eMedicine Specialties > Emergency Medicine > Environmental

Bites, Insects

Bo Burns, DO, FACEP, FAAEM, Assistant Professor, Assistant Residency Director, Medical Clerkship Director, Department of Emergency Medicine, University of Oklahoma School of Community Medicine; Attending Physician, Department of Emergency Medicine, St Francis Hospital Trauma Emergency Center
Kavon Charles Azadi, MD, Resident Physician, Oklahoma Institute for Disaster and Emergency Medicine, University of Oklahoma College of Community Medicine, Department of Emergency Medicine

Updated: Oct 13, 2009

Introduction

Background

Insects are arthropods of the class Insecta. Insects have an adult stage characterized by a hard exoskeleton, 3 pairs of jointed legs, and a body segmented into head, thorax, and abdomen. Insects comprise the most diverse and numerous class of the animal kingdom and include numerous species of praying mantis, dragonflies, grasshoppers, true bugs, flies, fleas, bees, wasps, ants, lice, butterflies, moths, and beetles. The number of species is estimated at between 6 and 10 million, with more than a million species already described. Insects represent more than half of all known living organisms and potentially represent more than 90% of the differing life forms on Earth. Hence, human contact with insects is unavoidable. Exposure to biting or stinging insects or to their remains can range in severity from benign or barely noticeable to life threatening.

Yellowjacket wasp. Image courtesy of CDC.

Louse, Pediculus humanus, dorsal view after feeding on blood. Most lice are scavengers, feeding on skin and other debris found on the host's body, but some species feed on sebaceous secretions and blood. Image courtesy of CDC.

Many patients confuse an insect bite with a sting and may use the terms interchangeably. A bite is usually from mouth parts and occurs when an insect is agitated to defend itself or when an insect seeks to feed. Bites from mosquitoes, fleas, bed bugs, and mites are more likely to cause itching than pain.

Anopheles albimanus mosquito feeding on human host. Image courtesy of CDC.

A bedbug, Cimex lectularius, feeding on human blood. The bedbug's name comes from its preferred habitat, including mattresses, sofas, and other furniture. Image courtesy of CDC.

While illness related to insect exposure in a particular locale may be easily recognizable, the emergency physician must also be aware of more exotic insect-related diseases as humans travel to more remote areas of the country and the world. Additionally, exotic insects are often kept as pets (sometimes illegally) or can be encountered in shipments of foreign origin.

Anaphylactic shock

Anaphylactic shock is the most notable immediate risk associated with insect exposures. Hypersensitivity to otherwise harmless insect saliva, venom, body parts, excretions, or secretions can cause systemic responses in some individuals. Diagnosing the early phases of a systemic allergic reaction preceding anaphylactic shock is of paramount importance in treating any patient in whom insect exposure is suspected. Severe anaphylaxis can be fatal in as little as 10 minutes.

The reoccurrence rate is 40-60% for insect stings. Hence, the patient should be instructed on how to avoid future exposure to the causative agent, if possible. A prescription and clear instructions on the use of an epinephrine autoinjector should be provided to patients when the risk of another reaction is judged to be substantial.¹

Diseases transmitted by insect bites

The need to be aware of diseases transmitted by insect bites is crucial; Lyme disease, transmitted by ticks, and malaria, transmitted by mosquitoes, are discussed in other articles (see Tick-borne Diseases, Lyme; Malaria).

Chagas disease, increasingly found in the desert southwest and in persons residing in or traveling to Central America or South America, should be considered, particularly when the bite site is on the soft skin of the periorbita or lips.² Because this infection may produce an acute and chronic illness with notable morbidity and mortality, especially in pediatric patients, clinicians should maintain a high index of suspicion (see Trypanosomiasis).

Mosquito and tick-borne encephalitides such as those produced by the eastern equine virus or the West Nile virus also should be considered in patients presenting with meningismus (see Encephalitis).

Of note, some illnesses transmitted by insects do not produce symptoms until long after the infecting bite. In South America and parts of Africa, blackflies (Simuliidae) are responsible for transmission of onchocerciasis. This illness is also known as river blindness and eventually can produce blindness years after the initial infection. This disease is extremely rare in the United States. Chagas disease, a leading cause of cardiomyopathy in the world, may present latently as well. Obtaining a history of international travel is important because this information can lead to a diagnosis that would otherwise be overlooked. Determining the destination, time of year, length of stay, and time since travel are all important pieces of history to obtain.

Exposure to arthropods may produce dermatitis, cellulitis, urticaria, or blistering unrelated to biting or stinging. Some species of moths, caterpillars, centipedes, beetles, and spiders have urticating hairs or secretions that can cause cutaneous irritation. For further information, please refer to the respective articles on these exposures (see Differentials).

An uncommon occurrence in North America is myiasis by fly larvae. Fly larvae enter the host through varying mechanisms ranging from oviposition of live, burrowing larvae on the host, on or near open wounds, to attachment to other bloodsucking insects. While not generally the result of an insect bite, myiasis can produce pustules and lesions similar to insect bites. These lesions generally contain one or more developing fly larvae. Severe cases of myiasis can cause seizures.

While plant-eating phytophagous insects can bite in self-defense, their bites generally are not purposeful. This article is limited to discussion of organisms that bite to feed on blood or to catch prey.

Relatively harmless insects

Cockroaches have been reported to bite humans, but their bite generally is harmless. Continued repeated exposure to their remains and feces poses a greater health threat, such as increased incidence of asthma, especially in inner cities, and their remains and feces are possible vectors for transmission of viral and bacterial diseases.

Earwigs generally are harmless insects that have earned an unpleasant reputation. This may be because of their depiction in popular culture, such as in the television series, "The Night Gallery." Although they appear to have a large pincer on the posterior abdomen, it is not capable of rendering anything more serious than a mild pinch. Additionally, and contrary to popular belief, they do not routinely enter the human ear canal and parasitize humans. Cockroaches are much more likely to be found lodged in a patient's auditory passage.

Pathophysiology

Mouthparts of biting insects can be classified into 3 broad groups: piercing, sponging, and biting. Tremendous diversity exists in the morphology of these groups. Insects discussed in this article generally are nonvenomous, yet many species inject saliva while biting. Their saliva may aid in digestion, inhibit coagulation, increase blood flow to the bite, or anesthetize the bite locus. Most lesions are the result of the victim's immune response to these insect secretions. In the case of Chagas disease, the infective organism is transmitted via the feces of a reduviid bug, which enters through the bite site when the wound becomes pruritic and is scratched. Most insect bites are minor and can result in superficial puncture wounds to the skin. Horseflies feed with a large scissorlike proboscis that can cause a relatively deep and painful wound.

Frequency

United States

In the United States, the American Association of Poison Control Centers reported 42,620 cases of exposures to insects in 2007. Just more than 200 of these were listed as resulting in moderate or major reactions. A moderate reaction is defined as signs or symptoms that were more pronounced or systemic, whereas a major reaction is life-threatening or lead to significant residual disability. Fatalities among these exposures are rarely reported to poison centers and usually result from allergic reactions to Hymenoptera stings. Because of underreporting, these numbers are only a glimpse as to what is actually occurring.³

International

Reliable statistics are not available for insect bite exposures because most cases are not reported and do not require hospital care.⁴ A study in tropical Zimbabwe, where biting insects are common, found that 1.5% of hospital admissions were related to insect exposure, including both bites and stings. A vast majority of these were arachnid or Hymenoptera related.

Mortality/Morbidity

Mortality associated with insect bites is from hypersensitivity reactions, either anaphylactic (immunoglobulin E [IgE] mediated) or anaphylactoid (non-IgE mediated), or from complications resulting from infection. Reliable figures on incidence and prevalence are not available. Estimates of mortality from insect-provoked anaphylaxis in the United States range from 50-150 persons annually. In Arizona, for example, death from reduviid-associated anaphylaxis has been reported as a leading cause of death from insect exposure. Worldwide, the greatest morbidity and mortality associated with insect bites are due to Anopheles species mosquito bites resulting in infection with malaria (see Malaria).⁴

Sex

No sexual preference known.

Age

No age preference known.

Clinical

History

Most patients are aware of insect bites when they occur or shortly thereafter, but because it is such a common occurrence, the exposure is typically dismissed unless a severe or systemic reaction occurs. 

• Reactions to bites may be delayed due to the host being asleep or because the saliva of some micropredators may contain an anesthetic secreted to allow uninterrupted blood-feeding.
• Patients who present with a history of homelessness or of staying in homeless shelters may have an exposure to organisms such as bedbugs.^5,6,7 Alternatively, patients with impairment from mental illness may also be susceptible to infestation with insect parasites.
• Exposure to feral animals or even to domesticated animals, such as livestock or house pets, may predispose patients to exposure to biting insects such as fleas, bedbugs,^8,6,7 or lice.
• Types of reactions
  • In a local reaction, the patient may complain of discomfort, itching, moderate or severe pain, erythema, tenderness, warmth, and edema of tissues surrounding the site. Although it may involve neighboring joints, local reactions cause no systemic symptoms.
  • In a severe local reaction, complaints include generalized erythema, urticaria, and pruritic edema. Severe local reactions increase the likelihood of serious systemic reactions if the patient is exposed again at a later time.
  • In a systemic or anaphylactic reaction, the patient may complain of localized symptoms as well as symptoms not contiguous with the bite location. Symptoms can range from mild to fatal. Early complaints typically include generalized rash, urticaria, pruritus, and angioedema. These symptoms may progress, and the patient may develop anxiety, disorientation, weakness, gastrointestinal disturbances (eg, cramping, diarrhea, vomiting), uterine cramping in women, urinary or fecal incontinence, dizziness, syncope, hypotension, stridor, dyspnea, or cough. As the reaction progresses, patients may experience respiratory failure and cardiovascular collapse.
  • Delayed reactions may appear 10-14 days after a sting. Symptoms of delayed reactions resemble serum sickness and include fever, malaise, headache, urticaria, lymphadenopathy, and polyarthritis.

Physical

• Without a clear patient history, diagnosis of an insect bite can be difficult since the initial response may be limited to erythema, local pain, pruritus, or edema.
• Wheals and urticaria are common initial signs and generally appear within a few minutes of the bite. Unfortunately, many dermatologic conditions also produce similar cutaneous signs and may confound the diagnosis.
• Identification of the insect responsible for the bite may be possible by examining the location, number, pattern, and sequelae of the bite(s).
• Physical examination elements indicating a systemic reaction include the following:
  • Cardiovascular - Hypotension, orthostasis
  • Cutaneous - Urticaria, wheals, angioedema, blood at bite site, pruritus
  • Respiratory - Tachypnea, stridor, wheezing, bronchospasm
  • Gastrointestinal - Hyperactive bowel sounds

Differential Diagnoses

Workup

Laboratory Studies

• Laboratory studies are seldom necessary. Appropriate laboratory studies should be ordered if the patient is compromised severely and requires hospital admission or end-organ failure is suspected, or for evaluation of secondary complications such as cellulitis.
• Biopsy of lesions generally is nondeterminant and is impractical in the ED.
• Microscopic examination of skin scrapings can be useful in the diagnosis of scabies or mite infestations but are not useful for most insect bites.
• Serology studies may be useful in determining infection due to an insect vector, but these are not available in the ED and may take weeks to obtain a result.

Treatment

Prehospital Care

• If the bee stinger is present in the wound, it should be removed. Although conventional teaching suggested scraping the stinger out to avoid squeezing remaining venom from the retained venom gland into the victim, involuntary muscle contraction of the gland continues after evisceration and the venom contents are quickly exhausted. Immediate removal is the important principle and the method of removal is irrelevant.
• Most insect bites may be treated acutely with a compress after routine wound cleaning with soap and water to minimize the possibility of infection.
• For a large local reaction, ice packs may minimize swelling. Apply ice for no more than 15 minutes at a time using a cloth barrier between ice and skin to prevent direct thermal injury to the skin.
• Epinephrine is the mainstay of prehospital treatment of a systemic reaction; the route of administration (subcutaneous, intramuscular, intravenous [IV], endotracheal) depends on the patient's condition and the expertise of the prehospital provider. Systemic antihistamines and corticosteroids, if available, help manage systemic reactions. Many patients who are allergic to stings carry commercially available bee sting kits containing an autoinjector of epinephrine. Refer to Hymenoptera Stings.
• Topical antihistamines should not be applied over large surface areas, and they should not be used concurrently with systemic H1 antihistamines. Systemic anticholinergic toxicity may result from misuse of these medications.
• Use of H2-blocking drugs (usually used to reduce gastric acid secretion) may be used concurrently with H1-blocking antihistamines.
• In many patients, transport to a hospital is not necessary. Those requiring transport include patients who develop signs or symptoms of a systemic response or individuals with a history of insect-related anaphylaxis. A phone call to the regional poison center may save a costly visit to the ED.

Emergency Department Care

• Endotracheal intubation and ventilatory support may be required for severe anaphylaxis or angioedema involving the airway.
• Treat emergent anaphylaxis in an atopic individual with an initial intramuscular injection of 0.3-0.5 mL of 1:1000 epinephrine. This may be repeated every 10 minutes as needed.
• A bolus of IV epinephrine (1:10,000) may be used cautiously in severe cases.
  • Solution of 1:10,000 typically is found in 10-mL vials. Repeated 1-mL doses are a reasonable initial approach in a critically ill patient with anaphylaxis.
  • Once a positive response is achieved, these boluses can be followed by a carefully monitored, continuous epinephrine infusion.
  • Use extra care in monitoring formulation, concentration, and dose when administering IV epinephrine to avoid inadvertent overdose.
• Severely hypotensive patients may require a large volume of IV fluids. Monitor for angioedema and pulmonary edema.
• Antihistamines, both H1 and H2 blockers, are useful in treating systemic reactions. Corticosteroids also are indicated routinely in such patients.
• Refer to Anaphylaxis and Serum Sickness for further guidance.
• Ensure appropriate tetanus prophylaxis.
• Undefined erythema and swelling seen may be difficult to distinguish from cellulitis. As a general rule, infection is present in a minority of cases and antibiotic prophylaxis is not recommended.
• Related diagnostic and treatment guidelines are available on anaphylaxis, travel medicine, and referral guidelines (also see Further Reading).^9,10,11

Consultations

• In cases in which determining the insect species is important, a health department, agriculture extension, or university entomologist may be useful.
• In cases of potential vector-borne disease transmission, an infectious disease specialist may be of help.
• If the potential infection is associated with travel to a tropical region, consider contacting a tropical medicine specialist or the Centers for Disease Control and Prevention (CDC) at 1-877-394-8747 (Traveler's Health Hotline).
• A regional poison center may be of assistance in difficult or complicated cases or for general information.

Medication

Goals of therapy are to treat anaphylaxis and prevent complications.

Cardiovascular agents

Act to decrease the muscle tone in the small and large pulmonary airways and increase vascular tone.

Epinephrine (Adrenalin, Bronitin, EpiPen)

Drug of choice for shock, angioedema, airway obstruction, bronchospasm, and urticaria in severe anaphylactic reactions. Administer IM; administer IV to patients in extremis; may be administered SL or ET when no IV access available. Continuous infusion may be given in cases of refractory shock.

Dosing

Adult

1 mL 1:10,000 solution slow IV; repeat prn
0.1-1 mcg/kg/min IV infusion
0.3-0.5 mL 1:1000 solution IM/SL/SQ q10-15min
1 mL 1:1000 solution in 10 mL NS ET

Pediatric

0.01 mL/kg (min 0.1 mL) 1:10,000 solution IV prn
0.1-1 mcg/kg/min IV infusion
0.01 mL/kg (min 0.1 mL) 1:1000 solution IM/SL/SQ q15min
0.01 mL/kg (min 0.1 mL) 1:1000 solution in 1-3 mL NS ET

Interactions

Epinephrine coadministered with other sympathomimetics may have additive effects; beta-blockers antagonize therapeutic effects of epinephrine; digitalis may potentiate proarrhythmic effects of epinephrine; TCAs and MAOIs potentiate cardiovascular effects of epinephrine; phenothiazines may decrease BP when coadministered with epinephrine

Contraindications

In a life-threatening anaphylactic reaction, epinephrine may be given with appropriate caution when any of the following relative contraindications are present: coronary artery disease; uncontrolled hypertension; serious ventricular dysrhythmias; second stage of labor

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Caution in elderly patients and those with prostatic hypertrophy, hypertension, cardiovascular disease, diabetes mellitus, hyperthyroidism, and cerebrovascular insufficiency; rapid IV infusions may cause death from cerebrovascular hemorrhage or cardiac dysrhythmias

Bronchodilators

Through activation of cyclic AMP, beta agonists stimulate the ATPase pump, thereby shifting potassium into the intracellular compartment and stimulating an adrenergic response.

Albuterol (Ventolin)

Beta agonist useful in treating bronchospasms refractory to epinephrine. Relaxes bronchial smooth muscle by action on beta2 receptors and has little effect on cardiac muscle contractility. Numerous inhaled beta agonists are used for treatment of bronchospasm; albuterol is used most commonly.

Dosing

Adult

0.5 mL 0.5% solution in 2.5 mL NS nebulized q15min

Pediatric

0.03-0.05 mL/kg 0.5% solution in 2.5 mL NS via nebulizer q15min

Interactions

Increases toxicity of beta-blocking and alpha-blocking agents and halogenated inhalational anesthetics

Contraindications

May be given in a life-threatening anaphylactic reaction, even when the following relative contraindications are present: severe coronary insufficiency; uncontrolled severe hypertension

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Caution in elderly patients and those with prostatic hypertrophy, hypertension, cardiovascular disease, diabetes mellitus, hyperthyroidism, and cerebrovascular insufficiency; rapid IV infusions may cause death from cerebrovascular hemorrhage or cardiac dysrhythmias

Antihistamines

Prevent histamine response in sensory nerve endings and blood vessels; more effective in preventing histamine response than in reversing it. H2 antihistamines are useful in treatment of anaphylactic reactions when used concomitantly with H1 antagonists. Many H2 blockers are available. Cimetidine is the prototype drug.

Diphenhydramine (Benadryl)

Used for symptomatic relief of allergic symptoms caused by histamines released in response to allergens; many effective H1 blockers; diphenhydramine is effective and widely available.

Dosing

Adult

50 mg PO q4-6h
25-50 mg IV/IM q4-6h

Pediatric

5 mg/kg/d PO divided q6h-8h
Severe cases: 1-2 mg/kg IV q6h; alternatively, 1-2 mg/kg IM q6h

Interactions

Potentiates effect of CNS depressants; due to alcohol content, do not give syr dosage form to patient taking medications that can cause disulfiramlike reactions

Contraindications

Documented hypersensitivity; MAOIs

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

May exacerbate angle-closure glaucoma, hyperthyroidism, peptic ulcer, and urinary tract obstruction

Cimetidine (Tagamet)

An H2 antagonist that, when combined with H1 type, may be useful to treat itching and flushing in anaphylaxis, pruritus, urticaria, and contact dermatitis that do not respond to H1 antagonists alone. Use in addition to H1 antihistamines.

Dosing

Adult

300 mg PO/IV/IM q6h

Pediatric

5-10 mg/kg PO/IV/IM q6h

Interactions

Can increase blood levels of theophylline, warfarin, TCAs, triamterene, phenytoin, quinidine, propranolol, metronidazole, procainamide, and lidocaine

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Elderly patients may experience confusional states; may cause impotence and gynecomastia in young males; may increase levels of many drugs; adjust dose or discontinue treatment if changes in renal function occur

Corticosteroid, Systemic

Have anti-inflammatory properties and cause profound and varied metabolic effects. In addition, these agents modify the body's immune response to diverse stimuli. Prednisone and methylprednisolone are typical drugs of this class. Oral bioavailability is generally similar to parenteral; administer oral prednisone when indicated if a patient is not in extremis and can comfortably take PO; administer parenteral steroid when indicated for a patient in more severe circumstances.

Prednisone

Believed to ameliorate delayed effects of anaphylactic reactions and may limit biphasic anaphylaxis. Doses below are general guidelines for usage; dosing is highly individualized.

Dosing

Adult

40-60 mg/d PO qd or divided bid/qid; no taper required if used for 5-7 d.

Pediatric

1-2 mg/kg PO qd or divided bid/qid; no taper required if used for 5-7 d.

Interactions

Coadministration with estrogens may decrease clearance; concurrent use with digoxin may cause digitalis toxicity secondary to hypokalemia; phenobarbital, phenytoin, and rifampin may increase metabolism of glucocorticoids (consider increasing maintenance dose); monitor for hypokalemia with coadministration of diuretics

Contraindications

Documented hypersensitivity; viral infection, peptic ulcer disease, hepatic dysfunction, connective tissue infections, and fungal or tubercular skin infections; GI bleeding or ulceration

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Abrupt discontinuation of glucocorticoids may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression, and infections may occur with glucocorticoid use

Methylprednisolone (Solu-Medrol, Depo-Medrol)

Useful to treat inflammatory and allergic reactions. By reversing increased capillary permeability and suppressing PMN activity, may decrease inflammation.
A multitude of corticosteroid preparations is available. Methylprednisolone is widely available in the ED due to other uses (ie, acute asthma, spinal cord injury) and is supplied in both parenteral and oral formulations.

Dosing

Adult

2-60 mg PO qd
40-250 mg IV/IM q6h

Pediatric

1-2 mg/kg PO/IV/IM qd

Interactions

NSAIDs may cause ulcers when taken concurrently; anticholinesterases may increase weakness in patients with myasthenia gravis when taken concurrently with steroids; risk exists of possible viral dissemination with live virus vaccines

Contraindications

Documented hypersensitivity; some evidence exists for fetal harm from corticosteroids (consider both benefits and risks of use during pregnancy); consider risks (eg, dissemination, activation, certain infections) when prescribing for immunosuppressed patients

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Short-term use of corticosteroids, even in large doses, has minimal harmful effects; long-term usage has multiple adverse effects; possible complications include hyperglycemia, edema, osteonecrosis, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, growth suppression, myopathy, or infections

Toxoids

For active immunity against tetanus.

Tetanus toxoid

Used to induce active immunity against tetanus in selected patients. The immunizing agents of choice for most adults and children > 7 y are tetanus and diphtheria toxoids. Necessary to administer booster doses to maintain tetanus immunity throughout life.
Pregnant patients should receive only tetanus toxoid, not a diphtheria antigen-containing product.
In children and adults, may administer into deltoid or midlateral thigh muscles. In infants, preferred site of administration is mid thigh laterally.

Dosing

Adult

Primary immunization: 0.5 mL IM; give 2 injections 4-8 wk apart and a third dose 6-12 mo after second injection
Booster dose: 0.5 mL q10y

Pediatric

Administer as in adults

Interactions

Patients receiving immunosuppressants, including corticosteroids or radiation therapy, may remain susceptible despite immunization due to poor immune response; cimetidine may enhance or augment delayed-hypersensitivity responses to skin-test antigens; avoid concurrent use of medication with systemic chloramphenicol since it may impair amnestic response to tetanus toxoid; concurrent use of tetanus immune globulin may delay development of active immunity by several days (interaction is nevertheless clinically insignificant and does not preclude concurrent use)

Contraindications

Documented hypersensitivity; history of any type of neurologic symptoms or signs following administration of this product; FDA recommends that elective tetanus immunization be deferred during any outbreak of poliomyelitis because tetanus toxoid injections are an important cause of provocative poliomyelitis

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Do not use to treat actual tetanus infections or for immediate prophylaxis of unimmunized individuals (use instead tetanus antitoxin, preferably human tetanus immune globulin); diminished antibody response to active immunization may be seen in patients receiving immunosuppressive therapy; better to defer primary diphtheria immunization until immunosuppressive therapy discontinued; routine immunization of symptomatic and asymptomatic HIV-infected persons is recommended

Immunoglobulins

Consists of administration of immunoglobulins pooled from serum of immunized patients.

Tetanus immune globulin (Hyper-Tet)

Used for passive immunization of any person with a wound that may be contaminated with tetanus spores.

Dosing

Adult

Prophylaxis: 250-500 U IM in opposite extremity to tetanus toxoid lesion
Clinical tetanus: 3,000-10,000 U IM

Pediatric

For prophylaxis: 250 U IM in opposite extremity to tetanus toxoid
Clinical tetanus: 3,000-10,000 U IM

Interactions

None reported

Contraindications

Since antibodies in globulin preparation may interfere with immune response to vaccination, do not administer within 3 mo of live virus immune globulin administration; may be necessary to revaccinate persons who received immune globulin shortly after live virus vaccination

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Persons with isolated IgA deficiency have potential for developing antibodies to IgA and may have anaphylactic reactions to subsequent administration of blood products that contain IgA; do not perform skin testing since intradermal injection of concentrated gamma globulin may cause localized area of inflammation and can be misinterpreted, causing medication to be withheld from a patient not allergic to this material; true allergic responses to human gamma globulin given in prescribed IM manner are extremely rare; do not admix with other medications since usually incompatible

Follow-up

Further Inpatient Care

• Patients with true anaphylaxis, particularly if associated with hypotension, often are admitted for monitoring or observation in the ED upon recovery. Accepted definition of "true" anaphylaxis requires the involvement of at least 2 of the following 4 systems: cardiovascular, gastrointestinal, skin, or respiratory. Literature provides no clear direction on who needs admission. Certain patients with a disease transmission (eg, malaria) may require admission.

Further Outpatient Care

• Follow-up monitoring for infection is advised for individuals bitten by an insect known to transmit a secondary disease, if exposed to the vector in an endemic area (eg, Chagas disease in the case of kissing bugs [Reduviidae]).
• Individuals who recover from a systemic reaction should consult with an allergist regarding desensitization and prevention measures.

Inpatient & Outpatient Medications

• Prescribe a bee sting kit with a device for self-administration of epinephrine prior to discharge if the patient had a systemic response to an envenomation (see Hymenoptera Stings).
• Corticosteroids and antihistamines usually are continued for a few (3-4) days after a systemic response. Serum sickness reactions may require longer therapy (see Serum Sickness).

Deterrence/Prevention

• Patients may be educated about avoidance measures. Refer to Patient Education.

Complications

• Secondary infection may result from an insect bite.
• Symptoms of disease transmitted by insect bites may not be evident for days, weeks, or even longer.

Prognosis

• Prognosis generally is good except in patients with severe untreated anaphylaxis or in those with chronic or invasive infections.

Patient Education

• Biting insects are ubiquitous in nearly all parts of the world, yet certain measures can be taken to minimize risk of exposure.
  • Periodic pest control may eliminate nests and minimize reproduction of biting insects.
  • Wear protective clothing (ie, long pants, long sleeves), especially when outdoors. Many insects are incapable of biting through clothing. Additionally, light-colored clothing appears to be less attractive to many biting insects, including mosquitos.¹² Avoid dark colors or brightly colored floral patterns. Wear protective footwear. Wear gloves when working with soil or in areas of heavy infestation.
  • Avoid use of heavy perfumes, scented soaps, sprays, or lotions that may attract insects.
  • Be aware of surroundings; for example, avoid dense vegetation or animals suspected of carrying fleas, chiggers, or ticks.
  • Prudent use of insect repellent can help minimize exposure to insect bites and stings (See Insect Repellents).¹³
  • Be aware of the potential for bees or other foraging insects to enter opened soft drink containers that are left idle.
• For excellent patient education resources, visit eMedicine's Bites and Stings Center. Also, see eMedicine's patient education articles Insect Bites, Allergy: Insect Sting, Severe Allergic Reaction (Anaphylactic Shock), Black Widow Spider Bite, Brown Recluse Spider Bite, and Ticks.

Miscellaneous

Medicolegal Pitfalls

• Failure to recognize early warning signs of anaphylaxis
• Failure to obtain a thorough travel or exposure history
• Failure to consider or recognize exotic diseases or diseases with vague prodromal signs and symptoms
• Failure to refer questionable cases for reasonable follow-up care
• Failure to warn patients about possible complications secondary to bites such as infection, serum sickness, and, in atopic individuals, biphasic anaphylaxis
• Failure to provide a referral to an allergist or to prescribe a bee sting kit to patients with systemic reactions

Multimedia

Media file 1: Yellowjacket wasp. Image courtesy of CDC.

Media file 2: Anopheles albimanus mosquito feeding on human host. Image courtesy of CDC.

Media file 3: A bedbug, Cimex lectularius, feeding on human blood. The bedbug's name comes from its preferred habitat, including mattresses, sofas, and other furniture. Image courtesy of CDC.

Media file 4: Louse, Pediculus humanus, dorsal view after feeding on blood. Most lice are scavengers, feeding on skin and other debris found on the host's body, but some species feed on sebaceous secretions and blood. Image courtesy of CDC.

References

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3. Bronstein AC, Spyker DA, Cantilena LR Jr, Green JL, Rumack BH, Heard SE. 2007 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 25th Annual Report. Clin Toxicol (Phila). Dec 2008;46(10):927-1057. [Medline].

4. Rodriguez M, Perez L, Caicedo JC, et al. Composition and biting activity of Anopheles (Diptera: Culicidae) in the Amazon region of Colombia. J Med Entomol. Mar 2009;46(2):307-15. [Medline].

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Keywords

insect bite, bug bites, Insecta, Hymenoptera, Arachnida, anaphylactic shock, Lyme disease, Chagas disease, trypanosomiasis, tick-borne encephalitides, blackflies, Simuliidae, onchocerciasis, river blindness, dermatitis, cellulitis, urticaria, myiasis, fly larvae, human botflies, NewWorld screwworms, Old World screwworms, Wohlfahrtia flies, Tumbu flies, fly maggots, delusional parasitosis, plant-eating phytophagous insects, cockroach bite, earwigs, reduviid bug, horsefly bites, mosquito, malaria, angioedema

Contributor Information and Disclosures

Author

Bo Burns, DO, FACEP, FAAEM, Assistant Professor, Assistant Residency Director, Medical Clerkship Director, Department of Emergency Medicine, University of Oklahoma School of Community Medicine; Attending Physician, Department of Emergency Medicine, St Francis Hospital Trauma Emergency Center
Bo Burns, DO, FACEP, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, Society for Academic Emergency Medicine, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Kavon Charles Azadi, MD, Resident Physician, Oklahoma Institute for Disaster and Emergency Medicine, University of Oklahoma College of Community Medicine, Department of Emergency Medicine
Kavon Charles Azadi, MD is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, American Medical Student Association/Foundation, and Oklahoma State Medical Association
Disclosure: Nothing to disclose.

Medical Editor

Robert M McNamara, MD, FAAEM, Chair and Professor, Department of Emergency Medicine, Temple University School of Medicine
Robert M McNamara, MD, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, American Medical Association, Pennsylvania Medical Society, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

John T VanDeVoort, PharmD, Regional Director of Pharmacy, Sacred Heart & St. Joseph's Hospitals
John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists
Disclosure: Nothing to disclose.

Managing Editor

Gino A Farina, MD, Program Director, Associate Professor of Clinical Emergency Medicine, Department of Emergency Medicine, Long Island Jewish Medical Center, Albert Einstein College of Medicine
Gino A Farina, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Jonathan Adler, MD, Attending Physician, Department of Emergency Medicine, Massachusetts General Hospital; Division of Emergency Medicine, Harvard Medical School
Jonathan Adler, MD is a member of the following medical societies: American Academy of Emergency Medicine and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

The authors and editors of eMedicine gratefully acknowledge the contributions of previous authors, Miguel C Fernandez, MD, and Nicolas F Arredondo, MD, to the development and writing of this article.

Clinical guidelines

The diagnosis and management of anaphylaxis: an updated practice parameter.
American Academy of Allergy, Asthma and Immunology - Medical Specialty Society
American College of Allergy, Asthma and Immunology - Medical Specialty Society
Joint Council of Allergy, Asthma and Immunology - Medical Specialty Society. 1998 Jun (revised 2005 Mar). 41 pages. NGC:004211

Consultation and referral guidelines citing the evidence: how the allergist-immunologist can help.
American Academy of Allergy, Asthma and Immunology - Medical Specialty Society. 2006 Feb. 29 pages. NGC:005003

The practice of travel medicine: guidelines by the Infectious Diseases Society of America. Infectious Diseases Society of America - Medical Specialty Society. 2006. 96 pages. NGC:005086

Clinical trials

Cause of Unexplained Anaphylaxis

Population Pharmacokinetics of Benznidazole in Children With Chagas Disease

Immunogenicity, Safety and Interchangeability of Two Tbe Vaccines Administered According to a Conventional Schedule in Children

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