1. Parasitic Infestations, Stings & Bites Part 2
Erik Austin, D.O., M.P.H.

2. Loaiasis
Aka Loa Loa, Calabar Swelling, Fugitive Swelling, Tropical Swelling
Asymptomatic localized subQ swellings, size of a hen’s egg
Prediliction for loose tissues such as eyes, frenulum of tongue, genitalia
Transmitted by the Mango fly Chrysops dimidia or silacea
Tx: Diethylcarbamazine

3. Loaiasis worm under the conjunctiva

4. Onchocerciasis River Blindness Central & South America, Mexico
Pretibial depigmentation: leopard skin
Thickened skin: elephant skin
May develop into subQ nodules
Mazzoti test + if edema, pruritis, fever & arthralgias w/50mg diethylcarbamazine
Tx: Ivermectin 150mg single dose

5. Black fly of the genus Simulium

6. Leopard skin, Elephant skin

7. Trichinosis Inadequately cooked pork, bear or walrus meat
Puffy eyelid edema, red conjunctiva and sometimes urticaria, fever, HA, muscle pains, neurologic S&S.
20% have maculopapular rash, very itchy, responsive to corticosteroids.
Diagnosis confirmed by muscle biopsy
Tx: Albendazole 400mg bid for 2w.

8. Trichinella spiralis – muscle bx

9. Phylum Arthropoda – 3 main classes
Myriapoda
Centipede
Millipedes
Insecta
Caterpillar
Moth
Arachnida

10. Myriapoda – Centipede Stings
Paired hemorrhagic puncta with erythematous swelling progressing to brawny edema or lymphangitis and lymphadenopathy.
U.S. = Scolopendra species, 15-20cm
Tx: Rub with garlic or local anesthetic injection.

11. Scolopendra sp.

12. Myriapoda – Millipede burns
Millipede bodies secrete a toxic liquid that causes brown discoloration, progresses to erythema & vesiculation – intense stinging and burning pain
Tx: wash site immediately, topical steroids.

14. Lepidoptera – Caterpillar Dermatitis
Nettling hairs contain a toxin that produces local pruritic erythematous macules and wheals.
MC campers, children playing in trees and lumberjacks in Fall.
Nygmia phoerrhoea (brown-tail moth)
Megalopyge opercularis (puss caterpillar)
Sibine stimulae (saddleback caterpillar)
Megalopyge crispata (crinkled flannel moth)
Tx: Antihistamines, resolves 48 hours.

15. Saddleback
Brown tail moth

16. Lepidoptera – Moth Dermatitis
Hairs of the moth – urticating toxin
Euproctis chrysorrhoea (brown tail)
Cossus cossus (goat)
Dicranura vinula (puss)
Lymantria dispar (gypsy)
Hemenocampa pseudotsugata (Douglas fir tussock)
Tx: oral steroids help, lasts 1 week

17. BROWN TAIL MOTH
GOAT MOTH
DOUGLAS FIR TUSSOCK
GYPSY MOTH

18. Hemiptera – Bedbug Bites
Aka Cimicosis, Cimex lectularis
Smelly parasite with non-functioning wings. Hides in crevices by day and feeds on human blood at night.
“Breakfast-Lunch-Dinner” linear bites
Sensitivity at site due to saliva
Hepatitis B surface antigen has been repeatedly demonstrated in the bugs, but transmission is controversial
Tx: Pt: topicals, House: call exterminator.

20. Hemiptera – Reduviid Bug Bites
Aka Kissing Bug, Assasin bug, conenoses
Attack face when asleep, bite is painless, bug defecates and rubs feces into wound, spreading Trypanosoma cruzi

22. Anoplura Pediculosis (Phthiriasis): Pediculosis Capitis
Pediculosis Corporis
Pediculosis Pubis (Crabs)

23. Pediculosis (Phthiriasis)
Pediculus humanus (head & body)
Phthirus pubis (pubic or crab louse)
Attach and suck blood, saliva is antigenic and creates dermatitis
Lice may transmit endemic typhus, relapsing fever or trench fever.

24. Pediculosis Capitis MC in children, scalp usually pruritic
Diagnosis straightforward.
Peripilar hair casts easily differentiated b/c moveable, but the breaks of trichorrhexis nodosum may mimic nits
Tx: Apply Permethrin 1% Cream Rinse (Nix) to DRY hair, then rinse out after minutes. Do not shampoo for 24 hours afterwards.

25. Pediculosis Capitis

26. Pediculosis Corporis
Aka: Pediculosis Vestimenti or Vagabond’s Dz. Likes pressure areas beneath collar, belt or in bedding.
LICE RARELY FOUND ON SKIN.
Dx: Generalized itching, parallel scratch marks, hyperpigmentation, LSC & red macules
Tx: Laundering clothing and bedding, 1% Malathion powder or 10% DDT may be dusted onto inner surface of underwear
Best to discard clothing as lice may live in clothing for 1 month without a blood meal

27. Pediculosis Pubis (Crabs)
MC Adults, STD, MC genitalia but may invade hypogastrium, axilla or eyelashes.
LICE COMMONLY FOUND ON SKIN
Pthirus pubis
Maculae ceruleae, bluish or slate colored papules, blancheable on sides of trunk or inner thighs.
Tx: Permethrin applied for 10 minutes, Repeat in 1 week, Tx Partner as well. Petrolatum for eyelash lice.

29. Diptera – 3 main problems
Mosquito bites
Ked itch
Myiasis

30. Mosquito bites – Culicinae
Moisture, warmth, carbon dioxide, estrogens and lactic acid in sweat attract the mosquito
Pruritic wheal, urticarial reactions.
West Nile Virus vector = mosquitoes acquire it from feeding on infected birds.
Avoid standing water, wear long sleeves.
TX: topical steroids, DEET.
Also a vector for filariasis, malaria, dengue, yellow fever.

32. Ked itch Sheep ked = Melophagus ovinus
Feeds with mouth and sucks blood
Woolsorters and sheepherder’s
Pruritic often hemorrhagic papules, nearly always with a central punctum
Deer keds attack people in a similar way, MC hips and abdomen, last 12m

33. Myiasis
Invasion of tissues by fly larvae, eggs hatch, burrow into skin.
Furuncle with maggots in the center.
Cochliomyia hominivorax (Screw worm) MC cause wound myiasis in USA
Phormia regina (Black Blowfly, USA)
Dermatobia hominis (botfly, New World)
Cordylobia anthropophaga (Tumbu Fly, Africa)

34. TX: EXCISION OR OCCLUSION W/ PETROLATUM

35. Blister Beetle Dermatitis
Meloidae, Oedemeridae release the vesicating agent cantharidin
Staphylinidae family releases pederin
Not biters, vesicant rubs off if beetles brushed against, pressed or crushed on the skin
Linear array of vesicle(s), bulla(e)
“Spanish Fly” or Lytta vesicatoria best known for medicinal purposes
TX: I&D, Cold compresses, Top CS.

36. Spanish Fly (Lytta vesicatoria)

37. Carpet Beetle Dermatitis
Anthrenus scrophulariae
Papulovesicular and urticarial involves chest, neck and forearms.
Reddish brown, fusiform 6mm long and covered by hairs
TX: Fumigate house with sulfuryl fluoride

38. Carpet beetle – note hairs Anthrenus scrophulariae

39. Bees and Wasps
Bees or APIDS – venom contains histamine, mellitin, hyaluronidase, HMW acid phosphatase, phospholipase A
Wasps or VESPIDS – venom contains phospholipase, hyaluronidase and a protein known as ANTIGEN 5.
Honeybee stinger stays in the skin and has a sac you must scrape off, because if you pick it up by the sac, you express more venom into the tissues.

40. Bee and Wasp Stings
Symptoms vary from a small pruritic wheal to anaphylactic shock.
Bee sting anaphylaxis may be first symptom of mastocytosis.
Treatment with IL steroids and xylocaine is highly effective.
ASA or dilute meat tenderizer compresses.
Anaphylaxis 0.3cc epi 1:1,000 SQ
Susceptible persons should carry an
Ana-Kit with syringe, epinephrine and
Antihistamines

41. Yellow jacket – MCC of allergic reaction to insect stings
Nest in the ground or in walls, interrupted by outdoor activity

42. Ants – Fireants most painful
Solenopsis saevissima, invicta, geminata, xyloni
S. saevissima is ferocious and vicious: multiple bites in seconds.
Intense pain, whealing and eventually sterile pustule with erythematous base, very characteristic lesion.
Seizures and mononeuropathy have been reported.
Tx: IL steroids  oral steroids, SQ epi

43. Solenopsis saevissima

44. Pulicosis (Flea Bites)
Human Flea – Pulex iritans
Cat Flea – Ctenocephalides felis
Dog Flea – Ctenocephalides canis
Extraordinary jumpers, no wings
Legs and waist MC sites
Hemorrhagic puncta surrounded by urticarial patch. “zigzag lines” or grouped
Well’s syndrome may occur (eosinophilic cellulitis

45. Pulex iritans (Human flea) below….
Ctenocephalides felis
Cat flea on the right 

46. Fleas as Vectors of Disease
Xenopsylla cheopis and X. brazilensis are vectors of plague and endemic typhus
Squirrel flea, Diamanus montanus transmits plague and tularemia

47. Flea Control
Malathion, Chlordane in kerosene, Lindane dusts or sprays – time to call the Orkin man.
Insect repellants OFF!, other DEET and pyrethrum preparations.

48. Tungiasis Tunga penetrans Aka nigua, chigoe, sand flea, jigger.
Reddish brown flea 1mm long
Africa, Central & S. America, India, Pakistan
Pregnant females burrow into skin of ankles, soles, feet and toes.
Lesions become infected and painful

49. Tunga penetrans
TX: Sx, Abx, Thiabendazole

50. Tick Bites & Disease Associations
Dermacentor andersoni – wood tick (USA) & Amblyomma americanum – Lone Star tick (Texas) both transmit Rocky Mountain Spotted Fever, Tularemia & tickborne encephalitis
Ixodes transmit Lyme dz in USA
Dermacentor variabilis (dog)  Tularemia
Rhipephalus sanguineus (dog)  Rickettsia conorii (Boutonneuse fever)
Ticks also transmit Q fever, Babesiosis, Ehrlichiosis, Arbovirus, Viral encephalitis, Hemorrhagic fevers.

51. Tick Bite Presentations
1) Urticarial wheal
2) Tick Bite Pyrexia – 7-12 days of fever, chills, headache, abdom. pain & N/V.
3) “Tick Paralysis” – usually in children, 6 days after attachment, rare, MC head/neck.
Flaccid paralysis of legs, then arms, neck, diaphragm, resembles Guillen-Barre syndrome. Tick toxins block NMJ’s.
Tick removal causes rapid recovery, but death may ensue if tick is not removed.

52. Other Tick Bite Diagnosis
Ornithodorus tholozani may be a vector for Borrelia duttonii, African endemic relapsing fever
Bite produces a typical small inflammatory nodule surrounded by a zone of normal skin with a circumferential brownish ring.

53. Scabies Distribution: Circle of Hebra
Imaginary circle intersecting sites of prediliction – areolae, axillae, elbow flexures, wrists, finger webs, umbilicus, lower abdomen, genitalia

54. Scabies Papular and burrow-type lesions
Face and scalp spared in adults, but not in infants or immunosuppressed.
Burrows may be barely visible
Dull red nodules persist in groin, called nodular scabies, may persist after cure, histo = pseudolymphoma
Norwegian – heavy crusting, scaling most common in malnourished, immuno-suppressed or pts with neurologic dz.

55. Sarcoptes scabiei Scybala
Mineral oil or Acry-Mount on a glass slide with cover slip on top
Scybala

56. Scabies Treatment Norwegian: Ivermectin 200mg/kg weekly x 3.
Permethrin 5% cream from head to toe at night, rinse off in AM x 3. May repeat weekly.
Lindane rarely neurotoxic to infants
Infants and Pregnant women 6-10% precipitated sulfur in petrolatum applied nightly x 3 nights
Treat family members

57. Animal Scabies Milder course than human scabies
Dogs, cats, poultry, birds, camels or horses
Self limited, no burrows or mites found.

58. Cheyletiella Dermatitis
Non-burrowing mites that are parasitic for dogs, cats, rabbits
May bite humans leaving an itchy dermatitis resembling scabies
Mites easily seen on pets.
Treatment of pet by veterinarian is the only necessary treatment

59. Demodex mites - Demodicidosis
MC adults > 30 y/o inhabit sebaceous glands of the nose, ala, forehead, chin and scalp
Significant only if in large numbers.
Readily found in adults without disease – pathogenicity controversial
Occasionally, recalcitrant rosacea patients may benefit from permethrin
Papulonodular eruption may be seen in AIDS patients

60. Demodex folliculorum – found in contents expressed from seb gland

61. Chigger Bite Eutrombicula alfreddugesi
MC legs and belt line and other sites where clothing causes constriction
Grass and bushes typically infested in summer or fall  aka Mower’s mites
Pruritic hemorrhagic puncta surrounded by red swellings
TX: TS, Prophylaxis: (DMP) demethylphthalate solution

63. Gamasoidosis Persons who handle canaries, pigeons and poultry
MC arms & hands, papular, urticarial
Diagnosis of urticaria is usually made
Ornithonyssus and Dermanyssus mites infest feathers, bite humans
Take about 1 week longer to resolve than most bug bites, Tx: malathion

64. Grocer’s Itch Pruritic dermatitis of forearms
Carpoglyphus passularum fournd on dates, prunes, figs.
Acarus siro and Tyrophagus longior found on cheese.

65. Grain Itch Pyemotes tritici
Lives in grain, attacks harvesters of wheat, hay, barley, oats and other cereals or other farmhands who work around straw.
Urticaria papule with vesicle hemorrhagic punctum
TX: malathion
Mite may not be demonstrable in skin.

66. Scorpion Sting
Hide during daytime in closets, shoes, folded blankets, children’s sandboxes.
Any sting by a large scorpion should be considered dangerous because venom is hemolytic and neurotoxic
MC US is Centruroides sculpturatus
Numbness, laryngeal edema, profuse sweating & salivation, cyanosis, nausea and paresthesia of the tongue
Tx: tourniquet, antivenin, phentolamine, atropine, barbituates

67. MC US: Centruroides sculpturatus

68. Latrodectism – Black Widow
Dark dry places under rocks, in cellars, in wood piles.
Severe pain in minutes, spreads from bite site to extremities and trunk, severe GI distress, abdominal rigidity delirium, paralysis. S/S last 2 days.
Abdominal pain so severe it may be mistaken for appendicitis, colic or food poisoning. Children may die.
Opiods, benzodiazepines, antivenin.

69. Lactrodectus mactans 13mm long, coal black with an orange red hourglass on abdomen

70. Loxoscelism – Brown Recluse
2 types of reactions
Localized – Necrotic Cutaneous
- extensive gangrene, severe edematous painful reaction within the first 8 hours. Starts as bulla with surrounding erythema and ischemia. In one week central dark gangrenous portion may become many cm wide and lasting months before healing.
Diffuse – Viscerocutaneous - rare

72. Loxoscelism Therapy 1) Rest, Ice, Compression, Elevation
2) No hot packs or surgery
3) Dapsone 100mg BID
4) Aspirin
5) Surgery, if any should be delayed 4 to 6 weeks.
6) No benefit to surgical excision, actually increases complications.

73. Sting Ray Injury Unwitting victim steps on partially buried stingray
Puncture wound that ulcerates.
Immediate sharp shooting pain with edema and cyanosis, symptoms of shock may occur
TX: Venom is detoxified by heat, so soak affected foot in hot water x 1 hr.
Pain control.

75. Snake Bite Rattlesnake, Cottonmouth, Copperhead
Venom = hydrolases, 30 enzymes, anticoagulant, hemolytic, increased capillary permeability
If treatment center cannot be reached within 1 hour, tourniquet, incision and suction in first 15 to 30 minutes, antivenin, antibiotics, tetanus toxoid, possibly surgical intervention

76. UR: Mocassin LR: Copperhead LL: Rattlesnake

77. Lizard Bite Heloderma suspectum AZ, NM Paralysis, Dyspnea, Convulsions
Death is rare, Tx= snakebite tx