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1.
N Engl J Med ; 379(9): 834-845, 2018 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-30157398

RESUMO

BACKGROUND: Mass campaigns with oral poliovirus vaccine (OPV) have brought the world close to the eradication of wild poliovirus. However, to complete eradication, OPV must itself be withdrawn to prevent outbreaks of vaccine-derived poliovirus (VDPV). Synchronized global withdrawal of OPV began with serotype 2 OPV (OPV2) in April 2016, which presented the first test of the feasibility of eradicating all polioviruses. METHODS: We analyzed global surveillance data on the detection of serotype 2 Sabin vaccine (Sabin-2) poliovirus and serotype 2 vaccine-derived poliovirus (VDPV2, defined as vaccine strains that are at least 0.6% divergent from Sabin-2 poliovirus in the viral protein 1 genomic region) in stool samples from 495,035 children with acute flaccid paralysis in 118 countries and in 8528 sewage samples from four countries at high risk for transmission; the samples were collected from January 1, 2013, through July 11, 2018. We used Bayesian spatiotemporal smoothing and logistic regression to identify and map risk factors for persistent detection of Sabin-2 poliovirus and VDPV2. RESULTS: The prevalence of Sabin-2 poliovirus in stool samples declined from 3.9% (95% confidence interval [CI], 3.5 to 4.3) at the time of OPV2 withdrawal to 0.2% (95% CI, 0.1 to 2.7) at 2 months after withdrawal, and the detection rate in sewage samples declined from 71.0% (95% CI, 61.0 to 80.0) to 13.0% (95% CI, 8.0 to 20.0) during the same period. However, 12 months after OPV2 withdrawal, Sabin-2 poliovirus continued to be detected in stool samples (<0.1%; 95% CI, <0.1 to 0.1) and sewage samples (8.0%; 95% CI, 5.0 to 13.0) because of the use of OPV2 in response to VDPV2 outbreaks. Nine outbreaks were reported after OPV2 withdrawal and were associated with low coverage of routine immunization (odds ratio, 1.64 [95% CI, 1.14 to 2.54] per 10% absolute decrease) and low levels of population immunity (odds ratio, 2.60 [95% CI, 1.35 to 5.59] per 10% absolute decrease) within affected countries. CONCLUSIONS: High population immunity has facilitated the decline in the prevalence of Sabin-2 poliovirus after OPV2 withdrawal and restricted the circulation of VDPV2 to areas known to be at high risk for transmission. The prevention of VDPV2 outbreaks in these known areas before the accumulation of substantial cohorts of children susceptible to type 2 poliovirus remains a high priority. (Funded by the Bill and Melinda Gates Foundation and the World Health Organization.).


Assuntos
Fezes/virologia , Poliomielite/virologia , Vacina Antipólio Oral , Poliovirus/isolamento & purificação , Esgotos/virologia , Adolescente , África , Ásia , Criança , Pré-Escolar , Erradicação de Doenças , Surtos de Doenças/prevenção & controle , Feminino , Humanos , Lactente , Recém-Nascido , Modelos Logísticos , Masculino , Poliomielite/prevenção & controle , Poliovirus/classificação , Vacina Antipólio de Vírus Inativado , Vigilância da População , Sorogrupo
2.
Emerg Infect Dis ; 22(3): 449-56, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26890053

RESUMO

As the global eradication of poliomyelitis approaches the final stages, prompt detection of new outbreaks is critical to enable a fast and effective outbreak response. Surveillance relies on reporting of acute flaccid paralysis (AFP) cases and laboratory confirmation through isolation of poliovirus from stool. However, delayed sample collection and testing can delay outbreak detection. We investigated whether weekly testing for clusters of AFP by location and time, using the Kulldorff scan statistic, could provide an early warning for outbreaks in 20 countries. A mixed-effects regression model was used to predict background rates of nonpolio AFP at the district level. In Tajikistan and Congo, testing for AFP clusters would have resulted in an outbreak warning 39 and 11 days, respectively, before official confirmation of large outbreaks. This method has relatively high specificity and could be integrated into the current polio information system to support rapid outbreak response activities.


Assuntos
Erradicação de Doenças , Surtos de Doenças/prevenção & controle , Diagnóstico Precoce , Paralisia/diagnóstico , Poliomielite/diagnóstico , Análise por Conglomerados , Congo , Monitoramento Epidemiológico , Humanos , Hipotonia Muscular/diagnóstico , Hipotonia Muscular/etiologia , Paralisia/etiologia , Poliomielite/epidemiologia , Poliomielite/fisiopatologia , Somália , Tadjiquistão , Fatores de Tempo
3.
J Infect Dis ; 210 Suppl 1: S91-7, 2014 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-25316881

RESUMO

BACKGROUND: As 1 of 3 remaining poliovirus-endemic countries, Nigeria has become key to the global polio eradication effort. We evaluated supplemental immunization activities, including team performance, communications/mobilization activities, and vaccine acceptance, in 3 high-risk states. METHODS: We used structured survey and observation instruments, document review, and stakeholder interviews. RESULTS: Observations or surveys were conducted at 1697 households. Vaccine acceptance ranged from 87%-94%; among households rejecting polio vaccine, 38% of mothers sought measles vaccine for their children. Teams performed between 4%-42% of assigned tasks. CONCLUSIONS: Acceptance is high but teams have a critical role in surmounting residual vaccine resistance.


Assuntos
Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Poliomielite/prevenção & controle , Vacinas contra Poliovirus/administração & dosagem , Vacinação/estatística & dados numéricos , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Nigéria/epidemiologia , Aceitação pelo Paciente de Cuidados de Saúde/psicologia , Poliomielite/epidemiologia
4.
J Infect Dis ; 210 Suppl 1: S98-101, 2014 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-25316882

RESUMO

The application of geospatial data to public health problems has expanded significantly with increased access to low-cost handheld global positioning system (GPS) receivers and free programs for geographic information systems analysis. In January 2010, we piloted the application of geospatial analysis to polio supplementary immunization activities (SIAs) in northern Nigeria. SIA teams carried GPS receivers to compare hand-drawn catchment area route maps with GPS tracks of actual vaccination teams. Team tracks overlaid on satellite imagery revealed that teams commonly missed swaths of contiguous households and indicated that geospatial data can improve microplanning and provide nearly real-time monitoring of team performance.


Assuntos
Sistemas de Informação Geográfica , Poliomielite/prevenção & controle , Vacinas contra Poliovirus/administração & dosagem , Vacinação , Feminino , Humanos , Masculino , Nigéria/epidemiologia , Projetos Piloto , Poliomielite/epidemiologia , Vacinação/estatística & dados numéricos
5.
J Virol ; 87(9): 4907-22, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23408630

RESUMO

Since 2005, a large poliomyelitis outbreak associated with type 2 circulating vaccine-derived poliovirus (cVDPV2) has occurred in northern Nigeria, where immunization coverage with trivalent oral poliovirus vaccine (tOPV) has been low. Phylogenetic analysis of P1/capsid region sequences of isolates from each of the 403 cases reported in 2005 to 2011 resolved the outbreak into 23 independent type 2 vaccine-derived poliovirus (VDPV2) emergences, at least 7 of which established circulating lineage groups. Virus from one emergence (lineage group 2005-8; 361 isolates) was estimated to have circulated for over 6 years. The population of the major cVDPV2 lineage group expanded rapidly in early 2009, fell sharply after two tOPV rounds in mid-2009, and gradually expanded again through 2011. The two major determinants of attenuation of the Sabin 2 oral poliovirus vaccine strain (A481 in the 5'-untranslated region [5'-UTR] and VP1-Ile143) had been replaced in all VDPV2 isolates; most A481 5'-UTR replacements occurred by recombination with other enteroviruses. cVDPV2 isolates representing different lineage groups had biological properties indistinguishable from those of wild polioviruses, including efficient growth in neuron-derived HEK293 cells, the capacity to cause paralytic disease in both humans and PVR-Tg21 transgenic mice, loss of the temperature-sensitive phenotype, and the capacity for sustained person-to-person transmission. We estimate from the poliomyelitis case count and the paralytic case-to-infection ratio for type 2 wild poliovirus infections that ∼700,000 cVDPV2 infections have occurred during the outbreak. The detection of multiple concurrent cVDPV2 outbreaks in northern Nigeria highlights the risks of cVDPV emergence accompanying tOPV use at low rates of coverage in developing countries.


Assuntos
Poliomielite/epidemiologia , Vacina Antipólio Oral/efeitos adversos , Vacinas contra Poliovirus/efeitos adversos , Poliovirus/fisiologia , Animais , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/imunologia , Surtos de Doenças , Feminino , Humanos , Masculino , Camundongos , Dados de Sequência Molecular , Nigéria/epidemiologia , Filogenia , Poliomielite/virologia , Poliovirus/classificação , Poliovirus/genética , Poliovirus/imunologia , Vacina Antipólio Oral/administração & dosagem , Vacinas contra Poliovirus/genética , Vacinas contra Poliovirus/imunologia
6.
MMWR Morb Mortal Wkly Rep ; 63(16): 356-61, 2014 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-24759658

RESUMO

In 2012, the World Health Assembly of the World Health Organization (WHO) declared completion of polio eradication a programmatic emergency. Polio cases are detected through surveillance of acute flaccid paralysis (AFP) cases and subsequent testing of stool specimens for polioviruses (PVs) at WHO-accredited laboratories within the Global Polio Laboratory Network (GPLN). AFP surveillance is supplemented by environmental surveillance, testing sewage samples from selected sites for PVs. Virologic surveillance, including genomic sequencing to identify isolates by genotype and measure divergence between isolates, guides Global Polio Eradication Initiative (GPEI) activities by confirming the presence of PV, tracking chains of PV transmission, and highlighting gaps in AFP surveillance quality. This report provides AFP surveillance quality indicators at national and subnational levels during 2012-2013 for countries that experienced PV cases during 2009-2013 in the WHO African Region (AFR) and Eastern Mediterranean Region (EMR), the remaining polio-endemic regions. It also summarizes the results of environmental surveillance and reviews indicators assessing the timeliness of reporting of PV isolation and of virus strain characterization globally. Regional-level performance indicators for timely reporting of PV isolation were met in five of six WHO regions in 2012 and 2013. Of 30 AFR and EMR countries that experienced cases of PV (wild poliovirus [WPV], circulating vaccine-derived poliovirus [cVDPV], or both) during 2009-2013, national performance indicator targets for AFP surveillance and collection of adequate specimens were met in 27 (90%) countries in 2012 and 22 (73%) in 2013. In 17 (57%) countries, ≥80% of the population lived in subnational areas meeting both AFP performance indicators in 2012, decreasing to 13 (43%) in 2013. To achieve polio eradication and certify interruption of PV transmission, intensive efforts to strengthen and maintain AFP surveillance are needed at subnational levels, including in field investigation and prompt collection of specimens, particularly in countries with current or recent active PV transmission.


Assuntos
Erradicação de Doenças , Saúde Global/estatística & dados numéricos , Poliomielite/prevenção & controle , Vigilância da População/métodos , Surtos de Doenças/estatística & dados numéricos , Humanos , Poliomielite/epidemiologia , Vacina Antipólio Oral/administração & dosagem , Vacinas contra Poliovirus/administração & dosagem , Vacinação/estatística & dados numéricos
7.
MMWR Morb Mortal Wkly Rep ; 63(34): 756-61, 2014 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-25166927

RESUMO

Since 1988, when the Global Polio Eradication Initiative (GPEI) began, the annual number of polio cases has decreased by >99%. Only three countries remain that have never interrupted wild poliovirus (WPV) transmission: Afghanistan, Nigeria, and Pakistan. Since 2001, outbreaks have occurred in 31 formerly polio-free counties in Africa, with outbreaks in 25 countries caused by WPV originating in Nigeria (2-4). After the declaration of the World Health Assembly of polio eradication as a programmatic emergency in 2012, efforts to identify areas at high risk for importation-associated outbreaks and to reduce that risk have been intensified. This report updates the 2013 assessment of the risk for outbreaks attributable to importation of poliovirus in 33 countries in Africa, using indicators of childhood susceptibility to poliovirus and proximity to countries currently affected by polio . From January 2013 to August 12, 2014, outbreaks occurred in five African countries. Four of the five (Cameroon, Equatorial Guinea, Ethiopia, and Somalia) have had recent transmission (cases within the previous 12 months). Based on the current risk assessment, 15 countries are considered to be at high risk for WPV outbreaks, five at moderate-to-high risk, seven at moderate risk, and six at low risk. In 15 of the 33 countries, less than half of the population resides in areas where surveillance performance indicators have met minimum targets. Enhanced, coordinated activities to raise childhood immunity are underway in 2014 to prevent additional WPV spread. Although substantial progress toward polio eradication has occurred in Nigeria, all African countries remain at risk for outbreaks as long as WPV continues to circulate anywhere on the continent.


Assuntos
Surtos de Doenças/prevenção & controle , Saúde Global , Poliomielite/epidemiologia , Gestão de Riscos/métodos , Afeganistão/epidemiologia , África/epidemiologia , Surtos de Doenças/estatística & dados numéricos , Humanos , Programas de Imunização , Incidência , Paquistão/epidemiologia , Vacinas contra Poliovirus , Vigilância da População , Medição de Risco/métodos
8.
J Infect Dis ; 203(7): 898-909, 2011 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-21402542

RESUMO

Wild poliovirus has remained endemic in northern Nigeria because of low coverage achieved in the routine immunization program and in supplementary immunization activities (SIAs). An outbreak of infection involving 315 cases of type 2 circulating vaccine-derived poliovirus (cVDPV2; >1% divergent from Sabin 2) occurred during July 2005-June 2010, a period when 23 of 34 SIAs used monovalent or bivalent oral poliovirus vaccine (OPV) lacking Sabin 2. In addition, 21 "pre-VDPV2" (0.5%-1.0% divergent) cases occurred during this period. Both cVDPV and pre-VDPV cases were clinically indistinguishable from cases due to wild poliovirus. The monthly incidence of cases increased sharply in early 2009, as more children aged without trivalent OPV SIAs. Cumulative state incidence of pre-VDPV2/cVDPV2 was correlated with low childhood immunization against poliovirus type 2 assessed by various means. Strengthened routine immunization programs in countries with suboptimal coverage and balanced use of OPV formulations in SIAs are necessary to minimize risks of VDPV emergence and circulation.


Assuntos
Surtos de Doenças , Poliomielite/epidemiologia , Poliomielite/virologia , Vacinas contra Poliovirus/efeitos adversos , Poliovirus/isolamento & purificação , Poliovirus/patogenicidade , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Feminino , Genoma Viral , Política de Saúde , Humanos , Incidência , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Mutação , Nigéria/epidemiologia , Poliomielite/patologia , Poliovirus/genética , Vacinas contra Poliovirus/administração & dosagem , Vacinação/estatística & dados numéricos , Adulto Jovem
9.
J Infect Dis ; 204 Suppl 1: S514-23, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21666208

RESUMO

A critical component of laboratory surveillance for measles is the genetic characterization of circulating wild-type viruses. The World Health Organization (WHO) Measles and Rubella Laboratory Network (LabNet), provides for standardized testing in 183 countries and supports genetic characterization of currently circulating strains of measles viruses. The goal of this report is to describe the lessons learned from nearly 20 years of virologic surveillance for measles, to describe the global databases for measles sequences, and to provide regional updates about measles genotypes detected by recent surveillance activities. Virologic surveillance for measles is now well established in all of the WHO regions, and most countries have conducted at least some baseline surveillance. The WHO Global Genotype Database contains >7000 genotype reports, and the Measles Nucleotide Surveillance (MeaNS) contains >4000 entries. This sequence information has proven to be extremely useful for tracking global transmission patterns and for documenting the interruption of transmission in some countries. The future challenges will be to develop quality control programs for molecular methods and to continue to expand virologic surveillance activities in all regions.


Assuntos
Saúde Global , Vírus do Sarampo/classificação , Vírus do Sarampo/genética , Sarampo/epidemiologia , Sarampo/virologia , Bases de Dados Factuais , Genótipo , Humanos , Epidemiologia Molecular , Organização Mundial da Saúde
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