The Tick Chick, c'est moi
For a while, my schtick was (is) ticks. In 2016, I was petrified by them, and I don't think I could have even told you what one looked like. In 2017-2018, I worked in a vector-borne disease laboratory at the Tennessee Department of Health. In 2019, I chose to specifically research ticks. I joined the entomology (bugs, not words) department at Cornell University and learned the ins and outs of tick ID, tick collection methods, ecology, and behavior. I collected ticks in different parks on Staten Island, New York, and I was dubbed the Tick Chick (I attracted a lot of attention with my white flag), even being invited onto a radio station. After graduating, I went to Delaware to do tick surveillance and pest control. Desiring to return to school to learn more, I joined a Ph.D. program at Upstate Medical University where I designed a field study at sites in New York to research Powassan virus, a rare but deadly tick-borne virus, in the tick population. If you want to learn more about Powassan virus, check this out.
Qualifications out of the way, you can find me posting tick-y things at @ecoErin_ Twitter.
About Ticks
Ticks are vectors, organisms that can carry and pass pathogens (such as viruses and bacteria) to other organisms, like humans. Some pathogens include agents that cause Lyme disease, Ehrlichiosis, Anaplasmosis, Rocky Mountain Spotted Fever, and Powassan virus disease. To be accurate, ticks actually don't give you a disease, it's the pathogen that is the one to blame here. The tick is just a very rude messenger.
All females at different stages of engorgement except for the male tick on the very left.
Ten Tick Factoids
Ticks aren't insects. They're actually more related to spiders and mites. Insects have six legs. Ticks have eight legs (except the larval tick stage which has six temporarily).
Ticks don't jump or fly. They are more like velcro- if you walk past, they will latch on.
Ticks are not in trees. It's not energetically favorable for ticks to climb trees because there aren't that many animals there. They need to position themselves in places where animals will be, like along trails. So, you don't have to worry about ticks falling down on you from tree tops. Generally speaking, ticks quest (flailing legs about to try and grab an animal moving) by crawling to the top of vegetation like tall weeds and grass. It is possible a tick could fall from an animal that is in a tree above you, but that would be coincidental and very unlikely.
There are hard ticks and soft ticks. Hard ticks are what we usually think of when we think of ticks, such as that in the featured photo. They have a hard outer shell (a scutum) to help protect the tick from weather fluctuations. Soft ticks look like old sponges, and they are more often live in animal burrows for many years. You are less likely to contact a soft tick. I will only talk about hard ticks here.
Ticks go through different life stages. They hatch out of eggs and are wee little larvae with six legs. After drinking blood from an animal, they will molt into a nymph and then have eight legs. The nymph will eat again and molt into an adult. The female adult tick has to eat again for egg production. So, there are three meals that a tick takes, and each meal increases the chance of the tick picking up a pathogen.
Female ticks are the ones that swell up like blueberries. Females need a lot more blood for egg production, so they expand to ingest more blood than the males. If you see a swollen tick, it was feeding for a couple days already (like 4+), so it's a slow process.
They are active in winter. On those weird, warm, winter days when the snow kind of melts for a day, there are ticks looking for you. A friend of mine was diagnosed with Lyme disease in winter.
Ticks get infected in many ways. They can get infected from feeding on an animal that was infected (deer ticks get the Lyme bacterium from mice). An uninfected tick can also get infected if it is feeding next to another infected tick. Also, the pathogen can remain in the tick across life stages, and sometimes, the female tick can pass the pathogen to her eggs. Pathogen transmission potential is variable by pathogen species.
But, not all ticks are infected. Rate of infection varies, and some ticks aren't infected at all. It's more likely that an adult will be infected than a nymph and a nymph more infected than a larva. The more times a tick has fed on an animal, the higher the chance it would have picked up a pathogen. Also, some pathogens are more prevalent in the tick population than others. For example, Powassan virus is rare in the deer tick population, but the Lyme bacteria is more common.
And not all ticks can give you the same pathogen. Only certain ticks can give you the Lyme disease bacterium, such as the deer tick in the Northeast United States. However, lone star ticks and dog ticks won't give you the Lyme bacterium. It's important to know which ticks are in your area, what each species and life stage looks like, and what potential pathogens they may carry. For example, here are three tick species and the diseases that are caused by the pathogens they carry:
Deer Ticks
Lyme disease
Anaplasmosis
Babesiosis
Powassan virus disease
Ehrlichiosis
Borrelia miyamotoi disease
Lone Star Ticks
Tularemia
Ehrlichiosis
Heartland virus disease
Associated with red meat allergy
American Dog Tick
Rocky Mountain Spotted Fever
Tularemia
Left to right: A female tick with eggs, two sets of mating ticks (the males are the smaller dark ones), and me dragging for ticks with a white drag cloth.
Why is it always going to be a bad tick year?
A tick needs to worry about two things: the environment and food. When food is available and the environment is favorable, the tick population will grow and expand. Spoiler: it's favorable.
The Environment
Ticks are vulnerable to environmental factors, like temperature, humidity, and rainfall, and the extent to which these variables affect ticks can depend on the specific species and how drastic the weather is. Generally, however, warmer temperatures are great for tick development and host seeking.
Oviposition [1,2]. It takes time for a tick mama to blood feed and produce thousands of eggs. Under warmer temperatures, she can do it faster!
Egg incubation [1]. The period of time it takes from eggs to be laid until they hatch is shorter when it’s warmer. This would be as if human pregnancy only took 5 months instead of 9.
Interstadial development [1]. Warmer temperatures increase the speed that ticks molt and transition to different life stages. This means that they are speeding through their teenage years to become sexually active adults faster, producing more baby ticks.
Questing behavior [3].Warmer temperatures and mild winters allow ticks to seek for hosts for longer periods of time.
Of course, there are limits: if it gets too warm, temperature will start to have negative effects on the tick population. Excessive heat leading to droughts and low humidity will dry out the ticks, making them die. So, it’s important that areas also have high humidity as well.
Ticks are also expanding in distribution to places where they weren’t previously [4,5]. You might have your own personal experience with this too. Growing up, I never worried about getting a tick. Maybe my cat would periodically get one, but I never worried. Now, ticks are seemingly everywhere, and guess what? They are bringing their pathogens with them into new areas too.
The Hosts
Climate change is leading to longer growing seasons and later frosts, meaning more food for wildlife. Wildlife will also have less harsh winters to overcome, increasing animal survival. Because ticks need hosts for food and for hitching a ride to new locations, the effect of climate change on host populations is an extremely important area of research. By increasing wildlife food and wildlife survival, you are helping the tick population thrive. For the deer tick, white-tailed deer and white-footed mice are major host species, and the distribution of these hosts are expanding [6,7], taking the ticks and the pathogens with them.
Human behavior
Warmer temperatures mean more time doing outdoor activities (yay!). Going outside more often can increase the risk of acquiring a tick and a tick-borne pathogen (boo!).
So, to summarize, we are seeing a range expansion of ticks into new locations. Warming temperatures helps the survival and growth of hosts which helps the growth and survival of ticks. Every year is a bad tick year, and there is no sign of it stopping. The best thing you can do besides fighting climate change is to protect yourself from ticks.
How to Not Get a Tick
Don't go into weeds or leaves
Stay on the trail, and keep your dog on trail (if possible)
Tuck your pants into your socks so ticks won't crawl up your pants
Tuck your shirt into your pants
Use repellent
Check for ticks thoroughly in all the nooks and crannies. They don't want to be found, remember that.
Shower after going outdoors
Wash your clothes after going outdoors
Check your pets and children for ticks
Know what ticks look like
But if You Do Get a Tick
Use tweezers and do not use: matches/fire, nail polish, vaseline, etc. You need to remove the tick ASAP so you don't get an infection, and waiting for the tick to self-remove only puts you at risk.
Grab the tick by the mouthparts (not the body) at the base of your skin where the tick is attached.
Pull upward, do not twist. Ticks do not twist to get in, so do not twist them to get out. This might break off the mouthparts.
Wash your skin with soap and water.
Watch for symptoms and contact your doctor if you are concerned.
Get the tick tested if you want, but take the results with a grain of salt. It takes a period of time for a pathogen to move from the tick to you (24+ hours for the Lyme bacteria). If your tick is positive, it doesn't mean you got the pathogen. If your tick is negative, don't assume that was the only tick on you. You could have been bit by a different one!
I am happy to answer tick questions, but I can't give medical advice.
References
1. Estrada-Peña, A.; Fernández-Ruiz, N. A Retrospective Assessment of Temperature Trends in Northern Europe Reveals a Deep Impact on the Life Cycle of Ixodes ricinus (Acari: Ixodidae). Pathog. 2020, 9.
2. Life Cycle of Ixodes pacificus (Acari: Ixodidae): Timing of Developmental Processes Under Field and Laboratory Conditions. J. Med. Entomol. 2001, 38, 684+.
3. Gilbert, L.; Aungier, J.; Tomkins, J.L. Climate of origin affects tick (Ixodes ricinus) host-seeking behavior in response to temperature: implications for resilience to climate change? Ecol. Evol. 2014, 4, 1186–1198, doi:10.1002/ece3.1014.
4. Li, S.; Gilbert, L.; Harrison, P.A.; Rounsevell, M.D.A. Modelling the seasonality of Lyme disease risk and the potential impacts of a warming climate within the heterogeneous landscapes of Scotland. J. R. Soc. Interface 2016, 13, 20160140, doi:10.1098/rsif.2016.0140.
5.Ripoche, M.; Bouchard, C.; Irace-Cima, A.; Leighton, P.; Thivierge, K. Current and future distribution of Ixodes scapularis ticks in Québec: Field validation of a predictive model. PLoS One 2022, 17, e0263243.
6. Roy-Dufresne, E.; Logan, T.; Simon, J.A.; Chmura, G.L.; Millien, V. Poleward expansion of the white-footed mouse (Peromyscus leucopus) under climate change: Implications for the spread of lyme disease. PLoS One 2013, 8, doi:10.1371/journal.pone.0080724.
7. Kennedy-Slaney, L.; Bowman, J.; Walpole, A.A.; Pond, B.A. Northward bound: the distribution of white-tailed deer in Ontario under a changing climate. Wildl. Res. 2018, 45, 220–228, doi:10.1071/WR17106.
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