Cases Of Poliomyelitis Research Articles

Oral Poliomyelitis Virus Type 2 Vaccines for the Posteradication Era

Poliomyelitis virus type 2 was declared eradicated in 2015, but the number of vaccine-derived poliomyelitis cases has risen since then. The novel oral

Australian National Enterovirus Reference Laboratory annual report, 2019

Australia monitors its polio-free status by conducting surveillance for cases of acute flaccid paralysis (AFP) in children less than 15 years of age, as recommended by the World Health Organization. Cases of AFP in children are notified to the Australian Paediatric Surveillance Unit or the Paediatric Active Enhanced Disease Surveillance System and faecal specimens are referred for virological investigation to the National Enterovirus Reference Laboratory. In 2019, no cases of poliomyelitis were reported from clinical surveillance and Australia reported 1.34 non-polio AFP cases per 100,000 children, meeting the World Health Organization’s performance criterion for a sensitive surveillance system. The non-polio enteroviruses coxsackievirus A2, coxsackievirus A16, echovirus 9, and enterovirus A71 were identified from clinical specimens collected from AFP cases. Australia also performs enterovirus and environmental surveillance to complement the clinical system focussed on children. In 2019, 175 cases of wild polio were reported, with three countries remaining endemic: Afghanistan, Nigeria and Pakistan.

Updated Characterization of Outbreak Response Strategies for 2019-2029: Impacts of Using a Novel Type 2 Oral Poliovirus Vaccine Strain.

Delays in achieving the global eradication of wild poliovirus transmission continue to postpone subsequent cessation of all oral poliovirus vaccine (OPV) use. Countries must stop OPV use to end all cases of poliomyelitis, including vaccine-associated paralytic polio (VAPP) and cases caused by vaccine-derived polioviruses (VDPVs). The Global Polio Eradication Initiative (GPEI) coordinated global cessation of all type 2 OPV (OPV2) use in routine immunization in 2016 but did not successfully end the transmission of type 2 VDPVs (VDPV2s), and consequently continues to use type 2 OPV (OPV2) for outbreak response activities. Using an updated global poliovirus transmission and OPV evolution model, we characterize outbreak response options for 2019-2029 related to responding to VDPV2 outbreaks with a genetically stabilized novel OPV (nOPV2) strain or with the currently licensed monovalent OPV2 (mOPV2). Given uncertainties about the properties of nOPV2, we model different assumptions that appear consistent with the evidence on nOPV2 to date. Using nOPV2 to respond to detected cases may reduce the expected VDPV and VAPP cases and the risk of needing to restart OPV2 use in routine immunization compared to mOPV2 use for outbreak response. The actual properties, availability, and use of nOPV2 will determine its effects on type 2 poliovirus transmission in populations. Even with optimal nOPV2 performance, countries and the GPEI would still likely need to restart OPV2 use in routine immunization in OPV-using countries if operational improvements in outbreak response to stop the transmission of cVDPV2s are not implemented effectively.

Primary immunodeficiency masks: A clinical case of vaccine-associated paralytic poliomyelitis

Human inborn immune-related errors comprise a heterogeneous group of rare genetically determined diseases of the immune system caused by loss or gain of function mutations altering relevant protein functions. The 2019 International Union of Immunological Societies recently proposed the classification for such pathologies now comprising 406 distinct disorders with 430 different gene defects. Predominantly antibody deficiencies represent most common group of human inborn immune-related errors, which diagnostics poses uneasy challenge for general practitioner due to a broad range of their clinical manifestations, such as infection, allergy, autoimmunity and malignancy. In addition, patients with human immune-related inborn errors may develop a vaccine-associated disease after administering live vaccines in accordance with the Russia-wide National Vaccine Schedule. Most common among vaccine-associated diseases are vaccine-associated paralytic poliomyelitis, vaccine-associated encephalitis (1 case per 1 000 000 doses of measles, rubella, varicella vaccine), vaccine-associated meningitis (1 case per 250 000 – 500 000 doses of mumps vaccine) as well as adverse effects related to BCG immunization: local (infiltration, cold abscess – 8.6 case per 100,000 vaccinated patients) and disseminated complications (BCG lymphadenitis – 15.5 case per 100 000 vaccinated patients, BCG osteitis – 3.5 case per 100 000 vaccinated patients). Vaccine-associated paralytic poliomyelitis in vaccinated patients occurs after the first, second and rarely third oral polio vaccine dose inoculation. Incidence rate for vaccineassociated paralytic polio after 1 and 3 oral vaccine inoculation ranges from 1 case per 700 000 vaccine doses to 1 case per 3 500 000, respectively. Vaccine-associated paralytic poliomyelitis mainly emerges due to inborn mutations related to humoral immunity after primary vaccination with oral polio vaccine or close contact of unvaccinated patients with subjects vaccinated with oral polio vaccine. Here, we describe a clinical case of vaccine-associated paralytic poliomyelitis in patient with primary immunodeficiency. Our is aimed at emphasizing importance of immunological alertness with regard to detecting primary immunodeficiencies and timely apply a replacement therapy prior to verifying type of immunodeficiency.

Case of Poliomyelitis Caused by Significantly Diverged Derivative of the Poliovirus Type 3 Vaccine Sabin Strain Circulating in the Orphanage.

Significantly divergent polioviruses (VDPV) derived from the oral poliovirus vaccine (OPV) from Sabin strains, like wild polioviruses, are capable of prolonged transmission and neuropathology. This is mainly shown for VDPV type 2. Here we describe a molecular-epidemiological investigation of a case of VDPV type 3 circulation leading to paralytic poliomyelitis in a child in an orphanage, where OPV has not been used. Samples of feces and blood serum from the patient and 52 contacts from the same orphanage were collected twice and investigated. The complete genome sequencing was performed for five polioviruses isolated from the patient and three contact children. The level of divergence of the genomes of the isolates corresponded to approximately 9–10 months of evolution. The presence of 61 common substitutions in all isolates indicated a common intermediate progenitor. The possibility of VDPV3 transmission from the excretor to susceptible recipients (unvaccinated against polio or vaccinated with inactivated poliovirus vaccine, IPV) with subsequent circulation in a closed children’s group was demonstrated. The study of the blood sera of orphanage residents at least twice vaccinated with IPV revealed the absence of neutralizing antibodies against at least two poliovirus serotypes in almost 20% of children. Therefore, a complete rejection of OPV vaccination can lead to a critical decrease in collective immunity level. The development of new poliovirus vaccines that create mucosal immunity for the adequate replacement of OPV from Sabin strains is necessary.

Supplementary data on virus-like particles in the brainstem of Parkinson’s disease patients and controls

In this study, we present 84 transmission electron microscopy (TEM) images of human brainstem tissue from 11 cases of late onset Parkinson's disease (PD). The tissues were fixed, embedded, sectioned, and stained for TEM application. In addition, we present 14 images from autopsy specimens of 1 case of human poliomyelitis infection as positive controls and 14 images from 8 cases of autopsy specimens of other conditions as negative controls. In the TEM images of the PD cases there were cytoplasmic inclusion bodies consisting of virus-like particles (VLP) 30 nm in diameter that were associated with endoplasmic reticulum membranes. In the nuclei of the PD neurons there were VLP ranging from 40 nm to 50 nm in diameter. In the poliomyelitis cases, similar particles as were observed in PD which were interpreted to be poliomyelitis virus particles. In the negative controls one case was identified which showed similar VLP (Figure 1, controls). A Lewy body was found in this "control" case (Figure 10) suggesting that this was an undiagnosed case of PD. Cytoplasmic ribosomes measuring approximately 17 nm were observed in the control neurons.

Australian National Enterovirus Reference Laboratory annual report, 2018

Australia monitors its polio-free status by conducting surveillance for cases of AFP in children less than 15 years of age, as recommended by the WHO. Cases of AFP in children are notified to the Australian Paediatric Surveillance Unit or the Paediatric Active Enhanced Disease Surveillance System and faecal specimens are referred for virological investigation to the National Enterovirus Reference Laboratory. In 2018, no cases of poliomyelitis were reported from clinical surveillance and Australia reported 1.24 non-polio AFP cases per 100,000 children, meeting the WHO performance criterion for a sensitive surveillance system. Several non-polio enteroviruses, coxsackievirus A4, coxsackievirus B1, echovirus 9, echovirus 30, enterovirus D68 and enterovirus A71, were identified from clinical specimens collected from AFP cases. Australia also performs enterovirus and environmental surveillance to complement the clinical system focussed on children. In 2018, 33 cases of wild polio were reported with three countries remaining endemic: Afghanistan, Nigeria and Pakistan.

Australian National Enterovirus Reference Laboratory annual report, 2016.

Australia monitors its polio-free status by conducting surveillance for cases of acute flaccid paralysis (AFP) in children less than 15 years of age, as recommended by the World Health Organization (WHO). Cases of AFP in children are notified to the Australian Paediatric Surveillance Unit or the Paediatric Active Enhanced Disease Surveillance System and faecal specimens are referred for virological investigation to the National Enterovirus Reference Laboratory. In 2016, no cases of poliomyelitis were reported from clinical surveillance and Australia reported 1.38 non-polio AFP cases per 100,000 children, meeting the WHO performance criterion for a sensitive surveillance system. Several non-polio enteroviruses, coxsackievirus A6, enterovirus A71, enterovirus A74 and enterovirus D68, were identified from clinical specimens collected from AFP cases. The global withdrawal of Sabin poliovirus type 2 from oral polio vaccine occurred in April 2016. This event represents the start of the polio endgame with an increased focus on the laboratory containment of all remaining wild and vaccine strains of poliovirus type 2. The National Enterovirus Reference Laboratory was designated as a polio essential facility as part of this process. In 2016, 37 cases of wild polio were reported with three countries remaining endemic: Afghanistan, Nigeria and Pakistan. Nigeria was declared polio-free in 2015, after 12 months without detection of wild poliovirus, but was reinstated as an endemic country after the reporting of four cases in August 2016. This is a salient reminder of the need to maintain sensitive surveillance for poliovirus until global eradication is certified.

Australian National Enterovirus Reference Laboratory annual report, 2015.

Australia conducts surveillance for cases of acute flaccid paralysis (AFP) in children less than 15 years as recommended by the World Health Organization (WHO) as the main method to monitor its polio-free status. Cases of AFP in children are notified to the Australian Paediatric Surveillance Unit or the Paediatric Active Enhanced Disease Surveillance System and faecal specimens are referred for virological investigation to the National Enterovirus Reference Laboratory. In 2015, no cases of poliomyelitis were reported from clinical surveillance and Australia reported 1.2 non-polio AFP cases per 100,000 children, meeting the WHO performance criterion for a sensitive surveillance system. Two non-polio enteroviruses, enterovirus A71 and coxsackievirus B3, were identified from clinical specimens collected from AFP cases. Australia complements the clinical surveillance program with enterovirus and environmental surveillance for poliovirus. Two Sabin-like polioviruses were isolated from sewage collected in Melbourne in 2015, which would have been imported from a country that uses the oral polio vaccine. The global eradication of wild poliovirus type 2 was certified in 2015 and Sabin poliovirus type 2 will be withdrawn from oral polio vaccine in April 2016. Laboratory containment of all remaining wild and vaccine strains of poliovirus type 2 will occur in 2016 and the National Enterovirus Reference Laboratory was designated as a polio essential facility. Globally, in 2015, 74 cases of polio were reported, only in the two remaining countries endemic for wild poliovirus: Afghanistan and Pakistan. This is the lowest number reported since the global polio eradication program was initiated.

Australian National Enterovirus Reference Laboratory annual report, 2017.

Australia monitors its polio-free status by conducting surveillance for cases of acute flaccid paralysis (AFP) in children less than 15 years of age, as recommended by the World Health Organization (WHO). Cases of AFP in children are notified to the Australian Paediatric Surveillance Unit or the Paediatric Active Enhanced Disease Surveillance System and faecal specimens are referred for virological investigation to the National Enterovirus Reference Laboratory. In 2017, no cases of poliomyelitis were reported from clinical surveillance and Australia reported 1.33 non-polio AFP cases per 100,000 children, meeting the WHO performance criterion for a sensitive surveillance system. Three non-polio enteroviruses, coxsackievirus B1, echovirus 11 and enterovirus A71, were identified from clinical specimens collected from AFP cases. Australia established enterovirus and environmental surveillance systems to complement the clinical system focussed on children and an ambiguous vaccine-derived poliovirus type 2 was isolated from sewage in Melbourne. In 2017, 22 cases of wild polio were reported with three countries remaining endemic: Afghanistan, Nigeria and Pakistan.

«Entrexto» de lo Real:

El presente artículo es el resultado del interrogante qué es lo Real en la práctica del psicoanálisis lacaniano en estos tiempos en los que lo Real está disputado entre los soldados de la realidad social, los defensores de las neurociencias y los discípulos millerianos. Lo Real depende menos hoy de la furia de los antiguos dioses que de las decisiones de las modernas corporaciones que producen la segregación de los cuerpos. La intertextualidad en el artículo se logra mediante elementos heteróclitos: los fundamentos freudianos sobre las parálisis, la enseñanza de Lacan, el texto de Badiou y la consagración del Dr. Ramón Carrillo como un nombre del padre, reciprocidad textual que permite la lectura clínica de una viñeta sobre un caso de poliomielitis

Acute Flaccid Myelitis: A Clinical Review.

Acute flaccid myelitis (AFM) is an emerging disorder primarily affecting children that is characterized by acute flaccid paralysis accompanied by abnormalities of the spinal cord gray matter on magnetic resonance imaging. In most cases, prodromal fever or respiratory symptoms occur, followed by acute-onset flaccid limb weakness. Respiratory, axial, bulbar, facial, and extraocular muscles may also be affected. The clinical manifestations have been described as "polio-like," due to striking similarities to cases of poliomyelitis. The primary site of injury in AFM is the anterior horn cells of the spinal cord, resulting in a motor neuronopathy. Seasonal peaks of cases have occurred in the United States every 2 years since 2012. However, AFM remains a rare disease, which can make it challenging for physicians to recognize and differentiate from other causes of acute flaccid paralysis such as Guillain-Barre syndrome, spinal cord stroke, and transverse myelitis. Epidemiological evidence suggests that AFM is linked to a viral etiology, with nonpolio enteroviruses (in particular enterovirus D68) demonstrating a plausible association. The epidemiology, possible etiological factors, clinical features, differential diagnosis, treatment, and outcomes of AFM are discussed in this review.

Acute Flaccid Paralysis Secondary to Poliomyelitis: 11 Years of Monitoring in Guinea (2005-2015)

The sustained worldwide use of the two available types of polio vaccines has significantly reduced the incidence of this disease. Our main objective is to report a 11-year monitoring period for acute flaccid paralysis secondary to poliovirus in Guinea. It was a retrospective descriptive study for all cases of acute flaccid paralysis (AFP) in which poliovirus was isolated by stool examination. During 11 years, 768 cases of AFP, including 8 cases of acute anterior poliomyelitis were collected at a frequency of 1%. The average age was 3.5 years with extremes of 1 year and 6 years, the most represented age group was 0-4 years with 7 cases. Six mothers were housewives doing gold panning as a revenue generating activity. The vaccine virus (serotype 2) was the most isolated with 6 cases.

Spatio-temporal games of voluntary vaccination in the absence of the infection: the interplay of local versus non-local information about vaccine adverse events.

Under voluntary vaccination, a critical role in shaping the level and trends of vaccine uptake is played by the type and structure of information that is received and used by parents of children eligible for vaccination. In this article we investigate the feedbacks of spatial mobility and the spatial structure of information on vaccination dynamics, by extending to a continuous spatially structured setting existing behavioral epidemiology models for the impact of vaccine adverse events (VAEs) on vaccination choices. We considered the simplest spatial setting, namely classical 'Fickian' diffusion, and focused on the noteworthy case where the infection is absent. This scenario mimics the important case of a population where a previously endemic vaccine preventable infection was successfully eliminated, but the re-emergence of the disease must be prevented. This is, for example, the case of poliomyelitis in most countries worldwide. In such a situation, the dynamics of VAEs and of the related information arguably become the key determinant of vaccination decision and of collective coverage. In relation to this 'information issue', we compared the effects of three main cases: (i) purely local information, where agents react only to locally occurred events; (ii) a mix of purely local and global, country-wide, information due e.g., to country-wide media and the internet; (iii) a mix of local and non-local information. By representing these different information options through a range of different spatial information kernels, we investigated: the presence and stability of space-homogeneous, nontrivial, behavior-induced equilibria; the existence of bifurcations; the existence of classical and generalized traveling waves; and the effects of awareness campaigns enacted by the Public Health System to sustain vaccine uptake. Finally, we analyzed some analogies and differences between our models and those of the Theory of Innovation Diffusion.

Vaccineassociated paralytic poliomyelitis and acute flaccid paralysis on some territories of Russia during 20 years

Aim: Analysis of the morbidity of vaccine-associated paralytic poliomyelitis and acute flaccid paralysis and the results of virological investigation of the patients on 14 territories of the Russian Federation in 1998-2017. Materials and methods: We investigated nearly 3000 stool samples from paralytic patients and contact persons. Isolation and identification of polioviruses were performed according to WHO recommendations with the help of cell lines RD and L20B. We conducted the sequencing of the genome fragments VP3-VP1, VP1-2A and full sequencing of genome region VP1 of 45 poliovirus strains. Results: From 1998 till 2017 1257 cases of acute flaccid paralysis were registered on 14 territories of Russia, 15 cases of which (1,2%) were classified as vaccine-associated paralytic poliomyelitis. From these patients 9 children were non vaccinated and 6 children received from one to four doses of oral poliomyelitis vaccine. The percentage of the detection of polioviruses from the patients and contact persons in different years was not equal and constituted from 3, 4±0,89% to 9, 5±0,79%. All in all from the patients with acute flaccid paralysis and contact persons we isolated 191 polioviruses, 60 of them belonged to type 1, 55 polioviruses were identified as types 2 and 76 as type 3. Some cases of vaccine-associated paralytic poliomyelitis are described in the article; polioviruses were isolated from all these patients. The sequencing of the genome fragments of 45 poliovirus strains showed that the majority of them had the nucleotide substitutions including neurovirulent substitutions. Conclusion:In order to prevent the risk of the appearance of vaccine-associated paralytic poliomyelitis it is necessary to maintain the high quality of surveillance of poliomyelitis and acute flaccid paralysis, to ensure the 95% coverage of children with poliomyelitis vaccine, to minimize the cases of groundless delays of vaccination according to medical recommendations and parents’ refusals to vaccinate children against poliomyelitis and to respect strictly the National calendar of vaccination.

Environmental Surveillance of Polioviruses in Armenia, Colombia before Trivalent Oral Polio Vaccine Cessation.

Although acute flaccid paralysis (AFP) surveillance is the “gold standard” for detecting cases of polio, environmental surveillance can provide supplementary information in the absence of paralytic poliomyelitis cases. This study aimed to detect the introduction and/or circulation of wild poliovirus or vaccine-derived polioviruses (VDPV) in wastewater, covering a significant population of Armenia, Colombia, before trivalent oral polio vaccine (OPV) cessation. Between March and September 2015, 24 wastewater samples were collected from eight study sites in eight communes of Armenia, Colombia. Virus detection and characterization were performed using both cell culture (i.e., RD or L20B cells) and RT-PCR. Polioviruses were isolated in 11 (45.8%) of 24 wastewater samples. All isolates were identified as Sabin strains (type 1 = 9, type 3 = 2) by intratypic differentiation. Type 2 poliovirus was not detected in any of the samples. No wild poliovirus or VDPV was detected among the isolates. Non-polio enterovirus was identified in 8.3% (2/24) of the samples. This study revealed the excretion of Sabin poliovirus from OPV-immunized individuals, as well as the absence of VDPV and wild poliovirus in wastewaters of Armenia, Colombia. This confirms that environmental surveillance is an effective method, as an additional support to AFP surveillance, to monitor poliovirus during the OPV-to-IPV (inactivated polio vaccine) transition period.

Poliovirus antibody levels and lameness among individuals in three regions of Ghana

ABSTRACT Introduction Ghana recorded the last case of poliomyelitis caused by wild poliovirus in 2008 and the country was declared polio-free in 2015. Polio-neutralizing-antibody levels in the population of three geographically representative regions of Ghana was determined, to identify possible immunity gaps. Methods Cross-sectional, hospital (1–70 years old) and school (primary, 1–15 years old)-based studies were undertaken in three regions in 2016. Individuals who visited the three teaching hospitals of the regions and were referred for haematology investigations were invited to participate in our study. Neutralizing-antibody titers to polio serotypes P1, P2, and P3 were assayed by WHO-standards. Antibody titers of ≥8 were considered protective. In the school lameness survey, clinical and epidemiological data were obtained from parents and their lamed children. Bivariate and multivariate analyses were conducted on subject characteristics, to assess potential factors for failure to seroconvert. P-values < 0.05 were considered statistically significant. Results Neutralizing-antibodies against poliovirus types 1, 2 and 3 were detected in 86% (264/307), 84% (258/307) and 75% (230/307) of the samples, respectively. Overall, 60.1% (185/307) were seropositive for the three polio serotypes and 2.9% (9/307) were seronegative. Polio neutralizing-antibodies (P1and P2) decreased with age (p < .001). Low seroprevalence of polio-neutralizing-antibodies was significantly associated with low school attendance of mothers (p < .001). Prevalence of residual paralysis was <1.0/1,000 among the school children. Conclusion Our study population is moderately protected against the three poliovirus serotypes. However, immunity appears to be lower with a higher age and low mother’s education. This may suggest the need for young-adult booster-dose to minimize the risk of wild poliovirus infection.

Immunogenicity of Oral Polio Vaccine and Salk Inactive Polio Vaccine Against Xinjiang Imported Type 1 Wild Poliovirus.

An outbreak of an imported Type 1 wild poliovirus from Pakistan occurred in the Xinjiang Uygur Autonomous Region of China in 2011, although the local immunity status of the oral polio vaccine (OPV) was relatively satisfied. Neutralizing antibody titers against the Xinjiang strain and Sabin 1 strain were measured in 237 sera from 3 groups of fully OPV-vaccinated persons and 1 group of infants fully vaccinated with the inactive polio vaccine (IPV). Additionally, 17 sera collected from 1 Xinjiang poliomyelitis case and his 16 contacts were also tested. Genomic sequencing was conducted the Xinjiang strain. The antibody titers against the Xinjiang strain in each of 237 sera were significantly lower than those against the Sabin 1 strain. Notably, 40.0% of children in Group 1 were seronegative against the Xinjiang strain, which indicated that they might play an important role in wild poliovirus transmission, although their antibody titers against the Sabin 1 strain varied between 1:8 and 1:512. Meanwhile, serological results of the Xinjiang poliomyelitis case and his contacts also provided evidence that a proportion of OPV-vaccinated children had indeed been involved in the transmission chain of the Xinjiang outbreak. Genomic sequencing indicated that the Xinjiang strain was greatly distinguishable from the Sabin 1 strain in neutralizing antigenic sites. The lack of neutralizing antibodies against the Xinjiang strain in persons vaccinated by OPV may be associated with the transmission of Type 1 wild poliovirus in Xinjiang. Using Salk IPV along with OPV might be considered in a wild poliovirus outbreak response, especially in the countries which continued to have persistent wild poliovirus circulation.

The eradication of polio in Bhutan in the context of global polio eradication

Bhutan has made tremendous health gains in public health, particularly in vaccine-preventable diseases. Polio was eradicated two years ahead of the launch of the Global Polio Eradication Initiative and only 12 years after the introduction of oral polio vaccination nationwide. The last case of clinical poliomyelitis in Bhutan was reported in 1986. Bhutan maintains a very high coverage of polio immunisation coupled with a strong health system and surveillance network. The success story in the elimination of polio provides examples for other successful public health programmes now and in the future.

Surveillance to Track Progress Toward Polio Eradication - Worldwide, 2017-2018.

When the Global Polio Eradication Initiative (GPEI) began in 1988, cases of poliomyelitis were reported from 125 countries. Since then, only Afghanistan, Nigeria, and Pakistan have experienced uninterrupted transmission of wild poliovirus (WPV). The primary means of detecting poliovirus is through surveillance for acute flaccid paralysis (AFP) among children aged <15 years with testing of stool specimens for WPV and vaccine-derived polioviruses (VDPVs) in World Health Organization (WHO)-accredited laboratories of the Global Polio Laboratory Network (GPLN) (1,2). AFP surveillance is supplemented by environmental surveillance for polioviruses in sewage at selected locations. Analysis of genomic sequences of isolated polioviruses enables assessment of transmission by time and place, potential gaps in surveillance, and emergence of VDPVs (3). This report presents 2017-2018 poliovirus surveillance data, focusing on 31 countries* identified as high-priority countries because of a "high risk of poliovirus transmission and limited capacity to adequately address those risks" (4). Some of these countries are located within WHO regions with endemic polio, and others are in regions that are polio-free. In 2018, 26 (84%) of the 31 countries met AFP surveillance indicators nationally; however, subnational variation in surveillance performance was substantial. Surveillance systems need continued strengthening through monitoring, supervision, and improvements in specimen collection and transport to provide sufficient evidence for interruption of poliovirus circulation.