Science - Timeline

4 May 1796: Edward Jenner tests his hypothesis: People that have had cowpox would be immune to smallpox. He observed this because he saw that many milk maids were immune to smallpox. He proved his hypothesis by inoculating (vaccinating) an eight year old boy. Later, he was exposed to variolous material, but no infection followed. He contributed because he subsequently showed how this worked and finally vaccination was accepted and variolation was later banned.

Many other people worked in parallel on the same discovery including: Fewster, Sevel, Jensen, Jesty, Rendell and Plett

1765: Lazzaro Spallanzani manages to prove that the theory of spontaneous generation is false because if water is boiled for one hour, then this feature doesn't occur. He could finally conclude that microorganisms can travel through air. He also paved the way for the experiments of Louis Pasteur.

1865: Louis Pasteur finds out that when liquids are heated to 60-100ºC, most microorganisms dye preventing whine, milk and other liquids from going bad. He patents this process and names it pasteurization.

28 September 1928: Fleming accidentally discovered penicillin because he had left his laboratory for a month in august and upon returning, he found that one of his stacked-up cultures was contaminated with a fungus and all the colonies of staphylococci immediately surrounding the fungus were destroyed. He analyzed this fungus and found out that he had discovered the first antibiotic or "bacteria killer".

1500: According to several accounts from the 1500s, smallpox inoculation was practiced in China and India (one is referred to in volume 6 of Joseph Needham's Science and Civilization in China). Glynn & Glynn, in The Life and Death of Smallpox, note that in the late 1600s Emperor K'ang Hsi, had his children inoculated. That method involved grinding up smallpox scabs and blowing the matter into nostril. It is difficult to pinpoint when the practice began, as some sources claim dates as early as 200 BCE.

1884: Hans Christian Gram develops a way of classifying bacteria into two major categories, Gram-positive and Gram-negative. This technique, the Gram stain, continues to be a standard procedure in medical microbiology today.

1901: Walter Reed finally completed his research on Yellow fever and finds out that it is not transmitted through water or inanimate objects, but was actually transmitted by mosquitoes. He observed this when only some of the army situated close to the Potomac river caught yellow fever even though everybody drunk from the same water. He also showed that those contaminated had habits of walking on muddy trails at night. Later he conducted a specific study with volunteers that were deliberately infected.

1882: Robert Koch Publishes findings on many diseases including Anthrax, Tuberculosis and cholera. He discovered the cause of Anthrax which is Bacillus Anthracis, the cause of Tuberculosis being Mycobacterium tuberculosis and Vibrio cholerae, the cause of cholera.

"Koch's Four postulates": 1. The organism must always be present, in every case of the disease. 2. The organism must be isolated from a host containing the disease and grown in pure culture. 3. Samples of the organism taken from pure culture must cause the same disease when inoculated into a healthy, susceptible animal in the laboratory. 4. The organism must be isolated from the inoculated animal and must be identified as the same original organism first isolated from the originally diseased host.

26 December 1900: Robert Koch also finds out about acquired immunity to malaria, because he arrives as part of a German expedition in German New Guinea and examined the blood of many inhabitants and noticed they contained Plasmodium parasites, the cause of malaria, but their bouts of malaria were mild or could not even be noticed

1880: Charles Louis Alphonse Laveran while working in the military hospital in Constantine, Algeria, he discovered that the cause of malaria is a protozoan, after observing the parasites in a blood smear taken from a patient who had just died of malaria. He found the causative organism to be a protozoan which he named Oscillaria malariae, but later renamed Plasmodium.

1849: In 1848 the second cholera epidemic arrived in London and was thought to be because of “miasma” or “bad air”. John Snow had first hand experience of the disease from 1832 and could directly exclude the hypothesis of "bad air" and went on to hypothesize that cholera was attributable to a self-replicating agent which was excreted in the cholera evacuations and inadvertently ingested, often through water. He could later test his hypothesis in 1854 when another outbreak occurred.

During World War I Fleming continued his investigations into antibacterial substances. Testing the nasal mucus from a patient with a heavy cold, he found that it had an inhibitory effect on bacterial growth. This was the first recorded discovery of lysozyme, an enzyme present in many secretions including: tears, saliva, skin, hair, nails and mucus. Unfortunately, the enzyme was only effective against small counts of harmless bacteria, and therefore had little therapeutic potential.