May 23, 2023
Words & Photos by Jens Odegaard 

Kacy Hayes spends her days “elbow deep in squirrel and beaver kidneys.” It’s not as gruesome as it sounds. For one, elbow deep is a figure of speech. Secondly, Hayes processes the kidneys with a bright smile on her face while enthusiastically explaining all the intricate details of her doctoral research. She’s like a ray of scientific sunshine. Excited about her work, and enthusiastic to share it. 

She’s advancing the scientific understanding of a common bacterial disease called leptospirosis that can cause serious issues and even death for all kinds of animals. The bacteria are spread through contact with the urine of infected animals. Typically this occurs through flooding events, or contaminated drinking water, but can happen when a person or animal exposes an injury to contaminated water.

Currently, there’s a knowledge void about the actual genetics of the bacteria that causes the disease – particularly in wild animals. 

We’ll circle back to that. But first a diversion into why Hayes cares about this research in the first place. 

Water-borne Wipeout

About a decade ago, Hayes was working on the big island of Hawaii studying invasive rodents for the United States Department of Agriculture. She had a colleague who loved to mountain bike. 

On a ride one day, he came into a section of dirt track a bit too hot and yard sailed into a huge puddle. Dripping wet and with a patch of road rash the size of Kauai on his leg, he wiped off as best he could and limped home thinking it was going to sting for a while, but that he’d be no worse for wear. 

But …

“A little while later he starts getting this weird fever and it gets really, really bad and then it goes away and then it gets really, really bad and then it goes away. And then he started getting super bad back pain and finally his wife drags him into the ER,” Hayes said. “Thank goodness for her.”  

His fever was so bad that in the ER they “dumped ice on him and then they dumped rubbing alcohol all over him to cool him off,” she continued. “It turns out his kidneys were trying to fail.”

The reason? He had leptospirosis from getting infected water into the scrapes on his leg. 

Thankfully for him, an ice bath and a few rounds of antibiotics later and he was back better and ready to bike again. If left untreated, he could have died.

For Hayes, the incident lingered in the back of her mind. “It just seemed like one of those kind of cool diseases in the landscape that isn't really examined enough.”

Leptospirosis Explainer 

Leptospirosis is a disease caused by the bacteria Leptospira interrogans

In animals and humans, infection causes a variety of symptoms and reactions. Like Hayes’ colleague, if left untreated in humans it can “lead to kidney damage, meningitis, liver failure, respiratory distress and even death,” according to the Centers for Disease Control and Prevention. For animals, similar side effects can occur (dogs are affected much the same as humans), as well as others like reproductive problems in cattle, sheep, goats and swine and cloudiness and light-sensitivity of the eyes in horses. Wild animals are also affected of course, but the challenge here is that there is little documentation of the extent of infection in wildlife or what the diversity of presentation looks like with their infection. 

There are different varieties of Leptospira interrogans that each have their own genetic makeup.  Currently, much of the current understanding of the disease as a whole relies on identifying the symptoms or reactions to the disease. “It’s identifying the reaction to the thing. It’s not actually identifying the actual organism,” Hayes said. That’s where her research comes in. 

Back in 2019, the scientific community “started just uprooting the taxonomy [classification] of lepto from the bottom,” Hayes said. “So now we are trying to get more of an understanding of the bacteria itself through its genetic diversity.”

Hayes' work is focused on better understanding the genetics of leptospirosis in wild animals, as this area in particular is still hugely unknown. The hope is that better classification and understanding of the disease across all sorts of wild mammals can in turn help inform what kind of safeguards need to be in place to combat the disease for all animals and humans. 

Circling Back to the Kidneys 

It’s not just squirrel and beaver kidneys that Hayes is processing. She's looking for leptospirosis in all kinds of wildlife from across the state of Oregon. We’re talking rats, porcupines, nutria, chipmunks, voles, opossums, “a marmot,” skunks and raccoons. “I have a freezer full of kidneys I need to go through,” she said. “This was a doozy of a semester.” The freezer is housed in a research laboratory in the Department of Biomedical Sciences at Oregon State University’s Carlson College of Veterinary Medicine. 

Hayes gets the deceased animals from a variety of wildlife agencies and organizations across Oregon like the Chintimini Wildlife Center in Corvallis, Think Wild in Bend and the United States Department of Agriculture to name a few. They’re animals that were brought in sick to rescue organizations and died, were collected as roadkill or were found dead in the field. 

“I reached out to the wildlife rehab places because if someone notices a sick animal, they're going to bring it to those guys. And if the animal recovers, that's great. But if the animal was so sick that it's succumbed, there's often not spare money to test what caused the mortality,” Hayes said. “So me reaching out and getting these carcasses is actually answering questions that the rehab places have had, but don't have the funds to really research.”

The deceased animals are necropsied by the anatomical pathologists at the college’s Oregon Veterinary Diagnostic Laboratory. “We take a small sample of kidney, not much more than a few grams,” said Dr. Duncan Russell, associate professor of anatomic pathology. Samples are taken from this organ because “the bacteria hide in the renal tubules in the kidney,” Hayes said. 

The samples are then tested for the disease and, if detected, run through further analysis.  

“Basically, I’m getting more strings of DNA that are from different parts of the DNA strand that can tell me how different things are,” Hayes said. With each kidney sample, Hayes is able to get a clearer picture of what species of wild animals are carrying the organism and the specific genetic makeup of the bacterial strain they are infected by. 

As more and more samples are processed, the idea is that she’ll be able to start identifying “reservoir species” of wild animals that carry the organism. In the scientific community, a reservoir species means one that the organism thrives in naturally and which, like a reservoir of water, supplies other species who come in contact with it with the bacteria. 

Your research is only as good as your notes and records.

Raccoon, beaver and nutria kidneys await processing by Hayes at her research station.

A sample of a nutria kidney is readied for analysis by Hayes.

This is important work for scientists and non-scientists alike.

As Hayes' advisor Dr. Bree Beechler, disease ecologist and assistant professor of research puts it: “For the general public, understanding wildlife reservoirs for this disease which can cause detrimental effects in humans and our loved pets may help us understand how to create better preventative measures and recommend appropriate vaccination protocols. For the scientific community I would say that understanding how strains differ in wildlife species is important to better understand cross-species transmission and which species are relevant to domestic animal and human transmission risks.” 

“We need to understand a disease so we can make real progress towards minimizing its impact in animal and human populations! There is still so much to learn about how this pathogen persists in wildlife reservoirs and how it spills over into domestic animals and humans,” Russell adds. “As our planet changes, including our relationship with wildlife and domestic animals, I think these kind of questions are likely to take on greater importance.”

For now, Hayes will keep on learning, one kidney at a time. “It's just a fun project that’s really filling some knowledge gaps on the disease itself – the organism that causes the disease. And I love the opportunity to collaborate with all these organizations, these people, who are all very awesome people, all dedicated to animal health, dedicated to human health,” Hayes said.