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

Experience and findings from surveillance peer review in Nigeria, August 2017-May 2019

Introduction

acute flaccid paralysis (AFP) surveillance is the gold standard of the Global Polio Eradication Initiative (GPEI) for detecting cases of poliomyelitis and tracking poliovirus transmission. Nigeria's AFP surveillance performance indicators are among the highest in countries of the World Health Organization (WHO) African Region. The primary AFP surveillance performance indicators are the rate of non-polio AFP among children and the proportion of timely, adequate specimen collection. The surveillance working group of the National Emergency Operations Centre assessed the quality of AFP surveillance data in some reportedly high-performing states.

Methods

we conducted a retrospective review of AFP surveillance performance indicators in Nigeria for 2010-2019. We also reviewed data in reports from four groups of surveillance peer reviews and validation visits (conducted by in-country GPEI partners) during August 2017-May 2019 in 16 states with high primary AFP surveillance indicators; the validation visits reviewed clinical information and the dates of specimen collection and onset of paralysis with caretakers.

Results

there were consistently increasing AFP surveillance primary performance indicators during 2010-2016, followed by declines during 2017-2019. From the data for 16 states with peer reviews conducted from August 2017-May 2019, overall concordance of reported and "true" (validated) AFP indicator data in peer review investigations was highly variable. True AFP concordance ranged from 58%-100%, and stool timeliness concordance ranged from 56%-95%. The most common clinical causes of reported AFP cases that were not true AFP were spastic paralysis, malaria, sickle cell disease, and malnutrition. All the states that participated in peer reviews developed surveillance improvement plans based on the gaps identified.

Conclusion

Nigeria has highly sensitive AFP surveillance according to reported primary AFP performance indicators. The findings of peer reviews indicate that the AFP surveillance system needs to be strengthened and well-supervised to enhance data quality.

Molecular evolution and antigenic drift of type 3 iVDPVs excreted from a patient with immunodeficiency in Ningxia, China

A 2.5-year-old pediatric patient with acute flaccid paralysis was diagnosed with primary immunodeficiency (PID) in Ningxia Province, China, in 2011. Twelve consecutive stool specimens were collected from the patient over a period of 10 months (18 February 2011 to 20 November 2011), and 12 immunodeficiency vaccine-derived poliovirus (iVDPV) strains (CHN15017-1 to CHN15017-12) were subsequently isolated. Nucleotide sequencing analysis of the plaque-purified iVDPVs revealed 2%-3.5% VP1-region differences from their parental Sabin 3 strain. Full-length genome sequencing showed they were all Sabin 3/Sabin 1 recombinants, sharing a common 2C-region crossover site, and the two key determinants of attenuation (U472C in the 5' untranslated region and T2493C in the VP1 region) had reverted. Temperature-sensitive experiments demonstrated that the first two iVDPV strains partially retained the temperature-sensitive phenotype's nature, while the subsequent ten iVDPV strains distinctly lost it, possibly associated with increased neurovirulence. Nineteen amino-acid substitutions were detected between 12 iVDPVs and the parental Sabin strain, of which only one (K1419R) was found on the subsequent 10 iVDPV isolates, suggesting this site's potential as a temperature-sensitive determination site. A Bayesian Monte Carlo Markov Chain phylogenetic analysis based on the P1 coding region yielded a mean iVDPV evolutionary rate of 1.02 × 10^-2 total substitutions/site/year, and the initial oral-polio-vaccine dose was presumably administered around June 2009. Our findings provide valuable information regarding the genetic structure, high-temperature growth sensitivity, and antigenic properties of iVDPVs following long-term evolution in a single PID patient, thus augmenting the currently limited knowledge regarding the dynamic changes and evolutionary pathway of iVDPV populations with PID during long-term global replication.

Building-level wastewater surveillance of SARS-CoV-2 is associated with transmission and variant trends in a university setting

The University of South Carolina (UofSC) was among the first universities to include building-level wastewater surveillance of SARS-CoV-2 to complement clinical testing during its reopening in the Fall 2020 semester. In the Spring 2021 semester, 24h composite wastewater samples were collected twice per week from 10 residence halls and the on-campus student isolation and quarantine building. The isolation and quarantine building served as a positive control site. The wastewater was analyzed using RT-ddPCR for the quantification of nucleocapsid genes (N1 and N2) to identify viral transmission trends within residence halls. Log₁₀ SARS-CoV-2 RNA concentrations were compared to both new clinical cases identified in the days following wastewater collection and recovered cases returning to sites during the days preceding sample collection to test temporal and spatial associations. There was a statistically significant positive relationship between the number of cases reported from the sites during the seven-day period following wastewater sampling and the log₁₀ viral RNA copies/L (overall IRR 1.08 (1.02, 1.16) p-value 0.0126). Additionally, a statistically significant positive relationship was identified between the number of cases returning to the residence halls after completing isolation during the seven-day period preceding wastewater sampling and the log₁₀ viral RNA copies/L (overall 1.09 (1.01, 1.17) p-value 0.0222). The statistical significance of both identified cases and recovered return cases on log₁₀ viral RNA copies/L in wastewater indicates the importance of including both types of clinical data in wastewater-based epidemiology (WBE) research. Genetic mutations associated with variants of concern (VOCs) were also monitored. The emergence of the Alpha variant on campus was identified, which contributed to the second wave of COVID-19 cases at UofSC. The study was able to identify sub-community transmission hotspots for targeted intervention in real-time, making WBE cost-effective and creating less of a burden on the general public compared to repeated individual testing methods.

Sustained detection of type 2 poliovirus in London sewage between February and July, 2022, by enhanced environmental surveillance

BACKGROUND

The international spread of poliovirus exposes all countries to the risk of outbreaks and is designated a Public Health Emergency of International Concern by WHO. This risk can be exacerbated in countries using inactivated polio vaccine, which offers excellent protection against paralysis but is less effective than oral vaccine against poliovirus shedding, potentially allowing circulation without detection of paralytic cases for long periods of time. Our study investigated the molecular properties of type 2 poliovirus isolates found in sewage with an aim to detect virus transmission in the community.

METHODS

We performed environmental surveillance in London, UK, testing sewage samples using WHO recommended methods that include concentration, virus isolation in cell culture, and molecular characterisation. We additionally implemented direct molecular detection and determined whole-genome sequences of every isolate using novel nanopore protocols.

FINDINGS

118 genetically linked poliovirus isolates related to the serotype 2 Sabin vaccine strain were detected in 21 of 52 sequential sewage samples collected in London between Feb 8 and July 4, 2022. Expansion of environmental surveillance sites in London helped localise transmission to several boroughs in north and east London. All isolates have lost two key attenuating mutations, are recombinants with a species C enterovirus, and an increasing proportion (20 of 118) meet the criterion for a vaccine-derived poliovirus, having six to ten nucleotide changes in the gene coding for VP1 capsid protein.

INTERPRETATION

Environmental surveillance allowed early detection of poliovirus importation and circulation in London, permitting a rapid public health response, including enhanced surveillance and an inactivated polio vaccine campaign among children aged 1-9 years. Whole-genome sequences generated through nanopore sequencing established linkage of isolates and confirmed transmission of a unique recombinant poliovirus lineage that has now been detected in Israel and the USA.

FUNDING

Medicines and Healthcare products Regulatory Agency, UK Health Security Agency, Bill & Melinda Gates Foundation, and National Institute for Health Research Medical Research Council.

Wastewater Surveillance for Infectious Disease: A Systematic Review

Wastewater surveillance for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been shown to be a valuable source of information regarding SARS-CoV-2 transmission and coronavirus disease 2019 (COVID-19) cases. Although the method has been used for several decades to track other infectious diseases, there has not been a comprehensive review outlining all of the pathogens that have been surveilled through wastewater. Herein we identify the infectious diseases that have been previously studied via wastewater surveillance prior to the COVID-19 pandemic. Infectious diseases and pathogens were identified in 100 studies of wastewater surveillance across 38 countries, as were themes of how wastewater surveillance and other measures of disease transmission were linked. Twenty-five separate pathogen families were identified in the included studies, with the majority of studies examining pathogens from the family Picornaviridae, including polio and nonpolio enteroviruses. Most studies of wastewater surveillance did not link what was found in the wastewater to other measures of disease transmission. Among those studies that did, the value reported varied by study. Wastewater surveillance should be considered as a potential public health tool for many infectious diseases. Wastewater surveillance studies can be improved by incorporating other measures of disease transmission at the population-level including disease incidence and hospitalizations.

Epidemiological surveillance of enteric viral diseases using wastewater in Africa - A rapid review

Viral enteric pathogens remain an important cause of diarrhoeal outbreaks among children in sub-Saharan Africa (SSA). Consequently, diarrhoeal illness remains a significant cause of morbidity and mortality in the under-fives in SSA. These outbreaks associated with viral pathogens tend to be seasonal and early warning systems for impending outbreaks could be very crucial for triggering preventive public health response and building public health resilience to deal with increased demand for medical services. Wastewater surveillance for pathogens is an important epidemiological component that could inform early warning systems. The objective of this rapid review was to evaluate the use of wastewater for epidemiology surveillance of enteric viral pathogens. Nine studies met the inclusion criteria. Eight viral pathogens were reviewed and analysed from 6 countries that performed wastewater analysis. Six studies explored the epidemiologic significance of viral pathogens in wastewater. The findings of this review revealed that monitoring of wastewater can provide an additional tool to determine the epidemiology of viral pathogens circulating in the community thereby providing early warning of potential outbreaks using wastewater-based epidemiology methods. Five of the included studies revealed the occurrence of viral pathogens in raw sewage and treated wastewater as an indication of inefficient elimination of viruses leading to potential release into water sources which presents a public health risk, increasing the risk of inducing gastroenteritis in the population. Six studies revealed the need for public health authorities to realise the potential benefit of environmental surveillance (ES) as an additional tool to determine the epidemiology of viral pathogens circulating in each community. Despite the significant public health challenge associated with enteric viral pathogens in sub-Saharan Africa, there remains remarkable underinvestment in potentially epidemiologically beneficial research, including wastewater-based epidemiology for these infections.

Progress toward poliomyelitis eradication in Kano State, Nigeria, 2010 - 2017

Introduction

Kano State in Northern Nigeria was a major source of Wild Polio Virus (WPV) cases in Nigeria up until 2015. In 2009, the State reported 168 WPV cases out of the 388 reported nationally. This paper characterizes the progress made by Kano State in polio eradication.

Methods

In December 2017, we conducted a descriptive review of Routine Immunization (RI) from both the District Vaccine Data Management Tool (DVD-MT) and District Health Information System (DHIS2) from 2010 to 2017. Also, we reviewed the Acute Flaccid Paralysis (AFP) and Supplementary Immunization Activities (SIAs) data reported for Kano State from 2010 to 2017. Also, we obtained the number of reported WPV cases by serotypes.

Results

From 2010 to 2017, a total of 65 confirmed WPV cases were reported in Kano State. Of these, 58 (89%) were WPV1 and 7 (11%) WPV3. Almost half of these cases were reported in 2012 from 14 LGAs. The number of reported cases fell to 15 (23%) in 10 LGAs in 2013, and further decreased to 5 (8%) in four LGAs in 2014. No new WPV cases have been detected in Kano since 2015. During the same period, 23 circulating Vaccine Derived Polio Viruses (cVDPV2) cases were reported in Kano. Specifically, 10 LGAs reported 10 cases in 2011. Three LGAs reported three cases in 2012, while eight LGAs reported 10 total cases in 2014. During the 2010 to 2017 period 61 SIAs were conducted.

Conclusion

Kano State made progress toward polio eradication. Sustained eradication efforts, in form of high quality RI, SIAs and AFP surveillance are necessary to avert possible importation from 2016 polio resurgence in nearby Borno State, Nigeria.

The importance of molecular diagnostics for infectious diseases in low-resource settings

In settings with limited resources and a wide range of possible etiologies, molecular technologies offer an effective solution for infectious disease diagnostics, because they are agile, fast and flexible. Health systems that routinely use molecular diagnostics will achieve economies of scale, maximize limited expertize and rapidly respond to new threats.

Environmental Surveillance for Polioviruses in Haïti (2017-2019): The Dynamic Process for the Establishment and Monitoring of Sampling Sites

Haïti is at risk for wild poliovirus (WPV) importation and circulation, as well as vaccine-derived poliovirus (VDPV) emergence. Environmental surveillance (ES) for polioviruses was established in Port au Prince and Gonaïves in 2016. During 2017–2019, initial ES sites were re-evaluated, and ES was expanded into Cap Haïtien and Saint Marc. Wastewater samples and data on weather, hour of collection, and sample temperature and pH were collected every 4 weeks during March 2017–December 2019 (272 sampling events) from 21 sites in Cap Haïtien, Gonaïves, Port au Prince, and Saint Marc. Samples were processed for the detection of polio and non-polio enteroviruses using the two-phase and “Concentration and Filter Elution” methodologies. Polioviruses were serotyped and underwent intra-typic characterization. No WPV or VDPVs were isolated. Sabin-like polioviruses (oral vaccine strain) of serotypes 1 and 3 were sporadically detected. Five of six (83%), one of six (17%), five of six (83%), and two of three (67%) sites evaluated in Cap Haïtien, Gonaïves, Port au Prince, and Saint Marc, respectively, had enterovirus isolation from >50% of sampling events; these results and considerations, such as watershed population size and overlap, influence of sea water, and excessive particulates in samples, were factors in site retention or termination. The evaluation of 21 ES sampling sites in four Haïtian cities led to the termination of 11 sites. Every-four-weekly sampling continues at the remaining 10 sites across the four cities as a core Global Polio Eradication Initiative activity.

Disease Surveillance Investments and Administration: Limits to Information Value in Pakistan Polio Eradication

In Pakistan, annual poliovirus investment decisions drive quantities of supplemental immunization campaigns districts receive. In this article, we assess whether increased spending on poliovirus surveillance is associated with greater likelihood of correctly identifying districts at high risk of polio with assignment of an elevated "risk ranking." We reviewed programmatic documents from Pakistan for the period from 2012-2017, recording whether districts had been classified as "high risk" or "low risk" in each year. Through document review, we developed a decision tree to describe the ranking decisions. Then, integrating data from the World Health Organization and Global Polio Eradication Initiative, we constructed a Bayesian decision network reflecting investments in polio surveillance and immunization campaigns, surveillance metrics, disease incidence, immunization rates, and occurrence of polio cases. We test these factors for statistical association with the outcome of interest-a change in risk rank between the beginning and the end of the one-year time period. We simulate different spending scenarios and predict their impact on district risk ranking in future time periods. We find that per district spending increases are associated with increased identification of cases of acute flaccid paralysis (AFP). However, the low specificity of AFP investment and the largely invariant ranking of district risk means that even large increases in surveillance spending are unlikely to promote major changes in risk rankings at the current stage of the Pakistan polio eradication campaign.

A multi-pronged scoping review approach to understanding the evolving implementation of the Smallpox and Polio eradication programs: what can other Global Health initiatives learn?

BACKGROUND

Previous initiatives have aimed to document the history and legacy of the Smallpox Eradication Program (SEP) and the Global Polio Eradication Initiative (GPEI). In this multi-pronged scoping review, we explored the evolution and learning from SEP and GPEI implementation over time at global and country levels to inform other global health programs.

METHODS

Three related reviews of literature were conducted; we searched for documents on 1) the SEP and 2) GPEI via online database searches and also conducted global and national-level grey literature searches for documents related to the GPEI in seven purposively selected countries under the Synthesis and Translation of Research and Innovations from Polio Eradication (STRIPE) project. We included documents relevant to GPEI implementation. We conducted full text data analysis and captured data on Expert Recommendations for Implementing Change (ERIC) implementation strategies and principles, tools, outcomes, target audiences, and relevance to global health knowledge areas.

RESULTS

200 articles were included in the SEP scoping review, 1885 articles in the GPEI scoping review, and 963 documents in the grey literature review. M&E and engagement strategies were consistently translated from the SEP to GPEI; these evolved into newer approaches under the GPEI. Management strategies including setting up robust record systems also carried forward from SEP to GPEI; however, lessons around the need for operational flexibility in applying these strategies at national and sub-national levels did not. Similarly, strategies and lessons around conducting health systems readiness assessments prior to implementation were not carried forward from SEP to GPEI. Differences in the planning and communication strategies between the two programs included fidelity to implementation blueprints appeared to be higher under SEP, and independent monitoring boards and communication and media strategies were more prominent under GPEI.

CONCLUSIONS

Linear learning did not always occur between SEP and GPEI; several lessons were lost and had to be re-learned. Implementation and adaptation of strategies in global health programs should be well codified, including information on the contextual, time and stakeholders' issues that elicit adaptations. Such description can improve the systematic translation of knowledge, and gains in efficiency and effectiveness of future global health programs.

Outcomes of the Deployment of the Auto-Visual Acute Flaccid Paralysis Detection and Reporting (AVADAR) System for Strengthening Polio Surveillance in Africa From 2017 to 2018: Evaluation Study

Background

As we move toward a polio-free world, the challenge for the polio program is to create an unrelenting focus on smaller areas where the virus is still present, where children are being repeatedly missed, where immunity levels are low, and where surveillance is weak.

Objective

This article aimed to describe a possible solution to address weak surveillance systems and document the outcomes of the deployment of the Auto-Visual Acute Flaccid Paralysis Detection and Reporting (AVADAR) project.

Methods

This intervention was implemented in 99 targeted high-risk districts with concerns for silent polio circulation from eight countries in Africa between August 1, 2017, and July 31, 2018. A total of 6954 persons (5390 community informants and 1564 health workers) were trained and equipped with a smartphone on which the AVADAR app was configured to allow community informants to send alerts on suspected acute flaccid paralysis (AFP) and allow health worker to use electronic checklists for investigation of such alerts. The AVADAR and Open Data Kit ONA servers were at the center of the entire process. A dashboard system and coordination teams for monitoring and supervision were put in place at all levels.

Results

Overall, 96.44% (24,142/25,032) of potential AFP case alerts were investigated by surveillance personnel, yielding 1414 true AFP cases. This number (n=1414) reported through AVADAR was higher than the 238 AFP cases expected during the study period in the AVADAR districts and the 491 true AFP cases reported by the traditional surveillance system. A total of 203 out of the 1414 true AFP cases reported were from special population settings, such as refugee camps and insecure areas. There was an improvement in reporting in silent health areas in all the countries using the AVADAR system. Finally, there were 23,473 reports for other diseases, such as measles, diarrhea, and cerebrospinal meningitis, using the AVADAR platform.

Conclusions

This article demonstrates the added value of AVADAR to rapidly improve surveillance sensitivity. AVADAR is capable of supporting countries to improve surveillance sensitivity within a short interval before and beyond polio-free certification.

Could Water and Sanitation Shortfalls Exacerbate SARS-CoV-2 Transmission Risks?

SARS-CoV-2, the etiologic agent of COVID-19, is shed in stool. SARS coronaviruses have been detected in wastewater during outbreaks in China, Europe, and the United States. In this perspective, we outline the risk fecal shedding poses at locations without safely managed sanitation, as in most of Nigeria where we work. We believe that feco-oral transmission could occur if community transmission becomes high and sustained in densely populated cities without proper sanitation in Nigeria and many other African and Asian settings. In the absence of basic sanitation, or where existing sanitation is not safely managed, groundwater, which is often drawn up from wells and boreholes for drinking and household use, can become contaminated with enteric bacteria and viruses from fecal matter. Endemic and epidemic transmission of multiple feco-oral pathogens via this route continues to be documented in areas without safely managed sanitation, and, therefore, the risk of SARS-CoV-2 transmission needs to be evaluated, tracked, and forestalled in such settings. We suggest that fecal matter from treatment facilities and recovered patients should be carefully and properly disposed. Furthermore, environmental surveillance of SARS-CoV-2 in wastewater and accumulated human waste, as well as efforts to mitigate the virus’ entry into unprotected household water sources, should be a priority part of the COVID-19 response in settings without safely managed sanitation for the duration of the pandemic.

Progress Toward Poliomyelitis Eradication - Nigeria, January 2018-May 2019

The number of wild poliovirus (WPV) cases in Nigeria decreased from 1,122 in 2006 to six WPV type 1 (WPV1) in 2014 (1). During August 2014-July 2016, no WPV cases were detected; during August-September 2016, four cases were reported in Borno State. An insurgency in northeastern Nigeria had resulted in 468,800 children aged <5 years deprived of health services in Borno by 2016. Military activities in mid-2016 freed isolated families to travel to camps, where the four WPV1 cases were detected. Oral poliovirus vaccine (OPV) campaigns were intensified during August 2016-December 2017; since October 2016, no WPV has been detected (2). Vaccination activities in insurgent-held areas are conducted by security forces; however, 60,000 unvaccinated children remain in unreached settlements. Since 2018, circulating vaccine-derived poliovirus type 2 (cVDPV2) has emerged and spread from Nigeria to Niger and Cameroon; outbreak responses to date have not interrupted transmission. This report describes progress in Nigeria polio eradication activities during January 2018-May 2019 and updates the previous report (2). Interruption of cVDPV2 transmission in Nigeria will need increased efforts to improve campaign quality and include insurgent-held areas. Progress in surveillance and immunization activities will continue to be reviewed, potentially allowing certification of interruption of WPV transmission in Africa in 2020.

Isolation of Vaccine-Like Poliovirus Strains in Sewage Samples From the United Kingdom

Background

Environmental surveillance (ES) is a sensitive method for detecting human enterovirus (HEV) circulation, and it is used worldwide to support global polio eradication. We describe a novel ES approach using next-generation sequencing (NGS) to identify HEVs in sewage samples collected in London, United Kingdom, from June 2016 to May 2017.

Methods

Two different methods were used to process raw sewage specimens: a 2-phase aqueous separation system and size exclusion by filtration and centrifugation. HEVs were isolated using cell cultures and analyzed using NGS.

Results

Type 1 and 3 vaccine-like poliovirus (PV) strains were detected in samples collected from September 2016 through January 2017. NGS analysis allowed us to rapidly obtain whole-genome sequences of PV and non-PV HEV strains. As many as 6 virus strains from different HEV serotypes were identified in a single cell culture flask. PV isolates contained only a small number of mutations from vaccine strains commonly seen in early isolates from vaccinees.

Conclusions

Our ES setup has high sensitivity for polio and non-PV HEV detection, generating nearly whole-genome sequence information. Such ES systems provide critical information to assist the polio eradication endgame and contribute to the improvement of our understanding of HEV circulation patterns in humans.

Towards an effective poliovirus laboratory containment strategy in Nigeria

BACKGROUND

The Global Commission for the Certification of the Eradication of Poliomyelitis will declare the world free of wild poliovirus transmission when no wild virus has been found in at least 3 consecutive years, and all laboratories possessing wild poliovirus materials have adopted appropriate measures of containment. Nigeria has made progress towards poliomyelitis eradication with the latest reported WPV type 1 on 21 Aug 2016 after 2 years without any case. This milestone achievement was followed by an inventory of biomedical laboratories completed in November 2015 with the destruction of all identified infectious materials. This paper seeks to describe the poliovirus laboratory containment process in Nigeria on which an effective containment system has been built to minimize the risk of virus re-introduction into the population from the laboratories.

METHODS

A national survey of all biomedical facilities, as well as an inventory of laboratories from various sectors, was conducted from June-November 2015. National Task Force (NTF) members and staff working on polio administered an on-site questionnaire in each facility. Laboratory personnel were sensitized with all un-needed materials destroyed by autoclaving and incineration. All stakeholders were also sensitized to continue the destruction of such materials as a requirement for phase one activities.

RESULTS

A total of 20,638 biomedical facilities were surveyed with 9575 having laboratories. Thirty laboratories were found to contain poliovirus or potentially infectious materials. The 30 laboratories belonged to the ministries of health, education, defence and private organizations.

CONCLUSIONS

This article is amongst the first in Africa that relates poliovirus laboratory containment in the context of the tOPV-bOPV switch in alignment with the Global Action Plan III. All identified infectious materials were destroyed and personnel trained to continue to destroy subsequent materials, a process that needs meticulous monitoring to mitigate the risk of poliovirus re-introduction to the population.

Stopping circulatory vaccine-derived poliovirus in Kaduna state by scaling up special interventions in local government areas along rivers of interest- kamacha basin experience, 2013-2015

BACKGROUND

The Kamacha river is one of the five polio environmental surveillance sites in Kaduna State where 13 circulating vaccine-derived polioviruses (cVDPDs) were isolated between 2014 and 2015. Kamacha river accounted for 5 of all reported cVDPVs in Kaduna State between 2014 and 2015. Poor quality Supplemental Immunization Activities (SIAs) and low population immunity have been reported in the 10 LGAs with tributaries that flow into the river. We described the processes of implementing the various health interventions in these targeted LGAs along the Kamacha River and assessed the effectiveness of the interventions in stopping cVDPV in Kaduna, state, Nigeria.

METHODS

Special interventions that had been proven to be functional and effective in reaching unreached children with potent vaccines in the state were scaled up in these targeted 10 LGAs along the Kamacha River. These interventions included revision of house based microplans, scaling up of transit vaccination, scaling up of youth engagement, intensified supportive supervision, scaling up of Directly Observed Polio Vaccination (DOPV) and in-between rounds vaccination activities. We analyzed immunization plus days (IPDs) administrative tally sheet and monitoring data from 10 rounds before and 10 rounds after the special interventions.

RESULTS

The number of children immunized increased from 1,862,958 in December 2014 before the intervention to 1,922,940 in March 2016 after the intervention. Lot Quality Assurance Sampling (LQAS) results showed an increase in the proportion of LGAs accepted at coverage > 90% after the interventions, from 67% before intervention to 84% after intervention. The proportion of non-polio AFP children with > 4 doses of oral polio vaccine increased from 2 to 8% before to 93-98% after the interventions.. No new environmental cVDPV has been isolated since the introduction of the interventions in April 2015 until July 2016.

CONCLUSION

Scaling up known working interventions in the 10 LGAs with tributaries that drain to Kamacha River environmental sample site may have contributed to improved immunity and interruption of cVDPV in Kaduna state. These interventions should be replicated in LGAs and states with persistent poliovirus isolation.

A Review of the Most Commonly Used Methods for Sample Collection in Environmental Surveillance of Poliovirus

We performed a review of the environmental surveillance methods commonly used to collect and concentrate poliovirus (PV) from water samples. We compared the sampling approaches (trap vs grab), the process methods (precipitation vs filtration), and the various tools and chemical reagents used to separate PV from other viruses and pathogens in water samples (microporous glass, pads, polyethylene glycol [PEG]/dextran, PEG/sodium chloride, NanoCeram/ViroCap, and ester membranes). The advantages and disadvantages of each method are considered, and the geographical areas where they are currently used are discussed. Several methods have demonstrated the ability to concentrate and recover PVs from environmental samples. The details of the particular sampling conditions and locations should be considered carefully in method selection.

Epidemiology of the silent polio outbreak in Rahat, Israel, based on modeling of environmental surveillance data

Israel experienced an outbreak of wild poliovirus type 1 (WPV1) in 2013-2014, detected through environmental surveillance of the sewage system. No cases of acute flaccid paralysis were reported, and the epidemic subsided after a bivalent oral polio vaccination (bOPV) campaign. As we approach global eradication, polio will increasingly be detected only through environmental surveillance. We developed a framework to convert quantitative polymerase chain reaction (qPCR) cycle threshold data into scaled WPV1 and OPV1 concentrations for inference within a deterministic, compartmental infectious disease transmission model. We used this approach to estimate the epidemic curve and transmission dynamics, as well as assess alternate vaccination scenarios. Our analysis estimates the outbreak peaked in late June, much earlier than previous estimates derived from analysis of stool samples, although the exact epidemic trajectory remains uncertain. We estimate the basic reproduction number was 1.62 (95% CI 1.04-2.02). Model estimates indicate that 59% (95% CI 9-77%) of susceptible individuals (primarily children under 10 years old) were infected with WPV1 over a little more than six months, mostly before the vaccination campaign onset, and that the vaccination campaign averted 10% (95% CI 1-24%) of WPV1 infections. As we approach global polio eradication, environmental monitoring with qPCR can be used as a highly sensitive method to enhance disease surveillance. Our analytic approach brings public health relevance to environmental data that, if systematically collected, can guide eradication efforts.

Insights from a Systematic Search for Information on Designs, Costs, and Effectiveness of Poliovirus Environmental Surveillance Systems

Poliovirus surveillance plays a critical role in achieving and certifying eradication and will play a key role in the polio endgame. Environmental surveillance can provide an opportunity to detect circulating polioviruses prior to the observation of any acute flaccid paralysis cases. We completed a systematic review of peer-reviewed publications on environmental surveillance for polio including the search terms "environmental surveillance" or "sewage," and "polio," "poliovirus," or "poliomyelitis," and compared characteristics of the resulting studies. The review included 146 studies representing 101 environmental surveillance activities from 48 countries published between 1975 and 2016. Studies reported taking samples from sewage treatment facilities, surface waters, and various other environmental sources, although they generally did not present sufficient details to thoroughly evaluate the sewage systems and catchment areas. When reported, catchment areas varied from 50 to over 7.3 million people (median of 500,000 for the 25% of activities that reported catchment areas, notably with 60% of the studies not reporting this information and 16% reporting insufficient information to estimate the catchment area population size). While numerous studies reported the ability of environmental surveillance to detect polioviruses in the absence of clinical cases, the review revealed very limited information about the costs and limited information to support quantitative population effectiveness of conducting environmental surveillance. This review motivates future studies to better characterize poliovirus environmental surveillance systems and the potential value of information that they may provide in the polio endgame.

Dynamics affecting the risk of silent circulation when oral polio vaccination is stopped

•

Silent circulation (SC) of wild polio viruses (WPV) when oral polio vaccine (OPV) use is stopped, could threaten eradication.

•

We analyzed a model designed to develop theory about mechanisms and factors that lead to SC and how SC risks can be assessed using surveillance data.

•

Prolonged low-level SC emerges as a threshold phenomenon through a mechanism related to balancing contributions of different populations to the effective reproduction number.

•

Factors that promote this mechanism are many years of inadequate vaccination efforts, ongoing waning of immunity against transmission years after last OPV or WPV infection, low transmissibility of OPV, and high transmission conditions.

•

Analyzing acute flaccid paralysis surveillance or environmental surveillance data by themselves cannot assess the risk that an SC threshold has been passed, but new methods to analyze them jointly could do so.

Waning immunity could allow transmission of polioviruses without causing poliomyelitis by promoting silent circulation (SC). Undetected SC when oral polio vaccine (OPV) use is stopped could cause difficult to control epidemics. Little is known about waning. To develop theory about what generates SC, we modeled a range of waning patterns. We varied both OPV and wild polio virus (WPV) transmissibility, the time from beginning vaccination to reaching low polio levels, and the infection to paralysis ratio (IPR). There was longer SC when waning continued over time rather than stopping after a few years, when WPV transmissibility was higher or OPV transmissibility was lower, and when the IPR was higher. These interacted in a way that makes recent emergence of prolonged SC a possibility. As the time to reach low infection levels increased, vaccine rates needed to eliminate polio increased and a threshold was passed where prolonged low-level SC emerged. These phenomena were caused by increased contributions to the force of infection from reinfections. The resulting SC occurs at low levels that would be difficult to detect using environmental surveillance. For all waning patterns, modest levels of vaccination of adults shortened SC. Previous modeling studies may have missed these phenomena because (1) they used models with no or very short duration waning and (2) they fit models to paralytic polio case counts. Our analyses show that polio case counts cannot predict SC because nearly identical polio case count patterns can be generated by a range of waning patterns that generate different patterns of SC. We conclude that the possibility of prolonged SC is real but unquantified, that vaccinating modest fractions of adults could reduce SC risk, and that joint analysis of acute flaccid paralysis and environmental surveillance data can help assess SC risks and ensure low risks before stopping OPV.

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.