UNDERSTANDING INFECTION TRANSMISSION Infectious agent or Pathogen: A biological, physical, or chemical agent capable of causing disease. Biological agents may be Bacteria; e.g. Staph, Strep, MRSA, E. coli, T. denticola, Porphyromonas gingivalis, etc.Viruses; e.g. Hepatitis B & C, HIV, flu, novel coronavirus (cause of COVID-19), Measles, etc.Yeast, fungus, mold; e.g. Candida albicans, Candida auris, etc.Parasites;...