Bihar, an eastern Indian state which has not reported a single case of polio since September 2010, is now turning its attention to \"kala azar\", a disease transmitted by the sand fly that killed at least 50 people and affected 15,000 in the state last year. \"Bihar has not reported even a single case of polio in the last 16 months and the state has virtually become polio free, now we will work hard to make it a kala azar free state,\" Health Minister Ashwani Kumar Choubey said in Patna, the capital of Bihar, over telephone. Kala azar, medically called Visceral leishmaniasis, is also known as the poor man\'s disease because it affects the poorest. Choubey said the government had decided to observe March 15 as the kala azar eradication day. He said special programs would be organized in all affected districts from March 15 to March 21 every year. \"We have to check and control the tiny sand fly that causes kala azar and create awareness about preventable measures among people, mostly the poorest of the poor in affected districts,\" Choubey said. The state government has launched a massive anti-kala azar strategy to contain the spread of sand fly vectors in 16 seriously affected districts. The government had constituted a task force headed by former central health minister and BJP leader C.P. Thakur to work for eradication of the disease. According to health officials, nearly 15,000 cases were reported in different hospitals in 31 of 38 affected districts and officially over 50 people died due to it last year. In 2010, at least 87 people died and over 20,000 people were affected by kala azar in Bihar despite efforts by government and non-government organizations to eradicate the killer disease. The sand fly which transmits the disease multiplies in the cow dung that villagers use liberally to plaster their shanties or as cow dung cakes for fuel. The flies survive on the sap in banana and bamboo groves and on decomposed cow dung heaps. They also make their home in the straw thatch of huts. The disease is characterized by fever, weight loss, swelling of the spleen and liver and can lead to cardiovascular complications resulting in death. Experts say poor living standards and unhygienic conditions make members of the Mushahar community of Dalits an easy prey to it. Many of the worst kala azar-hit areas of Bihar are the northern districts of Vaishali, Muzaffarpur, Sitamarhi, Sheohar and East and West Champaran. Bihar last faced a kala azar epidemic in 1991 when 250,000 cases were reported. In 2000, the numbers were low but started rising from 2003. The disease occurs in 62 countries, primarily in the developing world. Around 90 percent of world\'s cases are found in India, Bangladesh, Nepal and Sudan. Choubey said the state recorded the second highest number of polio cases in the country in 2009. \"Now Bihar is virtually a polio free state thanks to a special immunization drive,\" Choubey said.