NPR story points to a growing problem

Here is a link to a story on NPR about Tom Mather, a researcher at the University of Rhode Island. His monitoring of black-legged tick populations in Rhode Island suggests that tick-borne diseases are a growing problem.

Mather states that "people really need to become tick literate." I couldn't agree more. Some of the posted comments about the story highlight this need for "tick literacy." There are a lot of studies out there, some better than others, and only a small subset get any coverage in popular media. This is unfortunate because it means that public understanding of ticks and tick-borne disease is based on outdated information or mis-information resulting from oversimplified or simply incorrect coverage in the media. Public discourse can become fixated on a single research finding that may be incomplete, poorly supported, or outdated.

The reality is that we don't know as much about ticks and tick-borne disease as we think we do. Scientific research is all about building evidence and a single study can never be definitive. So in addition to tick literacy, we need a better understanding of the scientific process and better communication between scientists and the media.

Are Predators our Friends?

A recent publication in the journal Proceedings of the National Academy of Sciences (PNAS) suggests that they are. This study conducted by Levi and colleagues finds that, contrary to popular belief, large and expanding deer populations may not be solely to blame for the initial emergence of Lyme disease in the US northeast or its continued expansion.

Image obtained from wikimedia commons

Instead, the authors contend that loss of small mammal predators like foxes and their replacement by less efficient predators like coyotes, could be to blame. Over the time period in which Lyme disease emerged and human cases increased, there was an ongoing decline in red fox populations and coincident expanding coyote populations. In fact, the researchers found that "changes in predator abundance are more closely linked with increases in Lyme disease than are changes in deer abundance." Red foxes are very efficient small mammal predators, often killing far more than they can eat, caching their kills for later consumption, in times of high small mammal abundance. Thus, red foxes may have kept populations of small mammals (e.g. mice or chipmunks) that are integral hosts for both the ticks and Lyme bacteria in check.

This study is important in drawing attention to predators as important drivers of disease emergence, like Lyme disease. This research further underscores the importance of ecology to the understanding of Lyme disease and provides new direction for field studies of Lyme disease ecology.

The story of the western fence lizard

One of the most interesting differences between the Lyme disease systems in the eastern and western US is the presence of the western fence lizard (pictured below) in the western US as an important host for the ticks that transmit Lyme disease.

Image obtained from wikimedia commons

The immune system's of these lizards have been found to clear feeding ticks of the bacteria that causes Lyme disease. Essentially this means that when infected ticks feed on a western fence lizard, they are cleared of infection resulting in one fewer ticks capable of infecting humans and one fewer infected hosts capable of passing the infection along to a new tick.
 
However, in work conducted by Andrea Swei and colleagues, removal of western fence lizards was found to decrease Lyme disease risk. This is likely because the effect of removal of lizards, one of the most important hosts for ticks in the system, was to cause tick densities to decline, outweighing the effect of tick "cleansing". This finding is important because it suggests there are other factors at play that are contributing to the low Lyme disease prevalence on the west coast.

For those interested, I have posted my project on Lyme disease ecology to "Rockethub", a novel and innovative way to raise funds (called crowdfunding) for scientific research, entrepreneurial activity, philanthropy, you name it. I am trying to raise research funds to learn more about Lyme disease in the western US and the factors that are currently limiting its spread.

You can check out my project here and watch my video below:

Welcome!

Welcome to "tick talk!" A blog dedicated to:

1. Lyme disease research
2. A PhD dissertation on the ecology of Lyme disease in California
3. Other random interesting tid-bits about infectious disease in the headlines

My name is Andy MacDonald and I am a PhD student at UC, Santa Barbara in the department of ecology, evolution and marine biology. I am a member of the Briggs Lab, which is doing some really interesting work on the ecology of infectious diseases including chytrid fungus in amphibians and Lyme disease in California.

I will do my best to update this blog with current information on my field work and research progress, Lyme disease news and research, and other interesting stories of infectious diseases.