Stings, Bites, and More

1. Stings, Bites, and More Jack B. Cohen, D.O. Keller Dermatology, P.A Keller, TX Clinical Associate Professor Department of Dermatology UT Southwestern Medical Center Dallas, TX

2. Conflict of Interest and Off-Label Drug Use I have no conflicts of interest regarding this presentation. Off-label use of medications will be identified during the presentation.

3. Pre-Test Question 1. Anaphylaxis is: a. A mild, local reaction to hymenoptera toxin. b. Always mediated by an allergic reaction via IgE c. Occasionally mediated by allergic (immunologic) non-IgE process d. All of the above

4. Pre-Test Question 2. Itching and a hypersensitivity reaction to scabies usually occurs after an incubation period of: a. 1 week b. 2 weeks c. 3 weeks d. 4 weeks

5. Pre-Test Question 3. Insect bites confined to the lower legs most likely are caused by: a. bees. b. pediculosis c. fleas d. wasps e. caterpillars

6. Bites and Stings • Sting – noun; organ found in bees, many wasps, some ants, in scorpions and sting rays, used defensively, as well as, to paralyze or kill prey. verb; 1. to prick or wound with a venom bearing organ. 2. to affect painfully or irritatingly as a result of contact, as certain plants (nettles). The Columbia Encyclopedia, 6th Edition • Bite – verb; use of teeth to inflict injury or (insect, arachnid, or snake) to wound with a sting, pincers or fangs. noun; a wound made by a bite. Oxford Pocket Dictionary of Current English

7. Hypersensitivity to Insect Bites • Insect bite reactions account for at least 50 deaths/year in the U.S. Multiple Hymenoptera (bees, wasps, and ants) stings are the most common cause of anaphylaxis and death. Fire ants which tend to sting in swarms releasing formic acid, have increasingly been the cause of widespread and severe reactions in the South.

8. Hypersensitivity to Insect Bites • Mild reactions to flying insects such as mosquitoes, fire ants, are defined as only a few localized papules, wheals, or pustules. Treatment is simply, ice packs, oral antihistamines, and topical steroids.

9. Hypersensitivity to Insect Bites • Moderate insect bite/sting reactions include multiple sites with severe itching or pain that have diameters 2 – 10 cm diameter or bullous reactions. These often require systemic corticosteroids in addition to oral antihistamines and ice packs.

10. Papular Urticaria

11. Hypersensitivity to Insect Bites Severe reactions are defined as a sting site > 6 inches and lasting as long as 7 days. Generalized systemic reactions occur in 0.4 – 3.0% of hymenoptera stings. Anaphylactic reactions are not different from other causes of IgE mediated reactions and include generalized urticaria, angioedema, bronchospasm, and hypotension.

12. Hypersensitivity to Insect Bites • Treatment for severe insect bites would include: • SQ epinephrine is required for anaphylaxis • IV Benadryl and antihistamines • Systemic corticosteroids • Ice packs for local treatment of large insect bites

13. Angioedema from Insect Bite

14. Insect Bites by Location • Feet and legs: The most common location for flea bites. The erythematous papules and wheals often have a hemorrhagic punctum and are arranged in groups or zigzag lines. It is a hypersensitivity reaction to salivary glands when they extract a blood meal.

15. Flea Bites • 3 species attack man: the human flea (Pulex irritans), cat flea (Centocephalides felis), and dog flea (Centocephalides canis). You must treat the animals, and their environment: carpets, under beds, furniture and under sleeping cushions. Vacuum frequently. Bites are treated with topical steroids and antihistamines. DEET and pyrethrum repellents help.

16. Insect Bites by Location • Legs and beltline: Chigger (Red Bug) bites. Most commonly found in the summer and fall, after exposure to infested grass and bushes. Severely pruritic erythematous papules with hemorrhagic punctum, scratch marks, and erythema occur where clothing is tightly constricted.

17. “Good night, sleep tight, don’t let the bed bugs bite.” • Bed bugs (Cimex lecticularius) are making a comeback. These flat, oval, brown 3-5 mm insects emerge from their hiding places at night to feed on nearby mammal hosts, including man. They are found in homes, hotels, poultry houses, or bird and bat nests or roosts. Large infestations have an offensive odor. They may hitchhike in luggage or clothing to spread from place to place. The bug bites are seldom felt, but intense itching develops after several hours and the patient wakes up with the insect bites and sometimes bloody clothes or sheets. Leverkus, M, Jochim RC, et al. Bullous allergic hypersensitivity to bed bug bites mediated by IgE against salivary nitrophorin. J Invest Dermatol. 2006;126:91-96.

18. “Good night, sleep tight, don’t let the bed bugs bite.” • The clinical picture varies with the sensitivity of the patient to the saliva component, nitrophorin. Linear arranged erythematous papules or nodules with hemorrhagic punctum, and even vesicles are found chiefly on the distal legs, arms, buttocks, or face.

19. “Good night, sleep tight, don’t let the bed bugs bite.” • Epidemic • Propelled by travel & communal housing • ¼” long (not subtle) • Bite on exposed skin • Retreat to hiding places • Can live up to one year without a blood meal! Free Bed Bugs

20. “Good night, sleep tight, don’t let the bed bugs bite.” • The bed bugs and the eggs are found in the crevices of the bed furniture, the seams of the mattresses, floors and walls. Spraying the crevices and sometimes fumigation is needed to kill this stubborn ectoparasite.

21. Pediculosis capitis • Head lice is principally found in children, but occurs in adults also. There is intense itching of the scalp, and secondary impetigo and folliculitis occurs frequently. This should always be suspected in children with posterior cervical lymphadenopathy.

22. Pediculosis capitis • The lice may or may not be seen, but usually the nits are noticeable close (1-2 mm) to the scalp glued on to the hairshaft. • Transmission is head to head contact or sharing of hats, combs, or hair bands or clips.

23. Pediculosis capitis • Treatment is with OTC Permethrin 1% (Nix), is both pediculocidal and ovicidal. It is left on 10 minutes then washed out and towel dried. This should be repeated in 1 week. • Permethrin-based products (RID) is an OTC extract of natural pyrethrins from chrysanthemums combined with piperonylbutoxide to increase stability. These products are neurotoxic to lice, but not ovicidal and viable eggs may remain even after 2 treatments. • Malathion 0.5% (Ovide) can be applied for 10 minute or overnight, and repeated also in 1 week. It is a fast acting pediculocide and has the highest ovicidal activity. It has an unappealing odor and can cause stinging of the skin and eyes. • Lindane (gamma benzene hexachloride) is pediculocidal, but limited ovicidal ability. Because of increased side-effect potential including neurotoxicity and bone marrow suppression, it is a second line therapy.

24. Pediculosis capitis Oral agents can be used in severe or resistant cases • Ivermectin (Stromectol) an antihelmintic drug has been suggested as an off-label use for resistant head lice at a dosage of 200 µg/kg, repeated in 7 – 10 days. It is effective pediculocide with no resistance to date. It is thought to kill the gram negative gut bacteria needed to digest blood meals. Should not be used in children under 15 kg. • Trimethoprim/sulfamethoxazole (Bactrim, Septra) has been shown to be effective in small studies, presumably by destroying the gut flora of the louse and interfering with its ability to synthesize vitamin B. Combination with topical agents improves its efficacy. Malcom CE, Bergman JN. Trying to keep ahead of lice. Skin Therapy Lett. 2006 Dec-2007 Jan;11:1-6.

25. Pediculosis pubis • Pthirus pubis (crab) louse usually limits its excursions to the pubic area lower abdomen, and rarely to the axillae, or eyelashes. • Mostly a sexually transmitted adult disease. • Symptoms- mild to severe itching. • Brown-yellow or grey lice close to the skin and nits on the lower hair shaft are sometimes difficult to identify.

26. Pediculosis pubis

27. Pediculosis pubis • Occasionally, bluish-gray macules (macular ceruleae) are seen on the skin. • Can co-exist with other STDs, including scabies. Treatment- • The pubic lice are still rather sensitive to permethrin, pyrethrins, malathione, and less so to lindane are applied x 10 minutes then rinsed off.

28. Pediculosis corporis (Vagabond’s Disease) • Body lice live chiefly in the seams of clothing and are rarely found on the skin. • Generalized itching with accompanying erythematous macules, wheals, excoriated papules, and thickened skin is found. • Secondary infection is common. • Treat the clothing and bedding with insecticide.

29. Scabies • Sarcoptesscabiei infestations continue to be major worldwide disease.(300 million/year) • Transmission: skin - skin contact • Mites complete their entire lifecycle on humans. • The female mite burrows to lay eggs. • About 15- 20 female mites live on a host. • Symptoms develop 4 – 6 weeks after infection depending on the host immune response to the mite and its excrement.

30. Scabies • Re-infestation causes a brisk immune response and symptoms occur in 24-72 hours. • Itching is most severe at night. • The characteristic burrows are found in the fingerwebs, volar wrists, palms, ankles, waist, and axilla. • The nipples in women, and genitals in men are involved. • The periumbilical area is often involved.

31. Scabies • The head and neck can be involved in infants, otherwise the infestation does not get above the neck. • Papules with excoriations, vesicles, eczematous changes, and nodules can occur. • The clinical presentation is highly variable.

32. Scabies

33. Scabies

34. Scabies • Diagnosis: a presumptive diagnosis can be made on the clinical presentation of pruritus, itching worse at night, the varied skin lesions, and identification of burrows on exam. • Definitive diagnosis requires microscopic identification of the mites, ova, or fecal scybala. • Place a small drop of mineral oil over burrow and scrape with a #15 blade. Transfer oil to microscope and scan at 10X.

35. Norwegian (Crusted) Scabies • This is a thick scaling or crusted widespread eruption usually in an immunocompromised or institutionalized host. • There are thousands of mites and ova! • Itching may be slight. • Psoriasis-like scaling of the palms, around and under the nails, with crusted areas on the face and head occur.

36. Scabies • Treatment options: • Permethrin (Elimite) cream (92% cure) • Malathion cream (Ovide) - 20 TX • Lindane (86%)-neurotoxic • Ivermectin 200 ug/Kg weekly x 2 for resistant cases. • Precipitated Sulfur ointment • Crotamiton (Eurax) cream. • Change bed linens after each dose. • Contacts should be treated concomitantly.

37. Norwegian (Crusted) Scabies • Treatment is with repeated permethrin 5% cream weekly. • Must get the permethrin under the nails. • Urea 40% is keratolytic. • Ivermectin (Stromectol) 200 µg/kg, repeated in 7 days is effective.

38. Cutanea Larva Migrans (Creeping Eruption) • This serpiginous erythematous papular eruption is caused by the dog or cat hookworm (Ancylostoma braziliense or Ancylostoma caninum) larvae burrowing under the skin. • The feet, buttocks, arms, and hands are the most common sites. • Barefoot beach goers, children playing in sandboxes, gardeners, and plumbers or carpenters that work under homes are often victims.

39. Cutanea Larva Migrans(Creeping Eruption) • The pruritic papules extend up to 2 cm/day. • Complications- 2o infection, eosinophilia, and Loeffler’s syndrome can occur. • Treatment- • 1. Thiabendazole 50 mg/kg divided doses bid x 2 days. n/v are side effects. Can use suspension under occlusion. • 2. Albendazole 400 mg qd x 3-5 days. • 3. Ivermectin 12 mg X 1 dose. • 4. Cryosurgery

40. Myiasis • Myiasis is a condition where human tissue is invaded by botfly larvae. Larva and/or ova are deposited on the skin where they burrow into the skin and cause a papular, then a furuncular lesion. The opening is often seen. Treatment is surgical removal.

41. Myiasis

42. Tungiasis • The sand flea or chigoe (Tunga penetrans) is a minute parasite that attacks man, pigs, and other animals. Caribbean vacationers can return with it. The pregnant female burrows into the skin, lays her eggs, where they develop into larvae. The adult emerges in 10 days. Pea-size pruritic and painful papules develop that can ulcerate and become infected. Treatment is to curette or excise the lesions and treat the secondary infections.

43. Tick Bites • Several varieties of the family Ixodidea (hard ticks) and Argasidae (soft ticks) have been known to attach to humans, dogs, and other mammals that traffic through wooded areas, bushes, and grass. The female tick will attach for about 12 days, then falls off. • The lone star tick, Amblyomma americanum, is found in Texas. • Most victims do not feel the tick or have slightly itchy papule at the site.

44. Tick Bites • Ticks are an important vector of diseases: 1. Rocky mountain spotted fever. 2. Lyme disease. 3. Tick paralysis 4. Tick bite pyrexia. 5. Q fever 6. Ehrlichiosis

45. Leishmaniasis • Leishmaniasis is a chronic disease caused by the protozoan Leishmania, an obligate intracellular parasite, transmitted by the sandfly (genus Phlebotomus) between canines, rodents, and humans. Three forms exist worldwide: cutaneous form with only skin involvement, mucocutaneous form, and a visceral form. In the US, most cases are restricted to South Texas, and are caused by Leishmania mexicana, which causes only a cutaneous form.

46. Leishmaniasis • Cutaneous lesions begin as a papule , that enlarges into a nodule or plaque that may ulcerate or become verrucous with time. Typically the lesions occur on the face or extremities.

47. Leishmaniasis • Diagnosis is made on biopsy and the PCR confirms the species. • Most skin lesions resolve spontaneously with scarring, but some remain chronic or disseminate. Treatment depends on the nature of the infection. Pentavelent antimonies, pentamidine, fluconazole, itraconazole, amphotericin B, dapsone, rifampin, and surgical excision.

48. Caterpillar Dermatitis • Many species of caterpillars and moths have defensive hairs that produce itching and burning. Larvae, cocoon, and the adults all may contain the hairs. Toxins produce the inflamation and this is not an allergic reaction. Pain, erythema, papules , hemorrhage, and urticaria may be produced.

49. Caterpillar Dermatitis • Megalopyge opercularis, the wooly asp or puss caterpillar produces immediate pain and the characteristic linear train track hemorrhages in Central Texas. • Treatment is tape stripping of the hairs and EMLA cream for the acute pain. Mid- strength topical steroids and menthol/camphor preparations are helpful.

50. Spider Bites • Black widow, Lactodectusmactansare found in North America. They are large shiny black spiders with a red hour glass design on the abdomen. Widow spiders are common in woodpiles, shoes, and under outhouse seats. Bites to humans occur when the spider is disturbed or inadvertently trapped against the skin. They are more aggressive when protecting an egg sack.