SINGAPORE: Singapore stopped temperature screening in airports from Monday (Feb 23), less than a month after it was introduced as a precautionary measure against the Nipah virus.
The health ministry said that no cases had been reported locally and that the outbreak in India had stabilised. But some netizens are still concerned that this could increase the risk of the deadly virus entering the country.
Nipah virus infection is often severe, and there is currently no commercially available antiviral treatment or vaccine. Well over half of infected individuals develop symptoms of brain and/or lung involvement, and of these, between 10 per cent and 80 per cent will die.
This is likely why some have lingering concerns about the removal of airport screening.
But it’s worth bearing in mind that the World Health Organization assessed, with broad expert concurrence, that the risk of regional or global spread of Nipah virus was low. Airport screening was, in fact, not recommended.
On its own, thermal scanning at ports of entry is not effective in keeping pathogens out.
This is seen in evidence accumulated over two decades. Studies of the COVID-19 pandemic again showed that such screening was unreliable, failing to detect at least half of the passengers with SARS-CoV-2.
But this was a highly contagious, novel virus spreading rapidly across the globe, so it is understandable that temperature screening was attempted despite known limitations.
The considerations are different for a rare pathogen like the Nipah virus. Travellers picked up by temperature screening are likely to have other more common infections, say influenza or COVID-19. They will then be made to undergo intrusive testing and even isolation, since early Nipah infection symptoms are non-specific and indistinguishable from most other common causes of acute fever.
So why does thermal scanning at ports of entry persist? One universal reason is that it gives a public and symbolic signal that health authorities are taking pathogens seriously, to provide reassurance to the community.
But there is a strong case for discontinuing such a practice at least until more targeted, evidence-based screening tools for specific pathogens become available.
So how should non-endemic countries, like Singapore, protect themselves from Nipah virus importation and spread?
Fortunately, the Nipah virus is not very contagious. Even though the India outbreak suggested human-to-human transmission, the two major variants generally do not transmit efficiently between people.
Only around 10 per cent of symptomatic patients will infect another person, usually after prolonged contact – such as household caregivers or healthcare workers, rather than generally in the community – without precautions.
Unlike COVID-19 or measles, there is also no evidence of transmission before symptoms appear. Infected individuals are most infectious in the final stages of illness.
So when it comes to safeguarding public health in this case, the foundation lies in a functional national surveillance system.
Healthcare workers maintain a high index of suspicion for such rare but deadly pathogens circulating globally, supported by laboratories that can rapidly confirm infections through testing. This would enable early diagnosis and subsequent public health interventions such as contact tracing.
Those suspected to be infected are commonly subjected to isolation, movement restrictions and other intrusive measures such as repeated testing. Rapid and reliable testing thus also serves to ensure that such restrictions are proportionate, evidence-based and kept as short as possible.
Next, it is important to have a national agency or government team that is plugged into global surveillance networks and with strong professional ties to international counterparts. Such connections facilitate timely access to outbreak information that might not be in reports.
Finally, countries need healthcare facilities with robust infection prevention and control practices, as well as up-to-date policies to prevent or mitigate pathogen spread in hospitals. This was a bitter lesson Singapore took to heart after the SARS outbreak in 2003.
Pathogens like the Nipah virus cannot be effectively contained by a single sector, because human, animal and environmental health are interdependent.
Virtually all Nipah virus outbreaks have originated from spillover events, that is, animal-to-human transmissions.
The virus was first identified in 1999 by Professor Chua Kaw Bing from the University of Malaya, from an outbreak in which infected pigs transmitted the virus to pig farmers in Negeri Sembilan (in the village of Kampung Sungei Nipah, after which the virus is named) and abattoir workers in Malaysia and Singapore.
But the virus’ natural hosts and reservoirs are the large fruit bats of the Pteropus genus that are widely distributed throughout South and Southeast Asia. Pigs and horses likely become infected when they consume fruit contaminated by the saliva of infected bats.
In Bangladesh, outbreaks are linked to a centuries-old cultural practice of consuming raw date palm sap, which can be contaminated when bats drink from collection jars.
Managing the Nipah virus threat requires a joint approach, what public health professionals call “One Health”. For example, Bangladesh has seen success in community engagement efforts to educate, change sap consumption behaviour and promote the use of physical barriers that keep bats out of sap collection jars.
Field lab assistants catch a bat in their net as they collect specimens for their Nipah virus research in the Shuvarampur area of Faridpur, Bangladesh, Sep 14, 2021. (Photo: Reuters/Mohammad Ponir Hossain)
So the real defence starts overseas, in countries where the virus is endemic.
Early detection and containment of Nipah virus outbreaks requires resource-intensive surveillance systems. So more financial, technical and other support could be provided to countries that bear this upstream burden to prevent cross-border spread.
Countries that detect and transparently report outbreaks under the WHO International Health Regulations should be supported and not just penalised, especially when blunt border measures may not reduce the risk of virus importation.
Singapore is well prepared given our strong surveillance system, robust infection control practices in healthcare facilities, and the recent establishment of the Communicable Diseases Agency and One Health Masterplan.
It can also continue to contribute most meaningfully by building international trust through timely information sharing and offering technical assistance, as well as by participating in research for antiviral treatment and vaccines.
Ultimately, the best way to guard against Nipah virus, or other rare deadly pathogens that capture public imagination such as Ebola virus, is to be part of a collective regional and global health security response.
Professor Hsu Li Yang is Director, Asia Centre for Health Security at the Saw Swee Hock School of Public Health, National University of Singapore.
Continue reading...
The health ministry said that no cases had been reported locally and that the outbreak in India had stabilised. But some netizens are still concerned that this could increase the risk of the deadly virus entering the country.
Nipah virus infection is often severe, and there is currently no commercially available antiviral treatment or vaccine. Well over half of infected individuals develop symptoms of brain and/or lung involvement, and of these, between 10 per cent and 80 per cent will die.
This is likely why some have lingering concerns about the removal of airport screening.
But it’s worth bearing in mind that the World Health Organization assessed, with broad expert concurrence, that the risk of regional or global spread of Nipah virus was low. Airport screening was, in fact, not recommended.
MORE REASSURANCE THAN RELIABILITY
On its own, thermal scanning at ports of entry is not effective in keeping pathogens out.
This is seen in evidence accumulated over two decades. Studies of the COVID-19 pandemic again showed that such screening was unreliable, failing to detect at least half of the passengers with SARS-CoV-2.
But this was a highly contagious, novel virus spreading rapidly across the globe, so it is understandable that temperature screening was attempted despite known limitations.
The considerations are different for a rare pathogen like the Nipah virus. Travellers picked up by temperature screening are likely to have other more common infections, say influenza or COVID-19. They will then be made to undergo intrusive testing and even isolation, since early Nipah infection symptoms are non-specific and indistinguishable from most other common causes of acute fever.
So why does thermal scanning at ports of entry persist? One universal reason is that it gives a public and symbolic signal that health authorities are taking pathogens seriously, to provide reassurance to the community.
Related:
But there is a strong case for discontinuing such a practice at least until more targeted, evidence-based screening tools for specific pathogens become available.
NIPAH VIRUS IS NOT VERY CONTAGIOUS
So how should non-endemic countries, like Singapore, protect themselves from Nipah virus importation and spread?
Fortunately, the Nipah virus is not very contagious. Even though the India outbreak suggested human-to-human transmission, the two major variants generally do not transmit efficiently between people.
Only around 10 per cent of symptomatic patients will infect another person, usually after prolonged contact – such as household caregivers or healthcare workers, rather than generally in the community – without precautions.
Unlike COVID-19 or measles, there is also no evidence of transmission before symptoms appear. Infected individuals are most infectious in the final stages of illness.
HOW SINGAPORE CAN GUARD AGAINST NIPAH VIRUS
So when it comes to safeguarding public health in this case, the foundation lies in a functional national surveillance system.
Healthcare workers maintain a high index of suspicion for such rare but deadly pathogens circulating globally, supported by laboratories that can rapidly confirm infections through testing. This would enable early diagnosis and subsequent public health interventions such as contact tracing.
Those suspected to be infected are commonly subjected to isolation, movement restrictions and other intrusive measures such as repeated testing. Rapid and reliable testing thus also serves to ensure that such restrictions are proportionate, evidence-based and kept as short as possible.
Next, it is important to have a national agency or government team that is plugged into global surveillance networks and with strong professional ties to international counterparts. Such connections facilitate timely access to outbreak information that might not be in reports.
Finally, countries need healthcare facilities with robust infection prevention and control practices, as well as up-to-date policies to prevent or mitigate pathogen spread in hospitals. This was a bitter lesson Singapore took to heart after the SARS outbreak in 2003.
Related:
IMPORTANCE OF “ONE HEALTH”
Pathogens like the Nipah virus cannot be effectively contained by a single sector, because human, animal and environmental health are interdependent.
Virtually all Nipah virus outbreaks have originated from spillover events, that is, animal-to-human transmissions.
The virus was first identified in 1999 by Professor Chua Kaw Bing from the University of Malaya, from an outbreak in which infected pigs transmitted the virus to pig farmers in Negeri Sembilan (in the village of Kampung Sungei Nipah, after which the virus is named) and abattoir workers in Malaysia and Singapore.
But the virus’ natural hosts and reservoirs are the large fruit bats of the Pteropus genus that are widely distributed throughout South and Southeast Asia. Pigs and horses likely become infected when they consume fruit contaminated by the saliva of infected bats.
In Bangladesh, outbreaks are linked to a centuries-old cultural practice of consuming raw date palm sap, which can be contaminated when bats drink from collection jars.
Managing the Nipah virus threat requires a joint approach, what public health professionals call “One Health”. For example, Bangladesh has seen success in community engagement efforts to educate, change sap consumption behaviour and promote the use of physical barriers that keep bats out of sap collection jars.
Field lab assistants catch a bat in their net as they collect specimens for their Nipah virus research in the Shuvarampur area of Faridpur, Bangladesh, Sep 14, 2021. (Photo: Reuters/Mohammad Ponir Hossain)
COLLECTIVE GLOBAL HEALTH SECURITY
So the real defence starts overseas, in countries where the virus is endemic.
Early detection and containment of Nipah virus outbreaks requires resource-intensive surveillance systems. So more financial, technical and other support could be provided to countries that bear this upstream burden to prevent cross-border spread.
Countries that detect and transparently report outbreaks under the WHO International Health Regulations should be supported and not just penalised, especially when blunt border measures may not reduce the risk of virus importation.
Singapore is well prepared given our strong surveillance system, robust infection control practices in healthcare facilities, and the recent establishment of the Communicable Diseases Agency and One Health Masterplan.
It can also continue to contribute most meaningfully by building international trust through timely information sharing and offering technical assistance, as well as by participating in research for antiviral treatment and vaccines.
Ultimately, the best way to guard against Nipah virus, or other rare deadly pathogens that capture public imagination such as Ebola virus, is to be part of a collective regional and global health security response.
Professor Hsu Li Yang is Director, Asia Centre for Health Security at the Saw Swee Hock School of Public Health, National University of Singapore.
Continue reading...