Which bug could be responsible for this strange bite?

August 27, 2017 11:40 AM

Two weeks ago I was bitten by a mystery bug. The bites (two of them, on my ankle) remain sore and have a spreading rash. I’ve never had a reaction like this before; can you help figure out what bit me?

I’m pretty sure I was outside when I was bitten, walking on shortish grass in a private garden. I noticed a sharp pin-prick sensation on my ankle, looked down and saw two roughly 3mm marks, one of which was bleeding. I didn’t see any bugs. The marks looked petechial/purpuric - and not like any insect bite I’ve had before.

For the first week or so I didn’t notice the bites - they didn’t swell or become itchy, though they did perhaps become a bit larger. Roughly a week after I was bitten they became intermittently intensely itchy, and a rash around them started developing. Its now 2 weeks since I was bitten and the rash is still there, and still changing. The itching seems to be settling, but the bites and the skin around them remain very tender. There’s a red dot in the middle where each bite was, a small area of sparing around the centres, and a surrounding non-blanching rash. This is then surrounded by an area of redness that does blanch with pressure.

Photos here - the first is from the day I was bitten, the second roughly 10 days afterwards, the third from two days ago, and the last two were taken today (two weeks after the bite).

YANMD (or my entomologist). As it happens, I am a (junior) doctor - but that’s unfortunately not helping me figure out what’s going on. I suspect it’s some kind of hypersensitivity reaction to the bites, but I have no idea what might have bitten me. I can ask my colleagues (currently GPs) about it or see my own GP if necessary, but I’d rather not waste their time. The rash looks a tiny bit like a target rash, but I think it’s very unlikely that I was bitten by a Lyme carrying tick in the middle of a city, and I didn’t see a tick. It doesn’t seem infected - there’s no heat, swelling or exudate. I’m otherwise fit and well, and I live (and was bitten) in a city in East Anglia (UK). I've tried antihistamines, which helped the itch but didn't change the rash.

I’m hoping that someone might know what could have bitten me to cause this reaction. I’d also like to hear from people who have had similar reactions - what did you think caused it, and what (if anything) did you do about it?

posted by bored_now_flay to Health & Fitness (10 answers total)

It looks a lot like a Lyme rash, though I agree it is highly unlikely from everything you describe, not least the two side by side bites. Still, mice live in urban areas and Lyme starts with ticks on mice. Maybe you were unusually unlucky? My grandmother caught Lyme's disease right in the middle of Copenhagen, and the doctor's theory was that it was spread by tick-infested urban foxes.
Whatever it is, you should see a doctor. Don't be a hero.
posted by mumimor at 11:57 AM on August 27, 2017 [1 favorite]

Does it not look like cellulitis to you? I am not a doctor and you are, but I've had cellulitis (diagnosed by doctor) secondary to bug bites and there was no "heat." Whatever it was that bit you, it's probably time to have a colleague take a look.
posted by stowaway at 12:04 PM on August 27, 2017 [1 favorite]

Are you in London? I was in an inner=London park last year andf got bitten by something (possibly a midge, there was a large lake in the park) that caused a similar rash whjch then expanded into a horrible case of hives, so it was probably an allergic reaction.
posted by Fuchsoid at 12:11 PM on August 27, 2017

See your doctor without further delay, please. Any bug bite that remains sore for two weeks, plus it has that spreading rash, would not be a waste of their time; your more-experienced colleagues would be the first to tell you to get it professionally checked out, stat.
posted by easily confused at 12:20 PM on August 27, 2017 [1 favorite]

See a dermatologist.
posted by fingersandtoes at 12:32 PM on August 27, 2017

I wonder if it might have been a spider? This is an odd coincidence: I live nowhere near you (California) but last week I was also bitten by something that made my skin react in a way that it never has before, and it's somewhat similar to your bites. I actually got several bites. I have zero expertise but wondered if my bites might have come from a spider because they were not itchy (as insect bites always are for me). Mine seem to be getting better, though it's also very strange for me to have bites last so long—I was bitten on Tuesday—and I have somewhat similar red halos around mine. Mine were very sore at first, and felt somewhat like the soreness after getting a vaccine shot. I think I was bitten while I was asleep. Yours looks worse; I would definitely go to a doctor if I were you.
posted by pinochiette at 1:33 PM on August 27, 2017

Best answer: Blandford fly is a suspect. A spreading rash is one of the symptoms of a reaction to a bite. Last year's mild winter means they're everywhere this summer. I agree with those who say to get it checked out.
posted by Pallas Athena at 2:57 PM on August 27, 2017

Pruigo Nodularis is a skin condition that usually starts with a bug bite. It's fairly rare, and I only got it diagnosed through a biopsy. I would def go to a dermatologist to check it out. They probably can't tell you what bit you, since it's impossible to tell because everyone's reactions are different, but they can at least tell you what is happening and why it's progressing the way it is.
posted by monologish at 8:11 AM on August 28, 2017

Best answer: That looks a lot like the black / yellow / doctor fly bites I've gotten. Some of the bigger flies bite so deep that the wounds will actually run with blood. Other possibilities are sand fleas, assassin bugs, or maaaybe a tick.

Go to the doctor, open bites like that can be slow to heal and prone to infection.
posted by ananci at 10:25 AM on August 28, 2017

Response by poster: Thanks all. I suspect it was some kind of black fly as that fits best. GP not concerned and it's actually settling now (finally!)
posted by bored_now_flay at 11:48 AM on August 30, 2017