Indian health officials say the country is on the verge of eradicating polio, with no cases reported there in more than nine months.

Indian officials said Monday the last new case was reported in January in West Bengal state. According to the World Health Organization, a country is declared polio free when no cases are reported for three years.

Health Minister Ghulam Nabi Azad said India is “close” to its goal of complete polio eradication and pledged the government would remain vigilant against the virus returning to the country.

India is only one of four countries where polio remains endemic, The others are Afghanistan, Pakistan and Nigeria.

Polio usually infects children under age five through contaminated drinking water. The virus attacks the central nervous system, causing paralysis, muscular atrophy, deformation and, sometimes, death.

India's announcement came on World Polio Day, a day to spotlight the importance of the global eradication of polio.