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Outbreaks Following Wild Poliovirus Importations --- Europe, Africa, and Asia, January 2009--September 2010

MMWR Weekly
November 5, 2010 / 59(43); 1393-1399
(Full text available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5943a1.htm?s_cid=mm5943a1_e)

The Global Polio Eradication Initiative (GPEI) began in 1988. By 2006, indigenous transmission of wild poliovirus (WPV) had been interrupted in all but four countries ( Afghanistan, India, Nigeria, and Pakistan) (1). However, outbreaks following WPV importations into previously polio-free countries remain an ongoing risk until polio is eradicated (1--3). The GPEI Strategic Plan for 2010--2012 (4) set the following two goals for outbreak control: 1) end outbreaks occurring in 2009 by mid-2010 and 2) end outbreaks occurring during 2010 to mid-2012 within 6 months of confirmation. This report describes new outbreaks that have occurred in the World Health Organization (WHO) European Region and updates previous reports on the status of outbreaks in Africa and Asia (3). In 2010, the first WPV importation into the European Region since the region was declared polio-free in 2002 resulted in 476 confirmed cases: 458 in Tajikistan, 14 in Russia, three in Turkmenistan, and one in Kazakhstan. In Africa and Asia, 11 new importations into six countries were observed in 2010; 30 WPV importations that occurred during 2008--2009 resulted in 215 cases in 15 African countries during 2009--2010. An outbreak is considered interrupted if 6 months have elapsed since the latest confirmed case and surveillance performance indicators meet WHO standards. All 2009 outbreaks in Africa appear to have been interrupted, and 2010 outbreaks in three countries appear to have been interrupted. Maintaining high routine vaccination coverage and sensitive surveillance at all times and rapidly instituting additional immunization programs to control outbreaks are key to limiting and stopping the spread of WPV.

European Region Importations, 2010

On April 13, 2010, Tajikistan notified WHO of a sharp increase in reported acute flaccid paralysis (AFP) cases. On April 20, the designated WHO regional reference laboratory in Moscow, Russia, identified WPV type 1 (WPV1) in stool specimens from persons with AFP cases; the WPV1 was genetically most closely related to WPV1 isolated in Uttar Pradesh, India, in August 2009. As of November 1, 2010, Tajikistan had reported 458 laboratory-confirmed WPV1 cases from 35 of 61 administrative territories, with paralysis onset dates occurring February 1--July 4 (Figure 1). Ninety (20%) patients were aged <1 year, 208 (45%) were aged 1--4 years, 107 (23%) were aged 5--14 years, and 53 (12%) were aged ≥15 years. Early in the outbreak, the majority of cases were in children aged <5 years; after week 20, 78% of cases were in persons aged ≥5 years (Figure 1). Twenty-six (5.7%) patients died; 15 were aged <5 years, eight were aged 5--14 years, and three were aged ≥15 years.

The outbreak spread to three other polio-free countries, where 18 cases were confirmed, bringing to 476 the total number of cases in the European Region (Figure 2). Russia reported 14 cases following at least five independent importations, with onsets during May 4--September 25 (confirmed May 31). Turkmenistan reported three cases in June (confirmed June 27), and Kazakhstan reported one case in August (confirmed October 5) (Table 1). Nine of these 18 patients were aged <5 years.

Efforts to control the outbreak in Tajikistan began May 4 with the first of four rounds of national supplementary immunization activities (SIAs), 2 weeks apart, using monovalent type 1 oral poliovirus vaccine (mOPV1) (Table 2). The first two SIAs targeted children aged <6 years, and the third and fourth SIAs targeted children aged <15 years. Mop-up SIAs with mOPV1 were conducted in 34 districts in September; one national SIA using trivalent OPV was conducted in early October, and another is planned for November, each targeting children aged <15 years (Table 2). Reported vaccination coverage for each SIA was ≥98% of the target (Table 2).

In early May 2010, the risk for importation was assessed for 12 countries in the European Region to identify high-risk subnational areas for WPV transmission. National authorities were advised to strengthen surveillance through enhanced active case finding and weekly reporting and to implement SIAs as needed. Kazakhstan, Kyrgyzstan, Turkmenistan, and Uzbekistan conducted national SIAs to limit further spread; Russia conducted focal mop-up SIAs and catch-up immunizations (Table 2).

Importations in Africa and Asia, 2009--2010

Nineteen importations of WPV1 and 11 of WPV type 3 (WPV3) that occurred during 2008--2009 (nine in 2008 and 21 in 2009) resulted in 208 polio cases in 15 countries in 2009 and seven additional cases in 2010 (Table 1). As of November 1, 2010, no other 2009 outbreak-related cases had been detected during the 6 months since the latest case in Mauritania (April 28, 2010). In outbreaks with the first case occurring in 2010, seven importations of WPV1 and two of WPV3 resulted in 26 polio cases in four African countries, and WPV1 importation into one Asian country resulted in six cases to date (Table 1).

West Central Africa. In 2009, outbreaks related to increased circulation of WPV1 and WPV3 in Nigeria during 2008--2009 occurred in 12 countries (Table 1). Outbreaks in Mali, Mauritania, and Sierra Leone continued into 2010.

In 2010, Senegal had three importations (first confirmed January 18). New importations with no or limited subsequent transmission also occurred in Liberia (confirmed April 14), Mali (WPV1 confirmed April 8 and WPV3 confirmed October 15) and Niger (confirmed April 22) (Table 1). The most recent case among 2010 outbreaks occurred on September 8 in Liberia.

Horn of Africa. Outbreaks occurred in Kenya and Uganda in 2009 (the latest cases on July 30 and May 10, 2009, respectively) (Table 1). These represented two distinct importations from south Sudan, where WPV1 genetically related to viruses from the importation-related outbreak during 2004--2005 in Sudan was again confirmed from polio cases during June 2008--June 2009. A new 2010 importation case occurred in Uganda on September 28 (confirmed October 18), genetically related to virus last isolated in Kenya in 2009.

South Central Africa. Two cases occurred in Burundi in 2009, most recently on September 12, 2009 (Table 1). This outbreak spread from the Democratic Republic of the Congo (DRC) as a result of WPV1 importation from India into Angola in 2005 and subsequently into DRC (3).

Nepal. Two WPV1 importations from India caused six confirmed WPV1 cases in Nepal in 2010. The first case occurred on February 19 (confirmed on March 19), and the most recent occurred on August 30.

Reported by
Vaccine Preventable Diseases and Immunization, World Health Organization Regional Office for Europe, Copenhagen, Denmark; Polio Eradication Dept, World Health Organization, Geneva, Switzerland. Div of Viral Diseases, Global Immunization Div, National Center for Immunization and Respiratory Diseases, CDC.  

Last Updated on Friday, 12 November 2010 05:11

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