Seroprevalence and molecular characteristics of varicella-zoster virus infection in Chinese children

Phylogenetic Analysis of Varicella-Zoster Virus in Cerebrospinal Fluid from Individuals with Acute Central Nervous System Infection: An Exploratory Study

BACKGROUND

There is scarce information on Varicella-Zoster virus genetic variability in individuals with acute central nervous system infection in Brazil. The objective of this study was the molecular characterization of Varicella-Zoster virus isolates in cerebrospinal fluid from individuals with acute central nervous system infection.

METHODS

Cerebrospinal fluid samples were collected from individuals evaluated in emergency and community healthcare services in São Paulo, Brazil. Varicella-Zoster virus identification was performed using commercial platforms Biofire-FilmArray Meningitis/Encephalitis (BioMérieux, Craponne, France) and XGEN-UMLTI-N9® (Mobius Life, Pinhais, Brazil). Positive samples were further characterized as wild-type or vaccine-strain by a real-time polymerase chain reaction assay that targeted a single nucleotide polymorphism in open reading frame 62. We also estimated the mean genetic distance and phylogenetic reconstruction based on open reading frames 22, 38, 54, and 62 in relation to sequences of intercontinentally circulating Varicella-Zoster virus isolates.

RESULTS

Among the 600 cerebrospinal fluid samples, we identified Varicella-Zoster virus in 30 (5%) samples. None were positive for the vaccine-strain. Twelve samples were sequenced and phylogenetically classified into Clades 1 (41.7%), 2 (25%), 3 (8.3%), 5 (16.7%), or 6 (8%).

CONCLUSION

Enhanced characterization of circulating Varicella-Zoster virus Clades in Brazil identified previously unreported Clades 2 and 6 as well as three other Clades disseminated intercontinentally. These findings reinforce the importance of Varicella-Zoster virus molecular surveillance in cerebrospinal fluid.

Analysis of sero-epidemiological characteristics of varicella in healthy children in Wuxi, China

The aim of this study was to evaluate seroepidemiology of varicella in Wuxi, China, after two doses of immunization of varicella vaccine (VarV) for better control of varicella transmission. Participants were selected randomly by multistage stratified sampling. The positive rate of antibody and geometric antibody titer (GMC) was determined with enzyme-linked immunosorbent assays. Logistic and linear regressions were used to analyze the correlations between antibody seropositivity, GMCs, and corresponding factors. Serum samples (n = 697) were obtained from healthy children <7 years-of-age. Seropositivity and GMC were 67.84% and 190.97 mIU/mL, respectively, in subjects receiving two doses of VarV. Multivariate analysis revealed that both the rate of varicella-zoster virus immunoglobulin G seropositivity and GMC in vaccinated subjects were higher compared to those who had not been vaccinated. The strongest overall response was observed in subjects with two doses of VarV (4.055, 95% CI: 2.774 ~ 5.928). In 470 subjects with a history of VarV application, the antibody GMC value was reduced 4 years after vaccination. Two-dose vaccination with VarV was an effective prevention strategy varicella and should be included in a national immunization program.

Seroprevalence of VZV and HSV-2 Antibodies among Women of Childbearing Age Referring to Health Centres of Mashhad, Iran: The Need for Consideration of VZV Vaccination Program

Background

Infections with herpes simplex virus type 2 (HSV-2) and varicella-zoster virus (VZV) are associated with serious maternal and neonatal health consequences. The literature review reveals a research gap regarding the seroprevalence of HSV-2 and VZV among women of reproductive age in Mashhad, Northeast of Iran. The present study aims to evaluate the seroprevalence of these viruses among a group of women in Mashhad, Iran.

Methods

Sera were collected by health center personnel using a cluster sampling method from healthy women with specific age characteristics residing in three distinct socioeconomic regions of the city. The participants, aged 20-35, were divided into three groups (20-25, 26-30, and 31-35 years). The levels of VZV and HSV-2 IgG antibodies were evaluated using commercial ELISA kits. Subsequently, the results were analyzed using SPSS software.

Results

A total of 93 women were included in the study. Anti-HSV-2 IgG antibody was detected in 3 out of 93 participants (7.5%), while anti-VZV IgG antibody was found positive in 80 out of 93 individuals (83.3%). The HSV-2 positive cases were concurrently positive for the VZV antibody. There was no significant difference in the positivity of anti-HSV-2 and anti-VZV antibody positivity within age groups or socioeconomic status (P > 0.05).

Conclusions

The high seroprevalence of VZV among nonvaccinated participants indicates a widespread presence of the virus and underscores its potentially serious impact on community health. Therefore, it is recommended that a VZV vaccination program be considered by the health system. Furthermore, the reactivation of latent HSV-2, whether symptomatic or asymptomatic, during pregnancy should not be disregarded as a life-threatening threat.

Vaccination against Varicella Zoster Virus Infection in Less Developed Regions of Guangdong, China: A Cross-Sectional Serosurveillance Study

Vaccination is the key to prevent varicella zoster virus (VZV) infection in children. Voluntary and self-funded strategies have led to variable vaccination rates against VZV in China. For low-income populations, in particular, the effects of VZV vaccination have been insufficiently estimated. Community-based serosurveillance was conducted in two less developed regions, Zhanjiang and Heyuan, of Guangdong, China. Anti-VZV IgG antibodies in serum were detected by ELISA. The vaccination data were derived from the Guangdong Immune Planning Information System. A total of 4221 participants were involved, of which 3377 were from three counties of Zhanjiang and the other 844 were from one county of Heyuan, Guangdong, China. The total VZV IgG seropositivity rate in vaccinated individuals was 34.30% and 42.76%, while it was 89.61% and 91.62% in non-vaccinated populations of Zhanjiang and Heyuan, respectively. The seropositivity rate increased gradually with age, reaching ~90% in the >20- to 30-year-old group. The VarV vaccination rates of children aged 1-14 years were 60.47% for one dose and 6.20% for two doses in Zhanjiang, and 52.24% for one dose and 4.48% for two doses in Heyuan. Compared with the non-vaccinated group (31.19%) and one-dose group (35.47%), the positivity rate of anti-VZV IgG antibodies was significantly higher in the two-dose group (67.86%). Before the VarV policy was reformed, the anti-VZV IgG positivity rate was 27.85% in the one-dose-vaccinated participants, which increased to 30.43% after October 2017. The high seroprevalence in participants was due to infection of VZV in Zhanjiang and Heyuan, not vaccination against VZV. Children aged 0-5 years are still vulnerable to varicella, so a two-dose vaccination program should be implemented to prevent onward transmission of VZV.

A Dynamic Compartmental Model to Explore the Optimal Strategy of Varicella Vaccination: An Epidemiological Study in Jiangsu Province, China

Varicella (chickenpox) is highly contagious among children and frequently breaks out in schools. In this study, we developed a dynamic compartment model to explore the optimal schedule for varicella vaccination in Jiangsu Province, China. A susceptible-infected-recovered (SIR) model was proposed to simulate the transmission of varicella in different age groups. The basic reproduction number was computed by the kinetic model, and the impact of three prevention factors was assessed through the global sensitivity analysis. Finally, the effect of various vaccination scenarios was qualitatively evaluated by numerical simulation. The estimated basic reproduction number was 1.831 ± 0.078, and the greatest contributor was the 5-10 year-old group (0.747 ± 0.042, 40.80%). Sensitivity analysis indicated that there was a strong negative correlation between the second dose vaccination coverage rate and basic reproduction number. In addition, we qualitatively found that the incidence would significantly decrease as the second dose vaccine coverage expands. The results suggest that two-dose varicella vaccination should be mandatory, and the optimal age of second dose vaccination is the 5-10 year-old group. Optimal vaccination time, wide vaccine coverage along with other measures, could enhance the effectiveness of prevention and control of varicella in China.

Detection of Circulating VZV-Glycoprotein E-Specific Antibodies by Chemiluminescent Immunoassay (CLIA) for Varicella-Zoster Diagnosis

Varicella and herpes zoster are mild symptoms-associated diseases caused by varicella–zoster virus (VZV). They often cause severe complications (disseminated zoster), leading to death when diagnoses and treatment are delayed. However, most commercial VZV diagnostic tests have low sensitivity, and the most sensitive tests are unevenly available worldwide. Here, we developed and validated a highly sensitive VZV diagnostic kit based on the chemiluminescent immunoassay (CLIA) approach. VZV-glycoprotein E (gE) was used to develop a CLIA diagnostic approach for detecting VZV-specific IgA, IgG, and IgM. The kit was tested with 62 blood samples from 29 VZV-patients classified by standard ELISA into true-positive and equivocal groups and 453 blood samples from VZV-negative individuals. The diagnostic accuracy of the CLIA kit was evaluated by receiver-operating characteristic (ROC) analysis. The relationships of immunoglobulin-isotype levels between the two groups and with patient age ranges were analyzed. Overall, the developed CLIA-based diagnostic kit demonstrated the detection of VZV-specific immunoglobulin titers depending on sample dilution. From the ELISA-based true-positive patient samples, the diagnostic approach showed sensitivities of 95.2%, 95.2%, and 97.6% and specificities of 98.0%, 100%, and 98.9% for the detection of VZV-gE-specific IgA, IgG, and IgM, respectively. Combining IgM to IgG and IgA detection improved diagnostic accuracy. Comparative analyses on diagnosing patients with equivocal results displaying very low immunoglobulin titers revealed that the CLIA-based diagnostic approach is overall more sensitive than ELISA. In the presence of typical VZV symptoms, CLIA-based detection of high titer of IgM and low titer of IgA/IgG suggested the equivocal patients experienced primary VZV infection. Furthermore, while no difference in IgA/IgG level was found regarding patient age, IgM level was significantly higher in young adults. The CLIA approach-based detection kit for diagnosing VZV-gE-specific IgA, IgG, and IgM is simple, suitable for high-throughput routine analysis situations, and provides enhanced specificity compared to ELISA.

Evaluation of Varicella-Zoster Virus Immunoglobulin G in Children With Malignancies on Chemotherapy

Background: Varicella-Zoster Virus (VZV) infection in children with different malignancies on chemotherapy has become an alarming problem. There are insufficient data about VZV seroprevalence among patients in Iran. Objectives: The current study was conducted to assess the seroprevalence of VZV serum IgG antibodies in children with malignancies on chemotherapy. Methods: The current single-center cross-sectional study was conducted from January 2018 to December 2019 at Mofid children’s hospital, Tehran, Iran. Five milliliters of blood samples were collected from the patients. Serum samples were then tested in duplicate for the IgG antibody against VZV using Varicella-Zoster ELISA IgG/IgM kit. Results: A total of 54 children with different malignancies were included. Overall, 24 and 30 serum samples were collected from females and males, respectively. The children were five months to 15-years-old with a mean age of 5.5 years. The overall seroprevalence of VZV IgG in the children was 21.1% (n = 13/54). Of patients with positive VZV IgG antibody, 9 (69.2%) were male, and four (30.8%) were female. Besides, Acute Lymphocytic Leukemia (ALL) with 61.1% (n = 33/54) was the most common underlying malignancy among these patients. The prevalence of anti-VZV IgG antibodies was 21.2% (n = 7/33) in the group of children with ALL. The highest seroprevalence of the VZV IgG antibody was seen in 11 to 15-year-old children (n = 3/7; 42.9%). The prevalence rates of IgG antibodies against VZV among children aged 0-2 years, 3-5 years, and 6-10 years were 28.6%, 25.9%, and 7.7%, respectively. Conclusions: The results showed that children with different malignancies on chemotherapy are quite susceptible to chickenpox infection. It is suggested that a safe and effective live attenuated varicella vaccine in line with the WHO recommendations be incorporated into Iran’s national immunization program for children with various malignancies.

An adult co-presented with varicella and herpes zoster caused by varicella zoster virus genotype J, China: a case report

Background

Varicella zoster virus (VZV) causes varicella primarily in childhood, and some rare adults also report varicella. Herpes zoster mainly occurs in adults by endogenous reactivation of latent VZV. Until now, varicella and herpes zoster have seldom been reported simultaneously in one patient. Here, we report a rare case co-presenting with varicella and herpes zoster in a Chinese adult.

Case presentation

A 44-year-old Chinese man suffered papules and vesicles with pain on the left ear. Five days after onset, he was admitted to the Department of Dermatology of The Third Hospital of Xiamen. Physical examination revealed that small vesicles surrounded by erythema had developed on his trunk, back and neck, and unilateral papules and vesicles in ribbons had also developed on the left ear. This patient was excluded from human immunodeficiency virus and Treponema pallidum infections by ELISA antibody tests. Laboratory tests revealed that the ratio of eosinophils (0.1%) and eosinophil count (0.0 × 10⁹/L) were significantly downregulated. Treatment with valacyclovir, ebastine, mecobalamine, pregabalin and calamine lotion for 5 days was effective therapy for varicella and herpes zoster. Polymerase chain reaction for vesicular fluids from varicella and herpes zoster was positive for VZV, and further phylogenetic analysis and single nucleotide polymorphism variations confirmed that the VZV genotype was type J (clade 2).

Conclusions

This rare case highlights awareness of varicella and herpes zoster caused by VZV infection in adults. Our report provides novel insight into the rare clinical presentation of VZV genotype J.

Spatiotemporal Epidemiology of Varicella in Chongqing, China, 2014-2018

Although immunization against varicella using vaccines has been proven to be significant and effective in the past decades, varicella remains a major public health concern for many developing countries. Varicella vaccination has not been introduced into routine immunization programs in China, and varicella outbreaks have continued to occur. Taking the city of Chongqing, which has a high prevalence of varicella, as an example, this study explored the spatiotemporal epidemiology of varicella. Based on the reported data of varicella cases from 1 January 2014 to 31 December 2018 in Chongqing, hot spots and space-time clusters of varicella were identified using spatial autocorrelation analysis and scan statistics. Within this period, a total of 112,273 varicella cases were reported in Chongqing (average annual incidence: 73.44 per 100,000), including one death. The incidence of varicella showed an increasing trend with significant seasonal peaks, which occurred during April to July and October to January of the following year. The total ratio of male to female patients affected was 1.10:1. Children under the age of 15 and students accounted for the majority of the patient population. The hotspots detected through local spatial autocorrelation analysis, and the most likely clusters identified by scan analysis, were primarily in the main urban districts of Chongqing. The secondary clusters were mostly detected in northeast and southwest Chongqing. There were obvious spatial dependence and spatiotemporal clustering characteristics of varicella in Chongqing from 2014 to 2018. High-risk districts, populations, and peak periods were found in this study, which could be helpful in implementing varicella prevention and control programs, and in adjusting vaccination strategies for the varicella vaccine based on actual conditions.