Modifiers matching std:

• common,
• chronic,
• bacterial,
• inflammatory,
• prevalent,
• major,
• infectious,
• serious,
• viral,
• protozoal,
• nasty,
• ulcerative,

Simple categories matching nasty:

• bug,
• stuff,
• thing,
• vice,
• weather,
• cause,
• critter,
• disorder,
• predator,
• disease,
• germ,
• material,
• bacteria,
• creature,
• chemical,
• pest,
• std,
• emotion,
• sickness,
• infection,
• allergen,
• animal,
• insect,
• preservative,
• happening,
• component,
• item,
• illness,
• condition,
• content,
• microbe,
• software,
• compound,
• program,
• substance,
• virus,
• parasite,
• weapon,
• contaminant,
• beast,
• pathogen,