How do you contract tick-borne diseases?
The short answer: An infected tick bit you.
But where did the tick get the disease? How did the disease get from the tick into me? How did I get this tick in the first place?
This process is fairly complicated with many ifs ands and buts. Here, I’ll describe the basics of this process with plans to build upon this post in the future.
First, let’s start with the tick’s life cycle.
I’m a visual person, so I’m going to start off with a visual aid. Most hard tick’s life cycles look something like this:
After hatching, a tick goes through three different stages. In order to move onto the next life stage a tick must find a host, consume a blood meal, and go through a molt (with the exception of adult ticks which reproduce and then die).
Some ticks are single-host ticks (in this case host is just a fancy work for the organism a tick takes a blood meal from), others find a different host for every meal, and others use the same host for some, but not all, stages.
How do ticks find hosts?
In order to find a host a tick will “quest.” Questing is a behavior where a tick will basically stand on a piece of grass with its third and fourth legs, while holding its first set of legs extended. Imagine a child who wants to be picked-up.
Fun fact: Ticks use breath, odor, body heat, and vibrations to make sure their quest locations fall near well-used paths. This increases their chances of coming in contact with a host. Cool, right?
A questing tick. Image courtesy of: http://amberleaanimalhospital.com/
What happens once a tick finds a host?
Once a tick is on a host it will look for the spot it wants to feed and pierce the skin with its chelicerae. The tick uses its chelicerae to dig deeper into the skin, eventually inserting its hypostome, which can essentially be considered a feeding tube. Most ticks release a cement-like material that ensures the tick will stay attached to the host during feeding.
Once the tick has finished its blood meal, it will drop to the ground and attempt to molt or reproduce depending on its life stage.
Fun fact: Ticks filter out the excess water in blood while feeding in order to concentrate their meal.
A tick’s mouthparts. Photo curtsey of: http://southsidevets.ca/
How does a tick get a pathogen?
If a tick feeds on a host with a pathogen (disease causing agent), the tick will ingest not only the blood of that animal, but the pathogens found in the blood. The pathogen will then cross the gut wall, enter the hemolymph (essentially the equivalent to blood in invertebrates), and enter the ticks body tissue cells.
Alternatively, some pathogens are from an infected adult female tick to her eggs.
How does that pathogen get inside me?
While a tick is feeding, it may release some of its own saliva into the host, kind of like bug backwash. The saliva will contain any pathogens the tick has (either from ingestion or birth). If conditions are right, once the pathogens are released into the hosts blood stream, they can multiply and wreak havoc on their host.
A lot of this information is already available online, but I think it’s important for the basis of this study and for future, more intensive posts. Maybe you even learned something new 🙂
As always, don’t be afraid to ask questions or make suggestions!
Thanks for reading