[Public Health Issue] Pest-Related Emergent Care

It is a beautiful, warm, sunny day and you’re investigating a potential structure-infesting wasp problem. During your investigation, you experience the one thing that your customer does not want — and what you are there to prevent — an insect sting. You have reluctantly experienced this regrettable incident before, but this time, something is a little different. You begin to experience difficulty breathing, swelling of the lips and throat, faintness, a bit of confusion, a rapid heartbeat, hives, nausea, cramps and ultimately, vomiting. You are experiencing a severe allergic reaction which may be life threatening. You are experiencing pest-related trauma.
In the United States, arthropods cause more deaths by envenomation than snakes and lizards. Hymenoptera, (ants, bees and wasps), the Arachnida (spiders and scorpions) and Chilopoda (centipedes) cause significant trauma.
Neither Latrodectus (black widow spider) nor Loxosceles (brown recluse spider) are aggressive toward humans. These spiders live in crevices under ground cover, trash piles, barns, porches and outside toilets. Prevention of these spiders includes inspection, clearing debris and caution near these related areas. Nearly half of all bites could be prevented if toilets and clothing were inspected before use.

HYMENOPTERA.  The most common insect stings are from the Hymenoptera. Although it takes 300 to 500 stings to make a lethal dose of complex venom, hypersensitivity, which occurs in about 1 percent of the general public, may result in a life threatening anaphylactic reaction from a solitary sting. This is more common in adults than in children.
The Hymenoptera comprise four families: 1) honeybees, which account for the most stings and leave the stinger attached to their victims; 2) bumblebees; 3) hornets, yellow jackets and wasps; and 4) fire ants, whose alkaloid venom results in a sterile, burning, vesicular lesion.
Nearly all Hymenoptera stings result in a local pain, swelling and a redness. The honeybee stinger should be removed as soon as possible by the most expedient means to prevent the injection of still more venom. The sight may be treated locally with gentle cleansing, application of cold, elevation and immobilization. Calm the victim. Common remedies, such as applying a slurry of baking soda or meat tenderizer; often reduce pain. Commercial “sting-sticks” containing a topical anesthetic like xylocaine may be used unless the victim is known to be allergic to the drug. Oral aspirin or ibuprofen usually helps control pain.
Victims with serious allergic reactions have pruritis (itching), hives, angioedema (swelling) and respiratory distress. For these individuals apply a light restrictive band (not tourniquet) close to the site. Oral antihistamines (such as diphenhydramine) may be helpful. If a victim is carrying injectable epinephrine, have the victim administer it if swelling, respiratory distress, or hypotension (dangerously low blood-pressure) develops. Immediately call 911 for on site advanced life support and evacuation to a trauma center. Maintaining ABCs (airway, breathing and circulation) may be difficult without advanced knowledge and equipment.
If any signs of anaphylactic reaction are present, rescuers carrying epinephrine should administer the drug intramuscularly at 0.3 to 0.5mg for an adult, 0.01mg/kg up to the adult maximum for a child or via preloaded syringes as often as necessary, dependent upon the victim’s status. Care for the conditions you find.

SPIDERS and Scorpions. There are about 100,000 species of spiders worldwide, with a density of up to 2 million spiders per acre in some geographies. In the U.S., the most significant venomous spiders are the black widow (Latrodectus mactans) and the brown recluse (Loxosceles reclusa). The venoms of these spiders are potent toxins with numerous antigenic components capable of causing a systemic or local reaction.
“Black widow” is itself a misnomer because only three of the five species of widow spider (Family: Therdiidae) are actually black, the others being brown and gray. The female spider is the larger of the sexes, often measuring 1 to 1.5 cm long, with a leg span of 4 to 5 cm. The female has a unique hour-glass mark, usually red, on the ventral abdominal surface. Newly-hatched spiderlings are almost entirely red, darkening with progressive molts. Males are 3 to 5 mm long with white stripes along the lateral aspect of the abdomen.
Only adult females can envenomate. The bite usually feels like a mild pinprick (and may not be noticed) with subsequent slight redness that usually disappears within a few minutes to an hour. Systemic symptoms of envenomation begin 10 to 60 minutes after the bite of the female and are caused by the release of the neurotransmitters acetylcholine and norepinephrine. A few minutes after the bite a small weal appears, followed within 15 to 60 minutes by a band of excruciating cramping pain that remains localized or spreads to involve the thigh, shoulder, back and abdominal muscles. Hypertension, respiratory distress, seizures and, occasionally in the very young or old, cardiopulmonary arrest are all possible complications. These symptoms frequently subside in 24 hours, but in a few cases recur for several days to months. The very young, very old and those with hypertension have the greatest risk of morbidity from Latrodectus envenomation.
Brown recluse spiders are not always distinctly brown. They may have a distinctive violin or fiddle-shaped mark on the dorsal cephalothorax. They average 12 mm long with a leg span of up to 5 cm. The bite of both sexes is equally venomous, although usually painless. Within a few hours, a macule or vesicle may appear at the site. In a severe bite, erythema and blistering follow within six to 12 hours. The classic picture is a hemorrhagic vesicle surrounded by a white or pale zone and then by an erythematous region — the so-called bull’s eye lesion. By inspection of the lesion alone, however, it is usually impossible to differentiate a Loxosceles bite from many other skin lesions and bites. Pruritus and rash also can occur. Nausea, vomiting, headache and fever are common systemic symptoms. The lesion either resolves or becomes necrotic and indurated. This may require excision or grafting. Symptoms of envenomation with brown recluse bites are caused by cell and tissue injury and direct lytic action of sphingomyelinase on red blood cell membranes. Rarely and mostly in children, massive intravascular hemolysis develops after necrosis of the local bite. Deaths have been reported in the U.S.
Scorpions. About 650 species of scorpions inhabit the world, mainly distributed in tropical and subtropical regions. An estimated 40 of these species live in the United States, distributed across 75 percent of the country, but concentrated in warmer regions. All scorpions inject venom through a single sharp stinger at the tip of the metasoma or extension of the abdomen. Contact with scorpions is usually accidental. They feed at night. During the daytime they take shelter in clothing, footwear and bedding. Outdoors, scorpions often may be found under rocks and logs. Checking their hiding places in known scorpion areas is good advice for travelers.
Although the sting is painful, few species inject sufficient venom to be of concern to humans. The only potentially lethal United States scorpion is Centruroides exilicauda or sculpturatus. This scorpion is found primarily in Arizona.
 
CENTIPEDES. Centipedes (Chilopoda) are found all over the United States. They rarely cause serious injury in humans. The giant desert centipede, which may attain a length of 15 cm (6 inches), can give a painful bite. Most bite reactions are local and no fatalities have been documented, but renal (kidney) failure has been reported. Generally, centipedes hide in dark places. PCOs should recommend that customers check footwear, clothing and bedding before use while traveling into centipede-infested areas.
Local reactions to centipede bites, in addition to intense pain, may include edema and erythema, lasting four to 12 hours. In severe bites, tenderness may persist or recur. To prevent secondary infection, cleanse the wound with soap and water. Apply cold and/or give oral analgesics for pain. In more serious reactions, where there is local lymph-node swelling, evidence of local necrosis (dead or dying tissue), or the rare systemic reaction, evacuate the victim. In case there is severe pain, infiltrate locally with lidocaine.
For centipede bites, observe victims with minor reactions for approximately four hours, or until the reaction improves. Admit victims with evidence of significant reaction to the hospital because of potential rhabdomyolysis and acute renal failure. Tetanus prophylaxis should be current. Millipedes do not bite, but they do have secretions of hydrogen cyanide that irritate the skin. Treat by washing with soap and water (not alcohol) and applying a corticosteroid cream or lotion.
Bites and stings from fire ants, bees, wasps, hornets, yellow jackets and spiders are typically the most troublesome. Bites from mosquitoes, biting flies and ticks can cause reactions, but these are generally milder. Pest-related emergent care does not have to be a traumatic experience when you know how to recognize and care for the conditions you find.

The author is a consulting physician, medical entomologist and environmental health specialist with Springer Pest Solutions, Des Moines, Iowa. He can be reached at smitchell@giemedia.com.