An Outbreak of Wild Poliovirus in the Republic of Congo, 2010-2011

Patel, Minal; Kondé, Mandy Kader; Didi-Ngossaki, Boris Hermann; Ndinga, Edouard; Yogolelo, Riziki; Salla, Mbaye; Shaba, Keith; Everts, Johannes; Armstrong, Gregory L.; Daniels, Danni; Burns, Cara C.; Wassilak, Steve; Pallansch, Mark A.; Kretsinger, Katrina

doi:10.1093/cid/cis714

Cited by 35 publications

(31 citation statements)

References 8 publications

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“…2 A and B) following introduction of virus from Angola (3,15), as this lower income country, with a poorer level of sanitation, is likely to have had a different transmission pattern.…”

Section: Significancementioning

confidence: 99%

The role of older children and adults in wild poliovirus transmission

Blake

Martin

Goel

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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As polio eradication inches closer, the absence of poliovirus circulation in most of the world and imperfect vaccination coverage are resulting in immunity gaps and polio outbreaks affecting adults. Furthermore, imperfect, waning intestinal immunity among older children and adults permits reinfection and poliovirus shedding, prompting calls to extend the age range of vaccination campaigns even in the absence of cases in these age groups. The success of such a strategy depends on the contribution to poliovirus transmission by older ages, which has not previously been estimated. We fit a mathematical model of poliovirus transmission to time series data from two large outbreaks that affected adults (Tajikistan 2010, Republic of Congo 2010) using maximum-likelihood estimation based on iterated particle-filtering methods. In Tajikistan, the contribution of unvaccinated older children and adults to transmission was minimal despite a significant number of cases in these age groups [reproduction number, R = 0.46 (95% confidence interval, 0.42-0.52) for >5-y-olds compared to 2.18 (2.06-2.45) for 0-to 5-y-olds]. In contrast, in the Republic of Congo, the contribution of older children and adults was significant [R = 1.85 (1.83-4.00)], perhaps reflecting sanitary and socioeconomic variables favoring efficient virus transmission. In neither setting was there evidence for a significant role of imperfect intestinal immunity in the transmission of poliovirus. Bringing the immunization response to the Tajikistan outbreak forward by 2 wk would have prevented an additional 130 cases (21%), highlighting the importance of early outbreak detection and response.epidemiology | infectious diseases | mathematical modeling T he Global Polio Eradication Initiative (GPEI) has achieved >99% reduction in the global annual incidence of poliomyelitis since the program began in 1988, and in 2012, just three countries were yet to interrupt wild poliovirus transmissionAfghanistan, Pakistan, and Nigeria-and 223 poliomyelitis cases were reported, the lowest in history (1). However, the absence of wild poliovirus transmission from most of the world, together with long-standing suboptimal vaccination coverage, has created cohorts of susceptible children and adults. As a result, an increased number of polio outbreaks affecting older children and adults have occurred in countries previously free of wild poliovirus (2-6). These outbreaks have significantly raised the cost of the GPEI and are a major challenge to achieving the goal of stopping all transmission by end-2014.It has also become clear that intestinal immunity to poliovirus wanes over time, allowing individuals vaccinated with oral poliovirus vaccine (OPV) to become reinfected and shed poliovirus (7). Therefore, older children and adults could theoretically contribute to wild poliovirus transmission without developing poliomyelitis. The World Health Organization (WHO) has recommended vaccination of older age groups as a standard for outbreak response (8). In addition, the recent GPEI strategic...

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“…2 A and B) following introduction of virus from Angola (3,15), as this lower income country, with a poorer level of sanitation, is likely to have had a different transmission pattern.…”

Section: Significancementioning

confidence: 99%

The role of older children and adults in wild poliovirus transmission

Blake

Martin

Goel

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…However, highly consistent antibody titers against all three PV types and reports of at least partial vaccination coverage in Pointe Noire (5, 8) make prior immunization with tOPV the most likely explanation for the antibody titers observed in fatal cases. This does not exclude inefficient immune protection as the necessary and most likely cause of the outbreak (5,9,28). However, it is intriguing that the ROC outbreak was associated with a much higher CFR than similar outbreaks in regions where WPV circulation had been interrupted and a pronounced incidence in adult patients occurred due to vaccination gaps, such as in Albania in 1996 (29), Namibia in 2000 (5) or Tajikistan in 2010 (6).…”

Section: Discussionmentioning

confidence: 99%

“…Sustained vaccination regimens in polio-free regions, together with clinical and environmental poliovirus surveillance will be necessary to combat antigenetically variant polioviruses in the poliomyelitis eradication endgame. than three documented tOPV doses, and 15 (54%) had at least one dose (5). These data seem to be in conflict with current knowledge on the efficacy of OPV, as even low levels of vaccine-derived immunity should confer protection against paralytic disease (14,15).…”

Section: Significancementioning

confidence: 97%

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Robustness against serum neutralization of a poliovirus type 1 from a lethal epidemic of poliomyelitis in the Republic of Congo in 2010

Drexler

Grard

Lukashev

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Significance In 2010, a large outbreak of poliomyelitis involving 445 laboratory-confirmed cases occurred in the Republic of Congo. The 47% case-fatality rate was unusually high. Outbreak severity was attributed to low immunization coverage but vaccine-mediated immunity against the outbreak virus was never investigated. We isolated the poliovirus type 1 responsible for the outbreak and located its evolutionary origins to Southeast Asia. Fatal cases showed evidence for previous vaccination against polioviruses and the outbreak virus was refractive against neutralization by monoclonal and vaccine-derived antibodies. This pointed to immune escape contributing to the severity of the outbreak. Sustained vaccination regimens in polio-free regions, together with clinical and environmental poliovirus surveillance will be necessary to combat antigenetically variant polioviruses in the poliomyelitis eradication endgame.

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“…For this generation of physicians, it is worth pointing out that in several recent outbreaks of WPV, a majority of cases have been in adults, in whom paralysis is known to be more widespread and severe and the case-fatality rate higher than in young children. 7,8 This observation is not new and it was noted at the advent of poliovirus vaccination that paralytic poliomyelitis had been increasing in incidence in older children and adults for 25 years. 9 Although the increases in adults during recent outbreaks could be due to gaps in poliovirus immunization, the chronological increase in age of paralytic poliomyelitis remains enigmatic since this was occurring prior to poliovirus vaccination.…”

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confidence: 99%