Respiratory syncytial virus, human metapneumovirus, and influenza virus infection in Bangkok, 2016-2017

Abstract

Children and adults residing in densely populated urban centers around the world are at risk of seasonal influenza-like illness caused by respiratory viruses such as influenza virus, human metapneumovirus (hMPV), and respiratory syncytial virus (RSV). In a large metropolitan of Thailand’s capital city Bangkok, most respiratory infections are rarely confirmed by molecular diagnostics. We therefore examined the frequency of RSV, hMPV, and influenza virus in 8,842 patients who presented influenza-like illness and sought medical care at a large hospital in Bangkok between 2016 and 2017. Using a multiplex real-time reverse-transcription polymerase chain reaction (RT-PCR), 30.5% (2,699/8,842) of nasopharyngeal (NP) swab samples tested positive for one or more of these viruses. Influenza virus comprised 17.3% (1,528/8,842), of which the majority were influenza A/H3N2. Such infection was most prevalent among adults and the elderly. RSV was identified in 11.4% (1,011/8,842) and were mostly ON1 and BA9 genotypes. Of the hMPV-positive samples (3.6%, 318/8,842), genotypes A2, B1, and B2 were detected. A small number of individuals experienced co-infections (1.8%, 155/8,842), most commonly between RSV and influenza A/H3N2. RSV and hMPV co-infections were also found, but mainly in young children. Viral respiratory tract infection peaked locally in the rainy season (June to September). These findings support the utility of rapid nucleic acid testing of RSV, hMPV, and influenza virus in patients with ILI.

Epidemiology and genetic variability of respiratory syncytial virus in Portugal, 2014–2018

“…The remarkable number of tested samples (8212) during the 2017/18 season could be explained with the consciousness-raising of relevance of RSV disease among physicians. Therefore, from our point of view, the prevalence of this season (14.4%) might be the best representative in the country, being similar to findings from Senegal [33], Thailand [34], Spain [35] and different regions in India [36,37]. Nonetheless, a true comparison of RSV prevalence in different geographic areas is difficult to perform taking into account the differences in the study design and, even in our study, prevalence was wide-ranging according to the season.…”

Impact of COVID-19 public health interventions on influenza incidence in Thailand

“…Linear regression revealed influenza trends significantly differed between 2020 compared to 2019 (ILI, −6.773 vs −4.279 per week; positivity, −2.527 vs 1.099 per week (p < 0.05)). Although the respiratory syncytial virus (RSV), human norovirus (HNoV), and rotavirus A (RVA) infections have shown decreasing trends, these viral infections generally declined during the hot summer months of March through May (Figure 2) [2][3][4]. Conversely, the 2020 data from the Thai Ministry of Public Health for dengue were similar to the previous year and did not show a significant change even though COVID-19 interventions were implemented [5].…”

Respiratory syncytial virus infection trend is associated with meteorological factors

“…Illness associated with RSV infection is estimated to cause approximately 24.8 million episodes and 76,600 deaths annually 1 . Epidemiological studies have shown that infants, young children, and the elderly are especially at risk of RSV infection 2,3,4 . In regions with temperate climate, incidence of RSV infection concentrates during the winter months and may sometimes be absent in summertime 5 .…”

“…In the tropical climate of Thailand, RSV prevalence is historically highest during the rainy season, which is typically between May and November 4,25,26 . Thus far, there has been no studies examining any potential linkage between weather pattern and RSV infection cycle in Thailand.…”