VIRULENT

[adjective] - (of a disease or poison) dangerous and spreading or having an effect very quicklyA particularly virulent strain of flu has recently claimed a number of lives in the US.(formal) Virulent can also mean full of hate and fierce opposition.Several virulent attacks have been made on ethnic minorities in the area.A virulent critic of US foreign policy, he has made himself very unpopular in certain circles.She is very virulent about her former employer.