Second, as the situation in one country began to improve, it attracted patients from neighbouring countries seeking unoccupied beds for treatment, thus reigniting transmission chains. In other words, as long as one country experienced intense transmission other countries remained at risk, no matter how strong their own response measures were. The traditional custom of returning, often over long distances, to a native village to die and be buried near ancestors is another dimension of population movement that carries an especially high transmission risk. In past outbreaks, Ebola was largely confined to remote rural areas, with just a few scattered cases detected in cities. In West Africa, cities - including the capitals of the three main Ebola affected countries, Liberia, Guinea and Sierra Leone - have been epicentres of intense virus transmission. The Ebola outbreaks in West Africa demonstrated how swiftly the virus could move once it reached urban settings and densely populated slums.