Polio this week as of 22 March 2017
- From 25 to 28 March, synchronised polio campaigns will take place across 13 counties in west and central Africa including Nigeria, Chad, Cameroon, Guinea, Mali and Niger. Over 190 000 vaccinators will immunize more than 116 million children over the course of the campaigns.
- Summary of newly-reported viruses this week: No new WPV or cVDPV positives were reported this week.
NA: onset of paralysis in most recent case is prior to 2015. Figures exclude non-AFP sources. Lao PDR cVDPV1, all others cVDPV2. cVDPV definition: see document “Reporting and classification of vaccine-derived polioviruses” at [pdf]
Weekly country updates as of 22 March 2017
- No new wild poliovirus type 1 (WPV1) cases were reported in the past week. The total number of WPV1 cases for 2017 remains two, and for 2016 remains 13. The most recent case had onset of paralysis on 21 January, from Nahr-e-Saraj district, Helmand.
- No new environmental positive samples were reported in the past week. The most recent WPV1 positive sample was collected on 24 January, in Jalalabad, Nangarhar.
- Most areas of Afghanistan are without polio cases. Transmission in 2016/2017 is largely limited to small geographical areas in the eastern and south-eastern regions of the country. Two districts are of particular importance: Bermel in Paktika province, and Sheegal in Kunar, which together reported 11 of the 13 polio cases in 2016.
- Afghanistan and Pakistan continue to be treated as a single epidemiological block.
- No new wild poliovirus type 1 (WPV1) cases were reported in the past week. The total number of WPV1 cases for 2017 remains two, and for 2016 remains 20. The most recent case had onset of paralysis on 13 February, from Diamir district, Gilgit Baltistan.
- No new WPV1 positive environmental samples were reported in the past week. The most recent WPV1 positive sample was collected on 15 February, in Killa Abdullah district, Balochistan.
- The year 2016 saw the lowest ever annual number of polio cases in the country but poliovirus continues to be isolated through environmental surveillance over a significant geographical range.
- Efforts continue in Quetta Block to strengthen programme operations as well as supervision and monitoring mechanisms to stop transmission of WPV1 and VDPV2.
- No new cases of wild poliovirus type 1 (WPV1) were reported in the past week. The total number of WPV1 cases for 2016 remains four. The most recent case had onset of paralysis on 21 August in Monguno Local Government Area (LGA), Borno.
- Nigeria continues to implement emergency outbreak response to the detected WPV1 strain and circulating vaccine-derived poliovirus type 2 (cVDPV2) strains affecting the country.
- The response is part of a broader regional outbreak response, coordinated with neighbouring countries, in particular the Lake Chad sub-region, including northern Cameroon, parts of Central African Republic, Chad and southern Niger.
- Detection of polio cases underscores the risk posed by low-level undetected transmission and the urgent need to strengthen subnational surveillance.
- The detection of wild poliovirus type 1 (WPV1) and circulating vaccine-derived poliovirus type 2 (cVDPV2) in Nigeria poses a risk to the neighbouring countries of the Lake Chad basin and hence an outbreak response plan is being implemented as part of the response to the Nigeria outbreak.
- Emergency outbreak response efforts continue across the Lake Chad basin, together with activities to fill subnational surveillance gaps across the region.
- No circulating vaccine-derived poliovirus type two (cVDPV2) cases have been reported from Guinea in 2016 or 2017. The most recent case was reported from Kankan district with onset of paralysis on 14 December 2015. The total number of cVDPV2 cases for 2015 is seven.
- While it has been more than a year since the last case had onset of paralysis in Guinea, undetected circulation cannot be ruled out. A recently-conducted surveillance review in the country found significant improvements to surveillance sensitivity, though some remaining subnational gaps.
- Critical to long-term success will be to ensure that capacity and infrastructure is maintained to rapidly detect, and respond to, any potential further virus isolates.
- No new cases of circulating vaccine-derived poliovirus type one (cVDPV1) were reported in the past week. The most recent case was reported in Fuang district of Vientiane province, with onset of paralysis on 11 January 2016. The total number of cVDPV1 cases remains three in 2016 and eight in 2015.
- A recent outbreak response assessment, reviewing epidemiological and surveillance data, found significant improvements, in particular in surveillance, and concluded that it is unlikely that transmission is continuing in the country.
- Outbreaks of cVDPVs can arise in areas with low population immunity, emphasizing the importance of maintaining strong vaccination coverage.