This page provides information about tick bites.
What tick bites look like depends on the stage of the tick's life cycle and how long the tick is attached in the skin. The smallest "baby" ticks are barely visible, but adult ticks are quite well visible and recognizable. The tick stage also has influence on how the red bump or spot looks like, that develops at the site of the tick bite.
A tick has 4 life stages: egg, larva, nymph, adult. From the larval stage the tick can feed on blood from a host (human or animal) via a tick bite. After a blood meal the tick goes over to the next, larger, stage. In the adult stage only the female tick needs blood, namely for the production of eggs, in which case the tick enlarges greatly. The male tick does not necessarily need blood and only feeds occasionally to a limited extent.
A tick bite from a tick larva (sometimes called "seed tick") is very difficult to recognize, because the tick larvae are very small: smaller than 1 millimeter. The tick bite can easily occur unnoticed and upon discovery of the tiny tick it may appear only as a small skin crust. Even under a magnifying glass the tick is difficult to recognize and the legs (note: a tick larva has 6 legs) are hardly distinguishable. The tiny ticks are most noticeable when they move in their slow locomotion, because a dead or non-moving tick larva looks a lot like just a small bit of fluff.
However, fortunately only a small percentage of tick larvae is already infected when is comes out of the egg. A bite from a tick larva often gives a small red spot of a few millimeters wide.
The nymph is the second stage of the tick and the most insidious one. Nymphal ticks are still very small (a little over 1 millimeter) and because in an earlier stage, as larva, they already have had a meal from potentially infected blood from an previous host, a large part of the tick nymphs is infected with the Lyme disease bacterium and possibly other pathogens.
A tick bite from a tick in nymphal stage looks (greatly magnified) like on the photo below. On the left of the image a ruler with millimeter markings is visible. On the presence of 8 legs and the size it can be deduced that this is a tick bite from a tick nymph.
Although the tick nymph is slightly larger than the tick larva and is somewhat easier to detect and recognize, it will still often not or not soon be detected. A tick bite from a tick nymph often gives a slightly larger red spot than a bite from a tick larva, much like an average bump of a mosquito bite.
A tick bite from an adult tick is much easier to discover and to recognize. Usually it is a female tick, which is larger than the male tick and much larger than the larvae and nymphs. In case of the European ixodes ricinus tick the reddish-brown abdomen is very recognizable. On a human a tick bite of an adult tick will often be noticed.
If a female tick remains attached to the skin for a longer period of time and gets fully engorged, it will strongly enlarge (up to 1 centimeter and more spherical) and turn into a gray color. The larva and nymph will also become somewhat larger during a blood meal, but not nearly as extreme as an adult female tick.
The percentage of infected ticks in the adult stage is similar to that of the nymphs. It varies by year and by location for both stages. For example in the Netherlands the percentages are varying somewhere around 20%, so 1 in 5 ticks.
The bite of an adult tick often gives slightly heavier skin reactions, probably partly due to the thicker hypostome (body part with which the tick bites) of the adult tick. The red spot that can develop with a tick bite as a skin irritation, is often more irregular and slightly larger than with a tick bite of nymphs.
A tick bite is usually not felt, because the tick puts an anesthetic substance into the skin. After the tick bite, however, the bump can itch strongly, similar to that of a mosquito bite. The longer the tick has been attached in the skin, the more irritated the skin will have become.
In addition to this normal irritation of the skin at the site of the tick bite, some people also get heavier allergic reactions whereby a larger area of the skin turns red, just like what can happen after a mosquito bite when a person gets allergic reactions.
However, both phenomena are independent of an infection with the Lyme bacterium Borrelia burgdorferi, that can form a usually red gradually expanding (annular) rash around the site of the tick bite. This skin condition is the typical Lyme disease rash that is called an erythema migrans.