Scientists are demanding an international response to the "growing threat" posed by non-polio enteroviruses.
These "dangerous" viruses, which are closely related to polio, can cause "lasting paralysis" and have no cure, they warn.
High vaccination rates and global health surveillance programmes have virtually eradicated polio, yet the world is lacking the same measures to trace and control non-polio enteroviruses, scientists warn.
This complacency is unacceptable, they say. Like polio, these viruses can lead to acute flaccid paralysis (AFP) - an uncommon but serious neurological condition that affects the nervous system, specifically the area of the spinal cord called gray matter, which causes the muscles and reflexes in the body to become weak.
Acute flaccid paralysis (AFP) can cause the face to droop, arm and leg weakness
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The threat is also insidious. Non-polio enteroviruses, such as EV-D68, are thought to be very common, with most infections causing no symptoms or only mild symptoms initially, warns the Centers for Disease Control and Prevention (CDC).
Sleepwalking into disaster
Concerned about the lack of valid data on the burden of non-polio enteroviruses, Professor Thea Kølsen Fischer of the University of Copenhagen and her colleagues across Europe set up a network to understand the burden of enteroviruses causing severe disease including polio-like paralysis.
The ENPEN network have been investigating the circulation of paralytic enteroviruses in Europe including enterovirus D68 and enterovirus A71, and documented the circulation of these “poliovirus cousins” in all countries where they have looked.
Their investigations suggest genetic changes in the EVD68 virus is likely one of the explanations to the increased virulence and increased presence of this virus during the past decade.
In a recent study from the UK using biobanked blood samples from two decades, Dr Heli Harvala (University College London, UK) who is also a cofounder of the ENPEN network, documented how the seroprevalence of D68 is increasing over time in all age groups.
“Patients can enter hospital with severe respiratory symptoms, but a week after the respiratory symptoms have passed then sudden onset of paralysis can be seen and enterovirus D68 can end up as much more than just a cold,” explained Prof Fischer, although early in its progression the symptoms can be similar.
"Sadly in significant numbers of cases, these infections are progressing to serious complications including lasting paralysis. Yet we have this huge asymmetry in global health programmes, polio having strong surveillance and vaccination programmes. Yet non-polio enteroviruses have neither. Because we don’t have well developed surveillance in place, we can’t say for sure what proportion of these enterovirus infections are leading to serious complications.”
Within the poliovirus surveillance programmes, the clinical cases with central nervous system symptoms and the AFP cases can see non-polio enteroviruses detected, but analysis is usually incomplete and merely as a by-product as the enterovirus positive samples are usually not further tested into subtypes.
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The professor is calling for new surveillance systems and preventative vaccines
PA“When a child suffers from paralysis, to them and their family it doesn’t matter whether it’s actual polio or another enterovirus that has caused it. We need to get proper surveillance systems in place and work on vaccines for these dangerous non-polio enteroviruses.”
She concluded: “Polio is still a concern in 2024, even in the USA and Europe, and until fully eradicated, it always will be. We must never take our eyes off it and assume it has been dealt with forever. Yet, there is this growing threat of non-polio enteroviruses of which the public and health authorities seem so much less aware. Effective vaccines can be used to eradicate polio. Yet there is no cure, and no vaccines against the paralytic non-polio enteroviruses."
The professor is calling for new surveillance systems to be set up so that all patients who experience acute flaccid paralysis are routinely tested for these enteroviruses.
Only then "can we identify the scale of the threat", she says, adding that it can pave the way for preventive interventions like vaccines.