Sorry for the delay on this update! We have been very busy making sure we are prepared for next week’s Blandings Bowl!
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Though Lake County was spared the worst of the scary Illinois weather last week, rain still affected our ability to catch and sample as many turtles as we would have liked. While data is critical to our mission, it is important to ensure that human and animal safety is always at the top of our priority list. Setting out traps destined to flood or getting ourselves struck by lightning wouldn’t do anyone any good, so we pulled our traps on Wednesday. We had plenty to do for the rest of the week with Blanding’s Bowl coming up. We got all of our supplies prepared and worked out the logistics of how the week of competition will run.
This week’s topic is often overlooked… we are the Wildlife Epidemiology Lab, but do we fully understand what epidemiology even is?
Besides being a big word that makes us feel very smart and official, epidemiology is an important branch of veterinary and public health research that informs us about the distribution of diseases across populations. In a conservation context, this gives us the power to make informed management decisions that could potentially help our turtle friends to survive and thrive in the face of emerging threats.
Like any good investigation, an epidemiologic inquiry seeks to answer these 5 questions about the disease of interest: who, what, when, where, and why.
- WHO?
Unfortunately, in wildlife conservation, a mortality event or gradual decline is often the first indication that a population is in trouble. Therefore, we often know who our disease is affecting even before we know what the disease is.
“Who” may seem like a simple question to answer, but its complexity depends on the level to which you want to understand the pathogen’s interactions with the entire population. For example, some diseases may be carried and spread by males, but only cause clinically significant disease manifestations in females. An inadequate investigation in this case may have determined that only females need to be treated, when in reality, an informed management strategy would involve disease control in both sexes. This is just one example of the “tip of the iceberg” of epidemiology. Though Occam’s razor may be tempting to apply across veterinary contexts, it is important to dig deeper and explore all possibilities when the fate of a species is at stake. “Who” encompasses all involved in a disease process, not just those acutely affected by the disease.
- WHAT?
Once the population is identified, we can begin working out what is ailing it. Again, this is often more complicated than it seems. In the best case, we have a pre-existing test which can be feasibly applied to many individuals in a reasonable time frame. As you can imagine, all of these criteria are hard to meet simultaneously. Unlike many diseases in human medicine, a pre-existing test is a luxury that we cannot assume in wildlife. Every species has their own plethora of possible diseases, each with their own ever-evolving strains that may evade our detection with a test that worked just a few years ago.
Often, we have to make management decisions in the absence of a concrete answer to the “what.” Even if we don’t know the exact phylogenic identity of the virus attacking our species of interest, or the exact compound in a particular pesticide that is the culprit causing a die-off, with enough information of the effect it is having on the population, we can take steps to try and help mitigate the damage.
- WHEN?
Discovering patterns in time distribution of incidence and prevalence is helpful, especially when there is a seasonal component to the disease process. A relatable example of this in human medicine is the flu. Because we can reasonably predict when flu season will hit us, we can distribute vaccines at a time which will cause the peak of collective immunity to coincide with the peak incidence of disease, and hopefully reduce spread.
Going back to the “what”, details regarding the chronology of a specific infection can also help us figure out what bug we are dealing with. If we know when clinical signs started versus the possible exposures, we can use out knowledge of disease processes to narrow down our pathogen of interest or source of the infection.
- WHERE?
Similarly, knowing where to concentrate disease mitigation efforts can ensure that time, energy, and funds are being directed to the environments most in need of support. Our lab has shown that some counties in Illinois have much higher disease incidence than others, meaning that if we were to implement some sort of intervention, it would make the most sense to start in those locations versus others which aren’t as conducive to the spread of the disease of interest.
- WHY?
All other questions help us to reach a hypothesis as to why an outbreak has occurred. Let’s say, for example, a herpesvirus begins to wreak havoc on a population, outside of breeding season. We know that this virus is technically prevalent year-round in our populations, but only actively sheds during times of high stress, such as the breeding season. This is a physiological explanation for the higher rates of herpesvirus spread during the spring. However, if we were to suddenly detect an unexpected herpesvirus spike outside of the breeding season, we may look to other sources of stress, potentially anthropologic. If we were to correlate this spike to, let’s say, sudden habitat alteration due to a new construction project in the middle of the habitat, we could reason that this is potentially the impetus for higher movement rates among turtles, higher stress, and compromised immunity to the virus. Then, we can choose whether intervention is needed to combat these negative effects on the population. While completely hypothetical, this situation highlights why epidemiological monitoring and investigation is worthwhile. For all the reasons explained above, epidemiology represents the informational stepping stone between wanting to help a species in need and actually being able to do it.
Lake County is a great example of this. When faced with a disease threatening the future of the Blanding’s turtle, research provided the tools necessary to implement an intervention, treatment protocol, and reintroduction program that has helped contribute to maintaining the (relatively) large Blanding’s population that we enjoy working with so much. 😊
Stay tuned for next weeks blog to see how Blanding’s Bowl went!
