Department of Family Medicine, Loma Linda University Health, CA ejaqua@llu.edu
The authors reported no potential conflict of interest relevant to this article.
A thorough history and physical are key to proper diagnosis and treatment following a patient’s encounter with an insect, arachnid, or other arthropod.
❯Recommend that patients use an insect repellent, such as an over-the-counter formulation that contains DEET, picaridin, or PMD (a chemical constituent of Eucalyptus citriodora oil) to prevent flea bites. C
❯Prescribe nonsedating oral antihistamines as first-line symptomatic treatment of mild-to-moderate pruritus secondary to an insect bite. C
❯When indicated, refer patients for venom immunotherapy, which is approximately 95% effective in preventing or reducing severe systemic reactions and reduces the risk of anaphylaxis and death. C
Strength of recommendation (SOR) A Good-quality patient-oriented evidence B Inconsistent or limited-quality patient-oriented evidence C Consensus, usual practice, opinion, disease-oriented evidence, case series
References
Insect, arachnid, and other arthropod bites and stings are common patient complaints in a primary care office. A thorough history and physical exam can often isolate the specific offender and guide management. In this article, we outline how to identify, diagnose, and treat common bites and stings from bees and wasps; centipedes and spiders; fleas; flies and biting midges; mosquitoes; and ticks, and discuss how high-risk patients should be triaged and referred for additional testing and treatment, such as venom immunotherapy (VIT).
Insects and arachnids:Background and epidemiology
Insectsare arthropods with 3-part exoskeletons: head, thorax, and abdomen. They have 6 jointed legs, compound eyes, and antennae. There are approximately 91,000 insect species in the United States, the most abundant orders being Coleoptera (beetles), Diptera (flies), and Hymenoptera (includes ants, bees, wasps, and sawflies).1
The reported incidence of insect bites and stings varies widely because most people experience mild symptoms and therefore do not seek medical care. Best statistics are for Hymenoptera stings, which are more likely to cause a severe reaction. In Europe, 56% to 94% of the general population has reported being bitten or stung by one of the Hymenoptera species.2 In many areas of Australia, the incidence of jack jumper ant stings is only 2% to 3%3; in the United States, 55% of people report being stung by nonnative fire ants within 3 weeks of moving into an endemic area.4
Arachnids are some of the earliest terrestrial organisms, of the class Arachnida, which includes scorpions, ticks, spiders, mites, and daddy longlegs (harvestmen).5 Arachnids are wingless and characterized by segmented bodies, jointed appendages, and exoskeletons.6,7 In most, the body is separated into 2 segments (the cephalothorax and abdomen), except for mites, ticks, and daddy longlegs, in which the entire body comprises a single segment.5
Arthropod bites are common in the United States; almost one-half are caused by spiders.7 Brown recluse (Loxosceles spp) and black widow (Latrodectus spp) spider bites are the most concerning: Although usually mild, these bites can be life-threatening but are rarely fatal. In 2013, almost 3500 bites by black widow and brown recluse spiders were reported.8
Among beekeepers, the risk of a systemic reaction is higher in those stung < 15 times a year than in those stung > 200 times.
Risk factors
Risk factors for insect, arachnid, and other arthropod bites and stings are primarily environmental. People who live or work in proximity of biting or stinging insects (eg, gardeners and beekeepers) are more likely to be affected; so are those who work with animals or live next to standing water or grassy or wooded locales.
