Poliomyelitis laboratory network - overview
The polio laboratory network in the Western Pacific Region consists of one global specialized laboratory (GSL) in Japan, two regional reference laboratories (RRL) in Australia and China, and nine national laboratories (NLs), including 31 provincial laboratories in China. In addition to the GSL and RRLs, four national polio laboratories in the Region, namely, Hong Kong (China), Singapore, New Zealand and Malaysia, can conduct intratypic differentiation (ITD) of polioviruses.
Timely identification of polioviruses and VDPVs that can cause acute flaccid paralysis (AFP) is becoming increasingly important because of reported circulating-VDPV outbreaks. In this context, a new standard WHO algorithm for poliovirus isolation and identification has been introduced to the network. With the introduction of the new algorithm, all 12 national polio laboratories, excluding 31 subnational laboratories in China, are using the new algorithm for virus isolation. Virus isolation results are reported within 14 days of receipt of the samples and ITD results are reported within seven days after virus isolation.
To implement the real-time polymerase chain reaction (PCR) technique developed by the United States Centers Disease Control and Prevention (US CDC), five network laboratories from Australia, China, Japan, Malaysia and Singapore were trained to carry out real-time PCR for ITD of polioviruses and VDPV screening in August 2009. After this training, the new technique was implemented in five ITD laboratories in the Region.
In August 2011, China polio laboratory network quickly detected type 1 wild poliovirus importation from Pakistan and provided the rapid virus identification results to the national programme by adopting the molecular diagnosis method in parallel to the standard virus isolation method.
After experiencing a wild polio type 1 outbreak in Xinjiang province, China decided to introduce the new algorithm for virus isolation among all provinces and real-time PCR for intratypic differentiation of polioviruses and vaccine derived poliovirus among selected provincial laboratories. A polio national workshop to introduce the new algorithm for virus isolation and a hands-on training workshop for real-time PCR introduction were organized in February 2012 and in March 2012, respectively.
To further expand ITD laboratories in this region, the second regional hands-on training course to implement real-time PCR for rapid detection and characterization of polioviruses is planned during 3-7 December 2012.
After this training, most polio laboratories in the region will use real-time PCR technique for ITD and VDPV screening. The time needed for ITD and the frequency of shipping of virus isolates to the RRL or GSL for ITD and sequencing will be reduced. As a result, ITD results of polioviruses will be available earlier for appropriate programme actions.
Since the Region has been polio-free for more than a decade and celebrated its 10th anniversary on 29 October 2010, network laboratories have been actively involved in supplementary enterovirus surveillance. Supplementary environmental surveillance of polio has been strengthened in the Region to sustain the high level of performance. In particular, China has established a very extensive hand, foot and mouth disease laboratory network based on existing polio and measles/rubella laboratories.
Two polio laboratories in the Region, namely, China and Australia, have been involved in environmental surveillance. In China, environmental surveillance has been expanded to detect possible importation of wild poliovirus from bordering countries with wild poliovirus circulation, to detect VDPVs in high-risk areas and to assess the effect of supplemental immunization activities (SIAs) before and after an oral polio vaccine (OPV) campaign.
Since the certification of the Western Pacific Region as polio-free on 29 October 2000, the role of the poliomyelitis laboratory network in this Region has been focused on providing timely and accurate detection and ITD of polioviruses such as wild poliovirus, vaccine-derived poliovirus (VDPV) and vaccine strains, to maintain the polio-free status with available documented virological evidence.
As of September 2012, all 43 polio laboratories, including 31 provincial laboratories in China, have been fully accredited by WHO. The Tibet CDC laboratory was reviewed in August 2010 for the first time since the WHO accreditation programme was initiated and was fully accredited. Seven ITD laboratories in the Region have also been accredited for the ITD function.