Polio in Tajikistan, first importation since Europe certified polio-free
23 April 2010 - Poliovirus type 1 has been detected in diagnostic samples from cases of Acute Flaccid Paralysis (AFP) from Tajikistan. This represents the first importation of poliovirus in the WHO European Region since it was certified polio-free in 2002.
As of 21 April 2010, 120 cases of acute flaccid paralysis had been reported from Tajikistan. The majority of these have onset of paralysis within the past 2 weeks, prompting the Government to notify WHO of an outbreak. Ten of the children have died. The vast majority of the cases are children < five years of age. Preliminary data suggests >45% had four or more doses of oral polio vaccine.
To date, poliovirus type 1 has been isolated in diagnostic specimens from 7 of these cases. All cases are in the south-west of the country, in an area bordering Afghanistan and Uzbekistan. Afghanistan is one of the four remaining polio-endemic countries. No cases have been reported in the areas of Afghanistan bordering Tajikistan.
The Government of Tajikistan has requested technical guidance and support from WHO. Vaccine for three outbreak response rounds is being pre-positioned by UNICEF Supply Division for Tajikistan.
Tajikistan's last case of clinically confirmed polio was in 1997; the last case of polio confirmed by virological testing was in 1991. Reported OPV3 coverage nationwide was 87% in 2008, the last year for which complete data are available under the WHO/UNICEF joint reporting process. AFP surveillance indicators in Tajikistan meet certification standards at the national level. In 2009, Tajikistan reported 35 cases of acute flaccid paralysis, of which none were caused by wild poliovirus. Globally, more than 90,000 cases of acute flaccid paralysis were reported in 2009, of which 1606 were caused by wild poliovirus.
Three cases of acute flaccid paralysis have been reported in Uzbekistan on the Tajikistan border; poliovirus has not been isolated yet in laboratory testing. In addition, a child from Tajikistan travelled from Dushanbe to Tashkent for medical treatment shortly after onset of paralysis. The Government of Uzbekistan is planning one nationwide round of vaccination; the Government of Kyrgyzstan, is immunizing children <5 years over the course of European Immunization Week (26-30 April).
WHO is communicating with countries in the Region about the outbreak. It is important that neighboring countries strengthen surveillance for cases of acute flaccid paralysis, in order to rapidly detect any new poliovirus importations and facilitate a rapid response. Countries should also analyze routine immunization coverage data to identify any sub-national gaps in population immunity to guide catch-up immunization activities and thereby minimize the consequences of any new virus introduction. Priority should be given to areas at high-risk of importations and where OPV3/DPT3 coverage is <80%.
This outbreak demonstrates the need to maintain high population immunity until transmission of polio has been interrupted worldwide.
Public health measures such as enhanced surveillance and immunization may be put in place at the borders by Tajik health authorities and their counterparts. It is important that international travellers to and from polio affected areas are adequately immunized against polio as recommended in Chapter 6 of International Travel and Health (see link below).
WHO does not recommend the imposition of restrictions to the international movement of persons as a control measure at this time.