Table 1.

Infectious Causes of AFP: Clinical and Diagnostic Features

Causes	Endemic Regions	Epidemiological and Clinical Features	Diagnostic Aspects	References
Viral
Polio virus
Wild polio virus	Africa, Middle East, Pakistan	Ongoing endemic transmission in Pakistan, Afghanistan, Nigeria, central Africa. No new cases in Horn of Africa since August 2014. Viral culture is gold standard	Viral culture is gold standard but can take 1–3 weeks. Polio PCR on CSF and feces Serology (acute and convalescent titers)	[16]
Vaccine-derived polio virus		Similar epidemiology to wild polio virus
Nonpolio enteroviruses	Worldwide	Clinical syndromes similar to wild polio virus	PCR on CSF, feces, respiratory secretions, blood
Enterovirus D68	North America, Europe	Recent outbreak of “acute flaccid myelitis” in United States and Europe. Most reports in pediatric population.		[3]
Enterovirus 71	Asia, Australia	Outbreaks described in Asia-Pacific region. Recent vaccine trials.		[17]
Arthropod-borne viruses			PCR on CSF and blood Serological testing (virus-specific information below)	[18, 19]
West Nile virus	North America, Europe, Africa	Approximately 5%–10% of patients with neuroinvasive disease develop AFP with case fatality rate of 10%–50%.	Viremia transient, therefore serological diagnosis key. Plaque reduction neutralization assays are done for confirmation of serological testing.	[20]
Kunjin virus	Australia	Substrain of West Nile virus endemic to Australia. Similar clinical presentation.		[21]
Japanese encephalitis	Asia	Mosquito-borne flavivirus. Classically presents with encephalitic illness but case series of AFP described.		[22]
Chikungunya	Africa, Asia, Central and South America	Case reports of AFP described. Recent epidemics in Western Hemisphere. Frequently causes arthralgia.		[23]
Dengue	Africa, Asia, Central and South America	Case reports of AFP described. Recent epidemics in Western Hemisphere. Frequently associated with rash.	NS1 antigen testing on plasma	[24]
Murray Valley encephalitis virus	Australia	Mosquito-borne flavivirus, presentation similar to Japanese encephalitis. AFP presentation described, particularly in children. One-third mortality rate.		[25]
La Crosse virus	North America	Major cause of pediatric encephalitis in United States, particularly in central and eastern United States. Most cases in patients <15 years old.		[6, 26]
Tickborne encephalitis virus	Europe	Tickborne flavivirus, endemic in northern Europe. Usually biphasic illness with initial systemic symptoms followed by neurological symptoms.		[27]
Toscana virus	Europe and Africa	Transmitted by sandflies. Typically found in Mediterranean countries. Coinfection with West Nile described.		[19, 28]
Rabies	Africa, Asia, South Asia	AFP described in rare cases.	PCR testing of skin and saliva Serological testing on CSF and serum	[29]
Cosavirus	Worldwide	Noted in fecal samples of nonpolio AFP cases. Causative role uncertain.	PCR on fecal samples	[30]
Bacterial
Diphtheria	Africa, Central and South America, Asia, Europe	Neurological toxicity from absorption and dissemination of diphtheria toxin	Culture from throat and nose Need confirmation of toxin production	[31]
Lyme disease	North America, Europe	AFP is rare presentation	Serological testing PCR on CSF	[32]
Botulism	Worldwide		Isolation of Clostridium botulinum from wound site Serum assay for botulinum toxin Electromyography	[33]
Rickettsia conorii	Europe, Africa	Cause of Mediterranean spotted fever. Rash very common. Case reports of AFP.	Serological testing	[34]

Abbreviations: AFP, acute flaccid paralysis; CSF, cerebrospinal fluid; PCR, polymerase chain reaction.