Case Based Pediatrics For Medical Students and Residents
Department of Pediatrics, University of Hawaii John A. Burns School of Medicine
Chapter XXI.5. Bites and Stings
Todd T. Kuwaye, MD, MS
September 2002

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A 6 year old female was playing in the yard when she suddenly felt pain in her left ankle. Her ankle became swollen, red and painful, so her mother took her to the pediatrician's office. Upon close examination there is a central puncture lesion with a small amount of serosanguineous drainage. Her vital signs are normal. No other examination findings are present

What are the potential causes for this lesion? What current treatment is needed? What advice should be given to the child and parents?


In Hawaii, we are fortunate to have only a few arthropod bites and stings that are of a medical concern. An arthropod may bite with the use of mandibles or inflict a wound from a stinger. In Hawaii, arthropod bites can occur from mosquitoes, flies, fleas, ants, lice, centipedes, beetles, roaches, and spiders. These arthropod bites are rarely serious except for a few notable arthropods such as the brown violin spider and the black widow spider because of the toxicity contained in their venomous bite. Although bites from these spiders can be serious, they are not as frequent as the bites that occur from mosquitoes, ants, fleas and flies. All bites have the potential to cause local skin irritation, pruritus, swelling, erythema and pain. If not treated well with local skin care, a lesion can also become infected. Local allergic reactions are common from insect bites. Insect bites rarely cause systemic allergic reactions in children when compared to insect stings (1). Although uncommon, if a patient has enough of a repeated allergen load from proteins contained in the saliva of the biting arthropod, systemic allergic reactions could occur (1). Anaphylaxis has been reported from bites of the mosquito, horsefly, and the tick (2).

Another health problem associated with insect bites is the potential to transmit disease. An outbreak of dengue fever in Hawaii (2001) by mosquitoes demonstrated the disease carrying ability of insects as vectors. Another noteworthy vector in Hawaii is the flea and its ability to transmit the plague. Fortunately Hawaii does not have ticks and fleas that carry Lyme disease and Rocky Mountain spotted fever.

Envenomation occurs from such arthropods such as spiders and centipedes in Hawaii. A centipede's bites cause intense localized pain, swelling, and occasionally infection and local tissue necrosis. A few of the spiders in Hawaii contain venom in their bite that can lead to serious complications. Two of the more dangerous spiders are discussed in greater detail below.

The Southern Black Widow Spider (Latrodectus mactans), as well as its cousins, the brown widow (Latrodectus geometricus), and the Western Black Widow (Latrodectus Hesperus), are found in Hawaii (3). The black widow lives in warm, dark, dry places outdoors or in sheds, basements and garages. The Black Widow is a non-aggressive spider, which bites in self-defense. Its venom causes severe muscle cramping which is mediated by a neurotoxin that acts on the presynaptic membrane causing the release and decreased uptake of acetylcholine (4). The victim usually experiences a pinprick sensation, followed by regional lymph node tenderness (30-120 minutes later), a target lesion (at the bite site), and muscle cramping near the bite site (4). Dysautonomia manifested with nausea, emesis, sweating, hypertension, tachycardia, and malaise can occur (3,8). Symptoms may last 36-72 hours (4). Treatment is analgesia, while supportive care is given to hypertensive and tachycardic patients (4). Antivenom derived from horse serum is available but reserved for the severe cases due to the adverse effects from horse serum administration (4).

The brown violin spider (Loxosceles rufescens) is a cousin of the brown recluse spider (Loxosceles reclusa), which is responsible for most of the clinically significant necrotic spider bites in the United States (5). The Brown recluse spider is not found in Hawaii but the brown Violin spider is found locally (3). All Loxosceles spiders are venomous and produce the clinical condition called loxoscelism, also known as necrotic arachnidism (5). The brown violin spiders are non-aggressive, nocturnal and found under boards and loosened bark (3). The brown violin spider's venom is used to digest its prey, but has both a local and systemic effect in humans, causing dermonecrosis and hemolysis (5). Bites usually are seen in children and can be asymptomatic or it can cause a mild to sharp stinging pain followed by potential development of a central blister to dermonecrosis (5). Systemic reactions include fever, chills, arthralgias, malaise, nausea, emesis, leukocytosis, hemolytic anemia, jaundice, renal failure, shock, DIC and death (5). Systemic reactions are infrequent. Loxosceles envenomation can usually be treated as an outpatient unless there are systemic symptoms, serious infection, or extensive necrosis (5). There is no effective treatment for the dermonecrosis. An antivenom is currently experimental and appears promising (5).

Fortunately, most arthropod bites are more of an annoyance rather than a potential life-threatening situation. Keys to management include prevention of arthropod bites by eradication, avoidance of arthropod's habitats and use of protective clothing. Immediate management may include: local wound care, topical corticosteroids, antibiotics if infected, antihistamines if the lesion is pruritic for comfort and prevention of infection by excoriation, tetanus toxoid booster if not current, and analgesics.

In Hawaii, arthropod stings can occur from bees, wasp, ants and scorpions. All of these arthropods contain mild venoms. However, systemic allergic reactions occur more frequently from insect stings compared to insect bites in children (1). Stinging insects belonging to the order Hymenoptera (bees, wasp, and ants) are responsible for 40-50 deaths a year in the United States (2,7). Reactions to arthropod sting can be classified as usual, large local, anaphylactic and toxic reactions (2). The usual arthropod sting causes the local pain, swelling, and erythema, which resolves in a few hours (2). Large local reactions involve more extensive symptoms, which last 24-48 hours (2). Anaphylaxis is the most serious response (see chapter on anaphylaxis). A toxic reaction occurs from envenomation from multiple stings.

Immediate management is to ensure the removal of the stinger. The stinger of the bee is barbed and detaches after being imbedded into the victim's skin. Since wasps can sting repeatedly, one may find grouped lesions without any visible stinger. The bee stinger contains venom sacs which if pinched can increase the level of envenomation. It is recommended to brush the stinger out of the skin. The usual and local reactions of insect stings require control of pain, pruritus, and swelling, as well as local wound care to prevent infections. Localized hypersensitivity reactions can be treated with topical corticosteroids, urticaria can be treated with antihistamines and anaphylactic reactions are treated more intensively with epinephrine, antihistamines and corticosteroids.

Repeat anaphylactic reactions to insect stings are more common in adults than in children (2). Children under 16 years old, who have isolated allergic reactions (urticaria and angioedema) after stings have a 10% incidence of subsequent systemic reactions and only a less than 0.1% incidence of a life threatening respiratory or cardiovascular allergic reaction (2,7,9). Children's sensitivity to insect venom is expected to diminish over time (2). An allergist should evaluate any child with an anaphylactic reaction to insect stings. Immunotherapy for insects can be used on children depending on the severity of the allergic reaction. However, any child with a history of anaphylaxis and positive skin test or in vitro assay for venom specific IgE should receive immunotherapy for 4-5 years (2). In children with large localized reactions and who are at risk for future frequent or multiple stings, immunotherapy is an option (2). These children should also be given a self-administered epinephrine kit with instructions and a demonstration of its use. Patients should also obtain a medical alert bracelet.

Scorpions are found in Hawai'i, but their stinger contains a venom, which is not significantly toxic. Scorpions from other parts of the world do contain venoms, which can be substantially toxic.

Avoidance of stinging arthropods becomes an important part of management and includes: identification and elimination of stinging insect nests, avoiding brightly colored clothing or strongly scented lotions, wearing shoes or protective footwear outdoors, exercising caution around sites frequented by stinging insects (eaves, attics, and areas where food is present outside), and wearing protective clothing when outside (long shirt, pants, hat, gloves, socks and shoes) (6).

Marine envenomations common in Hawaii occur from box jellyfish, Portuguese man-of-war, and venomous fish. These animals produce protein-based venoms that are used in self-defense or to capture prey. Unfortunately the unwary beach goers may interact adversely with these animals and sustain intensely painful wounds. As a general rule, these venoms tend to be heat labile and can be denatured with heat.

Venomous snakes are not found in Hawaii. A discussion of snakebites is beyond the scope of this chapter.


Questions

1. A ten year old male is stung by a bee. Upon examination of the sting site, a stinger is still embedded in the skin. What should you do?
. . . . . a. Pinch it off
. . . . . b. Brush it off
. . . . . c. Wait till you seek medical attention

2. A twelve year old male moving boxes in the basement experienced a pinprick sensation on his right hand followed by muscle cramps and swelling in his right axilla. On presentation to the ER a target lesion is noted on his right hand. The patient is noted to be nauseated, sweating, hypertensive, and tachycardic. What is the probably culprit?
. . . . . a. Centipede
. . . . . b. Scorpion
. . . . . c. Yellow jacket
. . . . . d. Black widow
. . . . . e. Brown violin spider

3. True/False: Ticks, flies and mosquitoes can cause anaphylaxis.

4. True/False: Snakes and scorpions are some of the most venomous animals in Hawaii.

5. What two spiders are found in Hawaii that can inflict a serious and potentially deadly envenomation?

6. True/False: Repeat anaphylactic reactions to insect stings are more common in adults than in children.

7. A teenage boy fishing is accidentally poked by a spiny fish. The site becomes red and painful. What are reasonable management steps.
. . . . . a. Local wound care
. . . . . b. Epinephrine
. . . . . c. Application of heat to sting site
. . . . . d. Antibiotic ointment
. . . . . e. Tetanus toxoid
. . . . . f. Contact a poison information center


References

1. Ownby DR. Pediatric anaphylaxis, insect stings, and bites. Immunol Allergy Clin North Am 1999;19(2):347-361.

2. Yates AB, Moffitt JE, de Shazo RD. Anaphylaxis to Arthropod Bites and Stings. Immunol Allergy Clin North Am 2001;21(4);635-651.

3. Nishida GM, Tenorio JM. What Bit Me? Identifying Hawaii's Stinging and Biting Insects and Their Kin. 1993, Singapore: University of Hawaii Press.

4. Bond GR. Snake, Spider, and Scorpion Envenomation in North America. Pediatr Rev 1999;20(5):147-150.

5. Walter FG, et al. Envenomations. April 1999. Crit Care Clin 1999;15(2):353-386.

6. Portnoy JM, et al. Stinging Insect Hypersensitivity: A Practice Parameter. J Allergy Clin Immunol 1999;103(5 Pt 1):963-980.

7. Golden DBK. Immunotherapy: A Practical Review and Guide: Stinging Insect Vaccines. Immunol Allergy Clin North Am 2000;20(3);553-570.

8. Gueron M, Ilia R, Margulis G. Arthropod poisons and the cardiovascular system. Am J Emerg Med 2000;18(6):708-714.

9. Lichtenstein L. Insect Sting Allergy. In: Cecil RL, Goldman L, Bennett JC (eds). Cecil Textbook of Medicine, 21st edition. 2000, Philadelphia: W.B. Saunders Co. pages 1450-1454.


Answers to questions

1. b

2. d

3. True, anaphylaxis can occur from any repeated insect bite or sting in which re-exposure to an antigen occurs.

4. false

5. Southern black widow and Brown violin spider.

6. true

7. All except b.


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