Let's talk about Brief History of One Health. Let's review the One Health Concept. The term One Health is new but the concept is ancient. Embraced by indigenous peoples throughout history. One Health is very simply the concept that human, animal, including domestic and wildlife, and environmental and ecosystem health are linked. So One Health provides a useful framework to examine complex subjects such as global sustainability, food safety, food security, antimicrobial resistance, and emerging disease outbreaks. Over 75% of emerging infectious diseases are zoonotic. Meaning that they are diseases of animals that can infect humans. 60% of human pathogens are zoonotic. Most agents of bio-terrorism are zoonotic. But beyond zoonoses disease processes across species are often shared. Agriculture is the foundation of civilization, but it came with considerable costs. Including environmental destruction ecosystem disruption and diseases. In fact, measles came from cattle from the disease rinderpest. Q fever comes from goats and sheep and tularemia comes from rabbits. But it didn't go one way. The humans gave animals tuberculosis. Mycobacterium tuberculosis appeared about 40,000 years ago coinciding with human migration out of Africa. Two main lineages split about 20 to 30 thousand years ago. The second lineage is associated with animals. But genetic analyses suggest that humans probably infected their livestock and not the other way around. Now, Hippocrates was an ancient Greek physician and he recognized the link between human health and the environment, and he recognized that when people went to low-lying swampy areas, they would often get sick. And indeed, the term malaria literally means bad air. And since that time, it was believed all the way up till Jon Snow's time that bad air spread disease. The ancient Romans understood the importance of sanitation, and this is an image of people using a public lavatory. Unfortunately, the understanding of the importance of sanitation was lost during Medieval Europe. When people threw their waste out the window onto the heads of the passerbys below. And as a result of such poor sanitation, it created the conditions perfect for spreading the plague. This was in the 14th century caused by the bacterium yersinia pestis spread by the bite of fleas that were carried on rats. Smallpox also known as variola major was a major killer throughout history. This is an electron micrograph of the smallpox virion. Smallpox is thought to date back all the way to the Egyptian Empire around the 3rd Century BCE. It spread globally through trade and travel. Let's talk about variolation. Variolation was a practice that was developed some time in ancient China or India, where an astute observer noted that if you took dried pus from somebody who was recovering from smallpox and you either scratched it in the skin or blew it up the nose in somebody who is naive to the disease such as a child, you could reduce the mortality rate from smallpox from 30 percent to less than one or two percent. And that was a huge move in the right direction. In 1717, Lady Mary Wortley Montagu, wife of the British Ambassador in Constantinople, learned about this practice of variolation. And she wanted this practice to be done to her children. But not until it was practiced on a number of prisoners first to make sure that it was safe. So she had her children received dried pus from smallpox scratched into their skins. They got a little bit sick, but they recovered and were immune to smallpox. Now as I said the mortality rate dropped from 30%, from natural exposure, to around 1 to 2% from variolation,. And she introduced this practice then to England. Now the practice of variolation became widespread after the British royal family adopted it. In 1768 Dr. John Fewster, who was a surgeon and an apothecary in England, was variolating farmers and he found that some are already immune to smallpox. They had previously had cowpox and he relayed his findings a local medical meeting. Dr. Edward Jenner was an apprentice at that time and he learned about Dr Fewster's cowpox observations, and he tested the theory in 1796. So he obtained pus from the hand of Sarah Nelms who was a milkmaid. She had gotten cowpox from a cow named Blossom. And he scratched the pus into the arm of 8-year-old James Phipps, his gardeners son. That image is here. And he called the procedure vaccination as opposed to variolation. Vacca is the Latin word for cow. Now he submitted his findings to the local medical journals and they were rejected. So instead, he had to self publish his findings in 1798 and it was roundly criticized by the medical community because they were still using variolation. But it turned out that vaccination was actually better than variolation and it was slowly adopted. But as you can imagine, there was opposition to vaccination from the very beginning. And you can see in this cartoon little images of cows heads sprouting from people's bodies. Another major milestone in One Health history was the discovery of The Germ Theory of Disease. Doctor Louis Pasteur was a French chemist. And Dr Robert Cook was a German physician. Both of them are credited with discovering the germ theory of disease. Dr. Pasteur in 1880 was studying chicken cholera. Now, Dr. Pasteur had gone away on vacation. And when he came back, he discovered his old batch of chicken cholera and didn't know what to do with it. He decided to inject it into the chickens and surprise, surprise it did not kill the chickens. He saw an analogy with the smallpox vaccine, and he developed the theory of immunity from his chicken cholera study. So in other words, the old batch of chicken cholera had somehow become attenuated, and did not kill the chickens. And so in a way it helped the immune system to fight off the offending pathogen. He successfully applied this theory of immunity to rabies and developed the first rabies vaccine. Dr. Cook on the other hand, used evidence to establish the etiologic relationship between microorganisms and disease. His postulates included that microorganisms must be observed in every case of the disease. It must be isolated and grown in pure culture. Pure culture when inoculated in animals must reproduce the disease. And the microorganism must be recovered from the diseased animal. Dr. Rudolph Virchow was the first to coin the term zoonoses. And he said, "between animal and human medicine, there are no dividing lines nor should there be" and he developed the field of pathology. Now it might have helped that his father was a butcher to inspire him to examine thin slices of meat under the microscope. And when he did that he saw a number of parasites including trichinella spiralis that he found in pork meat and tania saginata or the beef tapeworm in beef, and he advocated for microscopic inspection of meat to ensure food safety. And this is an image of a German packing house in the early 20th century, not the most sanitary conditions. Another major discovery in the history of One Health is the discovery that insects or arthropods can transmit disease. Doctor Theobald Smith, a physician, pictured here, and Dr. Frederick L Kilbourne, a veterinarian, worked together as a team, and discovered the cause of cattle fever in 1893. They discovered that the cattle tick transmitted the parasite Babesia bigemina, that monumental discovery that insects could transmit disease set the stage for Dr Walter Reed and Dr Carlos Finlay to do an experiment to see if mosquitoes could indeed transmit yellow fever. Now, Dr Carlos Finlay had proposed that the aedes mosquito transmitted yellow fever, and it was up to Dr Walter Reed and his colleagues to set the stage and conduct the experiment to prove it. That's an image of the aedes mosquito. Now unfortunately, the experiments were rather unethical. And some of the fellow researchers died from yellow fever. But nevertheless they did prove that mosquitoes did indeed transmit yellow fever. An early advocate of One Health was Dr. James Steele. He's known as the Father of Veterinary Public Health by dedicating his career to advancing the understanding between human and animal health. And he wrote an influential report, Veterinary Public Health that served as a framework to understanding zoonotic diseases. And he became the first Chief Veterinary officer of the US Public Health Service in 1950. And he retired as the first assistant surgeon for veterinary Affairs in 1971. Dr. Calvin W Schwabe, a veterinarian, was an epidemiologist and a longtime colleague of Dr Steele. And he wrote the seminal text book Veterinary Medicine and Human Health and he coined the term One Medicine. So let's talk about One Health in the 21st century. Disease outbreaks including Avian Influenza triggered the realization that animal health profoundly impacts human health. Most emerging zoonotic diseases have been caused by viruses. And human activities such as deforestation contribute to these spillover events. Human population pressures, poor sanitation, intensive agricultural practices, bush meat consumption, the used tire trade, exotic animal trade, deforestation, and global travel all contribute to the emergence of diseases and their spread. Now the Wildlife Conservation Society held a meeting in New York City in September 2004, to discuss One World One Health hosted by the Rockefeller University. Expert panelists examined a number of case studies including avian influenza and chronic wasting disease, and they developed 12 recommendations called The Manhattan Principles. That include the need to recognize the link between humans and animals. Both domestic and wild, regarding disease threats, food security, and economic growth. Dr. Roger Mahr, A veterinarian and President of the American Veterinary Medical Association, met with Dr Ronald Davis, President of the American Medical Association, in June of 2006, and they discussed possible collaborative efforts between their two organizations. As a result, the American Medical Association passed a One Health resolution which included increasing communication and collaboration with the Veterinary Medical Community. And in particular, the AVMA. The AVMA subsequently established a One Health task force. Here are several One Health logos that recognize that healthy people, healthy animals, and unhealthy environment create a One Health scenario. And One Health advocates in Sweden developed this One Health Umbrella scenario. So the questions for this session then are what is the One Health concept? What were the benefits and costs of agriculture? What does the term malaria mean literally? What is the difference between variolation and vaccination? And why was vaccination an improvement over variolation? Which two scientists independently discovered the Germ Theory of Disease? Which of these two scientists identified the concept of immunity and developed the rabies vaccine? And which two discoveries illustrate the linkages between human, animal, and environmental health? And with that, I'd like to thank you for watching this session.
