Immunization
Countries reinfected with polio
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| © UNICEF/HQ06-1830/Josh Estey |
| INDONESIA: A child receives oral polio vaccine at the ‘Posyandu’ (integrated health post) in Sesawi District on West Timur. |
Between 2003 and 2007, twenty-seven countries were re-infected with imported poliovirus, 20 of them as a result of viruses originating from northern Nigeria. Consequently, 2005-2006 was a period of unprecedented innovation to address these challenges. Medical advancement — such as the development of monovalent vaccines (mOPV) and refined infection confirmation procedures — together with targeted communication activities helped many of the re-infected countries regain their polio free status.
The six remaining countries, Angola, Chad, Democratic Republic of Congo (DRC), Niger, Myanmar and Somalia, reported at total 64 cases on WPV in 2007, less than half of the number of the previous year. Activities at the global and regional level focused on outbreak response and capacity development. Rapid surveys of national capacity were conducted and countries were provided human resources as well as technical guidance. Communication activities have been tailored to the specific needs of each re-infected country, including national campaigns and localized efforts to reach underserved populations in at-risk areas. Country programmes have also been backed up by global support activities including training, strategic guidance and media/advocacy.
Nevertheless, virus circulation has persisted in Niger, spilling over again in to Chad and Sudan in 2007. The DRC has also had an increase in cases, with nearly five times as many cases reported this year as in 2006. A communication STOP team is being deployed to Niger, but activities in Chad and DRC will require longer term support through global monitors and continued technical guidance.
Synopsis of progress in reinfected countries
Angola
• In 2008, 5 cases have been reported, 1 type 1 and 4 type 3. This is the first importation of type 3 poliovirus into Angola. Genetic sequencing indicates that the first type 3 case detected (with onset of paralysis on 19 March) is related to virus from Uttar Pradesh, India.
• All cases have been in the Luanda area, where the second mop-up of the year was carried out on 18-20 April with mOPV1; a mix of mOPV1 and mOPV3 will be used during NIDs scheduled for 16-18 May due to the presence of type 3 poliovirus.
Central African Republic (CAR)
• CAR has reported its first case – a type 1 – since November 2004. Genetic sequencing is awaited to determine the origin of the virus.
• Detection of polio after a gap of over 3 years emphasizes the continued importance of sensitive surveillance, especially in the vicinity of endemic countries. NIDs were held on 4 April.
Chad
• With 2 cases reported this year, both type 3, Chad remains a high risk country for polio transmission due to weak operations during its 2 SIAs this year, conducted in the midst of insecurity. Following a meeting between government and partners in early April, SIAs have been scheduled in staggered phases across the country due to security constraints: the first of these took place in the last week of April; the next are due to take place end-May and end-June. It is critical to boost population immunity before the onset of the rains in June.
Democratic Republic of Congo
• Two cases have been reported this year, both type 1. The most recent is from the previously uninfected province of North Kivu; genetic sequencing is awaited to determine whether this represents a new importation.
• Following a mop-up targeting 400 000 children on 10-12 April, using mOPV1, large-scale SIAs are planned for 8-10 May and again in June (also with mOPV1).
Nepal and Niger
• Both countries continue to be exposed to repeated importations, due to their proximity to endemic areas of India and northern Nigeria respectively. Both also continue outbreak response activities; in Nepal, 4 SIAs have been held between December 2007 and April 2008, and no cases have been reported since 16 February. Niger's most recent campaigns were on 5 April, using mOPV1 along its border with Nigeria.
Horn of Africa
• Two polio cases were reported in the Ethiopia/south Sudan cross-border area, the first polio reported this year to the east of Chad.
• Confirmation of these cases, which are genetically related to previously circulating virus, underscores the need to sustain campaigns in this difficult-to-access area, and to urgently fill subnational surveillance gaps across central Africa. Although current population immunity levels across the Horn of Africa are higher than in 2004-2005, there is a risk of further polio spread, facilitated by frequent population movements.
• A combined cross-border outbreak response is currently being planned. Two large-scale SIAs covering the whole of southern Sudan (targeting 2.5 million children) and 52 districts of south-western Ethiopia bordering southern Sudan (targeting 400 000 children) will be held in early May and again in early June, using mOPV1. Longer-term plans, also to strengthen sub-national surveillance gaps across several countries in central Africa, are being formulated.
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