The rash of measles covers not only the skin but also the internal body surfaces of an affected child. This is what causes the complications of measles. The rash affects the intestines, and this leads to diarrhoea.
It affects the eyes, causing the characteristic redness, and also the covering
of the brain, called the meninges, and this causes the child to be irritable. The rash also affects the inner surfaces of the lungs, and this inflammation allows secondary infections to take hold, leading to pneumonia.
It is usually one of these complications, and especially pneumonia or diarrhoea, that is the direct cause of death during a bout of measles.
Measles so weakens a child that he or she is easily tipped into malnutrition.
The high fevers of measles can also precipitate vitamin A deficiency, which can in turn lead to a blinding disease called xerophthalmia. Both of these nutritional conditions can lead eventually to death.