Bacteria and micro-organisms were observed for the first time under a microscope by Antonie Van Leeuwenhock. Originally referred to as ‘animalculus’, it was the start of the science of microbiology.
While in Constantinople, Turkey, Lady Mary Wortley witnessed local healers expose individuals to the fluid of a smallpox blister. Referred to as inoculation, she observed the positive effect it had on protecting the native population from the effects of the disease. On her return to England her promotion of the procedure was met with resistance due to her being female and the procedure being seen as ‘Oriental’.
Edward Jenner conducted the first demonstration of the smallpox vaccine. Using material from sufferers of the cowpox disease, he inoculated patients and found that they become resistant to smallpox. He utilised a similar method to that promoted by Lady Mary Wortley, yet used a weaker strain of the disease. It was the first demonstration of cross immunity.
Ignaz Semmelweis drastically reduced the deathrate of new mothers from child bed fever through the compulsory washing of physicians’ hands before childbirth. He theorised that medical practitioners carried infectious particles on their bodies. By enforcing a policy of washing hands in chlorine bleach solution he believed it would destroy the causal poisons that could be transmitted. The observation conflicted with the scientific and medical opinion of the time and was rejected by the medical community.
The documented observation of phagocytosis by phagocytes was written by Ernest Haeckel. His studies were in relation to establishing and maintaining organism ‘harmony’ rather than a part of host defence.
Joseph Lister provided the effective use of antiseptics in the treatment of wounds during war time. Building on the work of Louis Pasteur, Lister developed and tested the use of antiseptics (in the form of carbolic acid solution). The solution, when wiped on the wounds of patients, greatly reduced infections and cases of gangrene. He later ensured that hands and instruments were also washed in the solution before surgery.
Robert Koch showed for the first time that microbes can cause disease. He demonstrated the transfer of anthrax bacillus between cows.
Though hinted at and theorised for some time by a number of scientists, Louis Pasteur confirmed the ‘Germ Theory of disease’. Through a series of experiments that soundly supported the claim, he was able to convince most of Europe of the discovery.
Elie Metchnikoff developed the cellular theory of immunity via the observation of phagocytosis by macrophages and microphages. Metchnikoff saw this as being the immune response in its entirety.
Later it was established that the phagocytes were the second line of defence against infection in the immune response.
Designed to establish the relationship between a microbe and a disease, the Koch postulates are developed by Robert Koch and Friedrich Loeffler. These postulates consisted of four criteria that enabled scientists to identify pathogens in the 19th century. Modern technology has rendered them unnecessary today.