Human breast milk is the healthiest form of milk for babies. There are few exceptions, such as when the mother is taking certain drugs or is infected with human T-lymphotropic virus, HIV, or has active untreated tuberculosis. Breastfeeding promotes health and helps to prevent disease. Artificial feeding is associated with more deaths from diarrhea in infants in both developing and developed countries. Experts agree that breastfeeding is beneficial, and have concerns about artificial formulas but there are conflicting views about how long exclusive breastfeeding remains beneficial.