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. 2012 Nov 15;55(10):1291-8.
doi: 10.1093/cid/cis714. Epub 2012 Aug 21.

An outbreak of wild poliovirus in the Republic of Congo, 2010-2011

Minal K Patel  1 , Mandy Kader Konde, Boris Hermann Didi-Ngossaki, Edouard Ndinga, Riziki Yogolelo, Mbaye Salla, Keith Shaba, Johannes Everts, Gregory L Armstrong, Danni Daniels, Cara Burns, Steve Wassilak, Mark Pallansch, Katrina Kretsinger
Affiliations

An outbreak of wild poliovirus in the Republic of Congo, 2010-2011

Minal K Patel et al. Clin Infect Dis. .

Abstract

Background: The Republic of Congo has had no cases of wild poliovirus type 1 (WPV1) since 2000. In October 2010, a neurologist noted an abnormal number of cases of acute flaccid paralysis (AFP) among adults, which were later confirmed to be caused by WPV1.

Methods: Those presenting with AFP underwent clinical history, physical examination, and clinical specimen collection to determine if they had polio. AFP cases were classified as laboratory-confirmed, clinical, or nonpolio AFP. Epidemiologic features of the outbreak were analyzed.

Results: From 19 September 2010 to 22 January 2011, 445 cases of WPV1 were reported in the Republic of Congo; 390 cases were from Pointe Noire. Overall, 331 cases were among adults; 378 cases were clinically confirmed, and 64 cases were laboratory confirmed. The case-fatality ratio (CFR) was 43%. Epidemiologic characteristics differed among polio cases reported in Pointe Noire and cases reported in the rest of the Republic of Congo, including age distribution and CFR. The outbreak stopped after multiple vaccination rounds with oral poliovirus vaccine, which targeted the entire population.

Conclusions: This outbreak underscores the need to maintain high vaccination coverage to prevent outbreaks, the need to maintain timely high-quality surveillance to rapidly identify and respond to any potential cases before an outbreak escalates, and the need to perform ongoing risk assessments of immunity gaps in polio-free countries.

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Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts.

All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Figures

Figure 1
Figure 1
Laboratory-confirmed and clinical poliomyelitis cases from the 2010–2011 outbreak and coverage with 3 doses of trivalent oral polio vaccine (tOPV3) by birth year, Republic of Congo. Data sources: tOPV3 administrative coverage is from the World Health Organization Joint Reporting Form [5]; coverage survey data is from the 2005 Demographic and Health Survey [20] and 2009 Expanded Program on Immunization Coverage Survey [6]. Abbreviations: OPV, oral polio vaccine; SIAs, supplementary immunization activities.
Figure 2
Figure 2
Classification of acute flaccid paralysis (AFP) cases by the National Poliomyelitis Expert Committee (NPEC) plotted by week of onset (n = 611). Arrows indicate start of an oral polio vaccine campaign. aNon-polio AFP case: patients with AFP with inadequate clinical specimens and who did not have symptoms consistent with poliomyelitis as determined by the NPEC. bClinical case: patients with AFP with inadequate clinical specimens with a strong likelihood of having poliomyelitis (ie, based on clinical presentation and residual paralysis at least 60 days after onset), as determined by the NPEC. This includes all clinically confirmed as well as clinically compatible cases. cLaboratory-confirmed WPV1 case: WPV1 isolated from clinical specimen.
Figure 3
Figure 3
Clinical status of acute flaccid paralysis cases, including paralysis on 60-day follow-up, loss to follow-up, and death, Republic of Congo, 1 January 2010–8 May 2011. Abbreviations: AFP, acute flaccid paralysis; ROC, Republic of Congo.
Figure 4
Figure 4
Laboratory-confirmed and clinical poliomyelitis cases by district of residence, Republic of Congo. Dots are placed randomly within a district and are not representative of the exact village of a given poliomyelitis case.
Figure 5
Figure 5
Case-fatality ratio (CFR) among persons with poliomyelitis reported in Pointe Noire and in the rest of the Republic of Congo, stratified by age group, September 2010–January 2011. P values provided compare CFR by geographic location within each age group. aCFR χ2 P = .02. bCFR 2-tailed Fisher exact P = .07. cCFR χ2 P = .51. dCFR 2-tailed Fisher exact P = .60. Abbreviations: CFR, case-fatality ratio; ROC, Republic of Congo.
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