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.

Molecular epidemiology and characterization of human coronavirus in Thailand, 2012-2013.

BACKGROUND: Coronavirus causes respiratory infections in humans. To determine the prevalence of human coronavirus (HCoV) infection among patients with influenza-like illness, 5833 clinical samples from nasopharyngeal swabs and aspirates collected between January 2012 and December 2013 were examined. RESULTS: HCoV was found in 46 (0.79 %) samples. There were 19 (0.32 %) HCoV-HKU1, 19 (0.32 %) HCoV-NL63, 5 (0.09 %) HCoV-229E, and 3 (0.05 %) HCoV-OC43. None of the sample tested positive for MERS-CoV. The majority (54 %) of the HCoV-positive patients were between the ages of 0 and 5 years. HCoV was detected throughout the 2-year period and generally peaked from May to October, which coincided with the rainy season. Phylogenetic trees based on the alignment of the spike (S) gene sequences suggest an emergence of a new clade for HCoV-229E. CONCLUSIONS: The data in this study provide an insight into the prevalence of the recent circulating HCoVs in the region.

Human norovirus genogroup II recombinants in Thailand, 2009-2014.

Norovirus (NoV) is a major cause of nonbacterial acute gastroenteritis worldwide. New strains emerge partly due to viral recombination. In Thailand, there is a lack of data on NoV recombinants among clinical isolates. We screened stool samples from pediatric diarrheal patients for norovirus by RT-PCR and found GII.4 to be the most prevalent genotype. Phylogenetic and SimPlot analyses detected seven intra-genogroup recombinant strains: three GII.21/GII.3, two GII.12/GII.3, and two GII.12/GII.1 recombinants. Maximum chi-square analysis indicated that all had similar breakpoints near the ORF1/ORF2 junction (p < 0.001), either slightly upstream within the C-terminus of RdRp or downstream within the N-terminal domain of VP1.

Seroprevalence of antibody against diphtheria among the population in Khon Kaen province, Thailand.

To assess diphtheria immunity in the northeastern region of Thailand, a seroepidemiological survey was undertaken in 2011 from 516 healthy individuals (age range 2-87 years) in Khon Kaen province. Diphtheria antitoxin levels were measured by enzyme-linked immunosorbent assay and titers of ≥0.1 IU/mL were considered to be protective antitoxin levels. Among the studied population, 94.8% have fully protective levels. The younger population (age range 2-19 years) has higher diphtheria immunity with seroprotection rates of 96.8% to 97.9%, compared with the adult population. The proportion of protective diphtheria antitoxin levels declines to 88.3% to 91.9% in the middle-aged group (20-50 years), and appeared to be higher again in the older age-group (50-70 years). To avoid epidemic spreading, promoting immunization booster programs will be helpful, especially among the adult population (20-50 years). Finally, this study may serve as a valuable guide in deciding exactly which age-groups should be targeted by such an effort.

Complete genome analysis of a rare human G3P[9] rotavirus posing as an AU-1 like strain.

BACKGROUND: We performed phylogenetic and sequence analysis by Basic Local Alignment Search Tool (BLAST) of a complete Human Rotavirus (HRV) genome isolated from a hospitalized child with acute gastroenteritis in Thailand. FINDINGS: The results indicated an uncommon strain characterized by multiple re-assortments in the VP3, VP4, VP6, NSP1, NSP4 and NSP5 genes. The uncommon strain is genotype G3-P[9]-I3-R3-C3-M3-A3-N3-T3-E3-H6, which displays aspects of the AU-1, FRV-1 and corresponds to the feline/canine prototype G3P[9] strain. CONCLUSIONS: The results suggested that nearly all the eleven gene segments of G3P[9] RVA strain CU365 might have originated from feline/canine RVAs (Rotavirus A).

Molecular characterization of human adenovirus infection in Thailand, 2009-2012.

BACKGROUND: Human adenovirus (HAdV) can cause a wide spectrum of human diseases worldwide. METHODS: Using PCR and sequence analysis, we investigated HAdV infection prevalence in the Thai population for four years from January 2009 to December 2012. We collected Nasopharyngeal swab/aspirate (NP) specimens from patients in Bangkok, Khon Kaen, and Nakhon Si Thammarat province and fecal specimens only from Bangkok and Khon Kaen province. RESULTS: We observed HAdV infection in 1.04% (82/7,921) of NP samples and in 5.84% (76/1,301) of fecal specimens. HAdV-B3 (32%) and HAdV-C1 (31%) were the genotypes most commonly associated with NP specimens followed by HAdV-C2 (13%) and HAdV-C5 (12%). In fecal specimens, we found that 25% harbored HAdV-F41 followed by HAdV-C1 (18%), HAdV-C2 (16%), and HAdV-B3 (13%). Out of all population subsets, children below the age of 3 years were the most likely to be HAdV positive (63.29%). In addition, HAdV infection occurred throughout the year without a seasonal distribution pattern, although HAdV infection of NP samples peaked from January-April while HAdV infection peaked from January to March and then again from May to July in fecal samples. CONCLUSIONS: This study has for the first time reported the HAdV infection rate in Thai NP and fecal specimens from 2009-2012. We observed that HAdV-B3 and HAdV-C1 were commonly found in NP specimens, and that HAdV-F41 was the most prevalence in fecal specimens in Thailand during the study period.

Epidemiological and serological surveillance of human pandemic influenza A virus infections during 2009-2010 in Thailand.

Since April 2009, the outbreak of human pandemic influenza A (H1N1) virus (pH1N1) infection has spread from North America to other parts of the world, and currently, pH1N1 is the predominant circulating strain of influenza viruses. Our objectives were to perform a serological survey of medical personnel at the Chumphae Hospital in Thailand and to investigate the prevalence of pH1N1 in randomly selected patients diagnosed with respiratory tract disease. Prevalence of pH1N1 in the patients was determined by performing real-time reverse transcription-polymerase chain reaction. The study was carried out between July 2009 and November 2010. Seroprevalence of hemaglutination inhibition (HI) titers among medical personnel was established in three cross-sectional studies at the end of each wave of the pandemic by performing HI assay to detect antibodies against pH1N1. Infection by the pH1N1 peaked between July and October 2009; the second wave was from January to March 2010 and the third wave from June to November 2010. The HI titers after the first, second, and third waves were 48.2%, 22.4%, and 25.7%, respectively. After the second and third waves, 52.1% and 45.3% of the medical personnel who had received pH1N1 vaccination had HI titers ≥ 40. These findings show that seasonal influenza strain in Chumphae and the predominant influenza strain from each wave was pH1N1. HI assay results also represent the severity of the attack rate in each wave.

Serological analysis of human pandemic influenza (H1N1) in Thailand.

The study was aimed at determining the prevalence of pandemic influenza (H1N1) 2009 among patients with respiratory tract diseases during July-December 2009 using real-time reverse transcription polymerase chain reaction. Haemagglutination inhibition (HI) assay was performed to detect antibody titres against pandemic influenza in 255 medical personnel, 307 members of the general population during the second week of December 2009 in Khon Kaen province, Thailand, and in 100 stored sera collected from people of different age-groups during 2008. The results showed that the pandemic (H1N1) 2009 had occurred during July-December 2009. The results of the HI test after the wave of this outbreak showed that 123 (48%) of the 255 sera collected from the medical personnel, 109 (36%) of the 307 sera obtained from the general population, and only two of the 100 stored sera from 2008 contained antibodies (HI titres > or = 40) against pandemic influenza. Antibody against the pandemic (H1N1) 2009 was found in at least one-third of the population. In conclusion, the prevalence of virus and serological data obtained from the study can be used as the serological background level of the Thai population after the July-December pandemic. Finally, the serological data might be useful for outbreak-prevention and control strategies and for the management of vaccination for the pandemic (H1N1) 2009 in Thailand.