Bites & Stings

Biting and Stinging Insects

Biting and stinging insects can cause a wide range of cutaneous and systemic reactions, mediated by both direct toxins and immune mechanisms. Immediate reactions are primarily due to histamine and serotonin release, while more severe systemic responses may result from specific toxins such as phospholipase E in Hymenoptera stings or Solenopsin D in fire ants. Hymenoptera species, including bees, wasps, and hornets, are responsible for about 25% of insect stings and may lead to exaggerated reactions in patients with CLL or chronic EBV infection. Secondary bacterial infections, often caused by Staphylococcus aureus, can complicate insect-related lesions. Fire ants are particularly notable for pustules on the lower extremities and their ability to cause linear lesions due to Solenopsin D, while bedbugs (Cimex lectularius) induce urticarial papules in a “breakfast, lunch, dinner” pattern due to nitrophorin. Blister beetles release cantharidin, producing vesiculobullous reactions at contact sites. Fleas, depending on species, are important vectors of human disease: rat fleas spread Yersinia pestis and Rickettsia typhi, while cat fleas transmit Bartonella henselae and Bartonella quintana, causing cat scratch disease and bacillary angiomatosis. Caterpillars can cause dermatitis with urticarial or hemorrhagic linear tracks, with puss caterpillars inducing painful linear petechiae. Recognition of these symbolic dermatologic associations is critical for diagnosis and management on board exams.

General Concepts

• On a field trip to the Department of Exciting Entomology Trips (DEET) = Biting and stinging insects
• Teacher checking stopwatch = Immediate reactions are due to
• History book = Histamine release
• Coke SERO = Serotonin
• Heisman trophy holding a quarter = 25% of cases are a result of stings from insects in the Hymenoptera order
• “PHAST” engraved on trophy = Phospholipase E is the toxin
• Surrounded by bees, wasps and hornets = Bees, wasps, and hornets are in the order Hymenoptera
• Golden staph = Secondary infections are usually from Staphylococcus

Exaggerated Reactions

• Red man with a bag of limes at the bar = Exaggerated bite reactions are usually in patients with CLL or those with chronic EBV

Fire Ants

• Ants on fire = Fire ants
• Milk drops on foot = Pustules on lower extremities
• Ants removed the sole of his shoe = Solenopsin D is toxin in fire ants

Bedbugs

• Bedbug made of cement = Cimex lectularius species
• Nitro cereal = Nitrophorin is salivary product responsible for immune reaction in humans
• Three bowls of cereal = Breakfast, lunch, dinner sign multiple urticarial papules

Blister Beetles

• Beetle exhibit = Blister beetle (Spanish fly aka Lytta vesicatoria)
• Crawling out of a can = Cantharidin → blisters at sites of contact

Fleas

• Flea on a rat = Rat flea
• Drinking Boba = Vector for Yersinia pestis which → bubonic plague
• Gentleman = Gentamicin for treatment
• Striped suit = Streptomycin for treatment as well
• Typhoon inside Boba = Also vector for Rickettsia typhi → endemic typhus
• Flea on a cat = Cat flea
• Cat name is Bart = Cat flea is the vector for Bartonella henselae
• Sharp claws = Bartonella henselae → cat scratch disease, bacillary angiomatosis
• Bart’s Queen = Bartonella quintana
• Red blood vessel-like yarn = Both Bartonella henselae and quintana cause bacillary angiomatosis

Caterpillars

• Caterpillar = Caterpillar dermatitis
• On a train track = Train-track appearance of urticaria or hemorrhage
• Puss in boots = Puss is a specific type of caterpillar
• Red claw marks = Results in painful, linear petechiae

Arachnids

Arachnids include ticks, mites, and spiders, all of which can be clinically relevant in dermatology due to their ability to transmit infections, cause direct envenomation, or induce hypersensitivity reactions. Ticks are hematophagous vectors that spread multiple diseases. Dermacentor ticks transmit Rocky Mountain Spotted Fever, ehrlichiosis, and human granulocytic anaplasmosis. Ixodes ticks carry Borrelia burgdorferi which is a spirochete that causes Lyme disease, and are also responsible for babesiosis and anaplasmosis. Mites can be free-living and are associated with summer penile syndrome in boys, typically from mite exposure in grassy environments. The spider family is clinically diverse with medically important species. Black widow bites involve neurotoxic α-latrotoxin that depolarizes neurons, producing abdominal pain, rigidity, and systemic symptoms. Treatment includes benzodiazepines, IV calcium gluconate, and sometimes antivenin. Brown recluse spiders inject sphingomyelinase D and hyaluronidase, leading to necrotic ulcers with eschar formation, and systemic complications such as hemolytic anemia, thrombocytopenia, DIC, shock, and death. Other spiders have unique toxins: jumping spiders secrete hyaluronidase, wolf spiders release histamine, sac spiders produce lipase, and hobo spiders display a characteristic herringbone abdominal pattern. Tarantulas release urticating hairs that can cause ophthalmia nodosa, a granulomatous ocular reaction that can lead to blindness.

Ticks

• Centaur = Dermacentor tick
• Rocky mountain = Transmits Rocky Mountain Spotted Fever (#1 cause)
• Plasma ball = Human granulocytic anaplasmosis
• Deer licking ear = Causes ehrlichiosis
• Eye with an “X” = Ixodes
• Lime with a target = Transmits Lyme disease
• Spiral = Caused by Borrelia burgdorferi which is a spirochete
• Baby = Causes babesiosis
• Plasma ball = Human granulocytic anaplasmosis

Mites

• Mite on boy’s shoulder = Free-living mites
• Boy in summer shorts pulling string on shorts = Causes summer penile syndrome in boys

Spiders: Black Widow

• Black spider = Black widow
• Red hour glass = Has characteristic red hourglass pattern on body
• Dripping lactose milk = α-latrotoxin depolarizes neurons
• Lactose = Latrodectus mactans
• Rigid man with abdominal pain = Abdominal pain and rigidity
• Holding keys to a Benz = Treatment includes benzodiazepine for supportive treatment
• Drinking calcium milk = IV calcium gluconate
• Vinyl on the ground = Antivenin

Spiders: Brown Recluse

• Brown spider = Brown recluse spider
• Holding a violin = Characteristic dark brown to black violin or fiddle shaped marking
• Black hole in the wall = Necrosis with eschar formation at bite location
• Sphinx = Sphingomyelinase D and hyaluronidase allow eschar to spread
• Broken tomatoes = Can have hemolytic anemia
• Broken plates = Thrombocytopenia
• Lightening shock = Shock
• Dice = DIC
• Dead fly = Death

Spiders: Others

• Spider jumping = Jumping spider
• Jumping high (sign that says high on it) = Hyaluronidase is toxin
• Wolf shaped like a spider = Wolf spider
• History book = Histamine is the toxin
• Spider on a sack = Sac spider
• Sack of fat = Lipase is toxin
• Spider on a hobo = Hobo spider
• Herringbone floor pattern = Herringbone pattern on abdomen
• Tarantula = Tarantula
• Hairy = Urticating hairs ejected when threatened
• Breaking a pair of glasses = Ophthalmia nodosa (chronic granulomatous reaction in the eyes that may result in blindness)

Marine Injuries, Snakebites, and Myriapods

Aquatic and terrestrial envenomations are important dermatologic considerations due to their potential to cause both localized skin manifestations and systemic complications. Marine injuries are often caused by cnidarians such as jellyfish, Portuguese man-of-war, corals, and anemones. These organisms use nematocysts, specialized stinging cells containing toxins, to induce cutaneous and systemic effects. Jellyfish stings may present with vesicular or hemorrhagic skin lesions, and flagellated eruptions are characteristic of certain cnidarian envenomations. Management can include vinegar (dilute acetic acid), which denatures nematocysts in some species but is not universally effective. Pacific box jellyfish (Chironex fleckeri) is particularly dangerous and may result in cardiovascular collapse, shock, and death. Snakebites vary by species, with pit vipers such as copperheads and rattlesnakes displaying triangular heads and deep nostril pits. Their venom can induce thrombocytopenia and disseminated intravascular coagulation, represented clinically with hemorrhage and systemic toxicity. Coral snakes, distinguished by their red-yellow-black color pattern and the mnemonic “red touching yellow kills a fellow,” deliver neurotoxic venom, unlike nonvenomous king snakes with red-black banding. Myriapod bites include centipedes, which cause puncture wounds due to their paired forcipules, and millipedes, which lack fangs but secrete chemical irritants that result in burning contact dermatitis with blistering.

Marine injuries

• Aquatic tank = Marine injuries
• Cysts inside dairy yogurt = Cnidarians produce specialized cells called nematocysts which contain the toxins
• Jellyfish = Jellyfish
• Portugal soldier = Portuguese man-of-war
• Blowing bubbles = Vesicular skin lesions
• Bleeding = Hemorrhagic lesions
• Coral reef = Coral
• Anemone = Anemones
• Flagellate scratch on window = Flagellated eruption in the affected areas
• Pouring vinegar on a jellyfish = Vinegar (dilute acetic acid) denatures nematocysts in some but not all species
• Box with jellyfish inside = Pacific box jellyfish
• Flickering light = Chironex fleckeri is its scientific name
• Electric shock = Can result in shock and death

Snakebites

• Snake with a copper penny = Copperhead
• Snake with rattle = Rattlesnakes
• Triangular head and big nose = Have triangular head with deep nostril pits
• Broken plates and dice = Multiple toxins resulting in thrombocytopenia and DIC
• Red, yellow, black snake next to a coral = Coral snake. Mnemonic is “red touching yellow kills a fellow” to help differentiate from a nonvenomous king snake that looks similar but has red touching black

Myriapods

• Centipede with 2 pincers = Centipede bites have 2 puncture wounds
• Millipede on fire = Millipede bites cause chemical irritant contact dermatitis that causes burning and blistering