Emily Oster

9 min Read Emily Oster

Emily Oster

A Decision Tree for Ticks and Lyme Disease

What to do when you find one on your kid

Emily Oster

9 min Read

One Monday afternoon in the fall of 2019 I got a text from our babysitter which said something to the effect of, “I found a tick on Finn’s face. What should I do?” Obviously, I choose the adult option of “panic”. I rushed home, calling Jesse on the way, to look at it and remove it.

The tick, when I arrived home, was right there on his cheek, a tiny black dot. I realized, of course, I had seen this at breakfast and assumed it was dirt (yes, I bathe my children. Sometimes.). I pried it off and put it in a little plastic bag, then took some photos and tried to figure out what to do.

Thus ensued a week or so of serious tick research, involving several doctor calls, extensive searches of UpToDate and a long email exchange with Jesse about next steps. I was tempted to include that email exchange verbatim in this post, but I think actually seeing inside our work process might be a little too real.

The culmination of that, though, was a better plan for what to do if this happened again, which I’ll describe to you below. It was a good thing, too, since our family is apparently a bunch of tick magnets. Finn had another one a few weeks later, then I did, and finally Jesse. Only Penelope has been spared (so far; it’s only a matter of time.)

What is the problem with ticks? Is it all ticks?

Ticks can spread a number of different diseases but by far the biggest concern in terms of numbers is Lyme disease. Lyme is caused by a bacteria, which is spread through the bite of blacklegged ticks (sometimes called deer ticks). The disease causes fever, fatigue and — often but not always — a particular bulls-eye pattern skin rash. It can be treated with antibiotics. But: if left untreated (either through lack of detection or confusion about the cause) it can cause serious and possibly long-term health problems. It’s much harder to treat at this stage.

Conclusion: you do not want to get Lyme disease, or have your child get it.

Not all ticks spread Lyme; it’s only deer ticks. A little cheat sheet is below. Of note is that dog ticks are much bigger. But if you are not an expert you may need some help figuring it out (one pediatrician I talked to told me “most of the calls we get turn out to be dog ticks”).

Which is why you should save the tick, despite your presumed instinct to flush it or, in my husband’s case, microwave it.

In the spring, you’ll get a lot of active nymph ticks, which are especially good at spreading Lyme and are also tiny so even a very good parent could totally think they were dirt. Adult ticks are more common in the fall.

A chart with images of various kinds of ticks.
Atlantic Pest Solutions

I found a tick on my kid (or on me!) What do I do?

First, take it off. To do this, you can use the CDC method involving tweezers. OR: you can use the dizzy tick method, illustrated in this amazing video. I’ll wait. Don’t throw it away!

Second: think about the length of time the tick was possibly attached to the victim. Lyme disease is spread through a tick bite, not just a tick walking around, so it’s key to think about when the tick actually sunk its teeth in.

This may be hard to know (this is part of the value of tick checks – see below). But often you will have a sense of the timing. In our case (for example) we had been hiking in a tick-heavy area the Saturday before, and I had a photo making clear the tick was NOT on Finn’s face Sunday mid-day. It must have been somewhere else (in his hair? eww), crawling around looking for a good spot. But it clearly was there Monday morning, when I thought it was dirt. We effectively narrowed the time range to something like 6 to 18 hours of tick attachment time.

This is important because tick attachment time closely relates to the risk of Lyme transmission. One study found a 25% Lyme rate in bites with more than 72 hour attachment versus no cases in those with less. A second shows a similar difference between before and after 72 hours. Mice studies corroborate this, showing that before 48 hours of attachment time, transmission is extremely unlikely.

If the tick was attached for a limited amount of time (say, less than 36 hours), a good course of action is to keep an eye on it but not to do anything else. (You should probably still tell your pediatrician, just so they are aware.)

In the case where the tick is attached for longer (or you do not know how long it’s been), you’re at another decision node. Specifically: there is a question of whether to (A) wait and see if a Lyme-indicating rash develops and treat if it does or (B) treat in advance (“prophylaxis”), typically with an antibiotic called doxycycline.

The idea with option (B) is that this advance treatment would mean less likelihood of developing Lyme disease at all. There is a medium-sized randomized controlled trial (482 people) which demonstrated that this works, significantly lowering rates of later illness. However: the small size of the trial makes it hard to pin down exactly how protective the treatment was.

The argument for option (A) — just waiting — lies in the fact that most people who are bitten by a tick do not develop Lyme disease. Further, in 80% of cases a rash will show up as a symptom and, if it does, treatment is very effective at that stage (this number is perhaps 90% in children). Together, this means that treating everyone with prophylaxis entails a lot of unnecessary treatment, which raises concerns about over-use of antibiotics and, more immediately, has a reasonably high rate of side effects.

The argument for option B is that if one is in the 10 to 20% of people who get Lyme and do not show a rash, much more serious illness can develop. If early treatment can lower that risk, it might make sense.

There is no obvious answer here and medical advice seems to linger on trying to isolate prophylaxis treatment to cases where Lyme is more likely — if you can be sure it was a deer tick, if it was on for a long time, if it was engorged with blood and if you’re in an area with a higher prevalence of the Lyme-causing bacteria (New England, some of the Mid-Atlantic, parts of Minnesota and Wisconsin).

The non-obviousness of this choice means you surely want to discuss with a doctor. I talked to three I trust a lot and they all told me a version of the above, but noted that they try to learn a lot more about the case and also evaluate the level of parental anxiety.

Regardless of which option you go with, you still want to be alert for a rash. Which, by the way, isn’t going to itch or be raised or anything — it’s a flat rash with a specific bullseye pattern. Note this can be harder to see on the face or scalp and on darker skinned people, where it sometimes looks more like a bruise.

Confused yet? Here’s a little decision graphic.

A decision tree for what to do if you notice a tick on your child.

Prevention: Tick Checks and DEET

One of the things the above makes clear is that the best way to deal with this is to not have a tick attached to you for a long time. In a way, this is very reassuring since you can check for ticks and take them off if you see one. If you are living in a tick-heavy area, it is a good general habit to check everyone for ticks after any extensive time outside.

This just means looking at everyone totally naked and seeing if there are any odd-looking marks. It’s actually quite a bit easier with kids because they do not have a lot of body hair and old scars and moles. But you should also check adults! It sounds weird but, really, it is the easiest way.

You may also want to use insect repellent, which will keep ticks away to at least some extent (and also mosquitos, which are a whole other ballgame and I’ll leave for another day). But then people worry about DEET! Non-DEET repellents do not work as well but…is DEET a poison?

Technically, yes. And like all chemicals of this type, a lot of care must be taken with not ingesting it. But the concerns many parents have is that DEET may be a dangerous neurotoxin, even when used correctly.

In response, I give you this review article, entitled “Is DEET a Dangerous Neurotoxicant?” To which the answer (by their reporting) is “No”. The CDC and other official bodies (notably the AAP) also support the use of DEET-containing repellants, although they note that you do not need “100% DEET” and, in fact, recommend no more than 30% DEET in repellants. These recommendations are based on the fact that data doesn’t suggest DEET is a neurotoxin in normal usage.

Everyone urges some caution — you should be careful not to spray repellant at kids faces, or get it on their hands, or really anything in which they could ingest it. And like with sunscreen: if possible, clothing coverage is better than repellant. But DEET also works better than anything else so if you’re going to be in a very insect-infested area, it’s a reasonable choice.

A Final Word

My mom told me recently I should write a post on “What you should worry about.” Here it is! Ticks. I mean, don’t obsess about them. But would I think you are crazy for doing a tick check every day that your family is outside in the yard? No, I would not.

Thank you on this post to Dr. Lauren Ward (our pediatrician!), Dr. Lauren Allister & Dr. Adam Davis for their consultation and tick removal videos.

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