Serological and molecular epidemiology of Japanese Encephalitis in Zhejiang, China, 2015-2018.

BACKGROUND: Shifts have occurred in the epidemiological characteristics of Japanese encephalitis (JE), extending from the molecular level to the population level. The aim of this study was to investigate the seroprevalence of JE neutralizing antibodies in healthy populations from different age groups in Zhejiang Province, and to conduct mosquito monitoring to evaluate the infection rate of Japanese encephalitis virus (JEV) among vectors, as well as the molecular characteristics of the E gene of isolated JEV strains. METHODOLOGY/PRINCIPAL FINDINGS: A total of 1190 sera samples were screened by a microseroneutralization test, including 429 infants (28d-11m) and 761 participants (2y-82y). For those under 1 year old, the geometric mean titers (GMTs) of the JE neutralizing antibody was 9.49 at birth and significantly declined as the age of month increased (r = -0.225, P<0.001). For those above 1-year old, seropositive proportions were higher in subjects aged 1-3 years old as well as ≥25 years old (65%-75%), and relatively lower in subjects aged between 4-25 years old (22%-55%). Four or more years after the 2nd dose of JEV-L (first dose administered at 8 months and the second at 2 years of age), the seropositive proportion decreased to 32.5%, and GMTs decreased to 8.08. A total of 87,201 mosquitoes were collected from livestock sheds in 6 surveillance sites during 2015-2018, from which 139 E gene sequences were successfully amplified. The annual infection rate according to bias-corrected maximum likelihood estimation of JEV in Culex tritaeniorhynchus was 1.56, 2.36, 5.65 and 1.77 per 1000, respectively. JEV strains isolated during 2015-2018 all belonged to Genotype I. The E gene of amplified 139 samples differed from the JEV-L vaccine strain at fourteen amino acid residues, including the eight key residues related to virulence and virus attenuation. No divergence was observed at the sites related to antigenicity. CONCLUSIONS/SIGNIFICANCE: Zhejiang Province was at a high risk of JE exposure due to relatively lower neutralizing antibody levels among the younger-aged population and higher infection rates of JEV in mosquitoes. Continuous, timely and full coverage of JE vaccination are essential, as well as the separation of human living areas and livestock shed areas. In addition, annual mosquito surveillance and periodic antibody level monitoring are important for providing evidence for improvement in JE vaccines and immunization schedules.

Factors Correlating to the Development of Hepatitis C Virus Infection among Drug Users-Findings from a Systematic Review and Meta-Analysis.

Hepatitis C remains a significant public health threat. However, the main routes of transmission have changed since the early 1990s. Currently, drug use is the main source of hepatitis C virus (HCV) infection, and some measures have been successively implemented and additional studies have been published. However, the factors correlating with HCV infection failed to clearly define. Our study pooled the odds ratios (ORs) with 95% confidence intervals (CIs) and analyzed sensitivity by searching data in the PubMed, Elsevier, Springer, Wiley, and EBSCO databases. Publication bias was determined by Egger's test. In our meta-analysis, HCV-infected and non-HCV-infected patients from 49 studies were analyzed. The pooled ORs with 95% CIs for study factors were as follows: Injecting drug use 10.11 (8.54, 11.97); sharing needles and syringes 2.24 (1.78, 2.83); duration of drug use >5 years 2.39 (1.54, 3.71); unemployment 1.50 (1.22, 1.85); commercial sexual behavior 1.00 (0.73, 1.38); married or cohabiting with a regular partner 0.88 (0.79, 0.98), and sexual behavior without a condom 1.72 (1.07, 2.78). This study found that drug users with histories of injecting drug use, sharing needles and syringes, drug use duration of >5 years, and unemployment, were at increased risk of HCV infection. Our findings indicate that sterile needles and syringes should be made available to ensure safe injection. In view of that, methadone maintenance treatment can reduce or put an end to risky drug-use behaviors, and should be scaled up further, thereby reducing HCV infection.

Safety and immunogenicity of hepatitis E vaccine in elderly people older than 65 years.

BACKGROUND: Hepatitis E virus (HEV) infection is a leading cause of acute hepatitis worldwide, and results in high morbidity and mortality rates among elderly people in China. The hepatitis E vaccine, Hecolin®, has been shown to be safe and highly efficacious among healthy adults aged 16-65 years old. However, there is no data about Hecolin® vaccination in elderly people older than 65 years (y). METHODS: An open-labeled, controlled trial was conducted to evaluate the safety and immunogenicity of Hecolin® among the elderly aged >65 y. A total of 601 eligible participants were enrolled. Among them, 200 elderly people aged >65 y and 201 adults aged 18-65 y were assigned to the Hecolin® groups and vaccinated at day 0, month 1 and month 6. Serum samples were collected for anti-HEV IgG determination at day 0 prior to immunization and at month 7. The remaining 200 elderly people aged >65 y were assigned to the safety control group and received no intervention but were instructed to report any adverse events that occurred during the whole study period in the same way as those in the Hecolin® groups. RESULTS: After receiving 3 doses of Hecolin® with the standard schedule, most (96.7%) of the vaccinated elderly people aged >65 y seroconverted at one month after the final dose (month 7). At month 7, the geometric mean concentrations of anti-HEV IgG were 5.36 (95% CI, 3.88-7.41) and 19.65 (95% CI, 16.81-22.98) among the baseline seronegative and seropositive elderly, respectively. Of the vaccinated elderly, 97.3% (177/182) had anti-HEV IgG levels higher than 1.0 WU/ml at month 7. Hecolin® was very well tolerated in this population. No vaccine-related SAEs were reported. CONCLUSIONS: Hecolin® is immunogenic and well tolerated in elderly people aged greater than 65 years.

[A safety assessment on adverse reaction of recombinant B-subunit/inactivated whole cell oral cholera vaccine among non-infected population].

OBJECTIVE: To observe the safety of recombinant B-subunit/inactivated whole cell (rBS/WC) oral cholera vaccine among non-infected population. METHOD: A method of double-blind and case control was conducted randomly. 3041 non-infected persons who aged from 5- to 60-years-old were divided randomly into 3 groups, including 2 vaccine groups and 1 placebo group. The vaccine and placebo were taken respectively by vaccine groups and placebo group on the 1st, 7th and 28th day in every months of sequential 3 months. The adverse reaction was observed in sequential 3 days after intaking orally. The follow-up interviews were conducted in 1, 2, 3 months. RESULTS: No severe adverse reaction was occurred. The rate of adverse reaction was 1.70% in vaccine groups, 1.74% in placebo group. There was no statistically significant difference between two groups (chi2=0.013, P=0.909). The adverse reaction were mainly abdominal pain, diarrhea, partly anaphylaxis, and the others of dizziness, fatigue, weakness. Most people recovered within short time without any medical treatment. The adverse reactions might be related to psychogenic reaction. CONCLUSION: The safety of oral rBS/WC cholera vaccine among non-infected population was pretty good.

[Community-based study on disease burden of diarrhea in Zhejiang province].

OBJECTIVE: To study the status on economic burden of diarrhea in Zhejiang province so as to provide evidence for allocation of health resource as well as decision-making on health issues. METHODS: Multi-phases stratified random cluster sampling was used to select samples in the population. Data was collected on the incidence of diarrhea in the last two weeks as well as on the related cost due to medical care etc. RESULTS: The overall incidence (person per year) of diarrhea was 0.26, with 0.29 in the rural and 0.22 in the urban areas respectively. The incidence of diarrhea in children less than 5 was 0.66 (person per year), higher than in any of the age groups. The average direct cost of medical treatment was 69.23 Yuan with average direct cost of non-medical care was 8.29 Yuan for every person, while the indirect cost was 48.43 Yuan. In conclusion, the average disease burden of diarrhea in the province was 1.697 billion Yuan per year, which accounted for 1 per thousand of the GDP, with 1.217 billion Yuan in rural area and 0.480 billion Yuan in the urban areas respectively. The direct cost of medical care was 0.886 billion Yuan (52.21%) and the direct cost due to non-medical care was 0.124 billion Yuan (7.31%). The indirect cost appeared to be 0.480 billion Yuan (40.48%). Factors that affecting the cost would relate to: severity of diarrhea, medical insurance, location of residential area, age and education background of the patients, etc. CONCLUSION: Programs on diarrhea prevention and control should be strengthened to reduce the economic burden caused by this disease while special attention should be paid to those children who are under 5 years of age and living in the rural areas.