India marked a year Friday since its last new case of polio, a major victory in the global effort to eradicate the disease.

If no previously undisclosed cases are uncovered in the coming weeks, India will be removed from the list of countries where the crippling disease is endemic. Polio remains a threat in Afghanistan, Nigeria and Pakistan.

The number of polio cases in India dropped from 741 in 2009, to 42 in 2010, and just one in early 2011.

If no new cases are found in India for three years, all of WHO's South East Asia region (Bangladesh, Bhutan, North Korea, India, Indonesia, Maldives, Myanmar, Nepal, Sri Lanka, Thailand and Timore-Leste) will be declared polio-free.

India's polio eradication program is a collaborative effort between the country's health ministry and WHO, UNICEF, Rotary International and the U.S. Centers for Disease Control.

India overcame huge challenges to stop the transmission of polio, including an inadequate health system, and a large migrant community, compounded by high population density and poor sanitation.

Polio usually infects children in unsanitary areas. It attacks the central nervous system, sometimes causing paralysis, muscular atrophy, deformation and death.