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National Reference Centre for Poliomyelitis and Enteroviruses (NRC PE)

Sabine Diedrich

Together with the partners within the network of the Global Polio Eradication Initiative (GPEI) – Unicef, Rotary International and the US CDCs – WHO has succeeded in pushing back poliomyelitis (polio) to a large extent.

As a result of the vaccination programmes carried out around the world since 1988, the number of polio cases was reduced by 99.9 %. Poliomyelitis occurs endemically only in Afghanistan, Pakistan and Nigeria (status: September 2012). However, it is not rare that wild polioviruses are imported (e.g. through migrants or travellers) into already polio-free regions (example: polio outbreak in Tadzhikistan with further spreading to Russia, amongst others, in 2010). The certification of polio-free status is initially carried out on a regional level. This presupposes the absence of cases of disease involving wild polioviruses for at least three years in a region with simultaneous disease surveillance. Three of the WHO regions are already considered to be polio-free. The American continent was certified in 1994, the Western Pacific region followed in 2000. Europe has been free from indigenous poliomyelitis since June 2002.

Apart from a consistent implementation of vaccinations, the programme for global polio eradication also includes a surveillance of poliovirus circulation as well as laboratory containment. For the surveillance of the polio situation the following methods can be used:

  • Surveillance of the acute flaccid paralysis (AFP-Surveillance = WHO Gold Standard)
  • Enterovirus surveillance
  • Environmental monitoring

In Germany the last indigenous polio case occurred in 1990. After importation of the disease by wild polioviruses from India and Egypt in 1992, up to three vaccine-associated paralytic polio cases were registered during the following years (so-called VAPP cases by live vaccines). In 1998 the vaccine strategy in Germany was switched from attenuated live virus (OPV) to inactivated virus (IPV). The national AFP surveillance was established as a surveillance system to monitor Germany’s polio-free status under the auspices of the Lower Saxony Regional Health Office in Hannover and carried out between 1998 and 2010. Since the results of the AFP surveillance were, however, insufficient regarding the WHO requirements, an alternative system for the surveillance was implemented.. Within this enterovirus surveillance (EVSurv) all paediatric and neurological hospitals in Germany have been offered a free-of-charge enterovirus diagnostics for the differential diagnostic clarification of viral meningites and/or encephalites since 2006. For this purpose a laboratory network for enterovirus diagnostic in Germany (LaNED) was established under the coordination of the NRC PE. To ensure that Enterovirus testing is carried out in quality-assessed laboratories, the LaNED-labs have to succeed annual proficiency tests. The organisation of proficiency tests for the detection of enteroviruses by virus cultivation (cell culture) and typing (neutralization test) as well as by genome detection (PCR) are part of the range of tasks of the NRC PE. These nationwide proficiency tests are carried out every two years in cooperation with INSTAND.

As a result of the investigation of faecal specimens or cerebrospinal fluid for enteroviruses by PCR, cultivation and typing this system allows the monitoring of circulating enteroviruses and hence the absence of polioviruses in Germany. The results of the laboratory and epidemiological investigations are recorded and evaluated by the Secretariat of the National Certification Committee for Polio Eradication in Germany at RKI (NCC).

Following a decision by the Federal Ministry of Health (BMG) all activities concerning the surveillance of polio-free status in Germany were were taken under the assignment of RKI in 2010. Since that time classical AFP surveillance has been discontinued. Within the nationwide enterovirus surveillance the more detailed enterovirus diagnostic is carried out at the NRC PE. This means that the network laboratories should send all

  • non-typeable enteroviruses
  • PCR positive and cultivation negative samples as well as
  • polioviruses

to the NRC PE for further analysis. The aim is to exclude polioviruses in these samples, (further analyses by sequencing different genomic regions) and/or to characterise their origin (vaccination/wild virus).

Date: 01.02.2013