self-perpetuating

这种恶性循环一旦形成就会自我延续，很难打破。

Once established, this vicious cycle becomes ___self-perpetuating and hard to break.

这种谣言具有自生性，被转发越多就越难消除。

This rumor is ___self-perpetuating - the more it's shared, the harder it is to stop.