Background
Several billion people are affected by one or more tropical diseases (TDs) such as Tuberculosis, Malaria, Leshmaniasis, Chagas Disease, African sleeping sickness, and Dengue fever. These diseases persist mainly in the poor and the marginalized communities. The first disease target taken up by OSDD is Tuberculosis (TB). TB is one of the leading causes of fatality in the developing nations. TB is a global infection and ranks second only to HIV as the leading killer infectious disease of adults worldwide. TB is a highly contagious air borne infection which has its main target, the respiratory system, though it affects other organs as well. TB is the most common opportunistic infection affecting people living with HIV worldwide.

 Global burden of TB
As per WHO report, one-third of the world's population is currently infected with the TB of which 80% are from the 22 high-burden countries alone. Global incidence of TB is increasing by 0.6% per annum. At least one person in the world is newly infected with the TB bacilli every second. Left untreated, each person with active TB will infect (on average) between 10-15 people every year.
450, 000 new Multiple Drug Resistant (MDR) -TB cases are estimated to occur every year. An estimated 5% of TB patients are co-infected with HIV.

 Lack of market incentives

Nature describes TB as an orphan giant that claims millions of lives every year. No new TB drugs have been developed in the past almost 50 years.It is often described as the disease of the poor and the pharma industries tend to bypass drug discovery for TB owing to the lack profitable markets.

The problem of Drug Resistance

Existing TB treatment makes use of combinatorial therapy involving 4 medicines (known as first-line drugs) and is administered for a period of 6 to 9 months. The treatment regimen is too long and risk prone as discontinuation of courses leads to the development of new deadly drug resistant strains.

The inadequacy and flawed administration of existing treatment has resulted in the emergence of MDR  (multiple drug resistant ) TB and XDR(extremely drug resistant ) TB. Multidrug resistant TB (MDR-TB) is defined by resistance to the two most commonly used drugs in the current four-drug (or first-line) regimen, isoniazid and rifampin. And XDR-TB is defined as TB that is resistant to any fluoroquinolone, and at least one of three injectable second-line drugs (capreomycin, kanamycin, and amikacin), in addition to isoniazid and rifampin. In such cases treatment with existing first line drugs along with second line drugs and antibiotics can take up to two years or more, and is highly complex, expensive, and toxic. It is estimated that a third of all MDR-TB patients die owing to the heavy dose regimen and complications associated with treatment. 70% of XDR-TB patients die within a month of diagnosis.

Besides being a global health burden robbing people of their lives, TB is major hindrance in economic development of the poor infecting adults in their most productive years (15-44) with impact on gross productivity of nations.

 The emergence of MDR-TB and XDR-TB along with the neglected status of the disease calls for innovative scientific interventions. There is an urgent need of faster and simpler treatment regimen for TB that requires novel and potent drugs