Many of our body parts are full of blood and lymph, and blood and lymph are composed of water+salt+others molecules, so yes the interior of your body is a good conductor.
Fortunately the (dry) skin has a high enough resistance to protect you from low voltages that we can encounter in the modern world.
However static electricity can accumulate on your body because of the movement of the clothes you wear, the shoes you wear, the car you drive, the devices you use.
You don't need to be infected to experience static electricity discharges...