1. One Health: A Concept for the 21st Century
Laura H Kahn, MD, MPH, MPP, FACP
Program on Science and Global Security
Woodrow Wilson School of Public and International Affairs
Princeton University

2. What is One Health?
The concept: human health is inextricably linked with animal and environmental health.
One Health seeks to increase communication and collaboration between human, animal, environmental health professionals.

3. Why One Health?
Zoonotic disease risks from wildlife, livestock, and pets.
Over 75% of emerging infectious diseases are zoonotic
60% of human pathogens are zoonotic.
Most agents of bioterrorism are zoonotic.
Beyond zoonoses: Disease processes across species are shared.

4. The Price of Agriculture and Domestication of Animals
Agriculture about 10,000 years ago.
Agriculture (aka food security) is foundation of civilization.

5. Why is food security so important?
Agriculture and food security (a.k.a. preventing hunger) form the foundation of civilization.
Food security is inextricably linked with global health, global sustainability, and international security.
There is no global health without global food security.
Many diseases (i.e. Ebola, Zika, Chikungunya, SARS, Nipah, etc.) are emerging and spreading because of widespread deforestation, environmental degradation, and bushmeat consumption—linked to food security.
Global climate change affects food security.

6. Time of Complex Life on Earth
Paleozoic Era
Cenozoic Era
Early hominids
Permian-Triassic Extinction
Cambrian Explosion: Thriving life in seas but barren land
Earth is 4.5 Billion Years Old

7. Diminishing Water Supplies in U.S.

8. Price of Agriculture Measles (Rinderpest) Cattle
Brucellosis Goats/Sheep
Q fever Goats/Sheep
Tularemia Rabbit/Squirrels
BSE Cattle

9. Went both ways…
Mycobacterium tuberculosis appeared about 40,000 years ago, coincided with human migration out of Africa.
Two main lineages 20-30,000 years ago: 2nd lineage associated with animals.
Humans probably infected livestock.

10. Hippocrates (ca. 460 BCE--ca. 370 BCE)
Recognized the
link between
human health and
the environment.
Malaria=“mal” +
“aria.”

11. Middle Ages (14th Century): Black Death
Bacteria: Yersinia pestis
Spread by fleas
carried by rats

12. Beginning in the 18th century…
Some of the greatest discoveries in the history
of medicine and public health were made at the
intersection between human and animal health.

13. 18th Century: Vaccination against smallpox
“Vacca” is
Latin word
for cow.
Dr. Edward Jenner vaccinating 8 yr old boy

14. Opposition to Vaccination

15. 19th Century: Germ Theory of Disease
Louis Pasteur, French chemist studied chicken cholera
Robert Koch, German physician studied anthrax

16. Additional 19th Century Developments
Rudolf Virchow ( ), a German physician and pathologist said, “between animal and human medicine there are no dividing lines--nor should there be.”
Coined term “zoonosis”
One Health concept is not new.
Hippocrates, famous ancient Greek physician, wrote “Airs, Waters, and Places” promoting the concept of health through a clean environment.
Virchow is considered the “father” of pathology, the microscopic study of tissues.
He coined the term, “zoonosis.”

17. Early Meat Inspection Programs Improved Food Safety
Virchow’s father was a butcher.
Animal experiments on life cycle of Trichinella spiralis in porcine muscular tissue.
Studied cysticercosis and tuberculosis in cattle.
Used data to advocate for raw meat inspections. Began a program in Europe in which veterinarians inspected meat. Program subsequently began in U.S.
An major advance in food safety.

18. 19th Century Developments
Sir William Osler received his medical degree from McGill University, Canada
Went to Berlin to work with Virchow
Returned to Canada in 1874
Est. veterinary pathology as an academic discipline in North America
Osler is considered the “father” of modern medicine because he introduced the scientific method to the practice of medicine. Medical students and residents were encouraged to collect data through history taking, physical examinations, and laboratory studies before developing differential diagnoses and treatment plans. Changed the way medicine was taught—at the bedside-- and not just in lecture halls.
What isn’t well known about Osler was that he practiced “One Health” long before the concept was developed.

19. 19th Century Discovery: Diseases can be transmitted by arthropods
Theobald Smith, MD (pictured) and F.L. Kilbourne, DVM discovered cause of cattle fever
Babesia bigemina transmitted by the cattle tick.
Set the stage for Walter Reed and colleagues’ discovery that mosquitoes transmit yellow fever.
Major discovery in 1893 in veterinary medicine that diseases could be transmitted by insect vectors. (
Set the stage for the discovery that mosquitoes transmitted yellow fever.

20. 20th Century Developments
Scientific knowledge exploded
Medicine became increasingly specialized
Medicine and veterinary medicine diverged

21. Emergence of new infectious diseases in 20th century

22. Why are these diseases emerging?
Increasing global population pressures
Deforestation and environmental destruction
Intensive agriculture
Global trade and travel
Climate change

23. 1999 West Nile Virus Outbreak in NYC

24. Two Simultaneous Outbreaks

25. Solving the Mystery Dr. Tracey McNamara, Chief Veterinary
Pathologist, Bronx Zoo
Birds native to North America

26. Challenges of the 21st century
Requires a new paradigm, One Health:
Zoonotic diseases
Cancer
Cardiovascular Diseases
Metabolic Diseases
Neurological Diseases
Degenerative Diseases and Injuries
And others…
Many of the infectious diseases that are causing some of the most serious public health problems today are zoonotic diseases.
70% EID are zoonotic
80% of bioterrorist agents are zoonotic
60% of all human pathogens are zoonotic.
Factors that promote zoonotic disease emergence are not going to go away, but rather increase.
Most important factor is increasing human population. UN estimates that by 2050, 9 billion people on the planet. These people will need to eat, have shelter, sanitation, use energy, transportation.
Deforestation, intensive agriculture, climate change, destruction of ecosystems all play a role in disease emergence.

27. Humans and Animals Get the Same Diseases: New Therapeutic Discoveries Can Benefit All Species
Animals get many of the same diseases as humans: cancer, heart disease, diabetes, obesity, organ failure, degenerative joint disease, …
USDA recently conditionally approved a vaccine to treat canine oral melanoma—the first therapeutic vaccine for the treatment of cancer in either animals or humans.
Merial is the company that produces it.
Should do more clinical trials in animals. Naturally occurring cancer in animals is important to study—not just artificially induced cancers in genetically alterred animals (mice) as an effort to mimic human disease.

28. Human and Animal Health: A Symbiotic Relationship
Pets, Livestock, Wildlife
Benefits our physical health
Benefits our mental health
Benefits our social health
Benefits our environmental health

29. Pets

30. Livestock

31. Wildlife
Healthy wildlife indicate healthy ecosystems, but wildlife do carry risks to humans--

32. Physical Health Owning a pet improves human health.
But risks must be acknowledged and addressed.

33. Pets American Pet Products Association 2013-2014 Owners Survey:
68% of U.S. households own a pet
Approx million homes
56.7 million households own a dog
45.3 million households own a cat
In 2013, est. $55.53 billion spent on pets in U.S.

34. Physical Health Benefits
Lower high blood pressure
Reduces risk of allergies in children
Increases exercise motivation

35. University of Missouri Human-Animal Center Established a Walk a Hound, Lose a Pound Program
Eric and Peety video:

36. Dog Walking

37. Risks of Pet Ownership: Microbes are shared New York Times, September 21, 2009
Dr. Elizabeth A. Scott et al.
swabbed household surfaces
at 35 randomly selected addresses. Nearly half of homes had MRSA on surfaces.
Cat owners were 8
times more likely than
others to have MRSA at home.
There is evidence that some deadly pathogens are shared between people and their pets.
In one study published by Elizabeth Scott, et al. in the American Journal of Infection Control found that households with cats were 8 times more likely to have MRSA on household surfaces than those without cats.
Scott E, Duty S, McCue K. A critical evaluation of methicillin-resistant Staphylococcus aureus and other bacteria of medical interest on commonly touched household surfaces in relation to household demographics.” Am J Infection Control. 2009; 37:
“Tie to pets has germ jumping to and fro”
Methicillin Resistant Staph aureus (MRSA)
is infecting both humans and animals.
American Journal Infection Control Aug. 2009: 37:

38. Zoonotic diseases and pets
Some people are at greater risk:
Chronically immunosuppresed
HIV/AIDS
Organ transplant recipients
People with autoimmune diseases
Pregnant women
Infants and very young children

39. Grant and Olsen Study, 1999
Grant and Olsen, EID, “Preventing zoonotic diseases in immunocompromised persons.”
Surveyed MDs and DVMs in Wisconsin
MDs generally not comfortable discussing role of animals in zoonotic disease transmission.
DVMs typically didn’t know pet owner’s health status.
Found nearly a complete lack of communication between MDs and DVMs.
Result: Zoonotic disease risk communication to patients falls through the cracks.

40. Grant and Olsen Study, 1999
MDs and DVMs asked to rank animals posing greatest risk to immunocompromised patients.
DVMS: ranked reptiles (Salmonella) and puppies (Campylobacter)
MDs: ranked cats and kittens
Both groups ranked Salmonella and Toxoplasma gondii as microbes of greatest risk.

41. Risks of Pet Ownership for Immunosuppressed
Reptiles carry Salmonella in their guts.
In U.S., exposure to these animals leads to 100,000 cases of reptile-associated salmonellosis each year.
Reptiles are popular pets: In 2001, estimated households with reptiles— 1.7 million

42. Risks of Exotic Pet Ownership

43. Monkeypox Outbreak 2003
Orthopoxvirus group: Includes smallpox, cowpox, and other pox viruses.
Viral disease found mostly in rainforest countries of Central and West Africa.
Called “monkeypox” because first identified in lab monkeys in 1958.
Natural host may be African squirrel
Shipment of rodents from Africa to U.S. set off Midwest outbreak requiring smallpox vaccinations to stop it.

44. Root Cause of Outbreak: People buying wild exotic animals as pets
Dormice
Giant Gambian Rat
Striped Mice
April 9, 2003:
Shipment of 800 small mammals
from Ghana
(including 762 African rodents)
arrived in Texas.
Brushtail Porcupines
Tree Squirrel

45. Monkeypox Chain of Transmission
Prairie Dog
Giant Gambian Rat
Human
35 laboratory confirmed cases.
28 adults and 2 children in 6 states
received the smallpox vaccine to
prevent further monkeypox transmission.

46. Trade in Exotic Animals
2000 to 2006: 1.5 billion live wild animals legally imported into U.S.
Approx. 120,000,000 per year.
90% destined for pet industry.
Minimal surveillance; health risks unknown.

47. Some animals simply shouldn’t be pets
15,000 big cats and
15,000 primates
in private hands
in U.S. according to
Humane Society of US.
400 tigers left in Sumatra.
Only 18 states have
outright bans on
exotic animals as pets. NYTimes
Jan. 10, 2012.
More tigers
are now kept
as pets
in the U.S.
than living
in the wild.
BuyTigers.com

48. Mental Health Benefits
Human-animal bond:
Lower feelings of loneliness
Reduces depression
32% of dog owners take their pets with them when gone for 2 or more nights.
Animal-assisted therapy
Hurricane Katrina 2005

49. Social Health Benefits
For elderly or people living alone, pet might be only family member.
Increases social interactions.
Increases sense of well-being.

50. Social Health Benefits
Animals teach responsibility and caring
Animals give people a sense of purpose and self esteem
Animals provide unconditional love
Puppies for Prisoners

51. Environmental Health Benefits
Which scene would you rather look at?
Plants and animals help people heal

52. Environmental Health Benefits
Healthy Environment = Healthy People and Animals

53. How can One Health be promoted?
DVMs are well positioned to promote One Health.
Establish inter-disciplinary, inter-species conferences.
Develop collegial relationships with human and environmental health professionals.
Educate policy makers and the public about the importance of One Health.

54. Take Home Messages Human, animal, and environmental health are linked.
One Health concept provides an important strategy to improve the lives of all species
Animals suffer from many of the same diseases as people: new therapies would benefit all species.
Animals (and plants) improve people’s physical, mental, social, and environmental health.
A healthy environment benefits everybody.
Animal health professionals should work with human health professionals to prevent zoonotic disease transmission, especially in high risk groups, that rely on pets for mental and social well-being.

55. The One Health Umbrella

56. One Health Endorsements
American Medical Association
American Veterinary Medical Association
American Nurses Association
American Association of Medical Colleges
American Association of Veterinary Medical Colleges
American Society for Microbiology
American Society of Tropical Medicine and Hygiene
Council of State and Territorial Epidemiologists
Association of Schools of Public Health

57. Acknowledgements Collaborators: Bruce Kaplan DVM, Dipl. AVES (Hon)
Tom Monath MD
Jack Yuill, PhD
Lisa Conti, DVM, MPH

58. Thank you!