What is the clinical evidence from this study?

Study design: Observational. Population: Nonpolio acute flaccid paralysis (NP-AFP) (n=3566). Intervention: Nonpolio enterovirus (NPEV) infection vs. Healthy children without acute flaccid paralysis. Primary outcome: NPEV positivity in cell culture.

October 31, 2012Open Access

Antigenic Diversity of Enteroviruses Associated with Nonpolio Acute Flaccid Paralysis, India, 2007–2009

Key Result

Nonpolio enteroviruses were detected in 29.5% of children with nonpolio acute flaccid paralysis compared to 2.6% of healthy controls, with 66 distinct serotypes identified, most frequently EV71.

Study Design

Type

Observational (n=3,566)

Multicenter

Yes

Structured PICO

Population

2,786 children under 15 years of age with nonpolio acute flaccid paralysis and 780 healthy controls from three states in India, evaluated for enterovirus serotypes between 2007 and 2009.

Comparator

780 apparently healthy children 3 months to 3 years of age who did not receive vaccine and did not have diarrhea or any other illnesses during the 2 weeks before sample collection.

Outcome

Spectrum and frequency of nonpolio enterovirus (NPEV) serotypes associated with NP-AFP.

A highly diverse spectrum of 66 nonpolio enterovirus serotypes, predominantly enterovirus 71, is associated with nonpolio acute flaccid paralysis in India, highlighting the need for continued surveillance post-polio eradication.

Main Result

Absolute Event Rate: 29.5% vs 2.6%

Limitations

No virus was isolated in approximately 70% of the acute flaccid paralysis cases, leaving the causative agents unidentified.
The genetic nature of the viral agents in approximately 35% of cases that were positive for virus in RD cells remains to be determined.
The association of a wide spectrum of serotypes with NP-AFP poses a challenging problem toward the development of effective anti-enteroviral strategies.

Abstract

Because of the broadened acute flacid paralysis (AFP) definition and enhanced surveillance, many nonpolio AFP (NP-AFP) cases have been reported in India since 2005. To determine the spectrum of nonpolio enterovirus (NPEV) serotypes associated with NP-AFP from polio-endemic and -free regions, we studied antigenic diversity of AFP-associated NPEVs. Of fecal specimens from 2,786 children with NP-AFP in 1 polio-endemic and 2 polio-free states, 823 (29.5%) were positive for NPEVs in RD cells, of which 532 (64.6%) were positive by viral protein 1 reverse transcription PCR. We identified 66 serotypes among 581 isolates, with enterovirus 71 most frequently (8.43%) detected, followed by enterovirus 13 (7.1%) and coxsackievirus B5 (5.0%). Most strains within a serotype represented new genogropups or subgenogroups. Agents for ≈35.0% and 70.0% of culture-positive and -negative cases, respectively, need to be identified. Association of human enterovirus with NP-AFP requires better assessment and understanding of health risks of NPEV infections after polio elimination.

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