BBC News Online: World: Africa

UN launches polio blitz

The disease usually affects children under five, causing paralysis and sometimes death.

The campaign is part of a programme by UN agencies to eradicate polio worldwide by 2005.

The first round of the current campaign took place in October, with mostly West African countries targeted.

Just over 10 years ago it was estimated that polio was infecting 1,000 children worldwide daily.

Immunisation has reduced that figure dramatically.

But the disease continues to thrive in western and central Africa.

Safe passage

Conflicts in the region and widespread migration have prevented thorough immunisation programmes in the past.

But this time the UN believes that it has secured safe passage for its teams.

The polio virus is vulnerable to eradication because it has no natural home outside the human body.

Health experts believe that if 80% of people in infected populations are vaccinated, that will be enough to break its chain of transmission.

The current campaign aims to completely halt wild poliovirus transmission within two years.

Signs in recent years have been encouraging - only 1,149 cases have been registered this year compared with 7,000 last year.

Just 12 years ago there were at least 350,000 cases.