How disease enter into the body through injuries in the skin

Wounds, even minor cuts and scratches, should be washed thoroughly with soap and water, including the area around the wound. If
the injury is not deep but merely a bruise with surface scratches and no bleeding, washing it as indicated above and painting with an antiseptic like iodine, and leaving the place unbandaged will be sufficient.

But even then care should be taken to protect the affected part from dust. If the injury is deep, however, it should be cleaned and treated the same way but definitely covered with a clean cloth to keep out the dust and dirt. An antibiotic ointment may be used in dressing the wound.