PracticalDermatology

Margaret Parsons, MD, FAAD, a Sacramento dermatologist and associate clinical professor of dermatology at the University of California, Davis, knows a lot about bugs, bug bites, and how best to diagnose and treat them. As such, she is widely quoted in the media about all things creepy crawly. Dr. Parsons shared some of her extensive knowledge with Practical Dermatology® magazine.

What clues do you look for when a patient presents with a bug bite?

As dermatologists we frequently see patients with a bug bite or a dermatitis they think may be caused by a bug bite. Reviewing the patient’s history—activities (such as gardening or hiking), travel, hospitalization, and visiting a friend or relative in a nursing home—can often elicit a clue to what to consider. Of course, looking at the eruption or lesion will also guide us in considering an insect or arthropod.

What are some of the more common bites you see?

The more common bites we see are mosquito bites, spider bites, bee stings, and flea bites. Flea bites usually cluster on the lower legs, mosquito bites in uncovered body parts such as legs and arms. Spider bites are often a single bite and can be on an extremity or trunk. In some parts of the country, “chiggers” would be another bite pattern of clustered bites usually on legs. Bed bugs usually cause a group of bites, and we can advise the patient to look carefully at their mattress for rice-sized bugs and review their travel history.

What about tick bites?

Tick bites are important to recognize in areas with Lyme disease risk. It’s important to know what ticks and risk of Lyme disease is in your regional area and in general if patients have travelled recently. Initially you might get a call for a “bleeding mole” that on examination turns out to be a tick still attached. Later, of course, the annular pink Erythema Chronicum Migrans can be recognized.

Scabies?

The varied eruptions of scabies can show the textbook trail, a non-specific eczematous dermatitis, or the crusted Norwegian scabies. More subtly, scabies can present as minimal eruption, but significant pruritus in a healthy young adult. A few times the clue in history has been the visiting of an ailing grandparent in a nursing home and holding their hand at bedside.

The less common eruptions would be something such as Leishmaniasis, with an eruption that is persistent and a travel history to somewhere such as the Amazon.

When should someone see a doctor for a bug bite?

Most importantly, if it is symptomatic, persistent, or worsening. A patient who is truly allergic would need to be aware of a risk of anaphylaxis and have the appropriate epinephrine injection by Epi-Pen or emergently in the emergency room or with Emergency Medical Technicians. A patient’s scratching of a bite can result in a cellulitis. So having staff triage with the appropriate phone calls of worsening, warmth, redness, or drainage is important to make sure patients are appropriately worked in for urgent appointments. If a patient has been bitten by a black widow or brown recluse spider, that would also be a time to contact their physician.

What are other skin conditions that could be mistaken for bug bites? 

Urticaria and hives can sometimes present similarly to bug bites. And while initial treatment with oral antihistamines, topical corticosteroids, and sometimes systemic steroids are similar, those conditions may become more persistent and require further evaluation.

Shingles may initially present with an urticarial look, but it’s grouped lesions and development to vesicles clarifies the clinical diagnosis, as well as the symptom of pain rather than itch.