Acute Gastroenteritis Associated with Norovirus GII.8[P8], Thailand, 2023.

Acute gastroenteritis associated with human norovirus infection was reported in Phuket, Thailand, in June 2023. We amplified GII.8[P8] from the outbreak stool specimens. Retrospective sample analysis identified infrequent GII.8[P8] in the country beginning in 2018. In all, the 10 whole-genome GII.8[P8] sequences from Thailand we examined had no evidence of genotypic recombination.

Inadvertent Platelet Transfusion from Monkeypox Virus-Infected Donor to Recipient, Thailand, 2023.

In Thailand, platelet product from a blood donor was transfused to a recipient who had dengue. Two days later, the donor was confirmed to have monkeypox virus infection. Monkeypox virus DNA was undetectable in recipient specimens up to 2 weeks after transfusion. The recipient remained asymptomatic at 4 weeks of monitoring.

Norovirus GII.3[P25] in Patients and Produce, Chanthaburi Province, Thailand, 2022.

An increase in acute gastroenteritis occurred in Chanthaburi Province, Thailand, during December 2021‒January 2022. Of the norovirus genotypes we identified in hospitalized patients and produce from local markets, genotype GII.3[P25] accounted for one third. We found no traceable link between patients and produce but found evidence of potential viral intake.

A G3P[9] rotavirus strain with an unusual genome constellation in a diarrheic cat in Thailand.

Rotavirus infection can cause diarrhea in many animal species. A 2-year-old indoor female Siamese cat with bloody mucoid diarrhea tested positive for rotavirus (RV) group A by real-time reverse transcription polymerase chain reaction (RT-PCR). Subsequent conventional RT-PCR amplification of the 11 RV segments and sequencing revealed a G3-P[9]-I2-R2-C2-M2-A3-N2-T3-E3-H3 genome constellation. Phylogenetic analysis showed that the VP4, VP7, NSP1, NSP3, NSP4, and NSP5 genes were closely related to those of human feline-like rotaviruses, while the VP1, VP2, VP3, VP6, and NSP2 genes were genetically closest to those of human bovine-like rotaviruses, suggesting that genetic reassortment had occurred. The uniqueness of this G3P[9] feline rotavirus strain expands our knowledge about feline rotaviruses.

Severe fever with thrombocytopenia syndrome virus genotype B in Thailand.

Severe fever with thrombocytopenia syndrome virus (SFTSV) has been reported in many countries in Southeast Asia, which expands the original geographic range of China, Korea, and Japan. Here, we report the complete genome sequences of two Thai SFTSV strains previously identified in patients with undifferentiated febrile illness in 2020. Phylogenetically, both clustered with SFTSV genotype B strains and were most closely related to those previously reported in central China (≥99.0% nucleotide sequence identity) in the L, M, and S gene segments. Nine amino acid residues encoded by one or more Thai SFTSV genomes differed from those found in global strains. Interestingly, the observed differences in numerous residues between the Thai strains suggest possible separate introductions of different variants into the region.

Molecular characterisation and tracking of severe acute respiratory syndrome coronavirus 2 in Thailand, 2020-2022.

The global COVID-19 pandemic, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first detected in China in December 2019. To date, there have been approximately 3.4 million reported cases of COVID-19 and over 24,000 deaths in Thailand. In this study, we investigated the molecular characteristics and evolution of SARS-CoV-2 in Thailand from 2020 to 2022. Two hundred sixty-eight SARS-CoV-2 isolates, collected mostly in Bangkok from COVID-19 patients, were characterised by partial genome sequencing. Moreover, the viruses in 5,627 positive SARS-CoV-2 samples were identified as viral variants - B.1.1.7 (Alpha), B.1.617.2 (Delta), B.1.1.529 (Omicron/BA.1), or B.1.1.529 (Omicron/BA.2) - by multiplex real-time reverse transcription polymerase chain reaction (RT-PCR) assays. The results revealed that B.1.36.16 caused the predominant outbreak in the second wave (December 2020-January 2021), B.1.1.7 (Alpha) in the third wave (April-June 2021), B.1.617.2 (Delta) in the fourth wave (July-December 2021), and B.1.1.529 (Omicron) in the fifth wave (January-March 2022). The evolutionary rate of the viral genome was 2.60 × 10-3 (95% highest posterior density [HPD], 1.72 × 10-3 to 3.62 × 10-3) nucleotide substitutions per site per year. Continued molecular surveillance of SARS-CoV-2 is crucial for monitoring emerging variants with the potential to cause new COVID-19 outbreaks.

Severe Fever with Thrombocytopenia Syndrome Virus Infection, Thailand, 2019-2020.

Infection with severe fever with thrombocytopenia syndrome (SFTS) virus, which can cause hemorrhagic febrile illness, is often transmitted by ticks. We identified 3 patients with SFTS in or near Bangkok, Thailand. Our results underscore a need for heightened awareness by clinicians of possible SFTS virus, even in urban centers.

Genetic diversity and evolution of enterovirus A71 subgenogroup C1 from children with hand, foot, and mouth disease in Thailand.

Enterovirus A71 (EV-A71) can cause hand, foot, and mouth disease (HFMD) in children and may be associated with severe neurological complications. There have been numerous reports of increased incidence of EV-A71 subgenogroup C1 (EV-A71 C1) infections associated with neurological diseases since the first occurrence in Germany in 2015. Here, we describe 11 full-length genome sequences of 2019 EV-A71 C1 strains isolated from HFMD patients in Thailand from 2019 to early 2020. The genetic evolution of 2019 EV-A71 C1 was traced in the outbreaks, and the emergence of multiple lineages was detected. Our results demonstrated that 2019 EV-A71 C1 from Thailand emerged through recombination between its nonstructural protein gene and those of other EV-A genotypes. Bayesian-based phylogenetic analysis showed that the 2019 EV-A71 C1 Thai strains share a common ancestor with variants in Europe (Denmark and France). The substitution rate for the 2019 EV-A71 C1 genome was estimated to be 4.38 × 10-3 substitutions/(site∙year-1) (95% highest posterior density interval: 3.84-4.94 × 10-3 substitutions/[site∙year-1]), approximating that observed between previous EV-A71 C1 outbreaks. These data are essential for understanding the evolution of EV-A C1 during the ongoing HFMD outbreak and may be relevant to disease outcomes in children worldwide.

Quantity and Quality of Antibodies After Acellular Versus Whole-cell Pertussis Vaccines in Infants Born to Mothers Who Received Tetanus, Diphtheria, and Acellular Pertussis Vaccine During Pregnancy: A Randomized Trial.

BACKGROUND: The blunting effect of pertussis immunization during pregnancy on infant antibody responses induced by whole-cell pertussis (wP) vaccination is not well-defined. METHODS: This randomized controlled trial (NCT02408926) followed term infants born to mothers vaccinated with tetanus, diphtheria, and acellular pertussis (Tdap) vaccine during pregnancy in Thailand. Infants received either acellular pertussis (aP)- or wP-containing vaccine at 2, 4, 6, and 18 months of age. A comparison group comprised wP-vaccinated children born to mothers not vaccinated during pregnancy. Antibodies against pertussis toxin (PT), filamentous hemagglutinin (FHA), and pertactin (PRN) were evaluated using commercial enzyme-linked immunosorbent assays. Functionality of antibodies against Bordetella pertussis was measured using Bordetella pertussis growth inhibition assay. RESULTS: After maternal Tdap vaccination, 158 infants vaccinated with aP-containing vaccines possessed higher antibody levels (P < .001) against all tested B. pertussis antigens postpriming compared to 157 infants receiving wP-containing vaccines. At 1 month postbooster, only anti-FHA and anti-PRN antibodies were still significantly higher (P < .001) in the aP group. Significantly higher anti-PT and anti-FHA (P < .001), but not anti-PRN immunoglobulin G, were observed among 69 wP-vaccinated infants born to control mothers compared with wP-vaccinated infants of Tdap-vaccinated mothers after primary and booster vaccination. The antibody functionality was higher in all wP-vaccinated infants at all times. CONCLUSIONS: Maternal Tdap vaccination inhibited more pertussis-specific responses in wP-vaccinated infants compared to aP-vaccinated infants, and the control group of unvaccinated women had highest PT-specific responses, persisting until after the booster dose. Antibody functionality was better in the wP groups. CLINICAL TRIALS REGISTRATION: NCT02408926.Infant whole-cell pertussis (wP) vaccine responses are blunted after maternal Tdap vaccination. Pertussis antibody titers are higher in acellular pertussis (aP)- than wP-vaccinated infants of immunized mothers, yet quality of antibodies, measured as serum-mediated bacterial growth inhibition, is better after wP than aP vaccination.

Rotavirus infection in children in Southeast Asia 2008-2018: disease burden, genotype distribution, seasonality, and vaccination.

BACKGROUND: Rotaviruses (RVs) are recognized as a major cause of acute gastroenteritis (AGE) in infants and young children worldwide. Here we summarize the virology, disease burden, prevalence, distribution of genotypes and seasonality of RVs, and the current status of RV vaccination in Southeast Asia (Cambodia, Indonesia, Lao People's Democratic Republic, Malaysia, Myanmar, Philippines, Singapore, Thailand, and Vietnam) from 2008 to 2018. METHODS: Rotavirus infection in Children in Southeast Asia countries was assessed using data from Pubmed and Google Scholars. Most countries in Southeast Asia have not yet introduced national RV vaccination programs. We exclude Brunei Darussalam, and Timor Leste because there were no eligible studies identified during that time. RESULTS: According to the 2008-2018 RV surveillance data for Southeast Asia, 40.78% of all diarrheal disease in children were caused by RV infection, which is still a major cause of morbidity and mortality in children under 5 years old in Southeast Asia. Mortality was inversely related to socioeconomic status. The most predominant genotype distribution of RV changed from G1P[8] and G2P[4] into the rare and unusual genotypes G3P[8], G8P[8], and G9P[8]. Although the predominat strain has changed, but the seasonality of RV infection remains unchanged. One of the best strategies for decreasing the global burden of the disease is the development and implementation of effective vaccines. CONCLUSIONS: The most predominant genotype distribution of RV was changed time by time. Rotavirus vaccine is highly cost effective in Southeast Asian countries because the ratio between cost per disability-adjusted life years (DALY) averted and gross domestic product (GDP) per capita is less than one. These data are important for healthcare practitioners and officials to make appropriate policies and recommendations about RV vaccination.

Genome sequences of chikungunya virus isolates from an outbreak in southwest Bangkok in 2018.

An outbreak of chikungunya virus (CHIKV) infection occurred in southwest Bangkok during the 2018 rainy season. The envelope glycoprotein E1 gene sequence of the infecting strain belonged to an East/Central/South African lineage with alanine at residue 226. Mutations in the predicted E1 (K211E) and E2 (V264A) proteins of CHIKV were identified in CHIKV-infected patients and in an Aedes aegypti mosquito. Analysis of the complete genome sequences showed marked differences from the strains causing previous outbreaks in Thailand in 2008-2009 and 2013 but showed similarities to strains from more recent CHIKV outbreaks in South and Southeast Asia.

Recombinant GII.Pe-GII.4 Norovirus, Thailand, 2017-2018.

During June 2017-December 2018, norovirus was responsible for 10.9% of acute gastroenteritis cases in Thailand. Genogroup I (GI) was found in 14% of samples, of which 12 were co-infected with genogroup II (GII). In 35.8% of samples, GII.Pe-GII.4 Sydney predominated. Diverse recombinant strains of GI and GII norovirus co-circulated year-round.

The History of Enterovirus A71 Outbreaks and Molecular Epidemiology in the Asia-Pacific Region.

Enterovirus A71 (EV-A71) is one of the common causative pathogens for hand foot and mouth disease (HFMD) affecting young children. HFMD outbreak can result in a substantial pediatric hospitalization and burden the healthcare services, especially in less-developed countries. Since the initial epidemic of predominantly EV-A71 in California in 1969, the high prevalence of HFMD in the Asia-pacific region and elsewhere around the world represents a significant morbidity in this age group. With the advent of rapid and accurate diagnostic tools, there has been a dramatic increase in the number of laboratory-confirmed EV-A71 infection over the past two decades. The population, cultural, and socioeconomic diversity among countries in the Asia-Pacific region all influence the transmission and morbidity associated with HFMD. This review summarizes the current state of epidemiology of EV-A71 in Asia-Pacific countries based on the most recent epidemiological data and available information on the prevalence and disease burden. This knowledge is important in guiding the prevention, control and future research on vaccine development of this highly contagious disease of significant socioeconomic implications in public health.

Hepatitis E virus infection in Thai blood donors.

BACKGROUND: Hepatitis E virus (HEV) infection in several industrialized and developing countries is associated with the consumption of pork and other meat products, an exposure risk among the majority of blood donors. We aimed to evaluate the prevalence of HEV in plasma from healthy blood donors in Thailand. STUDY DESIGN AND METHODS: We screened blood samples collected between October and December 2015, from 30,115 individual blood donors in 5020 pools of six, for HEV RNA using in-house real-time reverse-transcription polymerase chain reaction (RT-PCR). Thrice-reactive samples were subjected to a commercial real-time RT-PCR (cobas HEV test) and evaluated for anti-HEV immunoglobulin M and immunoglobulin G antibodies. Genotyping using nested RT-PCR, nucleotide sequencing, and phylogenetic analysis was performed. RESULTS: Twenty-six donors were positive for HEV RNA by the in-house assay, nine of whom were also positive by cobas test. None of the latter were reactive for anti-HEV immunoglobulin M or immunoglobulin G antibodies. Six samples were successfully genotyped and found to be HEV genotype 3. Thus, the frequency of HEV infection among healthy Thai blood donors is 1 in 1158. CONCLUSION: The presence of HEV RNA in the Thai blood supply was comparable to the rates reported in western European countries, but higher than in North America and Australia.

Enterovirus A71 Infection, Thailand, 2017.

An outbreak of hand, foot and mouth disease among children in Thailand peaked in August 2017. Enterovirus A71 subgenogroup B5 caused most (33.8%, 163/482) cases. Severe disease (myocarditis and encephalitis) was observed in 1 patient. Coxsackievirus A6 was detected in 6.0% (29/482) of patients, and coxsackievirus A16 was detected in 2.7% (13/482) of patients.

Global Spread of Norovirus GII.17 Kawasaki 308, 2014-2016.

Analysis of complete capsid sequences of the emerging norovirus GII.17 Kawasaki 308 from 13 countries demonstrated that they originated from a single haplotype since the initial emergence in China in late 2014. Global spread of a sublineage SL2 was identified. A new sublineage SL3 emerged in China in 2016.

Prevalence and molecular characterization of human rhinovirus in stool samples of individuals with and without acute gastroenteritis.

Human rhinovirus (RV) most often causes mild upper respiratory tract infection. Although RV is routinely isolated from the respiratory tract, few studies have examined RV in other types of clinical samples. The prevalence of RV was examined in 1,294 stool samples collected mostly from children with acute gastroenteritis residing in Bangkok and Khon Kaen province of Thailand between January 2010 and October 2014. In addition, 591 samples from hand-foot-mouth disease (HFMD) or herpangina patients who do not have gastroenteritis served as a comparison group. Samples were initially screened by semi-nested PCR for the RV 5'UTR through the VP2 capsid region. RV genotyping and phylogenetic analysis were performed on the VP4/VP2 regions. Among children with acute gastroenteritis, RV was found in 2.3% (30/1,294) of stool samples, which comprised 47% (14/30) RV-A, 17% (5/30) RV-B, and 37% (11/30) RV-C. In the comparison group, 0.8% (5/591) was RV-positive and RV-C (3/5) was the major species found. Interestingly, RV was recovered more often from children with acute gastroenteritis than from those with HFMD or herpangina. As many as 31 RV types were present in the gastroenteritis stools, which were different than the types found in those with HFMD or herpangina. J. Med. Virol. 89:801-808, 2017. © 2016 Wiley Periodicals, Inc.

In vitro study of Zika virus infection in boar semen.

Zika virus (ZIKV) is an important arbovirus that is capable of directly infecting neuronal cells. Infection can cause microcephaly in fetuses and Guillain-Barré syndrome in adults. Recent epidemiological studies have shown that ZIKV is sexually transmitted, especially from infected males to uninfected females. This study aimed to investigate the transmission pattern of ZIKV in semen using boar semen. Experiments were performed ex vivo using semen from healthy boar. The samples were infected with ZIKV, and viral RNA was detected and cell morphology was examined at different time points postinfection. ZIKV infection was confirmed by transmission electron microscopy. Viral RNA levels were found to markedly decrease as the time postinfection increased, without any evidence of virus replication. The sperm showed no significant changes in morphology. Transmission electron microscopy revealed the presence of virus-free sperm, suggesting that ZIKV cannot replicate in boar semen. We suggest three possible reasons underlying this phenomenon. First, the spermatozoa of boar might not be the target of ZIKV associated with sexual transmission. Second, the effect of the external environment on spermatozoa may affect ZIKV replication. Third, ZIKV may not be tropic for spermatozoa. This ex vivo study might be used as a platform to study the association of sexual transmission with ZIKV in other longer-lasting cells, such as Leydig or Sertoli cells.

Molecular epidemiology and the evolution of human coxsackievirus A6.

Coxsackievirus A6 (CV-A6) is a major aetiologic agent for hand, foot and mouth disease (HFMD) in recent years. HFMD outbreaks associated with CV-A6 resulted from the evolutionary dynamics of CV-A6 and the appearance of novel recombinant forms (RFs). To examine this, 151 variants collected in 2013 and 2014 from Germany, Spain, Sweden, Denmark and Thailand were genotyped for the VP1 capsid and 3Dpol genes. Analysis of the VP1 gene showed an increasing correspondence between CV-A6 genome recombination and sequence divergence (estimated substitution rate of 8.1×10-3 substitutions site-1 year-1 and RF half-life of 3.1 years). Bayesian phylogenetic analysis showed that recent recombination groups (RF-E, -F, -H, -J and -K) shared a common ancestor (RF-A). Thirty-nine full-length genomes of different RFs revealed recombination breakpoints between the 2A-2C and the 5' UTRs. The emergence of new CV-A6 recombination groups has become widespread in Europe and Asia within the last 8 years.

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.