- Objective evidence; a sign such as a chickenpox rash
- Subjective evidence; a symptom such as aching limbs or pains in the stomach
Asepsis and Antisepsis
Asepsis is the absence of infectious organisms and techniques are aimed at minimising the risk of infection. This came about when Semmelweiss (1847) realised washing hands between deliveries and examination of patients drastically reduced the numbers of cases in childbed fever.
Then it was seen that coal tar put on wounds would keep out most microbes- contained phenol (carbolic acid). Lister used pure phenol as antiseptic during and after surgery. If these chemicals were used to destroy bacteria on surfaces or in atmosphere it would be called a disinfectant, but called an antiseptic if used directly on people.