How to identify and treat common bites and stings
A thorough history and physical are key to proper diagnosis and treatment following a patient’s encounter with an insect, arachnid, or other arthropod.
PRACTICE RECOMMENDATIONS
❯ 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
The Centers for Disease Control and Prevention provide a general introduction to getting rid of fleas for pet owners.40 For specific guidance on flea-eradication strategies and specific flea-control products, advise patients to seek the advice of their veterinarian.
Flies and biting midges
Flies are 2-winged insects belonging to the order Diptera. Several fly species can bite, causing a local inflammatory reaction; these include black flies, deer flies, horse flies, and sand flies. Signs and symptoms of a fly bite include pain, pruritus, erythema, and mild swelling (FIGURE 5).41,42 Flies can transmit several infections, including bartonellosis, enteric bacterial disease (eg, caused by Campylobacter spp), leishmaniasis, loiasis, onchocerciasis, and trypanosomiasis.43
Biting midges, also called “no-see-ums,” biting gnats, moose flies, and “punkies,”44 are tiny (1-3 mm long) blood-sucking flies.45 Bitten patients often report not having seen the midge because it is so small. The bite typically starts as a small, erythematous papule that develops into a dome-shaped blister and can be extraordinarily pruritic and painful.44 The majority of people who have been bitten develop a hypersensitivity reaction, which usually resolves in a few weeks.
Management. Suppressing adult biting midges with an environmental insecticide is typically insufficient because the insecticide must be sprayed daily to eradicate active midges and generally does not affect larval habitat. Insect repellents and biopesticides, such as oil of lemon eucalyptus, can be effective in reducing the risk of bites.44,45
Mosquitoes
Mosquitoes are flying, blood-sucking insects of the order Diptera and family Culicidae. Anopheles, Culex, and Aedes genera are responsible for most bites of humans.
The bite of a mosquito produces an indurated, limited local reaction characterized by a pruritic wheal (3-29 mm in diameter) with surrounding erythema (FIGURE 6) that peaks in approximately 30 minutes, although patients might have a delayed reaction hours later.46 Immunocompromised patients might experience a more significant local inflammatory reaction that is accompanied by low-grade fever, hives, or swollen lymph nodes.46,47
Mosquitoes are a vector for serious infections, including dengue, Japanese encephalitis, malaria, and yellow fever, and disease caused by Chikungunya, West Nile, and Zika viruses.
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