Rich nations and global donors should be able to provide the $2.6 billion in aid needed to combat polio through 2012 despite the global credit crunch, Reuters quoted multi-billionaire philanthropist Bill Gates as saying today. The World Health Organisation has suggested a budget of $2.6 billion for its polio eradication efforts in 2010-2012, but says it faces a shortfall of about half of funds for that period. "We are going to the rich world donors at a time when their budgets are tight," Gates, the founder of software giant Microsoft , told reporters during a visit to Nigeria's capital Abuja. "But between what our foundation will do, what the others will do, I feel quite sure that we will be able to fund that fight," he added. The Bill & Melinda Gates Foundation, which has been active in fighting child and infectious diseases in poor countries, will commit more than $150 million of its $34 billion fund this year to mass polio immunisation and surveillance programmes. The number of worldwide cases has declined this year, most significantly in Nigeria which has recorded its lowest level of infections ever with only three so far in 2010. That is down from a total of 288 cases last year. Polio, which spreads in areas with poor sanitation, attacks the nervous system and can cause irreversible paralysis within hours of infection. Children under the age of 4 are the most vulnerable to the disease that until the 1950s crippled thousands of people every year in rich nations.