Poliovirus Surveillance Research Articles

Continued Endemic Wild Poliovirus Transmission in Security-Compromised Areas - Nigeria, 2016.

On August 10, 2016, 2 years after the most recent wild poliovirus (WPV) case was reported in Nigeria (in July 2014) (1), two WPV cases were reported in the northeastern state of Borno, which has been severely affected by insurgency-related insecurity since 2013. On September 9 and 26, 2016, two additional WPV cases were reported in Borno in children whose families migrated from security-compromised, inaccessible areas of the state. All four cases were WPV serotype 1 (WPV1), with genetic differences indicating prolonged undetected transmission. A large-scale emergency response plan was developed and implemented. The plan initially called for vaccination of 815,791 children during August 15-18 in five local government areas (LGAs) in the immediate vicinity of the first two WPV cases. Subsequently, the plan was expanded to regionally synchronized supplementary immunization activities (SIAs), conducted during August 27-December 6 in five Lake Chad basin countries at increased risk for national and regional WPV1 transmission (Cameroon, Central African Republic, Chad, Niger, and Nigeria). In addition, retrospective searches for missed cases of acute flaccid paralysis (AFP), enhanced environmental surveillance for polioviruses, and polio surveillance system reviews were conducted. Prolonged undetected WPV1 transmission in Borno State is a consequence of low population immunity and severe surveillance limitations associated with insurgency-related insecurity and highlights the risk for local and international WPV spread (2). Increasing polio vaccination coverage and implementing high-quality polio surveillance, especially among populations in newly secured and difficult-to-access areas in Borno and other Lake Chad basin areas are urgently needed.

Laboratory Surveillance of Polio and Other Enteroviruses in High-Risk Populations and Environmental Samples.

In the context of poliomyelitis eradication, a reinforced supplementary laboratory surveillance of enteroviruses was implemented in Greece. Between 2008 and 2014, the Hellenic Polioviruses/Enteroviruses Reference Laboratory performed detailed supplementary surveillance of circulating enteroviruses among healthy individuals in high-risk population groups, among immigrants from countries in which poliovirus is endemic, and in environmental samples. In total, 722 stool samples and 179 sewage water samples were included in the study. No wild-type polioviruses were isolated during these 7 years of surveillance, although two imported vaccine polioviruses were detected. Enterovirus presence was recorded in 25.3 and 25.1% of stool and sewage water samples, respectively. Nonpolio enteroviruses isolated from stool samples belonged to species A, B, or C; coxsackievirus A24 was the most frequently identified serotype. Only enteroviruses of species B were identified in sewage water samples, including four serotypes of echoviruses and four serotypes of coxsackie B viruses. Phylogenetic analysis revealed close genetic relationships among virus isolates from sewage water samples and stool samples, which in most cases fell into the same cluster. To the best of our knowledge, this is the first study to compare enterovirus serotypes circulating in fecal specimens of healthy individuals and environmental samples, emphasizing the burden of enterovirus circulation in asymptomatic individuals at high risk. Given that Greece continues to receive a large number of short-term arrivals, students, migrants, and refugees from countries in which poliovirus is endemic, it is important to guarantee high-quality surveillance in order to maintain its polio-free status until global eradication is achieved.IMPORTANCE This article summarizes the results of supplementary poliovirus surveillance in Greece and the subsequent characterization of enteroviral circulation in human feces and the environment. The examination of stool samples from healthy refugees and other individuals in "high-risk" groups for poliovirus enables the identification of enterovirus cases and forms the basis for further investigation of the community-level risk of viral transmission. In addition, the examination of composite human fecal samples through environmental surveillance links poliovirus and nonpoliovirus isolates from unknown individuals to populations served by the sewage or wastewater system. Supplementary surveillance is necessary to comply with the prerequisites imposed by the World Health Organization for monitoring the emergence of vaccine-derived polioviruses, reemergence of wild polioviruses, or disappearance of all vaccine-related strains in order for countries such as Greece to maintain their polio-free status and contribute to global poliovirus eradication.

High-Throughput Next-Generation Sequencing of Polioviruses.

The poliovirus (PV) is currently targeted for worldwide eradication and containment. Sanger-based sequencing of the viral protein 1 (VP1) capsid region is currently the standard method for PV surveillance. However, the whole-genome sequence is sometimes needed for higher resolution global surveillance. In this study, we optimized whole-genome sequencing protocols for poliovirus isolates and FTA cards using next-generation sequencing (NGS), aiming for high sequence coverage, efficiency, and throughput. We found that DNase treatment of poliovirus RNA followed by random reverse transcription (RT), amplification, and the use of the Nextera XT DNA library preparation kit produced significantly better results than other preparations. The average viral reads per total reads, a measurement of efficiency, was as high as 84.2% ± 15.6%. PV genomes covering >99 to 100% of the reference length were obtained and validated with Sanger sequencing. A total of 52 PV genomes were generated, multiplexing as many as 64 samples in a single Illumina MiSeq run. This high-throughput, sequence-independent NGS approach facilitated the detection of a diverse range of PVs, especially for those in vaccine-derived polioviruses (VDPV), circulating VDPV, or immunodeficiency-related VDPV. In contrast to results from previous studies on other viruses, our results showed that filtration and nuclease treatment did not discernibly increase the sequencing efficiency of PV isolates. However, DNase treatment after nucleic acid extraction to remove host DNA significantly improved the sequencing results. This NGS method has been successfully implemented to generate PV genomes for molecular epidemiology of the most recent PV isolates. Additionally, the ability to obtain full PV genomes from FTA cards will aid in facilitating global poliovirus surveillance.

Cessation of Trivalent Oral Poliovirus Vaccine and Introduction of Inactivated Poliovirus Vaccine - Worldwide, 2016.

Since the 1988 World Health Assembly resolution to eradicate poliomyelitis, transmission of the three types of wild poliovirus (WPV) has been sharply reduced (1). WPV type 2 (WPV2) has not been detected since 1999 and was declared eradicated in September 2015. Because WPV type 3 has not been detected since November 2012, WPV type 1 (WPV1) is likely the only WPV that remains in circulation (1). This marked progress has been achieved through widespread use of oral poliovirus vaccines (OPVs), most commonly trivalent OPV (tOPV), which contains types 1, 2, and 3 live, attenuated polioviruses and has been a mainstay of efforts to prevent polio since the early 1960s. However, attenuated polioviruses in OPV can undergo genetic changes during replication, and in communities with low vaccination coverage, can result in vaccine-derived polioviruses (VDPVs) that can cause paralytic polio indistinguishable from the disease caused by WPVs (2). Among the 721 polio cases caused by circulating VDPVs (cVDPVs*) detected during January 2006-May 2016, type 2 cVDPVs (cVDPV2s) accounted for >94% (2). Eliminating the risk for polio caused by VDPVs will require stopping all OPV use. The first stage of OPV withdrawal involved a global, synchronized replacement of tOPV with bivalent OPV (bOPV) containing only types 1 and 3 attenuated polioviruses, planned for April 18-May 1, 2016, thereby withdrawing OPV type 2 from all immunization activities (3). Complementing the switch from tOPV to bOPV, introduction of at least 1 dose of injectable, trivalent inactivated poliovirus vaccine (IPV) into childhood immunization schedules reduces risks from and facilitates responses to cVDPV2 outbreaks. All 155 countries and territories that were still using OPV in immunization schedules in 2015 have reported that they had ceased use of tOPV by mid-May 2016.(†) As of August 31, 2016, 173 (89%) of 194 World Health Organization (WHO) countries included IPV in their immunization schedules.(§) The cessation of tOPV use is a major milestone toward the global goal of eradicating polio; however, careful surveillance for polioviruses and prompt, aggressive responses to polio outbreaks are still needed to realize a polio-free world.

Newly Identified Enterovirus C Genotypes, Identified in the Netherlands through Routine Sequencing of All Enteroviruses Detected in Clinical Materials from 2008 to 2015.

Enteroviruses (EVs) are a group of human and animal viruses that are capable of causing a variety of clinical syndromes. Different genotypes classified into species can be distinguished on the basis of sequence divergence in the VP1 capsid-coding region. Apparently new genotypes are discovered regularly, often as incidental findings in studies investigating respiratory syndromes or as part of poliovirus surveillance. Recently, some EVs have become recognized as significant respiratory pathogens, and a number of new genotypes belonging to species C have been identified. The circulation of these newly identified species C EVs, such as EV-C104, EV-C105, EV-C109, and EV-C117, nevertheless appears to be limited. In this report, we show the results of routine genotyping of all enteroviruses detected in our tertiary care hospital between January 2008 and April 2015. We detected 365 EVs belonging to 40 genotypes. Interestingly, several newly identified species C EVs were detected during the study period. Sequencing of the 5′ untranslated region (5′ UTR) of these viruses shows divergence in this region, which is a target region in many detection assays.

Environmental surveillance of viruses by tangential flow filtration and metagenomic reconstruction.

An approach is proposed for environmental surveillance of poliovirus by concentrating sewage samples with tangential flow filtration (TFF) followed by deep sequencing of viral RNA. Subsequent to testing the method with samples from Finland, samples from Pakistan, a country endemic for poliovirus, were investigated. Genomic sequencing was either performed directly, for unbiased identification of viruses regardless of their ability to grow in cell cultures, or after virus enrichment by cell culture or immunoprecipitation. Bioinformatics enabled separation and determination of individual consensus sequences. Overall, deep sequencing of the entire viral population identified polioviruses, non-polio enteroviruses, and other viruses. In Pakistani sewage samples, adeno-associated virus, unable to replicate autonomously in cell cultures, was the most abundant human virus. The presence of recombinants of wild polioviruses of serotype 1 (WPV1) was also inferred, whereby currently circulating WPV1 of south-Asian (SOAS) lineage comprised two sub-lineages depending on their non-capsid region origin. Complete genome analyses additionally identified point mutants and intertypic recombinants between attenuated Sabin strains in the Pakistani samples, and in one Finnish sample. The approach could allow rapid environmental surveillance of viruses causing human infections. It creates a permanent digital repository of the entire virome potentially useful for retrospective screening of future discovered viruses.

Surveillance Systems to Track Progress Toward Polio Eradication — Worldwide, 2014–2015

Global efforts to eradicate polio began in 1988, and polio-free certification has been achieved in four of the six World Health Organization (WHO) regions. Nigeria was removed from WHO's list of countries with endemic polio in September 2015, achieving an important milestone toward interruption of wild poliovirus (WPV) transmission in the African Region (1). Afghanistan and Pakistan, both in the Eastern Mediterranean Region, were the only countries to report WPV cases in 2015. Previously reported outbreaks caused by WPV importation during 2013-2014 have ended (2,3). The primary means for detecting poliovirus transmission is surveillance for acute flaccid paralysis (AFP) among children aged <15 years (4,5). Stool specimens collected from children with AFP are tested for both WPV and vaccine-derived poliovirus (VDPV) in WHO-accredited laboratories within the Global Polio Laboratory Network (GPLN). In selected locations, AFP surveillance is supplemented with environmental surveillance (testing sewage for poliovirus) (6). Testing of stool and sewage samples includes genomic sequencing to characterize poliovirus isolates; results are used to map poliovirus transmission and identify gaps in AFP surveillance. This report presents poliovirus surveillance data from 2014 and 2015, focusing on the 20 countries in the African Region and six in the Eastern Mediterranean Region that reported a WPV or circulating VDPV (cVDPV) case during 2011-2015, including Guinea, Liberia, and Sierra Leone, which were most affected by the 2014-2015 Ebola virus disease (Ebola) outbreak.

Contribution of Environmental Surveillance Toward Interruption of Poliovirus Transmission in Nigeria, 2012-2015.

Background. Cases of paralysis caused by poliovirus have decreased by >99% since the 1988 World Health Assembly's resolution to eradicate polio. The World Health Organization identified environmental surveillance (ES) of poliovirus in the poliomyelitis eradication strategic plan as an activity that can complement acute flaccid paralysis (AFP) surveillance. This article summarizes key public health interventions that followed the isolation of polioviruses from ES between 2012 and 2015.Methods. The grap method was used to collect 1.75 L of raw flowing sewage every 2–4 weeks. Once collected, samples were shipped at 4°C to a polio laboratory for concentration. ES data were then used to guide program implementation.Results. From 2012 to 2015, ES reported 97 circulating vaccine-derived polioviruses (cVDPV2) and 14 wild polioviruses. In 2014 alone, 54 cVDPV type 2 cases and 1 WPV type 1 case were reported. In Sokoto State, 58 cases of AFP were found from a search of 9426 households. A total of 2 252 059 inactivated polio vaccine and 2 460 124 oral polio vaccine doses were administered to children aged <5 year in Borno and Yobe states.Conclusions. This article is among the first from Africa that relates ES findings to key public health interventions (mass immunization campaigns, inactivated polio vaccine introduction, and strengthening of AFP surveillance) that have contributed to the interruption of poliovirus transmission in Nigeria.

Poliovirus Excretion among Persons with Primary Immune Deficiency Disorders: Summary of Data from Enhanced Poliovirus Surveillance in Egypt, 2011-2014

Background: If exposed to oral poliovirus vaccine (OPV), persons with primary immune deficiency disorders (PID) are at increased risk of paralytic poliomyelitis; and can chronically excrete poliovirus. However, the risk of excretion of vaccine derived poliovirus among immunodeficient persons (iVDPV) is not well characterized. We present summary of data from poliovirus surveillance project among PID patients collected between 2011 and 2014 from 11 Egyptian Governorates. Methods: Stool was tested for polioviruses in suspected or confirmed PID children regardless of whether Acute Flaccid Paralysis (AFP) was present or not. Those excreting poliovirus were followed until three consecutive negative stool samples were obtained. Results: There were 122 patients with suspected or confirmed PID identified; 13/122 (11%) excreted poliovirus; of these, 6 excreted iVDPVs, the remaining 7 excreted Sabin virus. The duration of iVDPV excretion ranged from 1 to 21 months. AFP was detected in 3/6 (50%) of those excreting iVDPVs. All iVDPV excretors had history of receiving OPV. Conclusions: Chronic poliovirus excretion in PID patients is rare, however, poliovirus eradication requires removal of all polioviruses from circulation; and because PID individuals are not necessarily paralyzed they might be missed by current poliovirus surveillance based on detection of AFP. To achieve poliovirus eradication, surveillance for polioviruses among PID patients should be routinely conducted in all countries, and poliovirus antiviral therapy must be made available for those with chronic excretion.

Detection of Polioviruses in Sewage Using Cell Culture and Molecular Methods.

The work presented here demonstrates the utility of a two-step algorithm for environmental poliovirus surveillance based on: preselection of sewage samples tested for the presence of enteroviral genetic material-RT-PCR assay and detection of infectious viruses by cell culture technique (L20B for polioviruses and RD for polio and other non-polio enteroviruses). RD and L20B cell lines were tested to determine their sensitivity for isolation of viruses from environmental samples (sewage). Finally, we wanted to determine if sewage concentration affects the results obtained for RT-PCR and cell cultures.

Quality Assurance in the Polio Laboratory. Cell Sensitivity and Cell Authentication Assays.

The accuracy of poliovirus surveillance is largely dependent on the quality of the cell lines used for virus isolation, which is the foundation of poliovirus diagnostic work. Many cell lines are available for the isolation of enteroviruses, whilst genetically modified L20B cells can be used as a diagnostic tool for the identification of polioviruses. To be confident that cells can consistently isolate the virus of interest, it is necessary to have a quality assurance system in place, which will ensure that the cells in use are not contaminated with other cell lines or microorganisms and that they remain sensitive to the viruses being studied.The sensitivity of cell lines can be assessed by the regular testing of a virus standard of known titer in the cell lines used for virus isolation. The titers obtained are compared to previously obtained titers in the same assay, so that any loss of sensitivity can be detected.However, the detection of cell line cross contamination is more difficult. DNA bar coding is a technique that uses a short DNA sequence from a standardized position in the genome as a molecular diagnostic assay for species-level identification. For almost all groups of higher animals, the cytochrome c oxidase subunit 1 of mitochondrial DNA (CO1) is emerging as the standard barcode region. This region is 648 nucleotide base pairs long in most phylogenetic groups and is flanked by regions of conserved sequences, making it relatively easy to isolate and analyze. DNA barcodes vary among individuals of the same species to a very minor degree (generally less than 1-2 %), and a growing number of studies have shown that the COI sequences of even closely related species differ by several per cent, making it possible to identify different species with high confidence.

Environmental Surveillance of Polioviruses in Rio de Janeiro, Brazil, in Support to the Activities of Global Polio Eradication Initiative.

Wild polioviruses still remain endemic in three countries (Afghanistan, Pakistan, and Nigeria) and re-emergency of wild polio has been reported in previously polio-free countries. Environmental surveillance has been used as a supplementary tool in monitoring the circulation of wild poliovirus (PVs) and/or vaccine-derived PVs even in the absence of acute flaccid paralysis cases. This study aimed to monitor the presence of polioviruses in wastewater samples collected at one wastewater treatment plant located in the municipality of Rio de Janeiro, Brazil. From December 2011 to June 2012 and from September to December 2012, 31 samples were collected and processed. RD and L20B cell cultures were able to isolate PVs and non-polio enteroviruses in 27/31 samples. Polioviruses were isolated in eight samples (type 1 Sabin = 1, type 2 Sabin = 5, and type 3 Sabin = 2). Vaccine-derived polioviruses were not detected nor evidence of recombination with other PVs or non-polio enterovirus serotypes were observed among the isolates. The Sabin-related serotypes 2 and 3 presented nucleotide substitutions in positions associated with the neurovirulent phenotype at the 5′-UTR. Changes in important Amino acid residues at VP1 were also observed in the serotypes 2 and 3. Environmental surveillance has been used successfully in monitoring the circulation of PVs and non-polio enteroviruses and it is of crucial importance in the final stages of the WHO global polio eradication initiative. Our results show the continuous circulation of Sabin-like PVs and non-polio enteroviruses in the analyzed area during the study period.

Polio eradication in the African Region on course despite public health emergencies

The World Health Organization, African Region is heading toward eradication of the three types of wild polio virus, from the Region. Cases of wild poliovirus (WPV) types 2 and 3 (WPV2 and WPV3) were last reported in 1998 and 2012, respectively, and WPV1 reported in Nigeria since July 2014 has been the last in the entire Region. This scenario in Nigeria, the only endemic country, marks a remarkable progress. This significant progress is as a result of commitment of key partners in providing the much needed resources, better implementation of strategies, accountability, and innovative approaches. This is taking place in the face of public emergencies and challenges, which overburden health systems of countries and threaten sustainability of health programmes. Outbreak of Ebola and other diseases, insecurity, civil strife and political instability led to displacement of populations and severely affected health service delivery. The goal of eradication is now within reach more than ever before and countries of the region should not relent in their efforts on polio eradication. WHO and partners will redouble their efforts and introduce better approaches to sustain the current momentum and to complete the job. The carefully planned withdrawal of oral polio vaccine type II (OPV2) with an earlier introduction of one dose of inactivated poliovirus vaccine (IPV), in routine immunization, will boost immunity of populations and stop cVDPVs. Environmental surveillance for polio viruses will supplement surveillance for AFP and improve sensitivity of detection of polio viruses.

Respiratory viruses in children attending Kindergarten

No: 1626 Presentation at ESCV 2015: Oral 16 Routine sequencing of enteroviruses in clinical materials identifies the presence of new Group-C enterovirus types in the Netherlands C.C. Van Leer-Buter1,∗, R. Poelman1, R. Borger1, J. Weel2, C.H. Benne3, H.G.M. Niesters1 1 Division of Clinical Virology, Department of Medical Microbiology, University of Groningen, The Netherlands 2 Izore, Laboratory for Medical Microbiology, Leeuwarden, The Netherlands 3 CERTE Laboratory for Infectious Diseases, Groningen, The Netherlands Background: Enteroviruses (EV) that infect humans belong to four EV groups (A–D) while the rhinoviruses can be divided into three genogroups (A–C). While rhinoviruses are seen primarily as respiratory pathogens, EV can cause a wide variety of diseases in affecting different organ systems, The fact that respiratory infections may be caused by EV infections has been clear since the identification of EV-D68 in 1962. During the summer and fall of 2014, the largest EV-D68 outbreak took place in the USA and it was shown that the strains of the EV-D68 outbreak in North America also circulated in Europe. EV types are defined by sequence divergence in the VP-1 capsid coding region. Ongoing mutations and recombination of the viruses is causing the appearance of new EV types. The newest additions to the expanding cloud of EV typeswere identified either as new variants found in the poliovirus surveillance programs or in respiratory secretions that were sampled as part of studies investigating respiratory viruses. Methods: During a four-year period, all samples from patients with clinical presentations compatible with EV infections were screened using a laboratory-developed test All EV isolates were subsequently genotyped by sequencing the VP1 region. To complete the data with samples from secondary hospital care and general practice, EV isolates from two regional laboratories were included in the routine genotyping program. Results: Enteroviruses were detected in 657 clinical samples, and genotypes could be obtained from 607. EV was detected in 88 CSF samples, 7 vesicular fluids, 13 plasma and serum samples, 85 respiratory samples, and in 338 fecal samples. 76were unidentified materials from general practice. Genotypes from all four EV groups were found with EV-D68 being the only representative of group D. Group C enteroviruses were found either in respiratory samples and/or fecal samples. In respiratory materials, we found the following group C enteroviruses: CV-A21 (n=4), EV-C104 (n=1), EV-C105 (n=1), EV-C109 (n=5), and EV-C117 (n=1). Phylogenetic analysis shows that the four CV-A21 isolates are similar to the isolates found in North America in 2006. The EV-C109 isolates show 8–10% divergence from the other stains identified to date. Conclusion: Enteroviruses are increasingly identified as causes or respiratory disease. Routine screening followed by sequencing provides essential information about which enteroviruses are circulating and how new genotypes evolve. http://dx.doi.org/10.1016/j.jcv.2015.07.026 Abstract No: 1519 Presentation at ESCV 2015: Oral 17 Respiratory viruses in children attending Kindergarten N. Moe1,∗, L.H. Skanke1, S.A. Nordbo2, S. Krokstad2, A. Smyrnaios1, H. Dollner1 1 Department of Pediatrics, St. Olavs Hospital, Trondheim University Hospital, Norway 2 Department of Medical Microbiology, St. Olavs Hospital, Trondheim University Hospital, Norway Background: Many studies have investigated the prevalence of respiratory viruses in hospitalized children, but little is known about this prevalence outside hospitals. Methods: We examined 1–6 years old children attending 2 kindergartens four times from 2012 to 2014 and included a total of 379 cases. Near 80% of all children participated in the study. The children were clinically examined by a pediatrician for signs of respiratory tract infection (RTI). A nasopharyngeal swap was used to collect a nasopharyngeal secrete (NPS) at each examination and was analyzed by in-house real-time PCRs for a panel of 16 respiratory viruses. Results: NPS was positive for at least one virus in 42.5% of the cases, of which 30.6% had one virus and 11.9% had two or more viruses. Rhinovirus was detected in 24.2% of the samples, enterovirus in 11.7% and parechovirus in 8.7%. Adenovirus, human bocavirus, coronavirus-OC43/NL63/229E, influenza A and B virus, human metapneumovirus, parainfluenza virus type 1–4 and RSV were each detected in 0.3–2.6% of the samples. In two-thirds of the examinations, the children had clinically signs of a RTI. Children with clear signs of a RTI had frequently 1 or more viruses (70%), compared to childrenwith amilder RTI (40%) and childrenwithout signs of RTI (28%) (p<0.001). Conclusions:This is thefirstNorwegian study screeningkindergarten children with an extensive panel of respiratory viruses along with clinical examination. Surprisingly two-thirds of children attending Norwegian kindergartens had mild or clear signs of an upper respiratory tract infection. Our results furthermore showed a high prevalence of picornaviruses (rhino-, enteroand parechovirus) in childrenwith RTI, but even childrenwithout signs of RTI had often a positive PCR-test for picornaviruses. http://dx.doi.org/10.1016/j.jcv.2015.07.027

Modeling undetected live poliovirus circulation after apparent interruption of transmission: implications for surveillance and vaccination.

BackgroundMost poliovirus infections occur with no symptoms and this leads to the possibility of silent circulation, which complicates the confirmation of global goals to permanently end poliovirus transmission. Previous simple models based on hypothetical populations assumed perfect detection of symptomatic cases and suggested the need to observe no paralytic cases from wild polioviruses (WPVs) for approximately 3-4 years to achieve 95% confidence about eradication, but the complexities in real populations and the imperfect nature of surveillance require consideration.MethodsWe revisit the probability of undetected poliovirus circulation using a more comprehensive model that reflects the conditions in a number of places with different characteristics related to WPV transmission, and we model the actual environmental WPV detection that occurred in Israel in 2013. We consider the analogous potential for undetected transmission of circulating vaccine-derived polioviruses. The model explicitly accounts for the impact of different vaccination activities before and after the last detected case of paralytic polio, different levels of surveillance, variability in transmissibility and neurovirulence among serotypes, and the possibility of asymptomatic participation in transmission by previously-vaccinated or infected individuals.ResultsWe find that prolonged circulation in the absence of cases and thus undetectable by case-based surveillance may occur if vaccination keeps population immunity close to but not over the threshold required for the interruption of transmission, as may occur in northwestern Nigeria for serotype 2 circulating vaccine-derived poliovirus in the event of insufficient tOPV use. Participation of IPV-vaccinated individuals in asymptomatic fecal-oral transmission may also contribute to extended transmission undetectable by case-based surveillance, as occurred in Israel. We also find that gaps or quality issues in surveillance could significantly reduce confidence about actual disruption. Maintaining high population immunity and high-quality surveillance for several years after the last detected polio cases will remain critical elements of the polio end game.ConclusionsCountries will need to maintain vigilance in their surveillance for polioviruses and recognize that their risks of undetected circulation may differ as a function of their efforts to manage population immunity and to identify cases or circulating live polioviruses.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-015-0791-5) contains supplementary material, which is available to authorized users.

Prevalence of human cosaviruses in Tunisia, North Africa.

A new picornavirus, named human Cosavirus (HCoSV) was isolated recently from stools of children with acute flaccid paralysis (AFP) and healthy children in Pakistan and Afghanistan. Since then, it was also isolated from patients from other countries. Five species are presently identified forming a new genus in the Picornaviridae family. This study reports the detection of HCoSV in stool specimens collected as part of the National Poliovirus surveillance Program in Tunisia, between 2011 and 2012, from patients with AFP and healthy individuals among their contacts. One hundred and ninety four stool samples were investigated by RT-PCR in the 5' non-coding region of the genome. A total of 64 specimens (33%) tested positive for HCoSV. HCoSV positive specimens were found in 36 cases with neurological syndromes and 28 of their healthy contacts. The highest rate of HCoSV infection (62.5%) occurred in children younger than 6 years of age. The sampling date of stool specimens suggested that HCoSV infection occurred regularly over time. Also, the sampling origin of stool specimen showed that HCoSV infection was detected in almost all the governorates of Tunisia from the North to the South of the country. This study is the first report of HCoSV prevalence in the North African region. It contributes to a better knowledge on the geographic distribution and the epidemiology of these viruses.

Environmental surveillance of poliovirus in sewage water around the introduction period for inactivated polio vaccine in Japan.

Environmental virus surveillance was conducted at two independent sewage plants from urban and rural areas in the northern prefecture of the Kyushu district, Japan, to trace polioviruses (PVs) within communities. Consequently, 83 PVs were isolated over a 34-month period from April 2010 to January 2013. The frequency of PV isolation at the urban plant was 1.5 times higher than that at the rural plant. Molecular sequence analysis of the viral VP1 gene identified all three serotypes among the PV isolates, with the most prevalent serotype being type 2 (46%). Nearly all poliovirus isolates exhibited more than one nucleotide mutation from the Sabin vaccine strains. During this study, inactivated poliovirus vaccine (IPV) was introduced for routine immunization on 1 September 2012, replacing the live oral poliovirus vaccine (OPV). Interestingly, the frequency of PV isolation from sewage waters declined before OPV cessation at both sites. Our study highlights the importance of environmental surveillance for the detection of the excretion of PVs from an OPV-immunized population in a highly sensitive manner, during the OPV-to-IPV transition period.

Environmental Surveillance for Poliovirus in Polio High Risk States of Nigeria, 2011- 2012

Introduction: Nigeria is one of the three polio endemic countries in the world along Pakistan and Afghanistan. The detection of persons with Acute Flaccid Paralysis (AFP) and testing of stool specimens from these patients is the surveillance standard for detection of poliovirus. World Health Organization recommends complementary surveillance by testing sewage samples and stool of healthy children. Kano is the epi-center of polio in Nigeria. Environmental surveillance was introduced in June 2011 in Kano State and in April 2012 in Sokoto State. Methods: Grab method was used to collect sewage samples by trained environmental health workers. The samples were tested in Ibadan Polio Laboratory which is part of the Global Polio Laboratory Network. The Samples were concentrated using the two-phase separation method. Isolation of Poliovirus was carried out in RD and L20B cell lines. Poliovirus identification was done using the micro neutralization techniques. Results: In Kano State, from week 28 of 2011 to week 52 of 2012, a total of 60 samples were collected. In Sokoto State, from week 13 – 52 of 2012, a total of 80 sewage samples were collected from four sewage sites. In Kano and Sokoto, 62 and 93 single or mixed isolates were detected from the samples. In Kano, 39 (63%) of the isolates were Sabin viruses, 16 (26%) were circulating vaccine derived polio viruses type 2 (cVDPV2), 2 (3%) were wild polio virus type 1 (WPV1), 4 (6%) were non polio enteroviruses (NPENT) and 1 (3%) were wild polio virus type 3 (WPV3). In Sokoto, 33 (35%) of the isolates were cVDPV2, 27 (29%) were Sabin viruses, 16 (17%) were wild virus type 1 and 17 (18%) were non polio enteroviruses. No wild virus type 3 was detected from AFP cases and environmental samples in Sokoto State in 2012. Conclusion: The results confirm the prevailing immunity gap in polio high risk areas of Nigeria and pronounced immunity gap against type 2 polio virus in Sokoto. Long distance travelers such as nomads play important role in disseminating poliovirus. Special focus should be given to reach and vaccinate such underserved and migrant communities. In addition to the national campaigns with bivalent oral polio vaccine (bOPV) and trivalent oral polio vaccine (tOPV), an aggressive strategy should be adopted to mop up any detection of cVDPV in cases, contacts, or the environment.

Poliovirus excretion among persons with primary immune deficiency disorders: summary of a seven-country study series.

Persons with primary immune deficiency disorders (PID), especially those disorders affecting the B-cell system, are at substantially increased risk of paralytic poliomyelitis and can excrete poliovirus chronically. However, the risk of prolonged or chronic excretion is not well characterized in developing countries. We present a summary of a country study series on poliovirus excretion among PID cases. Cases with PID from participating institutions were enrolled during the first year and after obtaining informed consent were tested for polioviruses in stool samples. Those cases excreting poliovirus were followed on a monthly basis during the second year until 2 negative stool samples were obtained. A total of 562 cases were enrolled in Bangladesh, China, Iran, Philippines, Russia, Sri Lanka, and Tunisia during 2008-2013. Of these, 17 (3%) shed poliovirus, including 2 cases with immunodeficient vaccine-derived poliovirus. Poliovirus was detected in a single sample from 5/17 (29%) cases. One case excreted for more than 6 months. None of the cases developed paralysis during the study period. Chronic polioviruses excretion remains a rare event even among individuals with PID. Nevertheless, because these individuals were not paralyzed they would have been missed by current surveillance; therefore, surveillance for polioviruses among PID should be established.

Prevalence of asymptomatic poliovirus infection in older children and adults in northern India: analysis of contact and enhanced community surveillance, 2009.

In 2009, enhanced poliovirus surveillance was established in polio-endemic areas of Uttar Pradesh and Bihar, India, to assess poliovirus infection in older individuals. In Uttar Pradesh, stool specimens from asymptomatic household and neighborhood contacts of patients with laboratory-confirmed polio were tested for polioviruses. In Bihar, in community-based surveillance, children and adults from 250 randomly selected households in the Kosi River area provided stool and pharyngeal swab samples that were tested for polioviruses. A descriptive analysis of surveillance data was performed. In Uttar Pradesh, 89 of 1842 healthy contacts of case patients with polio (4.8%) were shedding wild poliovirus (WPV); 54 of 85 (63.5%) were ≥5 years of age. Shedding was significantly higher in index households than in neighborhood households (P<.05). In Bihar, 11 of 451 healthy persons (2.4%) were shedding WPV in their stool; 6 of 11 (54.5%) were ≥5 years of age. Mean viral titer was similar in older and younger children. A high proportion of persons≥5 years of age were asymptomatically shedding polioviruses. These findings provide indirect evidence that older individuals could have contributed to community transmission of WPV in India. Polio vaccination campaigns generally target children<5 years of age. Expanding this target age group in polio-endemic areas could accelerate polio eradication.