Nonpolio

Nonpolio is a term used in public health to denote conditions, pathogens, or events not caused by poliovirus in the context of polio eradication and surveillance. It is commonly encountered in two related uses: nonpolio enteroviruses (NPEV) and nonpolio acute flaccid paralysis (NPAFP). Both reflect the broader spectrum of enterovirus infections and polio-like illnesses that can occur alongside poliovirus surveillance.

Nonpolio enteroviruses refer to enteroviruses other than poliovirus. The genus Enterovirus (family Picornaviridae) includes Coxsackie A and B viruses, echoviruses, and many other enteroviruses such as EV-D68. They can cause a wide range of illnesses, from mild respiratory or gastrointestinal symptoms to aseptic meningitis, encephalitis, and, rarely, acute flaccid paralysis. They are commonly detected in stool, throat swabs, or other clinical specimens using RT-PCR and viral culture. Surveillance of NPEV helps contextualize enterovirus activity and can influence interpretation of AFP surveillance.

Nonpolio acute flaccid paralysis refers to cases of AFP in which poliovirus is not detected in stool or throat specimens. AFP surveillance, a core component of polio eradication programs, analyzes NPAFP to monitor poliovirus circulation and to identify other etiologies of AFP. The identification of NPAFP cases aids in differentiating poliomyelitis from nonpolio AFP and guides public health responses, vaccination strategies, and laboratory testing priorities.