Infectious Diseases - Timeline

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  • Infectious Diseases: Timeline
  • Edward Jenner and vaccination
  • Ignaz Semmelweiss and the spread of infection
  • Louis Pasteur and the germ theory of disease
  • Joseph Lister and antiseptic surgery
  • Alexander Fleming and the discovery of penicillin
  • Recent Events
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Edward Jenner and vaccination

Smallpox was a terrible disease which killed millions of people. It disfigured and disabled millions more all over the world. In the 18th century 'the pox' was common in Britain – around 20% of all deaths were caused by smallpox.

Edward Jenner was a country doctor who worked with the farmers in Gloucestershire in the late 18th century. He noticed that the girls who milked the cows often caught cowpox, which gave them spots rather like smallpox spots on their hands. He also noticed that milkmaids rarely caught smallpox.

In the 18th century no-one knew how infectious diseases were spread or how the immune system works. However Jenner began to wonder if deliberately infecting people with cowpox might protect them against smallpox.

Finally in 1794 Jenner decided to try out his idea. He took pus from the cowpox spots of a milkmaid and scratched it into the skin of a healthy young boy called James Phipps, who then developed cowpox.

Edward Jenner

Edward Jenner

Two months later Jenner scratched pus from a smallpox victim into James's arm. The little boy showed no signs at all of the deadly infection. Jenner's idea met with quite a lot of opposition but in the end the technique was so successful that protecting someone against a serious illness by exposing them to a similar but mild illness became widely accepted. The technique was called vaccination to link it with Jenner's work on cowpox (the Latin word for cow is vacca!).

Even in the 1960s millions of people were still infected with smallpox worldwide and around 2 million people a year died. But a massive international vaccination programme meant that in 1980 the WHO declared that smallpox had officially been eliminated from the world. The virus is now stored in a small number of laboratories around the world, and children are no longer vaccinated against a disease which does not exist.

Interestingly, Jenner's work would not be allowed today – it would be completely unethical to use a healthy child in an experiment in this way!

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Medicine that acts against bacterial infections. Penicillin is an example of an antibiotic.
Protein that is produced by lymphocytes (white blood cells) and that attaches to a specific antigen.
Molecule on the surface of a pathogen that identifies it as a foreign invader to the immune system.
Single-celled organism. Has a cell wall, cell membrane, cytoplasm. Its DNA is loosely-coiled in the cytoplasm and there is no distinct nucleus.
The use of biological organisms or enzymes to create, break down or transform a material
To cut apart, or separate, tissue especially for anatomical study.
Exponential growth
If something is growing exponentially the larger the quantity gets, the faster it grows
Micro-organism that can grow in long tubes called hyphae or as single cells. Fungi have a nucleus, cytoplasm and a cell wall.
Herd immunity
If a high percentage of a population is immune to a disease the disease cannot be passed on because it cannot find new hosts.
Infection caused by the human immunodeficiency virus (HIV). It attacks and destroys the immune system.
Hybridoma cells are formed by fusing a specific antibody-producing cell with a type of cancer cell that grows well in tissue culture
Immune system
The body's natural defence mechanism against infectious diseases.
A process which gives immune resistance to a particular disease. The human or animal is exposed to a harmless antigen in order to raise antibodies and provide an immune memory.
A type of white blood cell that make antibodies to fight off infections.
A type of white blood cell that consumes dead pathogens that have been killed by antibodies.
Organism that feeds off another living host and causes it some damage. An example of a parasite is a tapeworm that lives in the digestive system of a host organism.
A micro-organism that causes disease.
Phagocytes are the white blood cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells.
A polymer made up of amino acids joined by peptide bonds. The amino acids present and the order in which they occur vary from one protein to another.
Protozoa are one-celled animals
A spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavourable conditions.
A poisonous or toxic substance - produced by pathogens.
A small amount of dead or weakened pathogen is introduced into the body. It prepares the immune system to prevent future infections with the live pathogen.
Medicine that contains a dead or weakened pathogen. It stimulates the immune system so that the vaccinated person has an immunity against that particular disease.
The smallest of living organisms. Viruses are made up of a ball of protein that contains a small amount of the virus DNA. They can only reproduce after they have infected a host cell.
World Health Organization.
Chlorinated Lime
A mixture of calcium hydroxide, calcium chloride and calcium hypochlorite.
Free of pathogens. An aseptic technique is one performed under sterile conditions.
A chemical which can destroy microorganisms. Antiseptics are applied to the surface of the skin or to living tissue to reduce the possibility of infection.