Subject Categories: Clinical medicine
Published online 4 December 2013
Poliomyelitis, or polio for short, is a highly contagious viral infection that is notorious for crippling infants and children. It caused paralysis and death for much of human history prior to the introduction of vaccination.
Prior to 2011, the last case of poliovirus infection in China was reported in 1994. The country later obtained polio-free status from the World Health Organization in 2000.
In 2011, China reported a small outbreak of poliomyelitis in Xinjiang province. Between 3 July and 9 October, investigators identified 21 cases of poliovirus infection: ten people were below 15 years of age, while the remaining 11 people were between 15 and 53 years of age.
Yu Wang, Weizhong Yang and Wenbo Xu at the Chinese Center for Disease Control and Prevention in Beijing and co-workers have now investigated the 2011 outbreak and performed sequence analysis on the wild-type poliovirus that triggered the outbreak. Given the high degree of homologous nucleotide sequencing, they think it is likely that the wild-type poliovirus originated in Pakistan.
In response to the outbreak, the researchers conducted five rounds of vaccination in Xinjiang province from August 2011 to April 2012. The outbreak eventually stopped, 1.5 months after the laboratory confirmation of the index case.
The results show that polio-free countries, such as China, remain at risk of future outbreaks. The researchers believe that global eradication of poliomyelitis will benefit all countries, even those that are currently free of poliomyelitis.