a positive association between H.pylori infection and Hb A1 c level(WMD = 0.35,95%CI:0.05-0.64;P = 0.02),but there was no difference in those with type 2 DM(T2DM,WMD = 0.51,95%CI:-0.63-1.65;P = 0.38).A meta-analysis of six studies with 325 T2 DM participants showed a significant difference in the fasting plasma glucose levels between H.pylori-positive and H.pylori-negative participants(WMD = 1.20,95%CI:0.17-2.23;P = 0.02).Eradication of H.pylori did not improve glycemic control in the T2 DM participants in a threemonth follow-up period(Hb A1 c decrease:WMD =-0.03,95%CI =-0.14-0.08;P = 0.57;fasting plasma glucose decrease:WMD =-0.06,95%CI:-0.36-0.23;P = 0.68).Glycemic control was significantly better in T1 DM participants who were not reinfected than in those who were reinfected(Hb A1c:WMD = 0.72,95%CI:0.32-1.13:P = 0.00).CONCLUSION:H.pylori infection is associated with poorer glycemic control in T1 DM patients,but eradication may not improve glycemic control in DM in a short-term follow-up period.

SARS-CoV-2 infection rates after different vaccination schemes:An online survey in Turkey

Objective:To identify effects of various nationwide vaccination protocols on the evolution of new SARS-CoV-2 infections among adult population and to evaluate the safety of mRNA(BioNTech/Pfizer)vaccine.Methods:Totally 10735 adult volunteers that received at least one dose of BioNTech/Pfizer or triple doses of CoronaVac participated in this cross-sectional-online survey between 1 and 10 September 2021.The information was collected covering a 5-month period from April 2021 to September 2021.Information about people who were vaccinated with only single and double dose CoronaVac were not included in this study.Results:At least one side effect after single and double dose of BioNTech/Pfizer and triple doses of CoronaVac were observed in 42.1%,42.5%and 10.9%,respectively.The most common side effects were shoulder/arm pain,weakness/fatigue,muscle/joint pain and headache.The side effects were the most frequent in single BioNTech/Pfizer,while it was the least in triple CoronaVac.The rate of positive PCR tests before vaccination was 17.6%,and decreased to 3.0%after vaccination.The rates of positive SARS CoV-2-PCR were 18.8%,3.5%,3.1%,0.5%and 4.6%in single BioNTech/Pfizer,double BioNTech/Pfizer,double CoronaVac+single BioNTech/Pfizer,double CoronaVac+double BioNTech/Pfizer and triple CoronaVac,respectively.While 1.8%of PCR positive COVID-19 cases needed intensive unit care in the pre-vaccination period,intensive care unit was required in 0%,1.5%,2.4%,0%and 4.2%after single BioNTech/Pfizer,double BioNTech/Pfizer,double CoronaVac+single BioNTech/Pfizer,double CoronaVac+double BioNTech/Pfizer and triple CoronaVac,respectively.Reinfection rate after vaccination was 0.4%.Conclusions:The rarity of COVID-19 infection after vaccination suggests that efficacy of vaccines is maintained.On the other hand,the data underscore the critical importance of continued public health mitigation.

Identification of the Bacterial Gene in Patients Who Repeatedly Develop Streptococcal Pharyngitis

Background: We aimed at determining whether the pathogenic bacteria at the onset of disease are genetically different and whether this affects future choice of the therapeutic methods against group A β-hemolytic streptococcal acute pharyngitis/tonsillitis. Methods: A pharynx swab was collected from pediatric patients who visited our hospital. The swab was cultured, and hemolytic streptococcus was detected 230 times. We isolated pathogenic bacteria of patients infected more than once and examined the bacteria using pulse-field gel electrophoresis. Results: Based on gene search results, we found that if the period of developing relapse was within 1 month from the first infection, all patients had the same gene. However, all patients in whom reinfection occurred after 6 months or later had different pertinent genes. Conclusions: The number of relapse/reinfection is significant for this disease, and considerably caution is essential for its treatment. No changes to antibacterial drug administration may be necessary for the second administration unless more than 6 months have passed since the first infection.

Can Ursodeoxycholic Acid Prevent SARS-CoV-2 Infection or Reduce the COVID-19 Severity? Current Knowledge and Unresolved Issues

A recent study revealed that the inhibition of the farnesoid X receptor using ursodeoxycholic acid(UDCA)significantly reduces angiotensin-converting enzyme 2(ACE2)expression.Therefore,considerable attention has been paid to the use of UDCA to prevent severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection and reduce the severity of the disease.This review compre-hensively summarizes the role of ACE2 in SARS-CoV-2 infection and the potential role and mechanisms of UDCA in the prevention of SARS-CoV-2 infection or reinfection.It also discusses unresolved issues and the potential use of UDCA in the treatment of patients with coronavirus disease.

Efficacy of praziquantel on Schistosoma haematobium and re-infection rates among school-going children in the Ndumo area of uMkhanyakude district,KwaZulu-Natal,South Africa

Background:Despite its low cure rates and possible resistance,praziquantel(PZQ)is the only drug available for schistosomiasis treatment.Hence,monitoring its efficacy is crucial.This study assessed the efficacy of PZQ,determined re-infection and incidence rates of Schistosoma haematobium infection among school-going children in the Ndumo area,KwaZulu-Natal.Methods:A cohort of 320 school-going children(10-15 years)in 10 primary schools was screened for S.haematobium infection using the filtration technique.Infected children were treated at different times and hence were divided into two sub-cohorts;A1 and A2.Non-infected children constituted the sub-cohort B.Children who continued excreting viable eggs 4 weeks post-treatment received a second dose of PZQ.Re-infection rates were determined in sub-cohort A1 and A2 at 28 and 20 weeks post-treatment,respectively.Cure rates(CR)and egg reduction rates(ERR)were calculated.Incidence rate was assessed 28 weeks post baseline survey using children that were negative for schistosome eggs at that survey.Analysis of data was done using the Chi square and the Wilcoxon rank test.A 95%confidence interval with a P-value<0.05 determined significance.Results:At baseline,120(37.5%)of the 320 study participants were found infected with Schistosoma haematobium.Heavy infections accounted for 36.7%.The calculated cure rates were 88.07%and 82.92%for females and males,respectively.Egg Reduction Rates of 80%and 64%for females and males were observed 4 weeks after the initial treatment.After the second treatment,CR was 100%in females and 50%in males with an ERR of 100%in females and 70%in males.At 20 and 28 weeks post treatment,reinfection rates of 8.03%and 8.00%were observed,respectively,giving an overall rate of 8.1%.An incidence rate of 4.1%was observed 28 weeks after the baseline screening.Conclusions:The study indicated high CR while the ERR was low suggesting a reduced PZQ efficacy.The efficacy improved among females after the second dose.Re-infection rates at 20 and 28 weeks posttreatment were low.The study also indicated a low incidence rate for the 28 weeks period.

Neglected Rural Public Health Issue:The Case of Intestinal Roundworms

Despite increasing institutional and financial support, certain public health issues are still neglected by the Chinese Government. The present paper examines the soil-transmitted helminth （STH） infection and reinfection rates by conducting a survey on 1724 children in Guizhou Province, China. Our results indicate that 37.5 percent of children had been infected with one or more of the three types of tested STH. However, only 50.4 percent of children reported having taken deworming medicine during the 18-month period before the survey. Of those who reported being dewormed, 34.6 percent tested positive for STH infections. Poverty and number of siblings are significantly and positively correlated with infection and reinfection, and parental education is significantly and negatively correlated with infection and reinfection. Given the ineffectiveness of treatment in these areas to date, for anthelminthic campaigns to actually succeed, China must pay more attention to local- level incentives to improve children＇s health.

Community survey, treatment and long-term follow-up for human cystic echinococcosis in northwest China

Background Human cystic echinococcosis （CE） is a parasitic zoonosis of major public health importance throughout the world. CE is endemic throughout central Asia including northwestern China. In China, CE has been reported in 21 provinces, autonomous regions and municipalities, covering approximately 87% of China＇s territories. It is most common in the pastoral and semi-pastoral western provinces and regions. This study aimed to reveal the natural history, curative effect and possible re-infection risk factors of human CE through long termed follow-up of treated and untreated CE cases in Hobukesar, Xingjiang, China.Methods Follow-up studies on CE were performed twice in Hobukesar from August 2005 to October 2008, after an initial mass screening performed in 1995 and 1996. Ultrasound scan was the primary diagnostic method.Results Among 24 patients with confirmed CE, 22 were treated （surgery in 19 and chemotherapy in three）. Two recurrent cases and one re-infection case were subsequently found during follow-up. The CE type of one of the recurrent cases reverted from CE4 to CE3, as classified using World Health Organization （WHO） guidelines.Conclusions Ultrasound was required to differentiate primary, recurrent and re-infection cases during epidemiological investigation and follow-up of CE. Most patients did not change their habits, which may be one possible cause of reinfection. One recurrent case suggested that, despite initial suggestion from the WHO Informal Working Group on Echinococcosis, CE4-type cysts are not inactive.

Analysis of a mathematical model for the transmission dynamics of human melioidosis

A deterministic model for the transmission dynamics of melioidosis disease in human population is designed and analyzed.The model is shown to exhibit the phenomenon of backward bifurcation,where a stable disease-free equilibrium co-exists with a stable endemic equilibrium when the basic reproduction number R_(0) is less than one.It is further shown that the backward bifurcation dynamics is caused by the reinfection of individuals who recovered from the disease and relapse.The existence of backward bifurcation implies that bringing down R_(0) to less than unity is not enough for disease eradication.In the absence of backward bifurcation,the global asymptotic stability of the disease-free equilibrium is shown whenever R_(0)<1.For R_(0)>1,the existence of at least one locally asymptotically stable endemic equilibrium is shown.Sensitivity analysis of the model,using the parameters relevant to the transmission dynamics of the melioidosis disease,is discussed.Numerical experiments are presented to support the theoretical analysis of the model.In the numerical experimentations,it has been observed that screening and treating individuals in the exposed class has a significant impact on the disease dynamics.