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Importation and circulation of poliovirus in Bulgaria in 2001

Mira Kojouharova1, Patrick L F Zuber, Snejana Gyurova

  • 1Department of Epidemiology, National Center for Infectious and Parasitic Diseases, Sofia, Bulgaria.

Bulletin of the World Health Organization
|September 16, 2003
PubMed

Insights

An imported poliovirus circulated in Bulgaria among unvaccinated children in 2001. Supplemental immunization activities with oral poliovirus vaccine successfully halted wild poliovirus circulation.

Area of Science:

  • Epidemiology
  • Virology
  • Public Health

Background:

  • Poliomyelitis remains a global public health concern, requiring robust surveillance and response mechanisms.
  • Understanding the transmission dynamics of imported poliovirus is crucial for eradication efforts.

Purpose of the Study:

  • To investigate the circumstances surrounding three poliomyelitis cases in Bulgaria in 2001.
  • To describe the public health interventions implemented in response to the outbreak.

Main Methods:

  • Investigation of polio cases and contacts.
  • Screening of high-risk populations for poliovirus.
  • Enhanced surveillance for acute flaccid paralysis.
  • Supplemental immunization activities using oral poliovirus vaccine.

Main Results:

  • Three unvaccinated children from socioeconomically deprived areas were diagnosed with polio.
  • Evidence of wild type 1 poliovirus circulation was found in asymptomatic individuals from minority populations.
  • Genomic sequencing revealed the virus was imported, with high similarity to a strain from India.
  • No further cases or virus isolates were detected after immunization activities.

Conclusions:

  • An imported poliovirus strain circulated undetected for several months in Bulgaria, primarily within minority communities.
  • Supplemental immunization activities were effective in interrupting wild poliovirus transmission.
Abstract

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