Which term describes a skin infection caused by microorganisms smaller than bacteria that reproduce inside human cells (examples include chickenpox, hepatitis and cold sores)?

• A. Fungal infection
• B. Viral infection
• C. Bacterial infection
• D. Parasitic infection

Answer: (B)

Viruses are the smallest infectious agents and they replicate only inside living cells. A skin infection described as being caused by microorganisms smaller than bacteria that reproduce inside human cells points to a viral infection. Examples like chickenpox, hepatitis, and cold sores are all caused by viruses (varicella-zoster, hepatitis viruses, herpes simplex, respectively). Because viruses rely on our cells to multiply, they fit this description perfectly. In contrast, fungal infections are caused by fungi, which are different organisms; bacterial infections are caused by bacteria and are not defined by replication inside our cells; parasitic infections involve larger organisms like protozoa or worms.