What insect causes a round or almond shaped bump then round bruise?

Dr. Joshua’s Answer

It’s not possible to say which insect has caused the reaction, especially as I don’t know which part of the world you are from. It could be any insect that bites.

The most important question is, could it be a serious insect-borne disease or is it just a reaction to an insect bite? Most insect bites cause some skin reaction. The reaction can be mild or severe, depending on the individual. Even harmless insect bites can cause a significant skin reaction and even serious illness in an allergic individual.

Various insect-borne diseases exist. These are a major global health problem, predominantly in the tropics. The most important insect-borne disease in the western world (U.S.A. and Europe) is Lyme disease, which is caused by the bacteria Borrelia Burgdorferii and is transmitted by tick bite.

If you have a persistent reaction around an insect bite and especially if you live in an area where Lyme Disease is known to occur, you should see the doctor. Commonly, Lyme Disease causes a rash presenting as a red-purple widening circle around the location of the bite. However, variations exist and it’s not possible to be 100% sure of the diagnosis by just looking at the skin reaction. If in doubt, see the doctor.

Here are some pictures of tick bites and photos of tick bite reactions. The classic ring-shaped reaction is highly suggestive of Lyme disease. As you can see from the pictures, the reaction can vary quite a lot.