Abstract
Background
Nipah virus (NiV) infection causes encephalitis and has > 75% mortality rate, making it a WHO priority pathogen due to its pandemic potential. There have been NiV outbreak(s) in ...Malaysia, India, Bangladesh, and southern Philippines. NiV naturally circulates among fruit bats of the genus
Pteropus
and has been detected widely across Southeast and South Asia. Both Malaysian and Bangladeshi NiV strains have been found in fruit bats in Thailand. This study summarizes 20 years of pre-emptive One Health surveillance of NiV in Thailand, including triangulated surveillance of bats, and humans and pigs in the vicinity of roosts inhabited by NiV-infected bats.
Methods
Samples were collected periodically and tested for NiV from bats, pigs and healthy human volunteers from Wat Luang village, Chonburi province, home to the biggest
P. lylei
roosts in Thailand, and other provinces since 2001. Archived cerebrospinal fluid specimens from encephalitis patients between 2001 and 2012 were also tested for NiV. NiV RNA was detected using nested reverse transcription polymerase chain reaction (RT-PCR). NiV antibodies were detected using enzyme-linked immunosorbent assay or multiplex microsphere immunoassay.
Results
NiV RNA (mainly Bangladesh strain) was detected every year in fruit bats by RT-PCR from 2002 to 2020. The whole genome sequence of NiV directly sequenced from bat urine in 2017 shared 99.17% identity to NiV from a Bangladeshi patient in 2004. No NiV-specific IgG antibodies or RNA have been found in healthy volunteers, encephalitis patients, or pigs to date. During the sample collection trips, 100 community members were trained on how to live safely with bats.
Conclusions
High identity shared between the NiV genome from Thai bats and the Bangladeshi patient highlights the outbreak potential of NiV in Thailand. Results from NiV cross-sectoral surveillance were conveyed to national authorities and villagers which led to preventive control measures, increased surveillance of pigs and humans in vicinity of known NiV-infected roosts, and increased vigilance and reduced risk behaviors at the community level. This proactive One Health approach to NiV surveillance is a success story; that increased collaboration between the human, animal, and wildlife sectors is imperative to staying ahead of a zoonotic disease outbreak.
Live-bird markets have been implicated in transmission of avian influenza
viruses, most recently of influenza A (H7N9) in China. Low pathogenic avian
influenza (LPAI) viruses, such as H7N9, cause ...asymptomatic infections in poultry,
and active surveillance is required to detect infection and to prevent transmission
to humans. Although limited numbers of live birds for consumption are sold in
Bangkok live bird markets (LBM), transmission of H7N9 in nearby China has
prompted a program of active surveillance for avian influenza in Bangkok LBM to
determine LPAI viruses. In November 2013, Bangkok One Health team organized
avian influenza surveillance in all nine districts of Bangkok with LBMs. Oropharyngeal
swabs (n = 834), sera (n = 375) and fresh feces (n = 420) were taken from
400 chickens, 20 ducks, 20 geese and 394 pet birds from 75/87 shops. Additionally,
drinking water (n = 208) and waste water (n = 26) were collected. Samples were
tested for influenza A viruses using RT-PCR. In addition, samples were inoculated
in eggs and tested by hemagglutination (HA) and hemagglutination inhibition
(HI) assays using H5N1- and H7N9-specific antigens. Sera were tested by HI assay
using similar antigens. No sample was found positive for influenza A virus.
These data provide evidence that avian influenza viruses, including LPAI viruses
such as H7N9, were not circulating in Bangkok LBMs during the period surveyed.
Highly pathogenic avian influenza (HPAI) virus subtype H5N1 was first reported in Myanmar in 2006. In this study, we have characterized 6 HPAI (H5N1) viruses recovered from 2007-2010 as well as three ...additional available nucleotide sequences representing Myanmar AI outbreaks. Phylogenetic analysis showed that the Myanmar viruses belong to HPAI (H5N1) clades 7, 2.3.2 and 2.3.4. The result suggested that the HPAI (H5N1) viruses recovered from Myanmar had been introduced into the country by multiple introductions. Genetic analysis of the viruses confirmed the HPAI characteristics of the viruses.
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