Nasamon Wanlapakorn

The Success of a Universal Hepatitis B Immunization Program as Part of Thailand's EPI after 22 Years' Implementation.

Hepatitis B vaccination for newborns was introduced in two provinces in 1988 as part of Thailand’s Expanded Program on Immunization (EPI), and extended to the whole country in 1992. Our previous studies showed that children and adolescents who were born after the implementation of this program had a carrier rate of less than 1%, compared with 5–6% before implementation. In 2014 we performed hepatitis B serosurveys among 5964 subjects in the different geographic regions of the country to evaluate the long-term immunogenicity and impact of universal hepatitis B vaccination in newborns as part of the 22-year EPI program, by assessing HBsAg, anti-HBc and anti-HBs seropositivity status. The number of HB virus (HBV) carriers, both children and young adults, who were born after universal HB vaccination was markedly reduced. The carrier rates among the age groups 6 months to 5 years, 5–10, 11–20, 21–30, 31–40, 41–50 and >50 years were respectively 0.1, 0.29, 0.69, 3.12, 3.78, 4.67 and 5.99%. The seropositivity rate for HBsAg in the post-EPI group was 0.6%, whereas in the pre-EPI group it was as high as 4.5% (p<0.001). HBV infection by means of detectable anti-HBc had also drastically declined in the population born after the HB vaccine was integrated into the EPI program. We estimated that the total number of HBV carriers amounted to 2.22 million, or 3.48% of the total population, most of whom are adults. The HB vaccine is the first vaccine shown to be effective in preventing the occurrence of chronic liver disease and hepatocellular carcinoma. Universal vaccination campaign will contribute to the eventual eradication of HBV-associated disease.

Seroprevalence of Antibodies to Pertussis Toxin among Different Age Groups in Thailand after 37 Years of Universal Whole-Cell Pertussis Vaccination

Despite the high coverage of prophylactic vaccine against Bordetella pertussis infection in many countries for more than three decades, pertussis remains a common vaccine-preventable disease. Infections have been detected more commonly in countries using acellular pertussis vaccine in their Expanded Program of Immunization. Thailand implemented a routine infant immunization program with whole-cell pertussis vaccine in 1977, and since 1992, the national vaccine policy has offered a five-dose whole-cell pertussis vaccine for children given at the ages of 2, 4, 6, 18, and 48 months. This study aimed to investigate the seroprevalence of antibodies to pertussis toxin among healthy people across all ages to determine the level of whole-cell vaccine-induced immunity in the population, and to identify which age group should be targeted for a booster dose. The lowest seronegative rate and highest geometric mean concentrations were found in the 0–10 years age group, corresponding to their recent pertussis vaccination. The proportion of people with undetectable IgG level was prominent, starting after 11 years of age onwards. Now that a reduced-dose pertussis vaccine with fewer adverse effects is available, a booster dose during adolescence should be considered in order to reduce the incidence of pertussis disease. Further studies exploring how long the reduced-dose pertussis vaccine can provide protective immunity against pertussis disease when administered to adults and adolescents should also be performed.

A molecular epidemiological study of the hepatitis B virus in Thailand after 22 years of universal immunization

Hepatitis B virus (HBV) infection affects an estimated two billion people worldwide. Since 1992, Thailand implemented universal HBV vaccination as part of the expanded program on immunization (EPI) for newborns. This study aims to compare genotypes and characterize HBV by assessing pre‐S/S and basic core promoter (BCP)/precore (PC) mutations in populations born before and after EPI implementation. A nationwide serosurvey conducted in 2014 assessed the impact of universal HBV vaccination in Thailand. Two cohort groups were established based on whether they were born before or after 1992. HBV DNA was amplified from HBsAg positive samples by PCR and sequenced. HBV genotypes, pre‐S/S regions, and BCP/PC mutations were characterized. From a total of 5,964 subjects, there were 2,805 (47.0%) and 3,159 (53.0%) individuals who were born before and after EPI implementation, respectively. The overall prevalence of HBsAg was 2.2%. The prevalence of HBsAg was significantly higher in the before EPI group (4.3%) than in the after EPI group (0.3%) (P < 0.001). HBV DNA was detected in 119 samples; 111 HBV‐positive samples (93%) were genotype C (subgenotype C1). The “a” determinant mutation was only detected in the “before EPI” group. Twenty‐two years after implementation of the EPI program, the HBV carrier rate is significantly reduced. The most prevalent genotype for the remaining HBV was C1. The “vaccine escape” mutant, especially the “a” determinant, was not detected after the launch of the EPI program, and the current HBV vaccine remains highly effective. J. Med. Virol. 88:664–673, 2016.

Smooth muscle progenitor cells involved in the development of airway remodeling in a murine model of asthma.

BACKGROUND The mechanisms regulating airway remodeling changes remain poorly understood. Recently, a smooth muscle progenitor cell was identified in the peripheral circulatory system that plays an important role in the reconstruction of injured blood vessels. However, to the best of our knowledge, there is no report in the medical literature regarding the role of smooth muscle progenitor cells (SPCs) in asthma. OBJECTIVE The aim of this study was to investigate the relationship between SPCs and the development of airway remodelling in a murine model of asthma. METHODS Chronic asthma with airway remodeling was generated by sensitizing and stimulating BALB/c mice with atomized ovalbumin (OVA). Bronchoalveolar lavage fluid (BALF) was collected for eosinophils (EOS) counting and histological analysis. The Ficoll method was used to isolate mononuclear cells from peripheral blood. Smooth muscle myosin heavy chain (SM-MHC) and highly glycosylated type I transmembrane protein (CD34⁺) were selected as two markers to detect the expression of SPCs by Flow Cytometry. RESULTS Long-term inhalation of OVA produced thickening of the epithelial and smooth muscle layer, goblet cell hyperplasia, collagen deposition around smooth muscle, luminal exudates and inflammatory cell infiltration. The number of SPCs in the asthma group was significantly higher than in the control group. CONCLUSION Long-term inhalation of OVA results in airway remodeling and the smooth progenitor muscle cell are involved in the development of airway remodeling.BACKGROUND Little is known about the level of asthma control in Thai elementary school students living in the inner city of Bangkok. Our study aimed to evaluate the prevalence of asthma, level of asthma control and factors associated with asthma control in Thai students. METHODS We conducted a cross-sectional descriptive study in students aged between 6-12 years at 3 public schools and 3 private schools in Bangkok. The parent-completed questionnaire used to assess the prevalence of asthma and asthma symptoms was translated from the Phase I ISAAC (The International Study of Asthma and Allergies in Childhood) questionnaire. Univariate analysis was used to identify possible risk factors related to partly and uncontrolled asthma. RESULTS A population of 1,428 students was recruited by screening questionnaires (66.1% of response rate). The mean age was 9.5 years. Prevalence of physician-diagnosed asthma was 9% and the most common asthma symptom was night cough (23.8%). The level of asthma control was assessed in students with current asthma and classified as controlled (46.7%), partly controlled (43.3%) and uncontrolled (10%). Around 27% of students with current asthma in this study use controller medications. Factors associated with asthma control were analyzed but none approached significance. CONCLUSIONS The prevalence of asthma in elementary school students living in Bangkok has decreased since the previous survey and the use of controller medications has increased. Asthma management strategies should focus on encouraging awareness among physicians and parents about the importance of using controller medications to achieve better control of asthma.

Seroprevalence of Anti-EBV IgG among Various Age Groups from Khon Kaen Province, Thailand

Epstein-Barr virus (EBV) is an extremely common herpesvirus that may cause asymptomatic infection or various diseases, including infectious mononucleosis, certain lymphoproliferative diseases and several types of neoplasms. Vaccine development is an important strategy to reduce the burden of EBV-associated diseases and the timing of vaccinations should be before primary infection occurs. In the past, more than 90% of Thai children were infected with EBV in early childhood. Now, due to the improved healthcare system in Thailand, we aim to determine current prevalence of EBV infection among people in different age groups. A total of 538 sera were collected from residents of Khon Kaen province in northeastern Thailand for detecting anti-EBV IgG. Sera of infants under 2-years-old were also tested for anti-EBV IgM and EBV-DNA. The prevalence of anti-EBV IgG was 47.1% (95% CI: 23.3-70.8) in infants aged 0-6 months, 34.9% (95% CI: 23.1-46.7) in those aged 6-24 months, 87.9% (95% CI: 79.5-96.3) in children aged 3-5 years and then maintained at above 95% through adulthood. These seropositivity rates among Thai children remain similar to those found in a previous study conducted 20 years ago. Thai children are still exposed to EBV from an early age. Therefore, a prophylactic vaccine should be given within the first two years of life.

Detection of Human Papillomavirus in Male and Female Urine by Electrochemical DNA Chip and PCR Sequencing

BACKGROUND Cervical cancer is the second most common cancer in Thai women after breast cancer. Currently, the Papanicolaou (Pap) smear is the recommended procedure for cervical cancer screening in Thailand, but only a relatively small percentage of women follow this screening program. An alternative method to detect HPV genotypes associated with cervical cancer is self-sampling of urine, which is a more widely accepted method. Our study aimed to evaluate the prevalence of HPV in Thai women using urine and cervical swabs and prevalence of HPV in Thai men using urine samples. MATERIALS AND METHODS Tumorigenic HPV detection was accomplished by electrochemical DNA chip and PCR/direct sequencing. In addition to HPV prevalence, we report the concordance between different methods and sample types. One-hundred and sixteen women and 100 men were recruited. Histological examination revealed normal cytology in 52 women, atypical squamous cells of undetermined significance (ASCUS) in 9, low-grade squamous intraepithelial lesions (LSIL) in 24, and high-grade squamous intraepithelial lesions (HSIL) in 31. One-hundred men were classified as heterosexuals (n=45) and homosexuals (n=55). RESULTS The most prevalent HPV genotype in our study was HPV16. The HPV detection rate was generally lower in urine samples compared with cervical samples. Overall, there was good agreement for the detection of carcinogenic HPV from female cervical samples between the DNA chip and PCR/ sequencing, with 88.8% total agreement and a kappa value of 0.76. In male urine samples, the level of agreement was higher in heterosexuals compared with homosexuals. CONCLUSIONS Further improvement is required to increase an overall yield of HPV DNA detection in urine samples before clinical application of a urine-based HPV screening program. The electrochemical DNA chip test is a promising technique for carcinogenic HPV detection.

Compound heterozygosity of a novel exon 3 frameshift (p.R357P fs*24) mutation and Y486D mutation in exon 5 of the UGT1A1 gene in a Thai infant with Crigler-Najjar syndrome type 2.

Mutations in the UGT1A1 gene cause Crigler-Najjar syndrome (CN), which causes non-hemolytic unconjugated hyperbilirubinemia, and is categorized as CN1 and CN2 according to the severity of bilirubin levels. The UGT1A1 gene is responsible for encoding the liver enzyme uridine diphosphate-glucuronosyltransferase, UGT1A1. This protein adds glucuronic acid to unconjugated bilirubin in bilirubin metabolism to form conjugated bilirubin. CN2 occurs when UGT1A1 activity is low, while CN1 is the absence of UGT1A1 activity; therefore, the CN2 phenotype is not as severe as that of CN1. Here, we report a novel allele of compound heterozygous mutations in UGT1A1 in a Thai male infant with clinical symptoms of CN2. The patients compound heterozygosity was composed of a novel mutation, c.1069-1070insC, and the c.1456T>G mutation. The novel c.1069-1070insC mutation generated a premature stop codon in exon 4 (p.R357Pfs*24). The healthy parents were heterozygous for the c.1069-1070insC mutation (father) and c.1456T>G missense mutation (mother). Our results suggest that compound heterozygosity of the novel c.1069-1070insC and c.1456T>G (c211 G >A) missense mutation in the UGT1A1 gene played a primary role in the development of CN2 unconjugated hyperbilirubinemia.

Comparison of detection sensitivity for human papillomavirus between self-collected vaginal swabs and physician-collected cervical swabs by electrochemical DNA chip.

BACKGROUND Human papillomavirus (HPV) DNA testing is an effective method to screen for precancerous changes in the cervix. Samples from self-collection rather than Pap smear can potentially be used to test for HPV as they are more acceptable and preferred for use in certain settings. The objective of this study was to compare HPV DNA testing from self-collected vaginal swabs and physician-collected cervical swabs. MATERIALS AND METHODS A total of 101 self-collected vaginal and physician-collected cervical swabs of known cytology from Thai women were tested by electrochemical DNA chip assay. The specimens were divided into 4 groups: 29 with normal cytology, 14 with atypical squamous cells of undetermined significance (ASCUS), 48 with low- grade squamous intraepithelial lesion (LSIL), and 10 with high-grade squamous intraepithelial lesion (HSIL). RESULTS Positive detection rates of HPV from self-collected swabs were similar to those from physician-collected swabs. Among specimens with abnormal cytology, HPV was found in 50% of self-collected swabs and 47.2% of physician-collected swabs. In specimens with normal cytology, 17.2% of self-collected swabs and 24.1% of physician-collected swabs were positive for HPV. Concordance was relatively high between results from self- collected and physician-collected samples. The most common HPV genotype detected was HPV 51. CONCLUSIONS HPV DNA testing using self-collected swabs is a feasible alternative to encourage and increase screening for cervical cancer in a population who might otherwise avoid this important preventive examination due to embarrassment, discomfort, and anxiety.

Assessing the reactogenicity of Tdap vaccine administered during pregnancy and antibodies to Bordetella pertussis antigens in maternal and cord sera of Thai women

INTRODUCTION Pregnant Thai women have low antibody titers against B. pertussis antigens, which coincide with an increasing incidence of pertussis among Thai infants. Thus, there exists a potential benefit of a booster dose of tetanus- diphtheria-acellular pertussis (Tdap) vaccine administered during pregnancy. Here, we report the vaccine reactogenicity profile and birth outcomes in Tdap-vaccinated pregnant women who have or have not had prior immunization with tetanus vaccine, and the IgG levels to B. pertussis antigens in maternal and cord sera at delivery. MATERIALS AND METHODS Pregnant women (N = 370) aged 18-40 years were administered the Tdap vaccine (Boostrix®, GlaxoSmithKline, Rixensart, Belgium) at 26-36 weeks gestation. Adverse events following vaccination were identified by follow-up telephone call and medical record review. IgG against pertussis toxin (anti-PT), filamentous hemagglutinin (anti-FHA) and pertactin (anti-PRN) in both maternal and umbilical cord blood obtained at delivery were quantitatively evaluated using enzyme-linked immunosorbent assay (EUROIMMUN®, Lübeck, Germany). RESULTS There was no reported increase in the severity or duration of adverse events associated with the administration of an extra tetanus-containing vaccine within the previous five years (N = 181) or multiple doses of tetanus-containing vaccines during the current pregnancy (N = 98). Vaccination at least eight weeks prior to delivery resulted in high antibody titers to all B. pertussis antigens studied. CONCLUSIONS The reactogenicity of Tdap vaccine administered during pregnancy was not affected by prior tetanus toxoid immunization. High transplacental antibody against B. pertussis antigens in the cord blood provides evidence of antibody transfer and should thus help to protect newborns from pertussis during early life.

High prevalence of coxsackievirus A2 in children with herpangina in Thailand in 2015

Coxsackievirus (CV) is a member of the genus Enterovirus and the family Picornaviridae. CV infection can cause herpangina, a disease characterized by multiple ulcers on the tonsils and soft palate affecting mostly young children. CV strains are categorized by serotypes. Unfortunately, serotypes responsible for infections in patients are often undetermined. This knowledge gap partly contributes to the ineffective prevention and control of CV-associated herpangina in Southeast Asia. To characterize the viral etiology of children presented with herpangina, 295 throat swabs were tested for human enterovirus infection. Using RT-PCR specific for the viral 5′UTR/VP2 and the VP1 regions, two most frequent CV types found in these samples were CV-A2 (33.33%, 40/120) and CV-A4 (15.8%, 19/120). Phylogenetic analysis of the VP1 gene demonstrated that the CV-A2 strains in this study not only were closely related to those previously identified in Asia and Europe, but the majority clustered into a distinct group. Thus, infection predominantly by CV-A2 and CV-A4 caused herpangina in 2015 in Thailand.