Airborne killer: the virus behind the next pandemic
The next worldwide outbreak will most likely to be a virus that can spread through the air, say researchers
They may not yet know its name but the next pathogen to cause a deadly global pandemic is most likely to be a respiratory disease, spread by a virus that is contagious during incubation or when symptoms are only mild, according to researchers at the Johns Hopkins Centre for Health Security.
They developed the outline as part of a framework to help scientists and policy makers prepare for the next emerging, catastrophic threat.
Their report, The Characteristics of Pandemic Pathogens, concludes that the culprit is less likely to be one of the headline-grabbing diseases that currently cause frightening outbreaks, such as Ebola, which is carried in bodily fluids, or Zika, which is spread by mosquitoes.Instead Disease X, as it has been dubbed by the World Health Organisation, is most likely to be a virus that can spread through the air.As a result, more needs to be done to monitor the human infections from respiratory-borne viruses, particularly those caused by fast-evolving RNA viruses, which hold their genetic material in RNA rather than DNA.
The authors, led by Dr Amesh Adalja, a senior scholar at the centre, said current work to identify a micro-organism with a global catastrophic biological risk (GCBR) was based on recent outbreaks, historical precedent and biological warfare agents.
However, this failed to account for the likelihood that the next global disaster could be caused by a pathogen that had never previously caused an outbreak.
“Health security preparedness needs to be adaptable to new threats and not exclusively wedded to historical notions,” Adalja said.
“A more active-minded approach to this problem will, in the end, help guard against a GCBR event occurring.”
Enormity of the danger
Epidemiologists and healthcare professionals believe it is a case of when, not if, the world is hit by a global epidemic of a deadly infectious disease, killing millions of people.
The next big disease outbreak could be triggered by a mutated strain of a known virus or by the release of a biological weapon and examples such as the 1918 Spanish Flu pandemic, which killed up to 100 million people, show the enormity of the danger.
The challenge for policy makers is to identify what the next occurrence might look like. But rather than assuming that future disasters will look the same as previous ones, the authors went back to the drawing board, reviewing the literature and interviewing 120 experts to identify the features that would identify a micro-organism as a potential threat.Viruses emerged as the leading candidates because of their high mutation rates along with a lack of broad-based antiviral drugs – unlike bacteria, which are susceptible to antimicrobials, or fungi, few of which can infect warm-blooded hosts.
In particular they identified RNA viruses as a threat because of their genetic mutability, allowing them to evolve rapidly and stay one step ahead of vaccines and the host immune system.
“There is a strong consensus that RNA viruses represent a higher pandemic threat than DNA viruses,” the researchers wrote.
The mode of transmission for such a disease, they concluded, would most likely be respiratory, a considerably more difficult route to interrupt than those that are transmitted in blood, for example. It is also likely to be contagious during the incubation period, before symptoms emerge or when the effects are mild and before medical help is needed.
In addition, the absence of a widely available treatment of vaccine and a susceptible population would all help it gain traction.Of particular concern are certain classes of RNA virus, including coronaviruses. These are responsible for a significant proportion of cases of the common cold. They are also the cause of severe acute respiratory syndrome (Sars), which killed more than 700 people around the world during an outbreak in 2002, and Middle East respiratory syndrome (Mers), which has a fatality rate of almost a third since being identified in 2012.
To guard against the threat, more needs to be done to improve the surveillance of respiratory-borne RNA viruses.
Vaccines against these viruses, including a universal influenza vaccine, should be pursued with increased priority.
Adalja added: “We hope policy makers and practitioners consider our recommendations in their work to strengthen health-sector resilience and fortify pandemic preparedness.”
– © The Daily Telegraph
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