Author: V. Dimov, M.D., Allergist/Immunologist and Assistant Professor at University of Chicago
Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at NSU
This is a 18-year-old female who is here for evaluation of suspected allergic reaction to mosquito bites.
One year ago, she had two separate mosquito bites that caused delayed increased swelling and redness (thigh and ankle). Photos show erythema and swelling approximately 15 cm in size. They were associated with delayed chills and fatigue that lasted for 3 days each. No immediate systemic symptoms. She denies history of tick bite or rash with circular erythema with central clearing. The symptoms resolved after 3 days.
The patient also reports symptoms suggestive of allergic rhinitis.
What test would you recommend?
Percutaneous skin testing with indoor, outdoor allergens was negative. There is no standardized test for mosquito.
What is the most likely diagnosis?
Large local reaction to mosquito bite with delayed symptoms of fatigue and chills (Skeeter syndrome). No immediate systemic symptoms or delayed anaphylaxis. There is no standardized skin test for mosquito. ImmunoCAP sIgE can be helpful in some patients but the sensitivity is low. Some of the reactions are IgG-mediated and they will not be detected by an IgE test.
What is the next step?
Regarding Skeeter syndrome, the following was recommended:
- ImmunoCAP sIgE for mosquito for completeness. If the test is positive, IgE sensitization is likely. However, a negative sIgE test would not rule out mosquito allergy due to low sensitivity
- Use insect sprays and clothing to repel mosquitoes when outdoors
- If mosquito exposure is predictable or inevitable, take non-sedating H1-antihistamine (cetirizine 10 mg) for 2 days before and after spending time outdoors
Treatment of large local reactions to mosquito bites is symptomatic:
- For bothersome itching, take cetirizine as above
- For swelling and induration several centimeters in diameter, use a topical glucocorticoid cream - hydrocortisone 1% or mometasone 0.1%, applied twice daily for 5 to 10 days
- For patients extensive periorbital swelling that interferes with vision, lip swelling that interferes with liquid or food ingestion, or swelling of a limb that interferes with ambulation, take a short course of an oral glucocorticoid such as prednisone (1 mg/kg to a maximum of 50 mg) once daily for 5 to 7 days
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