virulent

adj

1. Of animals, plants, or substances: extremely venomous or poisonous.
2. (figuratively)Extremely hostile or malicious; intensely acrimonious.

   “The politicians were virulent in their hatred of the president.”

   “More venemous and much more virulent / Then any poyſoned tode, or any ſerpent.”

   “It was a casual sneer, obviously one of a long line. There was hatred behind it, but of a quiet, chronic type, nothing new or unduly virulent, and he was taken aback by the flicker of amazed incredulity that passed over the younger man's ravaged face.”

   “They were targeted by a virulent strain of nativism toward those from Southern and Eastern Europe that was largely about race.”

3. Of a disease or disease-causing agent: malignant, able to cause damage to the host.
4. Of a pathogen: replicating within its host cell, then immediately causing it to undergo lysis.