The traditional society took care of epidemic diseases by containing it within the geographic bounds. This gave rise to the tradition of vaidyas or doctors being untouchables unless they performed rituals which if understood in the context was nothing but disinfection.
The spreading of cow dung on the courtyard was disinfection combined with mosquito control. Stringent techniques on left over’s and eating seasonal food were other ways of combating disease.
The skin excoriates or constantly sloughed off, this prevents bacterial colonization.
The sweat and oils contain anti-microbial chemicals some are also body generated antibiotics.
The mucuss contains lysosomes, enzymes that destroy bacterial cell walls, normal flow of mucus washes bacteria and viruses off mucus membranes. Cilia in the respiratory tract move the mucus out of the lungs keeping the bacteria and virus out.
The blood contains white blood cells called the phagocytes which include macrophages and neutrophils these destroy invaders, some also destroy the damaged body cells, that emerge as the yellow pus around the wound, or the phlegm when we cough and sneeze.
The cells release a chemical called histamine which dilutes the toxins by collecting around the injury, this causing a swelling. The raise in temperature round the foreign body and the increase in the cellular pressure environment kill the microbes.
Even fever is a defence mechanism that can destroy many microbes. It helps to fight viral infection by increasing interferon production. Many a times it makes sense to let a fever run its course.