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Bites, Insects

Cancer & Biopsy

Bites, Insects

Coauthored by Nicolas F. Arredondo, Medical Student, University of Texas Health Science Center at San Antonio, University Hospital

Edited by Robert McNamara, MD, Chief, Professor, Department of Emergency Medicine, Temple University Hospital; John T. VanDeVoort, PharmD, ABAT, Clinical Assistant Professor, Pharmacy Manager, Regions Hospital Pharmacy, University of Minnesota College of Pharmacy; Gino A Farina, MD, Associate Program Director, Assistant Professor, Department of Emergency Medicine, Long Island Jewish Medical Center, Albert Einstein College of Medicine; John Halamka, MD, Executive Director, Center for Quality and Value, Instructor, Division of Emergency Medicine, Beth Israel Deaconess Medical Center; and Jonathan Adler, MD, Instructor, Division of Emergency Medicine, Harvard Medical School, Massachusetts General Hospital

 

Author's Email:	Miguel C. Fernandez, MD	Topic Last Updated:
Editor's Email:	Robert McNamara, MD	06/07/2000 16:55:04

 

INTRODUCTION

Background: Insects comprise the most diverse and numerous class of the animal kingdom, Insecta. Human contact with insects is unavoidable. Exposures to biting, stinging or urticating insects or their feces or their remains can range in severity from benign or barely noticeable to life-threatening.

Many patients will confuse an insect bite with an insect sting. Most stinging insects are of the Order Hymenoptera, which includes ants, bees and wasps. Other stinging organisms are in fact of the class Arachnida which share the phylum Arthropoda with insects and includes scorpions, spiders, ticks and mites. The discussion in this chapter will be limited to bites of the members of class Insecta and some of the members of class Arachnida. Stings by members of the order Hymenoptera and the order Scorpiones are discussed in other chapters, as are bites of venomous arachnids in the order Arachaneae (spiders) and bites of the subclass ascari (scabies and lice).

Exposures to millipedes (class Diplopoda), centipedes (class Chilopoda) and caterpillars (order Lepidoptera) are also discussed in other chapters; however, many of the principles that guide diagnosis and treatment of insect bites also apply to bites and stings of these other organisms.

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.

The most notable immediate risk associated with insect exposures is from anaphylactic shock. Hypersensitivity in certain individuals can cause systemic responses to otherwise harmless insect saliva or venom. In treating any patient suspected of insect exposure, diagnosing the early phases of a systemic allergic reaction preceding anaphylactic shock is paramount. Severe anaphylaxis can be fatal in as little as 10 min.

Also crucial is an awareness of the diseases for which insect bites serve as the vector for transmission. Specific diseases such as Lyme Disease, transmitted by ticks, or malaria, transmitted by mosquitoes, are covered in other chapters.

Exposure to some kinds of arthropods may produce dermatitis, cellulitis, urticaria or blistering. Some species of moths, caterpillars, centipedes, beetles and spiders have urticating hairs or secretions that will cause cutaneous irritation that is not due to biting or stinging. For further information, please refer to the respective chapters on these exposures.

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, it can produce pustules and lesions similar to an insect bite. In these cases, however, the lesions generally contain one or more developing fly larvae. Most varieties of larvae capable of myiasis in humans are parasites of other mammals and do not actively seek out human hosts, though this is not always the case. Human bot-flies are common in Mexico, Central and South America. New World screw-worms are now only found in Central and South America, while Old World Screw-worms are found in the Oriental and African tropical regions. Wohlfahrtia flies are found in northern regions of North America as well the southern Palaearctic. Tumbu flies are found in the African tropical region. Other varieties of fly maggots may also occasionally parasitize humans. Severe cases of myiasis can cause seizures. Myiasis by screw-worm flies has been reported to be fatal in a few cases.

Delusional Parasitosis is a condition in which the patient believes they are infested with tiny, imaginary insects. Prior to diagnosing the patient with this condition, a thorough examination of their residence and place of work by a qualified entomologist should be conducted if the physical exam is negative. Frequently these patients are elderly white females. Occasionally, their delusions may lead them to injure themselves in an effort to rid themselves of the bugs. Similarly, abusers of amphetamines or cocaine may develop a psychosis termed formication (Latin: formica, ant), typified by a hallucination of ants or other bugs crawling over the skin. These patients may harm themselves by gouging deeply into their skin in an attempt to rid themselves of their imagined infestation and may develop an ulcerative scarring impetigo termed ecthyma.

Plant-eating, phytophagous insects can bite in self-defense. These bites are not generally purposeful. The discussion in this chapter is limited to organisms that bite to feed on blood or to catch prey.

Cockroaches have been reported to bite humans, though their bite is generally harmless. These insects pose more of a threat to an individual from continued, repeated exposure to their remains and feces. Such exposure is attributed to an increased incidence of asthma, especially in the inner cities, and is also implicated as a vector for transmission of viral and bacterial diseases.

Earwigs are generally harmless insects that have earned an unpleasant reputation, perhaps due to their depiction in popular culture, such as in the television series “The Night Gallery." Though they appear to have a large pincer on the posterior abdomen, this is not capable of rendering anything more serious than a mild pinch. Additionally, contrary to popular belief, they do not routinely enter human ear canals 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 three broad groups: piercing/sucking, sponging and biting/chewing. There is tremendous diversity of the morphology of these groups. The insects discussed in this chapter are generally nonvenomous. Many species will inject saliva while biting. Although the saliva may serve to aid in digestion, inhibit coagulation, increase blood flow to the bite or anesthetize the bite locus, lesions are generally due to the victim’s immune response to the insect secretions. In the case of Chagas disease, transmission of the infective organism is via the feces of a reduviid bug, which enters through the bite site when the wound becomes pruritic and is scratched.

Other than horsefly bites, most insect bites are minor puncture wounds to the skin. Horseflies feed with a large scissor-like proboscis, which can cause a relatively deep and painful wound.

Some atopic individuals will produce anaphylaxis when bitten by an insect to which they have developed an allergy. Refer to the chapter on anaphylaxis for treatment of this response.

Frequency:

• In the US: Reliable statistics are not available.

• Internationally: Reliable statistics are not available for insect bite exposures; however, it is apparent that most cases are not reported and do not require hospital care. 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. The vast majority of these were arachnid or Hymenoptera-related.

Mortality/Morbidity: Mortality associated with insect bites is due to anaphylactic reaction or complications resulting from infection. Reliable figures are not available. Estimates of mortality from insect provoked anaphylaxis in the U.S. range from 50-150 persons annually. In Arizona, for example, death from Reduviid-associated anaphylaxis has been reported as a leading cause of death due to insect exposure.

 

CLINICAL

History:

• Generally, the patient is aware of the bite as it occurs or shortly thereafter. Frequently, they observe the insect as well. Reactions to insect bites can be classified as either local, severe local or systemic.

• In a local reaction the patient may complain of discomfort, moderate or severe pain, erythema, tenderness, warmth and edema of the tissues surrounding the bite site.

• In a severe local reaction complaints include generalized erythema, urticaria and pruritic edema.

• In a systemic response the patient might complain of localized symptoms as well as symptoms not contiguous with the bite location. Early complaints generally include generalized urticaria, pruritus and angioedema. These symptoms can be followed by progression of pruritus and urticaria as well as angioedema, erythema, anxiety, disorientation, weakness, gastrointestinal disturbances including cramping, diarrhea or vomiting, uterine cramping in women, urinary or fecal incontinence, dizziness, syncope, hypotension, stridor, dyspnea or cough.

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 and edema.

• Wheals, pustules or other lesions are common initial symptoms and generally appear within a few minutes of the bite. Unfortunately, many dermatological conditions also produce similar cutaneous symptoms and may confound the diagnosis.

• Determination of the identity of the insect responsible for the bite can be facilitated by an examination of the location, number, pattern and sequelae of the bite(s).

• Physical exam elements indicating a systemic reaction include the following:

• Cardiovascular: hypotension, orthostasis

• Cutaneous: urticaria, angioedema

• Respiratory: tachypnea, stridor, wheezing

• Gastrointestinal: hyperactive bowel sounds

 

DIFFERENTIALS

Anaphylaxis
Angina
Arthritis, Rheumatoid
Bites, Animal
Cat Scratch Disease
Caterpillar Envenomations
Dermatitis, Atopic
Dermatitis, Contact
Disseminated Intravascular Coagulation
Erysipelas
Impetigo
Lice
Millipede Envenomations
Pediatrics, Anaphylaxis
Pediculosis
Pityriasis Rosea
Plant Poisoning, Resins
Scabies
Scorpion Envenomations
Serum Sickness
Snake Envenomations, Cobra
Snake Envenomations, Coral
Snake Envenomations, Moccasins
Snake Envenomations, Mojave Rattle
Snake Envenomations, Rattle
Spider Envenomations, Brown Recluse
Spider Envenomations, Funnel Web
Spider Envenomations, Red Back
Spider Envenomations, Tarantula
Spider Envenomations, Widow
Tick-borne Diseases, Ehrlichiosis

 

WORKUP

Lab Studies:

• Lab studies are generally not necessary. If the patient is severely compromised and requires hospital admission routine laboratory studies should suffice.

• Biopsies of lesions are generally non-determinant and are impractical in the ED.

• Microscopic examination of skin scrapings can be useful in the diagnosis of scabies or mite infestations.

 

TREATMENT

Prehospital Care:

• Most insect bites may be treated acutely with a compress after routine wound cleaning, or using a mixture of one part household bleach to nine parts water. This will minimize the pain and help sterilize the wound to prevent secondary infection.

• In the case of a large local reaction, ice packs may also be useful in minimizing the swelling. Ice should be applied for no more than 15 min at a time and 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 (SQ, IM, IV, endotracheal) will depend on the patient's condition and the expertise of the prehospital provider. Systemic antihistamines and corticosteroids, if available, are beneficial in managing systemic reactions. Many allergic patients will carry a commercially available "bee sting" kit containing an auto-injector of epinephrine and occasionally other items.

• Topical antihistamines should not be applied over large surface areas, nor should they be used concurrently with systemic H1 antihistamines. Systemic anticholinergic toxicity may result from misuse of these medications.

• In many cases, there is no need for transport to a hospital. Those requiring transport include anyone who develops signs or symptoms of a systemic response and those with a history of insect-related anaphylaxis.

Emergency Department Care:

• Endotracheal intubation and ventilatory support may be required.

• Emergent cases of anaphylaxis in an atopic individual should be treated with an initial subcutaneous injection of 0.3-0.5 ml of 1:1000 epinephrine. This may be repeated every 10 min as needed.

• A bolus of IV epinephrine 1:10,000 may be used cautiously in severe cases. The 1:10,000 solution is typically found in 10 mL vials. Repeated 1.0 mL doses are a reasonable initial approach in the critically ill anaphylaxis patient. Once a positive response is achieved, these boluses can be followed with a carefully monitored continuous epinephrine infusion. Extra care in monitoring formulation, concentration, and dose is advised when administering IV epinephrine to avoid inadvertent overdoses.

• Severely hypotensive patients may require large volumes of IV fluids. They should be monitored for angioedema or pulmonary edema.

• Antihistamines, both H 1 and H 2 blockers, are useful in treating systemic reactions. Corticosteroids are also routinely indicated in such cases.

• Refer to the chapters on anaphylaxis and serum sickness for further guidance.

• Appropriate tetanus prophylaxis should be insured.

Consultations:

• In cases where determination of the insect specie 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, one should consider contacting a tropical medicine specialist or the CDC.

• A regional poison center may be of assistance in difficult or complicated cases or for general information.

 

MEDICATION

The goal of therapy is to treat anaphylaxis and prevent complications.

Drug Category: Parenteral Adrenergic Agents - These act to decrease the muscle tone in the small and large pulmonary airways.

Drug Name	Epinephrine - Is the drug of choice for shock, angioedema, airway obstruction, bronchospasm and urticaria in severe anaphylactic reactions. It is given subcutaneously, except for patients in extremis, for whom it is given iv. It may be administered sublingually or via the ETT when no iv access is available. A continuous infusion may be given in cases of refractory shock.
Adult Dose	SC: 0.3-0.5 ml 1:1000 soln. q 10-15min IV: 1.0 ml 1:10,000 soln. slow IV, repeat prn SL: 0.3-0.5 ml 1:1000 soln. q15min ETT: 1.0ml 1:1000 soln. in ~10cc NS IV infusion: 0.1-1.0 mcg/kg/min
Pediatric Dose	SC: 0.01 ml/kg (min 0.1 ml) 1:1000 soln. q15min IV: 0.01 ml/kg (min 0.1 ml) 1:10,000 soln prn SL: 0.01 ml/kg (min 0.1 ml) 1:1000 soln q15min ETT: 0.01 ml/kg (min 0.1 ml) 1:1000 soln in ~1-3cc NS IV infusion: 0.1-1.0 mcg/kg/min
Contraindications	In a life-threatening anaphylactic reaction, epinephrine may be given even when the following relative contraindications are present: (1) Coronary artery disease (2) Uncontrolled hypertension (3) Serious ventricular arrhythmias (4) Second stage of labor
Interactions	Epinephrine administered concurrently with other sympathomimetics may have additive effects. Beta blockers antagonize the therapeutic effects of epinephrine. Digitalis may potentiate the proarrythmic effects of epinephrine. Tricyclic antidepressants and MAO inhibitors potentiate the cardiovascular effects of epinephrine. Phenothiazines may decrease BP when administered concurrently with epinephrine.
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Some of the side effects include cardiac ischemia or arrhythmias, fear, anxiety, tremor, hypertension with subarachnoid hemorrhage. Use with caution in the elderly and in patients that have diabetes mellitus, hyperthyroidism, prostatic hypertrophy, hypertension, cardiovascular disease, and cerebrovascular insufficiency. Rapid iv infusions may also cause death from cerebrovascular hemorrhage or cardiac arrhythmias.

Drug Name	Albuterol sulfate (Ventolin) - Is a beta-agonist useful in the treatment of bronchospasm that is refractory to epinephrine. It relaxes bronchial smooth muscle by action on beta2-receptors and has little effect on cardiac muscle contractility. There are numerous inhaled beta agonists used for the treatment of bronchospasm. Albuterol is the most commonly used preparation.
Adult Dose	Administer 0.5 ml 0.5% soln in 2.5 cc NS nebulized q15min.
Pediatric Dose	Administer 0.03-0.05 ml/kg 0.5% soln in 2.5 cc NS via nebulizer q15min.
Contraindications	In a life-threatening anaphylactic reaction albuterol may be given even when the following relative contraindications are present: (1) Severe coronary insufficiency (2) Uncontrolled, severe hypertension
Interactions	Sympathomimetics can have an additive effect when administered concurrently with albuterol. Tricyclic antidepressants and MAO inhibitors potentiate the cardiovascular effects of albuterol. The therapeutic effects of beta-blockers may be antagonized by albuterol.
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Inhaled beta agonists are relatively well tolerated. Beta-2 agonists like albuterol have relatively few cardiovascular adverse effects compared to agents that have beta-1 agonist activity. Use with caution in patients diagnosed with hyperthyroidism, diabetes mellitus, or cardiovascular disorders.

Drug Name	Diphenhydramine (Benadryl) - Is used for the symptomatic relief of allergic symptoms caused by histamine released, in response to allergens. There are many effective H1 blockers. Diphenhydramine is effective and widely available.
Adult Dose	IV: 25-50 mg q4-6h IM: 25-50 mg q4-6h PO: 50 mg q4-6h
Pediatric Dose	IV (severe cases): 1-2 mg/kg q6h IM: 1-2 mg/kg q6h PO: 5mg/kg/24h divided q6h-8h
Contraindications	Antihistamines have a variety of adverse effects. However, there are no absolute contraindications to their use in severe anaphylactic reactions other than allergy to the antihistamine itself.
Interactions	This medication potentiates the effect of CNS depressants. Due to its alcohol content, do not give the syrup dosage form, to patients taking medications that can cause disulfiram reactions. MAO inhibitors may potentiate the anticholinergic effects of diphenhydramine.
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Anticholinergic effects include dry mouth, urinary retention, visual disturbances and CNS depression. Diphenhydramine may exacerbate angle closure glaucoma, hyperthyroidism, peptic ulcer, and urinary tract obstruction.

Drug Name	Cimetidine (Tagamet) - Is an H2 antagonist that when combined with an H1 type may be useful in treating itching and flushing in anaphylaxis, pruritus, urticaria, and contact dermatitis that do not respond to H1 antagonists alone. Use this medication in addition to H1 antihistamines.
Adult Dose	IV: 300 mg q6h IM: 300 mg q6h PO: 300 mg q6h
Pediatric Dose	IV: 5-10 mg/kg q6h IM: 5-10 mg/kg q6h PO: 5-10 mg/kg q6h
Contraindications	No absolute contraindications exist other than known previous severe reaction to the drug.
Interactions	There are multiple drug interactions related to inhibition of hepatic microsomal enzymes. The following are among the many drugs for which cimetidine is known to increase the blood concentration of. This is not a complete list: coumadin, benzodiazepines, lidocaine, tricyclic antidepressants, terfenadine and theophylline.
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	There are relatively few serious adverse effects from cimetidine, especially when only short-term, acute use is considered. The following are some of most important the adverse effects for emergency physicians to consider in the acute setting: (1) Headache and confusion (2) Cardiac arrhythmias and hypotension from rapid iv administration Elderly patients may suffer confusional states. In young males, it may cause impotence and gynecomastia due to weak antiandrogen properties. It may also increase the levels of many drugs. If changes in renal function occur during therapy, consider adjusting the dose or discontinuing the treatment.

Drug Name	Methylprednisolone (Solu-Medrol, Depo-Medrol) - Decreases inflammation by suppression of migration of polymorphonuclear leukocytes and reversal of increased capillary permeability. Is useful in the treatment of inflammatory and allergic reactions. By reversing increased capillary permeability and suppressing PMN activity, it may decrease inflammation. There are a multitude of corticosteroid preparations available. Methylprednisolone is widely available in the ED due to its other uses (acute asthma, spinal cord injury) and is supplied in both parenteral and oral formulations. It is therefore discussed here as a typical drug of this class.
Adult Dose	IV: 40-250 mg q6h IM: 40-250 mg q6h PO: 2-60 mg qd
Pediatric Dose	IV: 1-2 mg/kg q6h IM: 1-2 mg/kg q6h PO: 1-2 mg/kg qd
Contraindications	Other than a previous severe reaction to the drug, there are no absolute contraindications to the use of corticosteroids for treatment of severe anaphylaxis. There is some evidence for fetal harm from corticosteroids and both the benefits and risks should be considered in the pregnant woman. Immunosuppressed patients receiving corticosteroids are at risk for dissemination or activation or certain infections and this should be considered when prescribing for these patients.
Interactions	There are a limited number of drug interactions with corticosteroids likely to be significant in the acute setting of anaphylaxis. The most important are listed here: (1) NSAIDs may cause ulcers when taken concurrently. (2) Anticholinesterases may increase weakness in patients with myasthenia gravis when taken concurrently with steroids. (3) There is a risk of possible viral dissemination with live virus vaccines.
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Short-term use of corticosteroids, even in large doses, has minimal harmful effects. There are multiple adverse effects from chronic usage. Hyperglycemia, edema, osteonecrosis, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, growth suppression, myopathy, and infections are possible complications of glucocorticoid use.

 

FOLLOW-UP

Further Inpatient Care:

• Patients with true anaphylaxis, particularly if associated with hypotension, are often admitted for monitoring or observed in the ED upon recovery. The accepted definition of "true" anaphylaxis requires the involvement of at least two systems (CV, GI, skin, respiratory). There is no clear direction on who needs admission from the literature. Certain patients with a disease transmission (i.e. malaria) may also require admission.

Further Outpatient Care:

• Individuals bitten by an insect known to transmit a secondary disease such as Chagas’ disease in the case of kissing bugs (Reduviidae), if exposed to the vector in an endemic area, should receive follow-up to monitor for infection.

• Individuals who recover from a systemic reaction should consult with an allergist regarding desensitization measures

In/Out Patient Meds:

• A "bee sting" kit should be prescribed prior to discharge if the patient had a systemic response to an envenomation. This kit contains a device for the self-administration of epinephrine.

• Corticosteroids and antihistamines are usually continued for a few (3-4) d after a systemic response. Serum sickness reactions may require longer therapy (see specific chapter).

Deterrence/Prevention:

• Patients may be educated regarding avoidance measures. Refer to the section on Patient Education in this chapter.

Complications:

• Secondary infection

• Symptoms of disease transmitted by insect bite may not be evident for days, weeks or even longer.

Prognosis:

• Except in cases of severe untreated anaphylaxis, or in chronic or invasive infections, the prognosis is generally good.

Patient Education:

• Biting insects are ubiquitous in nearly all parts of the world; however, certain measures can be taken to minimize the risks of exposure.

• Periodic pest control may eliminate nests and minimize the reproduction of biting insects.

• Protective clothing (i.e., long pants and sleeves) can be worn especially when outdoors. Many insects are incapable of biting through clothing. Additionally, light colored clothing appears to be less attractive to many insects, including mosquitos. Avoid dark colors or bright colored floral patterns. Protective clothing should include footwear. Gloves should be used when working with soil or in areas of heavy infestation.

• Avoid the use of heavy perfumes, scented soaps, sprays or lotions, which may attract insects.

• Be aware of the surroundings; for example, avoid dense vegetation or animals that are suspected of carrying fleas, chiggers or ticks.

• Prudent and cautious use of insect repellent can help minimize the chances of insect exposure.

• Be aware of the potential for bees to enter soft drink containers that are left idle, particularly in the fall.

 

MISCELLANEOUS

Medical/Legal 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

• Failure to warn patients regarding 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 a "beesting" kit to those with systemic reactions.

 

TEST QUESTIONS

CME Question 1: A 38 y male presents to the ED with generalized pruritic urticaria and edema in one of his lower extremities. The patient reports working in a semi-enclosed animal pen prior to feeling a sharp stab of pain in the lower leg approximately 25 min prior to presenting. The patient is alert and oriented, but reports some wheezing. He does not appear to be in any acute distress. Vital signs are as follows: HR 80, BP 110/70, R:20, T=98.8ºF What should be the initial management?

A: Administer 0.5 mL 1:1000 epinephrine subcutaneous injection
B: Administer oral antihistamines, corticosteroids and observe
C: Initiate IV normal saline and administer IV antihistamines
D: Initiate an IV of normal saline and administer IV antihistamines and IV epinephrine 1:10,000, 5 ml
E: A and C

The correct answer is E: Wheezing could be a sign of imminent ventilatory distress due to anaphylaxis, so antihistamines and a small dose of epinephrine would be indicated. As the patient is not in immediate distress, however, 5 mL 1:10,000 epinephrine IV is more aggressive than is indicated. Given the potential for rapid deterioration, oral therapy alone is risky.

CME Question 2: A 5 y Hispanic female presents to the ED with classic signs of anaphylaxis. After successful stabilization, a thorough physical examination reveals a 1 cm erythematous plaque on the inferior margin of the lower lip. What do you advise the parents of the child?

A: No follow-up necessary
B: Follow-up consultation with an allergist
C: Follow-up consultation with an allergist and monitoring for prodromal signs of Chagas’ disease
D: Follow-up consultation with an allergist and monitoring for prodromal signs of Tularemia
E: Follow-up consultation with an allergist and monitoring for prodromal signs of encephalitis

The correct answer is C: Several findings suggest possible susceptibility to Chagas` disease: the location, size and character of the lesion suggest a Kissing Bug bite. Generally speaking, as a Hispanic child, she has a higher probability of travel to the southwest U.S. or Mexico where Triatoma species are known to carry Trypanosoma cruzi. Consultation with an allergist is always indicated after an anaphylactic episode.

Pearl Question 1 : T/F: Mosquito-borne viral encephalitis ought to be considered in the differential of a patient presenting with any one or more of the following signs and symptoms: fever, nausea, vomiting, focal seizures, hypersomnia, nuchal rigidity, cranial nerve findings, papilledema and mental status or behavioral changes.

The correct answer is : True: Meningitis and encephalitis can present with similar signs and symptoms. The diagnosis would require serological confirmation.

Pearl Question 2 : T/F: Mosquitos and ticks are 2 possible vectors responsible for transmission of eastern equine arbovirus.

The correct answer is : True: Mosquitos and ticks are both known to transmit this arbovirus responsible for encephalitis.

Pearl Question 3 : T/F: Onchocerciasis must be considered in the differential diagnosis of a patient presenting with decreased vision and a history of living in either South America or Africa.

The correct answer is : True: Blackflies (Simuliidae) are responsible for transmission of onchocerciasis, also known as River Blindness. Onset can be years after the initial bite.

Pearl Question 4 : T/F: Of all known insects, the insect genus responsible for the greatest human mortality and morbidity is the Aedes mosquito.

The correct answer is : False: The Anopheles mosquito is responsible for the transmission of malaria as well as other viral diseases.

 

BIBLIOGRAPHY

• Auerbach PS, ed: Wilderness medicine: management of wilderness and environmental emergencies. Mosby-Year Book; 1995.
• Busvine JR: Disease transmission by insects. Springer Verlag; 1993: 11-74.
• Davis CL: Insects, allergy and disease: Allergic and toxic responses to arthropods. 1979; 300-309.
• Edwards L, Lynch PJ: Anaphylactic reaction to kissing bug bites. Arizona Medicine 1984; XLI: 159-161[Medline].
• Garcia LS, Bruckner DA: Diagnostic medical parasitology, 3rd ed. Amer Society for Microbiology; 1997.
• Goddard J: Physician's guide to arthropods of medical importance. CRC Pr; 1996.
• Hoffman DR: Allergic reactions to biting insects. In: Levine MI, Lockey RF, ed. Monograph on Insect Allergy. 1981; 69-74.
• Krause RS: Immune system disorders, hypersensitivity. In: Aghababian R, ed. Emergency Medicine: The Core Curriculum. Lippincott Williams & Wilkins Publishers; 1998: 417-422.
• Lane RP, Crosskey RW: Medical insects and arachnids. Chapman & Hall; 1993.
• Lynch PJ, Pinnas JL: Kissing bug bites: Triatoma species as an important cause of insect bites in the southwest. Cutis 1978; 22: 585-591[Medline].
• Moffitt JE, Yates AB, Stafford CT: Allergy to insect stings: A need for improved preventive management. Postgraduate Medicine 1993; 93, No. 8: 197-208[Medline].
• Mueller UR: Insect sting allergy: Clinical picture, diagnosis, and treatment. Gustav Fischer; 1990: 144-147.
• Nhachi CF, Kasilo OM: Poisoning due to insect and scorpion stings/bites. Hum Exp Toxicol 1993 Mar; 12(2): 123-5[Medline].

 

NOTE:

Medicine is a constantly changing science and not all therapies are clearly established. New research changes drug and treatment therapies daily. The authors, editors, and publisher of this textbook have used their best efforts to provide information that is up-to-date and accurate and is generally accepted within medical standards at the time of publication. However, as medical science is constantly changing and human error is always possible, the authors, editors, and publisher or any other party involved with the publication of this text do not warrant the information in this text is accurate or complete, nor are they responsible for omissions or errors in the text or for the results of using this information. The reader should confirm the information in this text from other sources prior to use. In particular, all drug doses, indications, and contraindications should be confirmed in the package insert. FULL DISCLAIMER

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REMOVAL:  You can remove yourself from the subscription list in several different ways.  Click here to read about this entire newsletter system.  Every edition of The Wednesday Letter is delivered to your address with YOUR name and address in view on the letter, with a link that allows you to remove THAT name from the subscription list.  If you try to send this removal message from an address different from the one you used to send in your original confirmation, then you will get a warning notice first, sent to the subscription address, asking you to confirm that you want to be removed from the list -- by replying to THAT request for confirmation, you will then be automatically removed.  Thus, no one else can unsubscribe you, from some other computer, without your knowledge.  But, if you send in the unsubscribe notice from the same machine used to receive the Letter, then the removal from the subscription list is automatic.

Personal Message:  When you send a personal message to Karl Loren, you will receive a personal reply as per his instructions.  Karl pledges that every personal message will get a personal answer. When you provide your mail address, we will send you free information including our free catalog and a cassette tape lecture by Karl Loren about heart disease, no charge, by mail, even if outside the US.  You can select particular information you would like to receive, along with the free cassette tape and catalog.