Detection of enterovirus D68 among children with severe acute respiratory infection in Myanmar.

BACKGROUND: Enterovirus D68 (EV-D68) is an important reemerging pathogen that causes severe acute respiratory infection and acute flaccid paralysis, mainly in children. Since 2014, EV-D68 outbreaks have been reported in the United States, Europe, and east Asia; however, no outbreaks have been reported in southeast Asian countries, including Myanmar, during the previous 10 years. METHODS: EV-D68 was detected in nasopharyngeal swabs from children with acute lower respiratory infections in Myanmar. The samples were previously collected from children aged 1 month to 12 years who had been admitted to the Yankin Children Hospital in Yangon, Myanmar, between May 2017 and January 2019. EV-D68 was detected with a newly developed EV-D68-specific real-time PCR assay. The clade was identified by using a phylogenetic tree created with the Bayesian Markov chain Monte Carlo method. RESULTS: During the study period, nasopharyngeal samples were collected from 570 patients. EV-D68 was detected in 42 samples (7.4 %)-11 samples from 2017 to 31 samples from 2018. The phylogenetic tree revealed that all strains belonged to clade B3, which has been the dominant clade worldwide since 2014. We estimate that ancestors of currently circulating genotypes emerged during the period 1980-2004. CONCLUSIONS: To our knowledge, this is the first report of EV-D68 detection in children with acute lower respiratory infections in Yangon, Myanmar, in 2017-2018. Detection and detailed virologic analyses of EV-D68 in southeast Asia is an important aspect of worldwide surveillance and will likely be useful in better understanding the worldwide epidemiologic profile of EV-D68 infection.

Detection of parechovirus-A in hospitalized children with acute lower respiratory infection in Myanmar, 2017-2018.

Parechovirus-A (PeV-A) causes emerging infection in children, and clinical presentation depends on genotype. The virus has been investigated mainly in developed countries; however, data from developing countries, especially in Asia, are sparse. This study investigated whether PeV-A circulated in children in Myanmar. This retrospective study evaluated PeV-A in nasopharyngeal samples from children aged 1 month to 12 years who were hospitalized with acute lower respiratory infection at Yankin Children Hospital, Yangon, Myanmar, during the period from May 2017 to April 2019. Real-time polymerase chain reaction (PCR) was used to detect PeV-A, and PCR-positive samples were used for genotyping and phylogenetic analysis. In total, 11/570 (1.9%) of samples were positive for PeV-A; 7 were successfully genotyped by sequencing the VP3/VP1 region, as follows: PeV-A1 (n = 4), PeV-A5 (n = 1), PeV-A6 (n = 1), and PeV-A14 (n = 1). Median age was 10.0 months (interquartile range 4.0-12.0 months), and other respiratory viruses were detected in all cases. Phylogenetic analysis showed that all detected PeV-A1 strains were in clade 1 A, which was a minor clade worldwide. Four PeV-A genotypes were detected in Myanmar. The clinical impact of PeV-A in children should be evaluated in future studies.

Whole-Genome Analysis of Influenza A(H3N2) and B/Victoria Viruses Detected in Myanmar during the COVID-19 Pandemic in 2021.

An influenza circulation was observed in Myanmar between October and November in 2021. Patients with symptoms of influenza-like illness were screened using rapid diagnostic test (RDT) kits, and 147/414 (35.5%) upper respiratory tract specimens presented positive results. All RDT-positive samples were screened by a commercial multiplex real-time polymerase chain reaction (RT-PCR) assay, and 30 samples positive for influenza A(H3N2) or B underwent further typing/subtyping for cycle threshold (Ct) value determination based on cycling probe RT-PCR. The majority of subtyped samples (n = 13) were influenza A(H3N2), while only three were B/Victoria. Clinical samples with low Ct values obtained by RT-PCR were used for whole-genome sequencing via next-generation sequencing technology. All collected viruses were distinct from the Southern Hemisphere vaccine strains of the corresponding season but matched with vaccines of the following season. Influenza A(H3N2) strains from Myanmar belonged to clade 2a.3 and shared the highest genetic proximity with Bahraini strains. B/Victoria viruses belonged to clade V1A.3a.2 and were genetically similar to Bangladeshi strains. This study highlights the importance of performing influenza virus surveillance with genetic characterization of the influenza virus in Myanmar, to contribute to global influenza surveillance during the COVID-19 pandemic.

Evolutionary Dynamics of Whole-Genome Influenza A/H3N2 Viruses Isolated in Myanmar from 2015 to 2019.

This study aimed to analyze the genetic and evolutionary characteristics of the influenza A/H3N2 viruses circulating in Myanmar from 2015 to 2019. Whole genomes from 79 virus isolates were amplified using real-time polymerase chain reaction and successfully sequenced using the Illumina iSeq100 platforms. Eight individual phylogenetic trees were retrieved for each segment along with those of the World Health Organization (WHO)-recommended Southern Hemisphere vaccine strains for the respective years. Based on the WHO clades classification, the A/H3N2 strains in Myanmar from 2015 to 2019 collectively belonged to clade 3c.2. These strains were further defined based on hemagglutinin substitutions as follows: clade 3C.2a (n = 39), 3C.2a1 (n = 2), and 3C.2a1b (n = 38). Genetic analysis revealed that the Myanmar strains differed from the Southern Hemisphere vaccine strains each year, indicating that the vaccine strains did not match the circulating strains. The highest rates of nucleotide substitution were estimated for hemagglutinin (3.37 × 10-3 substitutions/site/year) and neuraminidase (2.89 × 10-3 substitutions/site/year). The lowest rate was for non-structural protein segments (4.19 × 10-5 substitutions/site/year). The substantial genetic diversity that was revealed improved phylogenetic classification. This information will be particularly relevant for improving vaccine strain selection.

Clinical manifestations and outcome of viral acute lower respiratory infection in hospitalised children in Myanmar.

BACKGROUND: Acute lower respiratory infection (ALRI) remains the leading cause of death in children worldwide, and viruses have been the major cause of ALRI. In Myanmar, ALRI is associated with high morbidity and mortality in children, and detailed information on ALRI is currently lacking. METHODS: This prospective study investigated the viral aetiologies, clinical manifestations, and outcomes of ALRI in hospitalised children aged 1 month to 12 years at the Yankin Children Hospital, Yangon, Myanmar from May 2017 to April 2019. The sample size was set to 300 patients for each year. Two nasopharyngeal swabs were obtained for the patients with suspected viral ALRI; one for rapid tests for influenza and respiratory syncytial virus (RSV), and the other for real-time PCR for the 16 ALRI-causing viruses. Pneumococcal colonization rates were also investigated using real-time PCR. Clinical information was extracted from the medical records, and enrolled patients were categorised by age and severity for comparison. RESULTS: Among the 5463 patients admitted with a diagnosis of ALRI, 570 (10.4%) were enrolled in this study. The median age of the patients was 8 months (interquartile range, 4-15 months). The most common symptoms were cough (93%) and difficulty in breathing (73%), while the most common signs of ALRI were tachypnoea (78%) and chest indrawing (67%). A total of 16 viruses were detected in 502 of 570 patients' samples (88%), with RSV B (36%) and rhinovirus (28%) being the most commonly detected. Multiple viruses were detected in 221 of 570 samples (37%) collected from 570 patients. Severe ALRI was diagnosed in 107 of 570 patients (19%), and RSV B and human rhinovirus were commonly detected. The mortality rate was 5%; influenza virus A (29%) and RSV B (21%) were commonly detected, and stunting and lack of immunization were frequently observed in such cases. Additionally, 45% (259/570) of the patients had pneumococcal colonization. CONCLUSIONS: Viral ALRI in hospitalised children with a median of 8 months has significant morbidity and mortality rates in Myanmar. RSV and rhinovirus were the most commonly detected from nasopharyngeal swabs, while influenza virus and RSV were the most frequently associated with fatal cases.

Epidemiology and Genetic Analysis of SARS-CoV-2 in Myanmar during the Community Outbreaks in 2020.

We aimed to analyze the situation of the first two epidemic waves in Myanmar using the publicly available daily situation of COVID-19 and whole-genome sequencing data of SARS-CoV-2. From March 23 to December 31, 2020, there were 33,917 confirmed cases and 741 deaths in Myanmar (case fatality rate of 2.18%). The first wave in Myanmar from March to July was linked to overseas travel, and then a second wave started from Rakhine State, a western border state, leading to the second wave spreading countrywide in Myanmar from August to December 2020. The estimated effective reproductive number (Rt) nationwide reached 6-8 at the beginning of each wave and gradually decreased as the epidemic spread to the community. The whole-genome analysis of 10 Myanmar SARS-CoV-2 strains together with 31 previously registered strains showed that the first wave was caused by GISAID clade O or PANGOLIN lineage B.6 and the second wave was changed to clade GH or lineage B.1.36.16 with a close genetic relationship with other South Asian strains. Constant monitoring of epidemiological situations combined with SARS-CoV-2 genome analysis is important for adjusting public health measures to mitigate the community transmissions of COVID-19.

Epidemic of influenza A(H1N1)pdm09 analyzed by full genome sequences and the first case of oseltamivir-resistant strain in Myanmar 2017.

A community outbreak of human influenza A(H1N1)pdm09 virus strains was observed in Myanmar in 2017. We investigated the circulation patterns, antigenicity, and drug resistance of 2017 influenza A(H1N1)pdm09 viruses from Myanmar and characterized the full genome of influenza virus strains in Myanmar from in-patients and out-patients to assess the pathogenicity of the viruses. Nasopharyngeal swabs were collected from out-patients and in-patients with acute respiratory tract infections in Yangon and Pyinmana City in Myanmar during January-December 2017. A total of 215 out-patients and 18 in-patients infected with A(H1N1)pdm09 were detected by virus isolation and real-time RT-PCR. Among the positive patients, 90.6% were less than 14 years old. Hemagglutination inhibition (HI) antibody titers against A(H1N1)pdm09 viruses in Myanmar were similar to the recommended Japanese influenza vaccine strain for 2017-2018 seasons (A/Singapore/GP1908/2015) and WHO recommended 2017 southern hemisphere vaccine component (A/Michigan/45/2015). Phylogenetic analysis of the hemagglutinin sequence showed that the Myanmar strains belonged to the genetic subclade 6B.1, possessing mutations of S162N and S164T at potential antigenic sites. However, the amino acid mutation at position 222, which may enhance the severity of disease and mortality, was not found. One case with no prior history of oseltamivir treatment possessed H275Y mutated virus in neuraminidase (NA), which confers resistance to oseltamivir and peramivir with elevated IC50 values. The full genome sequence of Myanmar strains showed no difference between samples from in-patients and out-patients, suggesting no additional viral mutations associated with patient severity. Several amino acid changes were observed in PB2, PB1, and M2 of Myanmar strains when compared to the vaccine strain and other Asian strains. However, no mutations associated with pathogenicity were found in the Myanmar strains, suggesting that viral factors cannot explain the underlying reasons of the massive outbreak in Myanmar. This study reported the first detection of an oseltamivir-resistant influenza virus in Myanmar, highlighting the importance of continuous antiviral monitoring and genetic characterization of the influenza virus in Myanmar.