The World Health Organisation (WHO) says a type of poliovirus - the virus which causes poliomyelitis or polio - has spread from Pakistan to China and precautions are being taken before the major movements associated with the Muslim pilgrimage to Mecca, or Hajj.
Wild poliovirus type 1 (WPV1) has been found in China and is believed to be linked to outbreaks of polio in Pakistan where the difficulty of safely reaching large parts of the country have hampered immunisation efforts. Another strain of the virus - WPV3 - has been found in Pakistan too; the first case in Asia this year.
Earlier this month Pakistan had 84 cases of the virus, up from 48 last year.
WHO says that efforts to inoculate Pakistani children have been made difficult by the country's fragile security situation and estimates that more than 200,000 in the tribal areas have not been vaccinated.
With large numbers of Pakistanis expected to travel to Saudi Arabia on pilgrimage the WHO rates as 'high' the likelihood that WPV viruses will be transmitted across national borders.
While immunisation efforts have been redoubled in Pakistan, WHO says the impacts of new programmes are yet to become apparent and is calling for urgent action to reach people in 'security compromised' areas where they will soon be meeting in large numbers at district councils.
WHO is calling for countries in Asia and on the eastern shores of the Mediterranean to be vigilant for cases of acute flaccid paralysis - the muscle weakness which is an early sign of polio infection - and to step up their own vaccination programmes.
WHO is advising travellers to and from Pakistan who in the past have received three or more doses of the oral polio virus (OPV) to top up their protection and says that anyone who has not been immunised should complete a full course of the treatment with at least one dose of OPV.
Pilgrims travelling to the Kingdom of Saudi Arabia from countries affected by the poliovirus are being required to prove that they have been vaccinated before travelling.
The latest updates on the worldwide polio situation can be found here.
Top Image Credit: Illustration of polio virus © krishnacreations