Imported wild poliovirus causing poliomyelitis--Bulgaria, 2001

Area of Science:

• Epidemiology
• Virology
• Public Health

Background:

• Wild poliovirus type 1 outbreaks pose a significant global health threat, particularly in regions with suboptimal vaccination coverage.
• Maintaining high routine vaccination coverage and robust surveillance systems are critical for preventing poliovirus importation and spread.

Observation:

• Three cases of poliomyelitis, caused by wild poliovirus type 1, were confirmed in unvaccinated Roma children in Bulgaria in March-May 2001.
• The isolated viruses were closely related to a strain previously identified in India, suggesting international transmission.

Findings:

• The outbreak was successfully contained through intensified acute flaccid paralysis (AFP) surveillance and mass vaccination campaigns implemented by the Bulgarian Ministry of Health.
• Contact investigations and screening of high-risk children were integral components of the outbreak response.

Implications:

• This event underscores the importance of sustained high vaccination rates and effective surveillance for early detection and rapid response to poliovirus importations.
• Certification-standard AFP surveillance is essential for polio-free countries to rapidly detect and prevent the re-establishment of poliovirus transmission.