pest - noun

a serious (sometimes fatal) infection of rodents caused by Yersinia pestis and accidentally transmitted to humans by the bite of a flea that has bitten an infected animal

any epidemic disease with a high death rate

a persistently annoying person

any unwanted and destructive insect or other animal that attacks food or crops or livestock etc.

pest - thesaurus

blighter   cuss   gadfly   pesterer   pestilence   pestis   plague