recrudescence
noun [ U ] formal uk/ˌriː.kruːˈdes.əns/ us/ˌriː.kruːˈdes.əns/
（尤指危险和不愉快的事情）再次爆发，复发
a sudden new appearance and growth, especially of something dangerous and unpleasant
There has been an unwelcome recrudescence of racist attacks. 令人憎恶的种族主义袭击再度爆发。