Prior to the present outbreak, Angola was not considered to fall within the geographical “hot zone”, thought to be in central and eastern Africa, for outbreaks and sporadic cases of this rare disease.

Levels of a substance called pregnancy zone protein had been unusually high, even before their symptoms appeared, in some of those who went on to develop Alzheimer's disease.

In refugee camps on the periphery of the disaster zone, tent areas appear clean and orderly, with adequate supplies of food and clean water. There have been no reports of serious outbreaks of disease.