In this edition, Mrinal Patnaik, MBBS, explains his fascination with snakes and how venomous reptiles have contributed to hematology. Dr. Patnaik is associate professor of internal medicine and oncology and a consultant in the Division of Hematology at the Mayo Clinic in Rochester, Minnesota.
In Sound Bites, Dr. Patnaik shares some practical tips if you find yourself face-to-face with a viper.
How did you become interested in snakes?
I did my medical training in India, which is home to a number of venomous snakes. After medical school, I completed a year of medical service in a rural area about 200 kilometers from Mumbai on the west coast of India, where dangerous snakes are common. It's estimated that 80,000 people die annually in India from venomous snake bites – and that is probably an underestimation.
Before I went into rural service, I had no idea how difficult it would be to manage snake bites. In that one year, I encountered several different snake envenomation syndromes (vasculotoxic and neurotoxic) and became fascinated by how these venoms were designed to wreak havoc in the body.
The "big four" venomous snake species responsible for most snake-bite cases in India are the Indian cobra, the Russell's viper, the saw-scaled viper, and the banded krait. These snakes live in rural areas like those I was working in, so snake-bite victims are usually farmers plowing the fields or children on their way to school accidentally coming across snake burrows.
The cities in India have good infrastructure, but the rural areas have almost nothing. We were equipped with only intravenous fluids and anti-snake venom. When patients with advanced-stage snake bites came to us with a swollen, bleeding hand and needed platelet transfusions and plasma, it was a huge challenge.
When did you recognize a connection between herpetology and hematology?
While I was caring for patients, I saw that many complications associated with snake bites – particularly from vipers and kraits – were hematologic. Bite victims would develop bleeding and clotting syndromes, including disseminated intravascular coagulation (DIC).
I realized that I needed to better understand how snake venoms affected the endothelium and coagulation cascade. After my year of service, I returned to Mumbai for an internal medicine residency at the Grant Medical College and Sir J.J. Hospital. The more I encountered patients with advanced snake bites in the intensive care unit, the more my fascination with venoms grew.
I began studying snakes and their venoms and uncovered the tremendous impact that they have on medicine in general and hematology in particular. Many hematologic lab tests are based on snake venoms as are many drugs in development originate from them. This compelled me to further study the mambas, taipans, and bushmasters in Australia and Africa and the rattlers and corals in America.
The way their venoms are designed to physiologically damage intricate animal systems is extraordinary. Pit vipers, for example, use sonar technology to size up their prey and decide how much venom they need. There's so much to learn!
I don't think I would have been a hematologist today had it not been for my exposure to snakes and snake venoms.
What is the connection between hematology and herpetology?
There are multiple tests to assess the integrity of the coagulation cascade that rely on snake venoms, including the dilute Russell's viper venom time, the Protac assay for protein c, the Taipan venom time, the ecarin time, the reptilase time, and more. None of these tests would exist without snake venoms.
Venomous snakes are one of two animals that have contributed to the development of systemic anticoagulants; the defibrinogenating agent ancrod, for instance, is derived from the venom of the Malayan pit viper. Snake venom, obviously, is also required to produce anti-venom. Snakes are "milked" through their fangs and their venom is injected into horses or other large animals, from which antibodies in the plasma are taken three weeks later.
In countries like India and Sri Lanka, where these snakes are indigenous, catching them is actually an occupation. Luckily, I never had to do this; I left that to the specially trained, extremely cautious professionals!
How did your experiences in the rural clinic affect your career path?
I was planning to specialize in coagulation, thrombosis, and hemostasis, and then focus more on DIC and consequences of venoms, but life takes you down different roads, and I became interested in myeloid malignancies, especially myelodysplastic syndromes and chronic myelomonocytic leukemia. But I credit my entry into hematology indirectly to herpetology. I don't think I would have been a hematologist today had it not been for my exposure to snakes and snake venoms.
When I came to the U.S. to pursue further training in hematology, I did an internal medicine residency at the University of Minnesota with Nigel Key, MBChB, who was an expert in coagulation. Then I came to Mayo Clinic, also in Minnesota, for my fellowship – a state with no venomous snakes! There have been a few timber rattlesnake sightings, but very little to quench my thirst for snake bites and coagulation.
Every now and then, I get phone calls from clinicians who need advice on managing snake-bite–related syndromes. About four years ago, I received a call at 8 p.m. from a clinician in the emergency department of a hospital in Duluth, Minnesota, because he had a patient who was bitten by his pet Egyptian cobra. That's the last thing you expect to happen in Duluth, so they had no experience in treating a cobra bite. I walked them through managing neurotoxic snake bites and connected them to the Centers for Disease Control and Prevention to get more help.
How did your reputation as an expert in herpe-hematology spread?
There was a global health course at the University of Minnesota, in which professors from around the world taught topics like clinical topical medicine, infectious diseases, or humanitarian aid during medical emergencies. When my professors learned how passionate I was about snakes and how much experience I had in this area, I was asked to teach in the global health course about snakes, scorpions, and other insects and reptiles that were relevant to hematology. Soon after that, I was invited to speak at the emergency room physician meetings. Dr. Key, who was still at the University of Minnesota then, invited me to speak at the coagulation forums, and my reputation spread by word of mouth from there.
I've also done a number of presentations around the U.S. about how the study of snake venoms has contributed to hematology and how snake venoms can be used to understand biology.
Have you ever been bitten by a venomous snake?
Fortunately, no – though not because I didn't have the chance! I learned a few lessons in how to avoid snake bites from my experiences in India. Even if a snake is dead or decapitated, it can still bite for up to two hours because of preserved monosynaptic reflexes. Many times, patients were taught to kill the snake that had bitten them and bring it in for identification so we could administer the appropriate anti-venom, but we saw plenty of people bitten by "dead" snakes. So, always steer clear!
Do snakes scare you?
No, not at all. You have to be careful, but most snakes don't attack unless someone stumbles into their environment. It's a side effect of what urbanization is doing to their habitats. Except for mambas and bushmasters, there are few snakes that are predatory to humans.
Snakes are usually shy. Most of the immediate bites are "dry" bites – serving more as a warning because they are afraid and trying to escape. If you're in Africa, though, the green and black mambas will come after you.
The more common snake-bite scenario in the U.S. is an accidental bite from an exotic pet snake, or someone who's drunk and thinks it's a good idea to pick up a rattlesnake.
Do you keep snakes as pets?
My interest hasn't extended to that yet. I do enjoy learning about them and visiting the snake exhibits at local zoos when I travel. My favorite was last year, when I was invited to speak at the Highlights of ASH® in Asia–Pacific in Brisbane, Australia. One of the first things I did was visit the Australia Zoo to look at the taipans, which are the most venomous snakes in the Outback.