Emergent Care / Stabilization:
For severe anaphylactic reactions, epinephrine and other vasoactive medications, fluids, and systemic glucocorticoids are required emergently. 

Diagnosis Overview:
Arthropods comprise a wide invertebrate phylum that includes insects (eg, bees, wasps, fire ants, mosquitoes, chiggers, fleas, and gnats) as well as arachnids (eg, ticks, mites, spiders, scabies, and body lice). While most arthropod bites are a simple nuisance, others may be vectors of disease or be toxic.

Most arthropod bites cause a localized, self-resolving inflammatory reaction manifested by edema, erythema, pain, burning, and pruritus. However, some individuals, particularly those with atopic conditions and immunodeficiencies, may develop skeeter syndrome: a robust, local immunoglobulin E (IgE)-, immunoglobulin G (IgG)-, and T lymphocyte-mediated hypersensitivity response to mosquito saliva. Skeeter syndrome can present with vesicles, bullae, fever, and lymphadenopathy.

Arthropod bite reactions generally may be more pronounced in immunocompromised individuals. An exaggerated, sometimes bullous reaction to an arthropod bite is characteristic of certain immunosuppressed states, especially a hematopoietic malignancy or HIV disease.

Less commonly, benign arthropod bites can cause systemic reactions, including anaphylaxis. 

Clinically important envenomations in the United States include widow spider bites (Latrodectus), which may cause neuromuscular symptoms such as painful muscle spasms and autonomic effects, and recluse spider bites (Loxosceles), which may be overdiagnosed and usually resolve with conservative management but may rarely progress to necrotic lesions or systemic hemolysis. Hymenoptera stings (eg, bees, wasps, hornets, fire ants) are the leading cause of arthropod-related mortality due to anaphylaxis, requiring prompt recognition and treatment. Other arthropods (eg, mosquitoes, flies, ticks) typically cause mild local symptoms but are important as vectors for infectious diseases such as African tick bite fever, Lyme disease, Rocky Mountain spotted fever, a variety of encephalitides, and malaria.

There are highly variable global distributions of insects and arthropods. In returning travelers, insect bites are the fourth most common skin complaint diagnosed.

Additional related topics: scabies, tick bite, mite dermatitis, body lice, chigger bite, bedbug bite, flea bite