Re: Africa - Congo - 500+ cases, 200 deaths in polio outbreak
http://www.promedmail.org/pls/apex/..._BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1000,87699
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[1] Rep. Congo
Date: 18 Mar 2011
Source: Morbidity & Mortality Weekly Report (MMWR), 18 Mar 2011,
60(10);312-313 [edited]
<http://cdc.gov/mmwr/preview/mmwrhtml/mm6010a4.htm?s_cid=mm6010a4_w>
Notes from the Field: Poliomyelitis Outbreak --- Republic of the
Congo, September 2010--February 2011
--------------------------------
On [4 Nov 2010], a case of wild poliovirus type 1 (WPV1) was
confirmed in a resident of the port city, Pointe Noire, the 1st WPV
case in Republic of the Congo (ROC) in 10 years. The WPV1 isolate from
this resident was genetically most closely related to WPV1 isolated in
Angola in 2010. Subsequent investigation, including active case
finding, revealed increased acute flaccid paralysis (AFP) hospital
admissions beginning in September [2010].
Weekly admissions rose from approximately 10 AFP patients in early
October [2010] to approximately 80 by the end of October and November
[2010]. With response immunization activities, weekly AFP admissions
fell to fewer than 5 by the end of December [2010]. A provisional
total of 554 AFP cases were identified nationally, with paralysis
onset from [20 Sep 2010] to [27 Feb 2011]; 374 (68 percent) of the AFP
cases were among males. Overall, 465 (84 percent) AFP cases were among
residents of the neighboring departments of Kouilou and Pointe Noire,
where the outbreak apparently began and where approximately 21 percent
of ROC's 4.2 million persons reside. The case-fatality rate (CFR) in
Kouilou and Pointe Noire was 40 percent (187 deaths of 465 cases),
compared with 11 percent (10 of 89) elsewhere in ROC. Additionally,
the median age of patients with AFP in Kouilou and Pointe Noire was 20
years (range: 0--63 years), compared with 7.5 years (range: 1--68
years) elsewhere in ROC.
Vaccination status was unknown for all but 149 of the 554 AFP
patients. Among those with known vaccination status, 107 (72 percent)
reported having received at least one oral polio vaccine (OPV) dose,
and 73 of those patients reported receiving at least 3 doses of OPV.
As of [8 Mar 2011], WPV1 had been confirmed virologically in
specimens from 70 AFP patients. Adequate stool specimens were not
available for 468 (84 percent) patients, of whom 190 died;
nonetheless, 32 (46 percent) of the 70 WPV cases were confirmed among
those 468 patients. Because investigation of the outbreak was
compromised by the collection of
adequate specimens from only 16
percent of patients, the clinical classification algorithm of AFP
cases was used. Patients without adequate specimens who died, were
lost to follow-up, or had residual paralysis on follow-up were
considered to have clinically confirmed polio. This algorithm was
applicable when adequate stool specimens were collected for fewer than
65 percent of cases (4) and was last used in countries of the World
Health Organization African Region in 2000. Provisionally, 317
additional patients have been classified as having clinically
confirmed polio. Thus, as of [8 Mar 2011], the total number of
confirmed polio cases was 387, pending further laboratory
investigation, follow-up, and review.
Outbreak control efforts have included 4 rounds of national
supplementary immunization activities (SIAs) targeting the entire
population of ROC, beginning [12-16 Nov 2010] with a round of
monovalent type 1 OPV. Subsequent SIA rounds were conducted [3-7 Dec
2010], using monovalent type 1 OPV; [11-15 Jan 2011], using bivalent
(types 1 and 3) OPV; and [22-26 Feb 2011], using bivalent OPV. The 1st
3 SIA rounds were coordinated with areas of other countries
neighboring Kouilou (Cabinda in Angola and Bas-Congo in Democratic
Republic of the Congo), where outbreak cases subsequently were
reported; the 4th round was synchronized with neighboring Gabon, where
a WPV confirmed case occurred in January [2011].
This outbreak appears nearly controlled, with onset of the most
recent confirmed WPV case on [22 Jan 2011]. Only 14 AFP cases have
been reported provisionally in 2011, approximating the expected
background frequency in ROC. Preliminary results suggest that several
factors contributed to this outbreak 10 years after the last confirmed
WPV1 case in ROC. These include a low rate of childhood polio
vaccination among young adults and a protracted period without WPV1
transmission in the area. Vaccination coverage has been low over the
last 2 decades,* secondary to weaknesses in the delivery of
health-care and routine vaccination services, complicated by civil war
and conflict during 1997--1999. The last national SIA was in 2006.
Other possible contributing factors are crowding of residents and
severe limitations in water supply and sanitation.
The high proportion
of cases among adolescents and adults (who are known to be at higher
risk for bulbar paralysis than children) might have contributed to the
high CFR, which might have been accentuated by suboptimal medical care
and delays in seeking care. CFRs of 12-32 percent have been observed
in previous WPV1 outbreaks involving adults (1--3). An investigation
is ongoing to determine reasons for the elevated CFR in Kouilou and
Pointe Noire.
All international travelers are advised to have completed a primary
series of polio vaccinations before travel (5,6). Travelers from the
United States to countries with recent WPV transmission or countries
neighboring them also should receive a single adult booster
inactivated poliovirus vaccine dose before departure.** Travelers who
are inadequately vaccinated against polio or whose past vaccination
history is uncertain should contact their physician to discuss polio
vaccination options before traveling. The World Health Organization
recommends that all travelers who reside in countries with WPV
transmission not only complete a course of vaccination against polio,
preferably with OPV, before leaving the country of residence, but also
receive an additional dose of OPV within 12 months before each
international trip (6). However, whether many travelers from countries
with WPV transmission follow these recommendations, except when
required (e.g., pilgrimage to Mecca), is uncertain (7).
Reported by:
Ministry of Health, Republic of the Congo; World Health Organization
Republic of the Congo Country Office, World Health Organization
Regional Office for Africa, Brazzaville; Republic of the Congo. Dept
of Polio Eradication, World Health Organization, Geneva, Switzerland.
Div of Viral Diseases and Global Immunization Div, National Center for
Immunization and Respiratory Diseases, CDC.
