As our readers in the U.S. celebrate Thanksgiving Day, we pause to acknowledge several historic milestones that changed the landscape of detecting and defending against infectious diseases.
We also give our gratitude to those working to expand the reaches of science and technology, improve our local and global public health programs, and provide frontline response to emergencies.
1. Germ Theory and the First Laboratory Vaccine French chemist Louis Pasteur’s development of the germ theory of disease in the 1860s was perhaps the most significant breakthrough in medicine, led to the invention of sterilization techniques and ultimately improved the health of everyone on the planet.
Pasteur is also credited with the development of vaccines, most notably for rabies and anthrax. He produced the first laboratory-developed vaccine in 1879, targeting chicken cholera. Through a lab mix-up that delayed bacteria injections into his test subjects, allowing time for the bacteria to weaken, Pasteur discovered the method of vaccine attenuation.
2. Army Researchers Discover the Cause of Yellow Fever Spurred by the massive yellow fever-related casualties in the Spanish-American War, members of the U.S. Army Yellow Fever Commission, headed by Walter Reed, traveled to Cuba to study the disease. Observations on the 10-17 day incubation period of the disease led to the theory of a living host for transmission, ultimately identified in 1900 as being from mosquitos.
3. Typhoid Vaccination Commonplace in the United States By 1914, the typhoid vaccination had moved beyond military forces in the United States and into use for the general public. Updated, safer vaccines are still recommended to this day for travel to endemic areas, where an estimated 16–33 million annual cases of typhoid fever result in over 200,000 deaths.
4. Penicillin In 1928, Alexander Fleming discovered the first antibiotic, penicillin, which he grew in his lab using mold and fungi. By the 1940s, penicillin was being mass-produced and changed the world in ways that are almost difficult to understand today. Prior to penicillin, infections from a cut or illness such as strep throat often proved deadly.
5. Yellow Fever Vaccine Developed Max Theiler and his colleagues developed a live attenuated vaccine for yellow fever in 1936 using tissue cultures prepared from embryonated chicken eggs. The vaccine was easily adapted for mass production, and became the universal standard.
6. Polio Vaccine Approved In 1955 a press conference was held to reveal the Salk poliovirus vaccine trial demonstrated 80-90% effectiveness against paralytic polio. The U.S. government licensed Salk’s vaccine later this same day, paving the way for widespread distribution.
7. Smallpox Declared Eradicated Smallpox, or variola, was responsible for an estimated 300–500 million deaths during the 20th century. After decades of global vaccination campaigns, the World Health Assembly in 1980 accepted the WHO Global Commission’s recommendation and declared the world free from smallpox.
8. Deoxyribonucleic acid (DNA) In 1953, James Watson of the United States and Francis Crick of England revealed what is now accepted as the first correct double-helix structure of DNA.
Cracking the structure of DNA explained how the gene works as the fundamental unit of inheritance and how it is replicated from one cell to the next and one generation to another. Follow-on discoveries of how these genes can be damaged and create mutations which cause harmful diseases has revolutionized biological sciences and medicine.
9. Polio Declared Eliminated from the Americas Wild poliovirus was declared eliminated from the Americas in September 1994, making it the first World Health Organization Region to meet the goal of polio elimination. The global eradication effort, begun in 1988 and led by the World Health Organization, UNICEF and The Rotary Foundation, has reduced the number of annual diagnosed cases from the hundreds of thousands to around a thousand. Critical immunization efforts continue in remaining polio endemic countries such as Nigeria, Pakistan and Afghanistan.
10. Polymerase Chain Reaction (PCR) Developed in 1983 by Kary Mullis, PCR is now an indispensable technique used in medical and biological research for DNA cloning for sequencing, functional analysis of DNA genes, identification of pathogens, diagnosis of hereditary diseases, and for forensic sciences.
PCR allows scientists to make millions of copies of a scarce sample of DNA. When completed manually, Mullis’ PCR technique was slow and labor-intensive. With the addition of thermostable Taq enzymes, thermocycling techniques advanced the method and paved the way for commercial development of what is now an indispensible laboratory technology.
Important variants of PCR grew from these foundations including Reverse transcription polymerase chain reaction (RT-PCR), Real-time polymerase chain reaction (qPCR) and combined techniques. Such methods are commonly used in studying or identification of viruses such as Influenza A and filoviruses, as well as other pathogens.