title: Phylogeny of imported and reestablished wild polioviruses in theDemocratic Republic of the Congo from 2006 to 2011.
abstract: BACKGROUND
  The last case of polio associated with wild poliovirus (WPV) indigenous to the Democratic Republic of the Congo (DRC) was reported in 2001, marking a major milestone toward polio eradication in Africa. However, during 2006-2011, outbreaks associated with WPV type 1 (WPV1) were widespread in the DRC, with >250 reported cases.
  
  
  METHODS
  WPV1 isolates obtained from patients with acute flaccid paralysis (AFP) were compared by nucleotide sequencing of the VP1 capsid region (906 nucleotides). VP1 sequence relationships among isolates from the DRC and other countries were visualized in phylogenetic trees, and isolates representing distinct lineage groups were mapped.
  
  
  RESULTS
  Phylogenetic analysis indicated that WPV1 was imported twice in 2004-2005 and once in approximately 2006 from Uttar Pradesh, India (a major reservoir of endemicity for WPV1 and WPV3 until 2010-2011), into Angola. WPV1 from the first importation spread to the DRC in 2006, sparking a series of outbreaks that continued into 2011. WPV1 from the second importation was widely disseminated in the DRC and spread to the Congo in 2010-2011. VP1 sequence relationships revealed frequent transmission of WPV1 across the borders of Angola, the DRC, and the Congo. Long branches on the phylogenetic tree signaled prolonged gaps in AFP surveillance and a likely underreporting of polio cases.
  
  
  CONCLUSIONS
  The reestablishment of widespread and protracted WPV1 transmission in the DRC and Angola following long-range importations highlights the continuing risks of WPV spread until global eradication is achieved, and it further underscores the need for all countries to maintain high levels of poliovirus vaccine coverage and sensitive surveillance to protect their polio-free status.
authors.affiliation: National Institute for Communicable Diseases, Johannesburg, South Africa.
authors.forename: Nicksy
authors.initials: N
authors.lastname: Gumede
authors.affiliation: Division of Viral Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Jaume
authors.initials: J
authors.lastname: Jorba
authors.affiliation: Indian Council of Medical Research, Mumbai.
authors.forename: Jagadish
authors.initials: J
authors.lastname: Deshpande
authors.affiliation: Division of Viral Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Mark
authors.initials: M
authors.lastname: Pallansch
authors.affiliation: National Institute for Biomedical Research, Kinshasa/Gombe, Democratic Republic of the Congo.
authors.forename: Riziki
authors.initials: R
authors.lastname: Yogolelo
authors.affiliation: National Institute for Biomedical Research, Kinshasa/Gombe, Democratic Republic of the Congo.
authors.forename: Jean Jacques
authors.initials: JJ
authors.lastname: Muyembe-Tamfum
authors.affiliation: Division of Viral Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Olen
authors.initials: O
authors.lastname: Kew
authors.affiliation: National Institute for Communicable Diseases, Johannesburg, South Africa.
authors.forename: Marietjie
authors.initials: M
authors.lastname: Venter
authors.affiliation: Division of Viral Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Cara C
authors.initials: CC
authors.lastname: Burns
mesh_terms: D036022:Capsid Proteins / Q000235:genetics; D016000:Cluster Analysis; D015023:Democratic Republic of the Congo / Q000453:epidemiology; D004196:Disease Outbreaks; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D010802:Phylogeny; D011051:Poliomyelitis / Q000453:epidemiology* / Q000635:transmission / Q000821:virology*; D017955:Poliovirus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA
chemical_list: D036022:Capsid Proteins; C442540:VP1 protein, Poliovirus
keywords: Democratic Republic of Congo; importation; molecular epidemiology; polio eradication; wild poliovirus