By Richard Black
BBC science correspondent
The World Health Organization says it is optimistic that polio can be eradicated globally by the end of 2004.
The campaign needs extra funding to keep going
The claim follows the resumption of vaccination campaigns in parts of northern Nigeria.
However the WHO says significant obstacles remain, not least a shortage of funds.
Vaccination campaigns resumed at the weekend in the Nigerian states of Kaduna and Kano, after the programme had been suspended in 2003.
Vaccinations were halted after local Muslim leaders claimed the vaccines were unsafe - and during the suspension the disease spread from Nigeria to other African nations.
Between now and the end of the year, the WHO aims to run national immunisation projects in 22 African countries.
Campaigns are also continuing in the other endemic region, South Asia, with the aim of eradicating the virus globally by the end of the year.
However the initiative faces a funding shortfall running to several hundred million dollars, and unless further more money is donated quickly, some of these campaigns may not take place.
This is a critical period for the polio eradication initiative, which commenced in 1988.
Spectacular successes were achieved rapidly in the early years, but it is proving much more difficult to finish the job.
However, if it is not finished, polio will re-emerge as a major global disease.