The strong relationship between malnutrition and infection was originally described by Scrimshaw et al. From this framework, much investigation was done in this area and there is a total agreement among authors that mortality is significantly more elevated in undernourished child compared to healthy ones. The study by Man et al. , which included a large population of hospitalized Gambian children, clearly illustrated the relationship between undernourishment, characterized by lower weight relative to age, and higher mortality indexes associated with many infectious diseases.

One-third of the world's population is infected with M. tuberculosis, the main agent that provokes death among infectious diseases. This infection is particularly influenced by undernutrition and is a major cause of morbidity and mortality in developing countries where PCM is also prevalent . Furthermore, malnutrition as an important risk for tuberculosis has also being reinforced by findings in experimental models . Similarly, undernutrition may also affect the clinical outcome of tuberculosis . A recent meta-analysis suggested that low serum vitamin D levels are associated with higher risk of active tuberculosis . It is important to emphasize that tuberculosis is a typical condition whose evolution, characterized by a chronic inflammatory process, accentuates undernutrition and causes a typical cachexia. This has been partially attributed to IgG1 antibodies, that up-regulate TNF-α and IL-6 (proinflammatory cytokines), but not to IL-10 (anti-inflammatory cytokines) . Emergence of highly virulent drug-resistant strains of M. tuberculosis has been largely attributed to a combination of poorly implemented drug regimen and coinfection with HIV. It