The Global Polio Laboratory Network as a Platform for the Viral Vaccine-Preventable and Emerging Diseases Laboratory Networks.

The Global Polio Laboratory Network (GPLN) began building in the late 1980s on a 3-tiered structure of 146 laboratories with different and complementary technical and support capacities (poliovirus isolation, molecular strain characterization including sequencing, quality assurance, and research). The purpose of this network is to provide timely and accurate laboratory results to the Global Polio Eradication Initiative. Deeply integrated with field case-based surveillance, it ultimately provides molecular epidemiological data from polioviruses used to inform programmatic and immunization activities. This network of global coverage requires substantial investments in laboratory infrastructure, equipment, supplies, reagents, quality assurance, staffing and training, often in resource-limited settings. The GPLN has not only developed country capacities, but it also serves as a model to other global laboratory networks for vaccine-preventable diseases that will endure after the polio eradication goal is achieved. Leveraging lessons learned during past 27 years, the authors discuss options for transitioning GPLN assets to support control of other viral vaccine-preventable, emerging, and reemerging diseases.

Emergence of vaccine-derived polioviruses, Democratic Republic of Congo, 2004-2011.

Polioviruses isolated from 70 acute flaccid paralysis patients from the Democratic Republic of Congo (DRC) during 2004-2011 were characterized and found to be vaccine-derived type 2 polioviruses (VDPV2s). Partial genomic sequencing of the isolates revealed nucleotide sequence divergence of up to 3.5% in the viral protein 1 capsid region of the viral genome relative to the Sabin vaccine strain. Genetic analysis identified at least 7 circulating lineages localized to specific geographic regions. Multiple independent events of VDPV2 emergence occurred throughout DRC during this 7-year period. During 2010-2011, VDPV2 circulation in eastern DRC occurred in an area distinct from that of wild poliovirus circulation, whereas VDPV2 circulation in the southwestern part of DRC (in Kasai Occidental) occurred within the larger region of wild poliovirus circulation.

Detection of imported wild polioviruses and of vaccine-derived polioviruses by environmental surveillance in Egypt.

Systematic environmental surveillance for poliovirus circulation has been conducted in Egypt since 2000. The surveillance has revealed three independent importations of wild-type poliovirus. In addition, several vaccine-derived polioviruses have been detected in various locations in Egypt. In addition to acute flaccid paralysis (AFP) surveillance, environmental surveillance can be used to monitor the wild poliovirus and vaccine-derived poliovirus circulation in populations in support of polio eradication initiatives.

Global surveillance and the value of information: the case of the global polio laboratory network.

Effective control and eradication of diseases requires reliable information from surveillance activities, including laboratories, which typically incur real financial costs. This article presents data from a survey we conducted to estimate the costs of the Global Polio Laboratory Network (GPLN), which currently supports aggressive global surveillance for acute flaccid paralysis (AFP) to detect circulating polioviruses. The Global Polio Eradication Initiative (GPEI) of the World Health Organization (WHO) provides resources for some of the laboratory network costs, but the total cost of the network remains relatively poorly characterized given the limited documentation of national contributions. We surveyed network laboratories to quantify AFP surveillance support costs and provide data for cost estimates of potential posteradication surveillance policies related to the laboratories. We estimate that the GPLN currently requires millions (US dollars 2002) in total support annually, and that half of the support for national and regional reference laboratories comes from external donors through the WHO or bilateral agreements and half from within nations that host those laboratories. The article also presents the framework for considering the value of information from this global surveillance network and suggests that the expected value of surveillance information from the GPLN currently exceeds its costs. We also provided important insights about how the value of information may change after successful eradication of wild polioviruses.

Antenatal rubella serosurvey in Maputo, Mozambique.

OBJECTIVE: To describe the epidemiology of rubella in Mozambique. METHODS: Cross-sectional serosurvey of rubella IgG antibodies among women attending antenatal clinics in Maputo in February-April 2002 to assess the prevalence and titres. RESULTS: Rubella IgG antibodies were detected in 95.3% (95% confidence interval 94.0%-96.6%) of 974 pregnant women. Age and residence did not significantly affect the prevalence of rubella IgG antibodies. However, the mean titre of rubella IgG antibodies was higher in women <20 years of age than in women > or =30 years of age (P < 0.01), and women living in urban areas had higher antibody titres than those living in suburban areas (P < 0.0001). CONCLUSIONS: The seroprevalence of rubella IgG antibodies among pregnant women in Maputo is high. Whether this is due to recent exposure to wild rubella virus or to exposure to rubella virus earlier in life is unclear. Studies on the burden of congenital rubella syndrome could address this matter.

Containment of polioviruses after eradication and OPV cessation: characterizing risks to improve management.

The goal of the World Health Organization is to stop routine use of oral poliovirus vaccine shortly after interruption of wild poliovirus transmission. A key component of this goal is to minimize the risk of reintroduction by destruction of polioviruses except in an absolute minimum number of facilities that serve essential functions and implement effective containment. Effective containment begins with a complete facility risk assessment. This article focuses on characterizing the risks of exposure to polioviruses from the essential vaccine production, quality control, and international reference and research facilities that remain. We consider the potential exposure pathways that might lead to a poliovirus reintroduction, including para-occupational exposures and releases to the environment, and review the literature to provide available estimates and a qualitative assessment of containment risks. Minimizing the risk of poliovirus transmission from a poliovirus facility to increasingly susceptible communities is a crucial and ongoing effort requiring understanding and actively managing the potential exposure pathways.

Vaccine-derived polioviruses and the endgame strategy for global polio eradication.

As the global eradication of wild poliovirus nears, the World Health Organization (WHO) is addressing challenges unprecedented in public health. The live, attenuated oral poliovirus vaccine (OPV), used for more than four decades to interrupt poliovirus transmission, and the vaccine of choice for developing countries, is genetically unstable. Reversion of the small number of substitutions conferring the attenuated phenotype frequently occurs during OPV replication in humans and is the underlying cause of the rare cases of vaccine-associated paralytic poliomyelitis (VAPP) in OPV recipients and their close contacts. Whereas VAPP has long been recognized, two other adverse events have been identified more recently: (a) long-term excretion of highly evolved vaccine-derived polioviruses (VDPVs) in persons with primary immunodeficiencies, and (b) polio outbreaks associated with circulating VDPVs in areas with low rates of OPV coverage. Developing a posteradication strategy to minimize the risks of VDPV emergence and spread has become an urgent WHO priority.

Polio eradication: the OPV paradox.

Routine and mass administration of oral polio vaccine (OPV) since 1961 has prevented many millions of cases of paralytic poliomyelitis. The public health value of this inexpensive and easily administered product has been extraordinary. Progress of the Global Polio Eradication Initiative has further defined the value of OPV as well as its risk through vaccine-associated paralytic poliomyelitis (VAPP) and vaccine-derived polioviruses (VDPV). Although both are rare, once wild poliovirus transmission has been interrupted by OPV, the only poliomyelitis due to poliovirus will be caused by OPV. Poliovirus will be eradicated only when OPV use is discontinued. This paradox provides a major incentive for eventually stopping polio immunization or replacing OPV, but it also introduces complexity into the process of identifying safe and scientifically sound strategies for doing so. The core post eradication immunization issues include the risk/benefits of continued OPV use, the extent of OPV replacement with IPV, possible strategies for discontinuing OPV, and the potential for development and licensure of a safe and effective replacement for OPV. Formulation of an informed post eradication immunization policy requires careful evaluation of polio epidemiology, surveillance capability, vaccine availability, laboratory containment, and the risks posed by the very tool responsible for successful interruption of wild poliovirus transmission.

Prolonged detection of indigenous wild polioviruses in sewage from communities in Egypt.

Environmental surveillance for polioviruses has been implemented in Egypt. This paper reports on a study in which 130 sewage samples were collected between January 2001 and December 2001 from eight provinces of Egypt. Samples were analyzed by virus isolation in L20B and RD cell cultures, and wild polioviruses were characterized by sequencing of the VP1 protein coding region. Wild type 1 polioviruses were detected in 57% of the sewage samples and 91% of the study sites, only two of which reported paralytic poliomyelitis cases in 2001. Three genetic lineages of a single indigenous type 1 poliovirus genotype were detectable in sewage, and only one lineage was also detected through surveillance for acute flaccid paralysis. Wild polioviruses persisted in the environment despite implementation of oral poliovirus vaccine immunization campaigns. Continued analysis of sewage samples, critical evaluation of immunization coverage, and performance of surveillance for acute flaccid paralysis are proposed as follow-up activities.