Polio outbreaks in Africa caused by mutation of strain in vaccine

New cases of highly infectious disease that should be 'consigned to the history books' reported in Nigeria, the DRC, CAR and Angola

New cases of polio linked to the oral vaccine have been reported in four African countries and more children are now being paralysed by vaccine-derived viruses than those infected by viruses in the wild, according to global health numbers.

The World Health Organization (WHO) and partners identified nine new cases caused by the vaccine in Nigeria, the Democratic Republic of the Congo, Central African Republic and Angola last week. Along with seven other African countries with outbreaks, cases have also been reported in Asia. In Afghanistan and Pakistan polio remains endemic, and in Pakistan officials have been accused of covering up vaccine-related cases.