Under-nutrition is currently most frequently associated with civil unrest, which disrupts local agriculture, drought, which increasingly is recognized as connected to ocean and atmospheric factors, which, in turn is probably amplified by global warming due to greenhouse gas emissions. However, while drought is common, war and refugee movements are more common causes of the more widely recognized calorific and protein malnutrition. While primary malnutrition is due to insufficient food, secondary malnutrition can occur, even when there is an adequate diet, due to parasite infestation.

Parasitosis is a common cause of growth retardation among children, affecting both physical and cognitive development.