No matter if you choose to believe it or not, our world is changing. This is not an attempt to sway your opinion of why or if change is occurring, but a discussion of a specific change that should be of concern to us all.
Ebola is still in the news and unfortunately will probably continue to be so for the foreseeable future. But think back and you will probably remember other deadly diseases that seemingly appeared out of nowhere, bursting on to the news cycle. Remember SARS, Hanti Virus, and HIV? All these are zoonotic diseases: originating in animal populations and making the jump to a human host. In a review of 1,415 pathogens know to infect humans, 61% (863 pathogens) of them are zoonotic. The occurrence of zoonotic diseases is not a new phenomenon, but does seem to be capturing our attention more in the last couple of years and especially as of late. The emergence of pathogens from one species to a new host species, such as humans, is called “disease emergence.” This dates back into our history as a species and a civilization.
Much of our prehistory was spent in small groups of hunter-gatherers that were not often in contact with other groups of humans. This facilitated diseases entering into the human population. Once in a population, the disease tended to burn itself out by killing everyone in the first run of the infected population. The pathogens mutated to become a chronic infection in the human population, allowing the infection to stay alive in a host for longer periods or develop a non-human reservoir in which to live and wait for new host to infect.
In many instances, humans are actually accidental victims and a dead end host. Most of human development has been shaped in relation to zoonotic diseases. Among the best known examples of this are the Bubonic Plague of the Middle Ages and the AIDS/HIV crisis. There is good evidence that diseases such as measles, smallpox, the common cold, and tuberculosis may have jumped from animals to humans. Now current research is showing human actions and activities are helping this process along.
Human population booms, habitat encroachment (think the Everglades and the cutting of the rain forest), consumption of bush meat, and climate change are forcing people and animals into closer contact. Species formally living isolated in remote areas and deep in the rain forest are now being forced to eke out a living in very close proximity to humans. The concentration of humans, domesticated animals, and wildlife facilitate the spillover of pathogens between species. Highly mobile species like birds and bats present a greater risk of zoonotic transmission due to their increased mobility.
Thankfully, we have begun to come to a consensus that actions should be taken to combat the climate and environmental changes we are beginning to experience. Hopefully these actions will not be too little, too late to make a difference.
Dr. Pierre Bland is owner of “Dr. Bland’s Vet House Calls” a veterinary house call service. He can be reached at 954 673-8579 or at doctorblandvet.com.