Investigation of elevated case-fatality rate in poliomyelitis outbreak in Pointe Noire, Republic of Congo, 2010.

BACKGROUND: Multiple cases of paralysis, often resulting in death, occurred among young adults during a wild poliovirus (WPV) type 1 outbreak in Pointe Noire, Republic of Congo, in 2010. We conducted an investigation to identify factors associated with fatal outcomes among persons with poliomyelitis in Pointe Noire. METHODS: Polio cases were defined as acute flaccid paralysis (AFP) cases reported from 7 October to 7 December 2010 with either a stool specimen positive for WPV or clinically classified as polio-compatible. Data were obtained from medical records, hospital databases, AFP case investigation forms and, when possible, via interviews with persons with polio or surrogates using a standard questionnaire. RESULTS: A total of 369 polio cases occurred in Pointe Noire between 7 October and 7 December 2010. Median age was 22 years for nonsurvivors and 18 years for survivors (P = .01). Small home size, as defined by ≤2 rooms, use of a well for drinking water during a water shortage, and age ≥15 years were risk factors for death in multivariate analysis. CONCLUSIONS: Consideration should be given during polio risk assessment planning and outbreak response to water/sanitation status and potential susceptibility to polio in older children and adults. Serosurveys to estimate immunity gaps in older age groups in countries at high risk of polio importation might be useful to guide preparedness and response planning.

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

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.