[biofunsf]

Aren’t viruses much harder to detect than bacteria? Viruses are generally smaller and are completely inert without a host cell. Bacteria, besides be larger, also have their own metabolic processes and distinct structures you can do things like grow them in a laboratory culture until the colony is much obvious.

Your comment makes it sound like bacteria are harder to detect but if we’re already identifying viruses, locating bacteria seems easier.

(Though some viruses are bigger than the smallest bacteria, like Mycoplasma at 200nm, viruses are generally smaller)

[londons_explore]

Both are hard to detect if there are only hundreds of them amongst trillions of human cells.

At that point, 'just look with a good microscope' becomes infeasible, and you end up needing biological tricks like DNA amplification.