title: Importation and circulation of poliovirus in Bulgaria in 2001.
abstract: OBJECTIVE
  To characterize the circumstances in which poliomyelitis occurred among three children in Bulgaria during 2001 and to describe the public health response.
  
  
  METHODS
  Bulgarian authorities investigated the three cases of polio and their contacts, conducted faecal and serological screening of children from high-risk groups, implemented enhanced surveillance for acute flaccid paralysis, and conducted supplemental immunization activities.
  
  
  RESULTS
  The three cases of polio studied had not been vaccinated and lived in socioeconomically deprived areas of two cities. Four Roma children from the Bourgas district had antibody titres to serotype 1 poliovirus only, and wild type 1 virus was isolated from the faeces of two asymptomatic Roma children in the Bourgas and Sofia districts. Poliovirus isolates were related genetically and represented a single evolutionary lineage; genomic sequences were less than 90% identical to poliovirus strains isolated previously in Europe, but 98.3% similar to a strain isolated in India in 2000. No cases or wild virus isolates were found after supplemental immunization activities were launched in May 2001.
  
  
  CONCLUSIONS
  In Bulgaria, an imported poliovirus was able to circulate for two to five months among minority populations. Surveillance data strongly suggest that wild poliovirus circulation ceased shortly after supplemental immunization activities with oral poliovirus vaccine were conducted.
authors.affiliation: Department of Epidemiology, National Center for Infectious and Parasitic Diseases, Sofia, Bulgaria.
authors.forename: Mira
authors.initials: M
authors.lastname: Kojouharova
authors.forename: Patrick L F
authors.initials: PL
authors.lastname: Zuber
authors.forename: Snejana
authors.initials: S
authors.lastname: Gyurova
authors.forename: Lucia
authors.initials: L
authors.lastname: Fiore
authors.forename: Gabriele
authors.initials: G
authors.lastname: Buttinelli
authors.forename: Angel
authors.initials: A
authors.lastname: Kunchev
authors.forename: Nadejda
authors.initials: N
authors.lastname: Vladimirova
authors.forename: Neli
authors.initials: N
authors.lastname: Korsun
authors.forename: Radosveta
authors.initials: R
authors.lastname: Filipova
authors.forename: Roumiana
authors.initials: R
authors.lastname: Boneva
authors.forename: Eugene
authors.initials: E
authors.lastname: Gavrilin
authors.forename: Jagadish M
authors.initials: JM
authors.lastname: Deshpande
authors.forename: George
authors.initials: G
authors.lastname: Oblapenko
authors.forename: Steven G
authors.initials: SG
authors.lastname: Wassilak
mesh_terms: D000914:Antibodies, Viral / Q000097:blood; D002031:Bulgaria / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000517:prevention & control*; D005243:Feces / Q000821:virology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D032541:Mass Vaccination; D008913:Minority Groups; D011051:Poliomyelitis / Q000453:epidemiology* / Q000517:prevention & control; D017955:Poliovirus / Q000302:isolation & purification; D011055:Poliovirus Vaccine, Oral / Q000600:supply & distribution*; D011159:Population Surveillance; D006178:Romani People; D012959:Socioeconomic Factors
chemical_list: D000914:Antibodies, Viral; D011055:Poliovirus Vaccine, Oral