A8 Immune response in human pathology: Infections caused by bacteria, viruses, fungi, and parasites

In the middle of the 19th century, it became clear that micro-organisms could cause disease. Effective treatment, however, was not possible at that time; prevention and spread of infectious diseases depended solely on proper hygienic means. At the beginning of the 20th century, passive and active vaccination procedures were developed against a number of these PATHOGENIC MICRO-ORGANISMS to prevent the diseases in question (rabies, diphtheria, tetanus, etc.). Thanks to the discovery of antimicrobial chemicals (by Paul Ehrlich) and antibiotics (by Sir Alexander Fleming), the threat of infectious diseases seemed to be minimised. Large scale vaccination programmes against childhood diseases (diphtheria, whooping cough and polio), started in the early 1950s, raised hopes of finally being able to eradicate these diseases from the planet.