It's hard to believe that medical researchers could underestimate the dangers of tuberculosis -- the world's deadliest infection.
Yet according to a study published by Lancet Infectious Diseases, a medical journal, one form of the disease is a far bigger threat than previously thought -- animal TB.
The illness, which can be acquired through contaminated food or close contact with animals, afflicts roughly 120,000 humans around the world. It's harder to treat than the conventional form of the disease -- and is resistant to the main antibiotic used to treat TB.
Zoonotic diseases -- illnesses spread between animals and humans -- represent some of the most serious public-health threats the world faces. Battling them effectively will require a broader approach to human health -- one that takes into account the relationship between human beings, animals, and the wider ecosystem.
Nearly 3 million people die annually of animal-borne diseases. These illnesses include everything from influenza and salmonella, to Ebola, malaria, and Zika.
In an alarming number of cases, zoonotic illnesses have led to devastating epidemics. The 2014 Ebola outbreak, for instance, is believed to have started when a bat transmitted the illness to a young boy in Guinea. The disease soon spread throughout West Africa, with cases emerging as far away as the United States. Ultimately, more than 11,000 people died.
The mosquito-borne Zika virus has infected tens of thousands of people in 73 countries and territories -- including 3,800 people in the continental United States.
We haven't seen the last of these kinds of outbreaks. Scientists estimate that nearly 75 percent of newly emerging infectious diseases will originate in animals.
Addressing the risk posed by zoonotic diseases will require an approach to global health that sees humans, animals, and the environment as deeply interconnected. Known as One Health, this holistic view calls for collaboration among experts in disciplines from veterinary medicine to public health and environmental science.
If researchers can understand the interconnected causes of zoonotic outbreaks, they'll be better equipped to prevent the next epidemic.
Fortunately, the One Health movement is gaining traction in the public health community. USAID, for instance, has spearheaded a One Health Workforce initiative which partners with universities around the world to train future health professionals in this collaborative approach.
One Health is a guiding philosophy at St. George's University, where I teach. Our veterinary, medical, and public health students frequently collaborate on projects and coursework, like our recent effort to control the spread of rabies on the island of Grenada by providing vaccinations and hosting community clinics.
The rise of zoonotic diseases like Zika, and animal TB shows just how interconnected animal health and human health are. To effectively combat zoonotic disease, the medical community must recognize those connections -- and explore them fully.
Satesh Bidaisee is an Associate Professor of Public Health and Preventive Medicine and Assistant Dean for Graduate Studies at St. George’s University, Grenada. Calum Macpherson is the Dean of the School of Graduate Studies and Director of Research at St. George's University in Grenada.