Global disease surveillance is built to spot known threats. Tests are designed around familiar pathogens, case definitions follow past outbreaks, and warning systems often activate only when something looks recognisable.
That approach leaves a growing blind spot: infections that imitate known diseases but are caused by something else entirely.
Public health experts have warned for years that this diagnostic gap could allow new zoonotic viruses to circulate undetected.
A recent study adds weight to that concern, showing how easily human infections can slip past surveillance when they fall outside standard testing frameworks.
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When tests look the wrong way
Researchers from Columbia University’s Mailman School of Public Health revisited patient samples collected through a Nipah virus surveillance program.
These were cases where symptoms strongly suggested Nipah, yet lab tests came back negative.
Using advanced sequencing tools that scan broadly for viral genetic material, scientists identified Pteropine orthoreovirus (PRV), a bat-borne virus rarely tested for in routine clinical settings.
In several patients, live virus was confirmed, indicating active infection rather than incidental exposure.
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The findings point to a structural issue in outbreak detection: surveillance programs may be too narrowly focused to detect unfamiliar spillover events.
Why Bangladesh matters
The cases were identified in Bangladesh, where human contact with bats is relatively common due to agricultural and food practices.
All patients had consumed raw date palm sap, a known interface between bats and humans.
While the setting is local, the implications are global. Similar gaps could exist anywhere surveillance is centered on a short list of expected pathogens.
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A wider spillover problem
PRV joins a list of animal-origin viruses that initially caused human illness without immediate recognition, much like early cases of SARS or MERS.
Researchers say expanding diagnostic scope, not just geographic coverage, may be key to preventing the next global health crisis.
Kilde: ScienceDaily and CDC
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