 A review of public and private initiatives found that of the 1393 new chemical products that were marketed in the period of 1975 and 1999, just 16 related to tropical diseases and tuberculosis.The same review additionally found that there was a 13-fold greater chance of a drug entering the market being for central-nervous-system disorders and cancer than an NTD.Due to lack of incentive in the pharmaceutical industry, successful NTD treatment programs have often relied on the donation format.