Interconnected
HUMANS DO NOT STAND ALONE IN THE WORLD, WE FORGET THIS AT OUR PERIL.
Our world today looks very different than it did just 2-3 months ago, and perhaps the real reason is that only in times of extreme crises do we choose to acknowledge the obvious: that humans are not distinct from the rest of the animal kingdom, yet we often ignore this simple fact to our own peril.
The CDC estimates that 3 out of every 4 emerging diseases originate in animals, meaning, not only is it important to be aware of diseases circulating within the animal kingdom, but that we have many opportunities to study disease variation, different responses to diseases, and differences immune responses that result in very different outcomes for the affected human or animal.
August Krogh (1874-1949)
Pioneer in Comparative Physiology
For example, it is well-known that while bats are reservoirs for many of our most feared viruses (Rabies, Hendra, Ebola, Marburg and SARS-CoV), they do not actually cause diseases in these hosts. A recent study released by scientists at Girihlet examined immune responses in Egyptian rousette bats to Ebola and Marburg infections and documented key differences not only in the immune response, but also in pathways relating to blood pressure regulation and clotting that allow bats to survive infections that rapidly kill humans. It is not only mammals that we should be looking to for clues to novel viruses. A few months ago, investigators identified a novel nidovirus in Pacific Salmon causing localized infections of the gills. Nidoviruses are evolutionarily closely related to coronaviruses, and by examining similarities and differences in respiratory disease resulting from this viral family across a range of species, we can start to understand more about how different species respond to infection. The many ways that human and animal data intersect is an emerging field and there are a multitude of avenues to explore -- including how to apply these learnings to inform treatment and improve human health.
Peyton Rous (1879-1970) and the chicken that changed how we think of cancer
Even before Krogh, Peyton Rous -- an American virologist -- in 1911 expanded his observations of naturally occurring cancers in chickens into two major discoveries: the first being that viruses can cause cancer and the second demonstrating how viruses can co-opt our own genes to drive cancer. This -- the discovery of oncogenes -- is one of the core discoveries in cancer biology and genomic medicine. It paved the way for therapies that target mutated, fused or overactive cancer genes like Gleevec (approved in 2001) and much more recently Vemurafenib, the first targeted therapy for melanoma (and a drug I studied during my own PhD). And, it was discovered in chickens, not in humans or mice injected with human tumor cells.
The work of these researchers, and many others, drives the expansion of genomic studies, which build on decades of detailed studies of physiology and biology, into an ever-expanding set of species (from tiny water bears to grizzly bears). More scientists today are beginning to recognize the limitations of our narrow species focus on humans and the model organisms we often attempt to mold to mimic human biology.
Outside of basic physiology and genomics, the linkage between animals and humans (which really are two false categories) affects nearly every aspect of our lives, from the environment to antimicrobial resistance to food security to rare disease biology.
Yes, in some states kangaroos are legal pets
Right now, the world is focused on one of them, but let’s not have this current situation make us myopic.
In addition to identifying and tracking zoonotic diseases, improvements in animal and human data sharing can help us better understand outcomes for many different types of diseases (not just infectious). Machine learning techniques can allow earlier and more accurate identification of increased disease incidence, leading to improved clinical outcomes. Inclusion of geolocation data can help identify possible environmental associations to animal disease that may inform related human diseases.
Companion animals (and trust me, the definition of ‘companion’ animals varies widely!) share homes and, often, food with humans, which in addition to providing comfort and companionship, makes them excellent means to understand environmental and infectious disease, not to mention lifestyle diseases like obesity. Pets are exposed to environmental contaminants, infectious agents, and pollutants and may be more susceptible to them than their human counterparts. Several studies have shown the power of using animal data as environmental indicators.[link1][link2][link3] This is particularly true within the aquatic environment where animals can be keys to understanding the current environmental status.
One of the less frequently considered examples are rare diseases, defined as affecting 1 in 10 (or fewer) Americans, which are being identified at increasing rates and present diagnostic and treatment challenges. Naturally occurring disease models in companion animals that are representative of rare human diseases can result in translation therapies that improve both animal and human lives. For example, osteosarcoma (OSA) is a type of bone cancer that while being the most common bone tumor in humans, is still very rare with <1000 new cases diagnosed in the United States each year. Half of those diagnosed are under the age of 25. Even with diagnosis, they generally require surgery and chemotherapy for disease control, with the continued risk of metastasis. In dogs, however, OSA is the most common primary bone tumor with an incidence 27 times that of humans. Ongoing research bridges the gap between OSA in dogs and humans and provides an example of how linking human and animal data has the potential to greatly improve human and veterinary health.
I discuss all of this because now is the time to use all of the resources at our disposal and not ignore what we can learn from the estimated 7.7million animal species on the planet (of which we’ve only described a little over 1 million). Recently, physicians in Italy summarized their findings of the number of cardiac arrest patients in cities with increasing levels of COVID-19 infection, discovering a very strong correlation. Investigators studying 13-lined ground squirrels have already discovered that these animals have developed ways to reduce clotting and resist damage from cardiac infarction. Fauna Bio is investigating these (and data from many other species) to pinpoint the genes and pathways involved and discover new ways to protect human hearts from damage.
As we move forward in our understanding of COVID-19 and related diseases on humans, let's not lay aside the data we can collect from the animals that are inevitably used for pre-clinical testing of vaccines and new therapies. We are keenly interested in gathering and using data from these animals to discover differences in response to infection, development of respiratory and cardiac syndromes and routes to recovery. By building a more holistic view of the virus' effect on humans (and animals), as well as our responses to the virus, we can more quickly pinpoint how to intervene to save lives.