outbreak

1. N-COUNT If there is an outbreak of something unpleasant, such as violence or a disease, it suddenly starts to happen. (暴动、疾病等的) 爆发

The four-day festival ended a day early after an outbreak of violence involving hundreds of youths. 由于一起数百名年轻人参与的暴力事件的爆发，为期4天的庆祝活动提前1天结束。

...an outbreak of chickenpox. …水痘的暴发。