Potential for international spread of wild poliovirus via travelers

Abstract

BackgroundThe endgame of polio eradication is hampered by the international spread of poliovirus via travelers. In response to ongoing importations of poliovirus into polio-free countries, on 5 May 2014, WHO’s Director-General declared the international spread of wild poliovirus a public health emergency of international concern. Our objective was to develop a mathematical model to estimate the international spread of polio infections.MethodsOur model took into account polio endemicity in polio-infected countries, population size, polio immunization coverage rates, infectious period, the asymptomatic-to-symptomatic ratio, and also the probability of a traveler being infectious at the time of travel. We applied our model to three scenarios: (1) number of exportations of both symptomatic and asymptomatic polio infections out of currently polio-infected countries, (2) the risk of spread of poliovirus to Saudi Arabia via Hajj pilgrims, and (3) the importation risk of poliovirus into India.ResultsOur model estimated 665 polio exportations (>99 % of which were asymptomatic) from nine polio-infected countries in 2014, of which 78.3 % originated from Pakistan. Our model also estimated 21 importations of poliovirus into Saudi Arabia via Hajj pilgrims and 20 poliovirus infections imported to India in the same year.ConclusionThe extent of importations of asymptomatic and symptomatic polio infections is substantial. For countries that are vulnerable to polio outbreaks due to poor national polio immunization coverage rates, our newly developed model may help guide policy-makers to decide whether imposing an entry requirement in terms of proof of vaccination against polio would be justified.

Expected immunizations and health protection for Hajj and Umrah 2018 —An overview

“…There are reports of Hajj associated poliomyelitis cases. In a mathematical model, it was estimated that there is a potential of 21 importations of poliovirus into Saudi Arabia via Hajj pilgrims [27]. Table 1.…”

Polio Immunization Social Norms in Kano State, Nigeria: Implications for Designing Polio Immunization Information and Communication Programs for Routine Immunization Services

“…Polio reimportation has the potential to erode the gains of the GPEI. In response to ongoing importations of poliovirus into polio-free countries, on May 5, 2014, the Director-General of the WHO declared the international spread of wild poliovirus a public health emergency of international concern (O' Reilly, 2011;Wilder-Smith, 2015).…”

Vaccination in Hajj: An overview of the recent findings

“…[47] Therefore, to participate in the Hajj rituals, polio vaccination against poliomyelitis is also recommended. [48]…”