BACKGROUND Most poliovirus infections occur with no symptoms and this leads to the possibility of silent circulation, which complicates the confirmation of global goals to permanently end poliovirus transmission. Previous simple models based on hypothetical populations assumed perfect detection of symptomatic cases and suggested the need to observe no paralytic cases from wild polioviruses (WPV...

BACKGROUND Poliovirus rapidly evolves by nucleic acid substitutions and genetic recombination with other polioviruses and non-polio enteroviruses. Evolving oral poliovaccine can rapidly revert to neurovirulence and undergo antigenic alterations. OBJECTIVES To evaluate the threat of vaccine-derived poliovirus (1-15% divergence from the respective Sabin strain) for a poliomyelitis-free populati...

BACKGROUND Sensitive poliovirus surveillance to detect vaccine-derived-polioviruses will continue to increase in importance. OBJECTIVE Isolating and identifying poliovirus strains from children of pediatrics age in Nigeria. METHODS A total of 120 fecal samples were randomly collected from children under the age of five who presented with acute flaccid paralysis. Samples were tested by tissu...

This paper is concerned with the correlation of an in ~tro marker of poliovirus particles, the capacity for multiplication on a monkey stable (MS) cell line, with thc degree of ncurovirulence for monkeys. Vogt a M. (I) discovered that the plaque formation of most attenuated strains of poliovirus is delaycd or inhibited, when the amount of bicarbonate in the agar overlay is reduced. However, a n...

To determine the prevalence of vaccine-associated paralytic poliomyelitis (VAPP) in immunodeficient infants, we reviewed all documented cases caused by immunodeficiency-associated vaccine-derived polioviruses in Iran from 1995 through 2008. Changing to an inactivated polio vaccine vaccination schedule and introduction of screening of neonates for immunodeficiencies could reduce the risk for VAP...

To the Editor: Poliomyelitis outbreaks caused by pathogenic vaccine-derived polioviruses (VDPVs) are primarily a result of low polio vaccine coverage. Low coverage enables interhuman circulation of polioviruses (PVs) from the oral polio vaccine (OPV), and it enables genetic drift of the viruses and their subsequent reversion to neurovirulent phenotypes (1). Polio outbreaks associated with type ...

From 2001 to 2004, Switzerland switched from routine vaccination with oral polio vaccine (OPV) to inactivated polio vaccine (IPV), using both vaccines in the intervening period. Since IPV is less effective at inducing mucosal immunity than OPV, this change might allow imported poliovirus to circulate undetected more easily in an increasingly IPV-immunized population. Environmental monitoring is...

Global measures to eradicate polio began in 1988; as of 2014, four of six World Health Organization (WHO) regions have been certified polio-free. Within the two endemic regions (African and Eastern Mediterranean), Nigeria, Afghanistan, and Pakistan have never interrupted transmission of wild poliovirus (WPV) (1). The primary means of detecting poliovirus transmission is surveillance for acute f...

BACKGROUND & OBJECTIVES Significant progress has been made towards eradication of poliomyelitis in India. Surveillance for acute flaccid paralysis (AFP) has reached high standards. Among the 3 types of polioviruses, type 2 had been eliminated in India and eradicated globally as of October 1999. However, we isolated wild poliovirus type 2 from a small number of polio cases in northern India in 2...