The health of people, animals, and the environment is intertwined. A health hazard for people may likely be a health hazard for animals. For example, smoking is not only harmful to people; it’s harmful to pets too. Medical advances in understanding and treating a disease in one species, such as heart disease in people, may be applied to other species. And a change in the environment can affect all living things, from people to animals to plants. The One Health Initiative recognizes this inter-connectedness and advocates a comprehensive approach to health and environmental problems versus a piecemeal approach. By building bridges between physicians, veterinarians, environmental scientists, and public health professionals, the One Health Initiative aims to “promote, improve, and defend the health and well-being of all species.”1
“No one discipline or sector of society has enough knowledge and resources to prevent emergence or resurgence of diseases in today's globalized world. Through mutual collaborations, veterinarians and physicians can accomplish so much more together to advance the health of humans and animals,” said Dr. Bernadette Dunham, former director of FDA’s Center for Veterinary Medicine and currently a visiting professor at the Milken Institute School of Public Health at George Washington University in Washington, D.C.
Zoonotic Diseases and Comparative Medicine
The link between human and animal health can be seen with bovine tuberculosis (TB) and brucellosis. Both are zoonotic diseases, meaning they can spread from animals to people. Bovine TB, caused by the bacteria Mycobacterium bovis, is most commonly found in cattle and other animals such as bison, elk, and deer. Brucellosis is another bacterial disease seen in livestock such as cattle, goats, and sheep, wild animals such as bison and elk, and other animals. People can become infected with both M. bovis and brucellosis by consuming contaminated, unpasteurized (raw) milk or dairy products and through direct contact with infected live animals or carcasses.
In the U.S., it was once common for cattle to spread bovine TB and brucellosis to people. But efforts to eliminate both diseases in cattle and routine pasteurization of cow’s milk have led to a dramatic decline in the number of human cases. At the beginning of the 20th century, about 20 percent of TB cases in people were caused by M. bovis.2 Today, that number is less than 2 percent in the U.S.3 From 1930 to 1941, about 29,600 cases of brucellosis in people were reported in the U.S.4 But from 1993 to 2010, fewer than 2,000 human cases were reported in the U.S.5
Initially, One Health efforts concentrated on preventing the spread of diseases from farm animals and wild animals to people. But more recently, One Health has begun to incorporate companion animals into its framework. The World Small Animal Veterinary Association established a One Health committee to not only focus on diseases that can spread from dogs, cats, and other pets to people but also on comparative medicine and the human-animal bond.6 The field of comparative medicine focuses on the similarities and differences between veterinary medicine and human medicine.
“One Health (formerly called One Medicine) is dedicated to improving the lives of all species—human and animal—through the integration of human medicine, veterinary medicine, and environmental science.
One Health shall be achieved through:
- Joint educational efforts between human medical [schools], veterinary medical schools, and schools of public health and the environment;
- Joint communication efforts in journals, at conferences, and via allied health networks;
- Joint efforts in clinical care through the assessment, treatment and prevention of cross-species disease transmission;
- Joint cross-species disease surveillance and control efforts in public health;
- Joint efforts in better understanding of cross-species disease transmission through comparative medicine and environmental research;
- Joint efforts in the development and evaluation of new diagnostic methods, medicines and vaccines for the prevention and control of diseases across species and;
- Joint efforts to inform and educate political leaders and the public sector through accurate media publications."
Obesity and Diabetes as Examples of Comparative Medicine
Obesity is a prime example of a medical condition that affects a variety of species, especially when the species share similar habits and environments. According to the Centers for Disease Control and Prevention, almost 71 percent of Americans over the age of 20 are overweight or obese.7 And according to the Association for Pet Obesity Prevention, a little over 53 percent of dogs and a little over 58 percent of cats are overweight or obese.8
Obesity goes a lot further than skin deep. It’s a major health hazard for all creatures, increasing the risk for several complications including:9
- Heart disease;
- High blood pressure;
- Breathing complications;
- Cancer; and
- Type 2 diabetes.
Diabetes is a metabolic disorder that results in high blood glucose (blood sugar) levels. In type 2 diabetes—the most common form of diabetes in people—the body doesn’t use insulin properly. Normally produced by beta cells inside the pancreas, insulin helps the body use or store the blood glucose from food for energy. In people and animals with diabetes, the glucose builds up in the blood instead of going into cells. An immediate effect is that the cells are starved for energy. And over time, the high blood glucose levels may cause skin and eye complications, nerve damage, and other problems.10
Diabetes is also common in cats, and feline diabetes closely resembles type 2 diabetes in people in many ways. For example, in both species, the disease is typically seen in middle-age patients, is associated with obesity, and is on the rise. As suggested in the article, Feline Models of Type 2 Diabetes Mellitus, “…the incidence of diabetes in cats is increasing for the same reasons it is increasing in humans—an increase in obesity and a decrease in physical activity.”11 Both people and cats are eating more, but exercising less.
Because feline diabetes shares many of the same features, risk factors, and complications as type 2 diabetes in people, cats are a good animal model for studying the human disease. Studies in cats may lead to better ways to prevent and treat diabetes in both felines and humans.12
A human-centric approach to studying health problems, such as obesity and diabetes, doesn’t do much good for animals. And insights gained from understanding diseases in animals may benefit people (and vice versa). A One Health approach tackles problems from an animal perspective as well as a human perspective for the benefit of all, and in the end, that’s really what One Health is all about.
For more information on One Health and the One Health Commission go to:
1One Health Initiative website. Mission statement. Available at: http://onehealthinitiative.com/mission.php Accessed Nov 1, 2016.
2 Animal and Plant Health Inspection Service website. What is One Health? Available at: www.aphis.usda.gov/animal_health/one_health/downloads/one_health_info_sheet.pdf Accessed Oct 28, 2016.
3 Centers for Disease Control and Prevention website. Mycobacterium bovis (bovine tuberculosis) in humans. Available at: www.cdc.gov/tb/publications/factsheets/general/mbovis.htm. Accessed Oct 28, 2016.
4 Animal and Plant Health Inspection Service website. What is One Health? Available at: www.aphis.usda.gov/animal_health/one_health/downloads/one_health_info_sheet.pdf Accessed Oct 28, 2016.
5 Centers for Disease Control and Prevention website. Brucellosis surveillance. Available at: www.cdc.gov/brucellosis/resources/surveillance.html. Accessed Oct 28, 2016.
6 Sandøe P, Palmer C, Corr S, et al. Canine and feline obesity: a One Health perspective. Vet Rec 2014;175:610-616.
7 Centers for Disease Control and Prevention website. Obesity and overweight. Available at: www.cdc.gov/nchs/fastats/obesity-overweight.htm Accessed Oct 28, 2016.
8 Association for Pet Obesity Prevention website. 2015 obesity facts & risks. Available at: http://petobesityprevention.org/pet-obesity-fact-risks. Accessed Oct 28, 2016.
9 Mayo Clinic website. Obesity complications. Available at: www.mayoclinic.org/diseases-conditions/obesity/basics/complications/CON-20014834. Accessed Oct 28, 2016.
10 American Diabetes Association website. Available at: www.diabetes.org/?loc=bb-dorg. Accessed Nov 1, 2016.
11 Henson MS, O’Brien TD. Feline models of type 2 diabetes mellitus. ILAR J 2006;47:234-242.
12 Osto M, Zini E, Reusch CE, et al. Diabetes from humans to cats. Gen Comp Endocrinol 2013;182:48-53.