Undernutrition, nutritionally acquired immunodeficiency, and tuberculosis control

Nutrition is essential to life, health, and protection from disease. Pneumocystis jiroveci pneumonia—the first opportunistic infection associated with AIDS and indicative of advanced immunosuppression—was initially described in undernourished infants in wartime Europe.1 Undernutrition increases the frequency, severity, and fatality of many infections (including tuberculosis (TB)), while infections in turn worsen undernutrition.2 Undernutrition is the commonest cause of secondary immunodeficiency worldwide, which affects both innate and adaptive immunity, and this has been termed nutritionally acquired immune deficiency syndrome.3 Immunodeficiency related to malnutrition contributes to nearly half of deaths from common childhood infections in children under 5 years.4

Undernutrition in adults is an under-recognised driver of TB epidemics, which are declining only slowly in high burden countries despite treatment programmes.5 Large cohort studies have consistently shown a strong, inverse, and exponential relation between body mass index and incidence of TB.6 In the most recent study, new cases of TB were 12 times higher in people with …