infestations and bites n.
Download
Skip this Video
Download Presentation
Infestations and Bites

Loading in 2 Seconds...

play fullscreen
1 / 81

Infestations and Bites - PowerPoint PPT Presentation


  • 87 Views
  • Uploaded on

Infestations and Bites. Medical Student Core Curriculum in Dermatology. Last updated August, 2011. Goals and Objectives.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Infestations and Bites' - lenore-holder


Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
infestations and bites

Infestations and Bites

Medical Student Core Curriculum

in Dermatology

Last updated August, 2011

goals and objectives
Goals and Objectives
  • The purpose of this module is to help medical students develop a clinical approach to the evaluation and initial management of patients presenting with bites and infestations
  • After completing this module, the learner will be able to:
    • Recognize risk factors for lice infestation and scabies
    • Identify nits and adult lice as diagnostic of pediculosis
    • Identify a burrow as the primary morphology of scabies
    • Identify common causes and clinical presentations of insect bite reactions, with an emphasis on bedbugs and brown recluse spider bites
    • Discuss treatment options and patient education for pediculosis capitis, scabies, and insect bite reactions
case one

Case One

Mary Thompson

case one history
Case One: History
  • HPI: Mary is a 6-year-old girl with a two week history of an itchy scalp. It has not been relieved by over-the-counter dandruff shampoo. She recently stayed over at her cousin’s house who now has the same problem.
  • PMH: no chronic illnesses or prior hospitalizations
  • Allergies: no known allergies
  • Medications: none
  • Family history: noncontributory
  • Social history: lives at home with parents and attends first grade
  • ROS: negative
case one question 1
Case One, Question 1
  • What information is relevant in Mary’s history?
      • Recent contact with similar complaint
      • Scalp pruritus (itching)
      • School-aged child
      • All of the above
case one question 11
Case One, Question 1

Answer: d

  • What information is relevant in Mary’s history?
      • Recent contact with similar complaint
      • Scalp pruritus
      • School-aged child
      • All of the above
pediculosis lice the basics
Pediculosis (Lice): The Basics
  • Three different varieties of lice may infest humans
    • Head louse – Pediculus humanus var. capitis
    • Body louse – Pediculus humanus var. corporis
    • Pubic or crab louse – Phthirus pubis
  • Head lice are spread by close physical contact and may be transferred by use of head gear, combs, brushes, and pillows
  • Commonly affects school-age children
pediculosis capitis the basics
Pediculosis Capitis: The Basics
  • Affects all ethnic and socioeconomic groups, but is less common in African-Americans.
  • Frequently has associated scalp pruritus and may also have posterior cervical lymphadenopathy.
  • Live adult lice and nits (ova or eggs) may be noted on examination.
    • Most common sites to find nits are the retroauricular and occipital scalp.
    • Nits within 0.6 cm of the scalp are typically viable. In warm environments the distance may be greater.
    • Nits must be distinguished from hair casts. Hair casts encircle the hair shaft and move freely in contrast to the nit which is cemented to the hair.
skin exam findings
Skin Exam Findings

Exam of occipital scalp: Structures on the hair are not freely movable

case one question 2
Case One, Question 2
  • How would you describe Mary’s exam?
    • Multiple hair casts present in the occipital scalp. No nits or lice noted.
    • Multiple nits present in the occipital scalp. No lice noted.
    • Negative exam, no nits or lice noted.
case one question 21
Case One, Question 2

Answer: b

  • How would you describe Mary’s exam?
    • Multiple hair casts present in the occipital scalp. No nits or lice noted.
    • Multiple nits present in the occipital scalp. No lice noted.
    • Negative exam, no nits or lice noted.
skin exam findings1
Skin Exam Findings

Exam of occipital scalp: numerous nits

pediculosis pathogenesis
Pediculosis: Pathogenesis
  • Female adult lice live 30 days and lay 5-10 eggs (nits) per day at the base of the hair where it meets the scalp.
  • Eggs hatch in 8-12 days.
  • Lice typically survive 1-2 days away from the scalp. Eggs may survive up to 10 days away from the scalp.
  • Live eggs remain close to the scalp to maintain warmth and moisture but as the hair grows, the nits move off the scalp with the hair.
  • Because hair grows at a rate of ~ 1cm per month, the duration of infestation can be estimated by the distance of the nit from the scalp.
pediculosis pathogenesis1
Pediculosis: Pathogenesis
  • The adult louse at the right typically is 2-3 mm in length.
  • The presence of live adult lice, immature nymphs, and/or viable eggs indicates active infection.
follow up
Follow-up
  • Mary returns to clinic in four weeks for follow-up. Therapy was completed as directed but she still has nits present on exam which are approximately one inch from the scalp. A sample is on the slide that follows.
hair mount
Hair Mount

This image shows a nit without an intact cap (operculum) and is not viable (no larva inside).

Continued presence of nits does not always represent treatment failure.

pediculosis treatment
Pediculosis: Treatment
  • Physical removal of nits may be facilitated by using a fine-toothed comb (or nit picker) on wet, well-conditioned hair.
  • Occlusive methods have also been used to suffocate head lice using substances such as petroleum jelly and mayonnaise, but study results have been variable.
  • Over-the-counter and prescription topical therapies are listed on the following slide.
pediculosis treatment2
Pediculosis: Treatment
  • Individual patient risks should be assessed prior to choosing a topical therapy (age, allergy history, prior treatment, etc.).
  • It is prudent to retreat with topical therapies one week after initial therapy to kill the newly hatched lice.
  • Patients with refractory lice should be referred to a dermatologist.
case one question 3
Case One, Question 3
  • If Mary had live lice in the scalp on follow-up, what would be possible causes of treatment failure?
    • Not treating contacts (reinfestation)
    • Not properly cleaning the environment
    • Not retreating in 7-10 days
    • Incorrect application of the medication
    • Resistance of the organism to medication
    • All of the above
case one question 31
Case One, Question 3

Answer: f

  • If Mary had live lice in the scalp on follow-up, what would be possible causes of treatment failure?
    • Not treating contacts (reinfestation)
    • Not properly cleaning the environment
    • Not retreating in 7-10 days
    • Incorrect application of the medication
    • Resistance of the organism to medication
    • All of the above
pediculosis patient education
Pediculosis: Patient Education
  • All persons living in the home should be examined to avoid reinfestation.
    • If it is not possible to examine household members, treat without an exam if the treatment is not contraindicated.
  • Clothing and bedding should be washed and dried on the hot cycle.
  • Non-washable items may be placed in the dryer or stored in a sealed plastic bag for two weeks.
pediculosis patient education1
Pediculosis: Patient Education
  • Combs and brushes should also be washed in hot water and may be treated with a pediculocide.
  • Floors, furniture, and vehicles should be vacuumed to remove hair with potentially viable nits attached.
case two history
Case Two: History
  • HPI: Mike is a 21-month-old boy who was referred to the dermatology clinic for a rash that has been present for two weeks. He has been having problems sleeping due to itching.
  • PMH: no history of major illness or hospitalizations
  • Allergies: no known drug allergies
  • Medications: none
  • Family history: noncontributory
  • Social history: lives in the city and attends day care
  • ROS: pruritus
case two skin exam
Case Two: Skin Exam
  • Multiple erythematous papules throughout the trunk, extremities. Also involving the scrotum.
  • Burrows present in the 2nd-3rd web space on the right hand.
case two question 1
Case Two, Question 1
  • What in-office procedure would best help to confirm the diagnosis?
    • KOH preparation
    • Nail clipping
    • Skin scraping (mineral oil prep)
    • Wood’s light examination
case two question 11
Case Two, Question 1

Answer: c

  • What in-office procedure would best help to confirm the diagnosis?
    • KOH preparation
    • Nail clipping
    • Skin scraping (mineral oil prep)
    • Wood’s lamp examination
case two question 2
Case Two, Question 2
  • You perform a skin scraping on the patient and see the image on the following slide when you look through the microscope. What is present on the slide?
    • Eggs
    • Scabies mite
    • Scybala (scabies feces)
    • All of the above
case two question 22
Case Two, Question 2

Answer: d

  • You perform a skin scraping on the patient and see the image on the following slide when you look through the microscope. What is present on the slide?
    • Eggs
    • Scabies mite
    • Scybala (scabies feces)
    • All of the above
case two question 23
Case Two, Question 2

mite

scybala (feces)

egg

scabies the basics
Scabies: The Basics
  • Sarcoptes scabiei (scabies) affects patients of all ages and all socioeconomic classes, although more common in women and children.
  • Patients incongregated facilities are more prone to the infestation, such as nursing homes.
  • Most infections occur from direct contact with an infected individual. However, fomites can transmit the infection.
  • Females lay about three eggs per day, which hatch in four days. Most patients have less than 20 mites on the skin at a time.
scabies the basics1
Scabies: The Basics
  • The time from initial infestation to symptoms is 3-4 weeks because the rash is caused by hypersensitivity to the mites.
    • Papules may commonly involve the breasts, umbilicus, penis, scrotum, finger webs, wrists, and axilla.
    • The scalp and head are more frequently involved in infants, elderly, and immunosuppressed.
case two question 3
Case Two, Question 3
  • Which of the following clinical findings are considered pathognomonic for scabies?
    • Burrows
    • Diffuse involvement
    • Erythematous papules
    • Sparing of the groin
case two question 31
Case Two, Question 3

Answer: a

  • Which of the following clinical findings are considered pathognomonic for scabies?
    • Burrows
    • Diffuse involvement
    • Erythematous papules
    • Sparing of the groin
scabies
Scabies
  • Burrows are linear markings in the skin due to the movement of the mite. They are 1-10 mm in length and may be found most readily in the interdigital spaces, wrists, and elbows.
case two question 4
Case Two, Question 4
  • Mike’s mother tells you his uncle has AIDS and is currently hospitalized. Why is this important?
    • His uncle may have been the source of infection
    • If his uncle has scabies, it could cause an institutional outbreak
    • If his uncle gets scabies, it may be a more severe form
    • All of the above
case two question 41
Case Two, Question 4

Answer: d

  • Mike’s mother tells you his uncle has AIDS and is currently hospitalized. Why is this important?
    • His uncle may have been the source of infection (Immunosuppressed patients are at increased risk for infection)
    • If his uncle has scabies, it could cause an institutional outbreak (Patients with crusted scabies harbor more mites)
    • If his uncle gets scabies, it may be a more severe form (Immunosuppressed patients may develop crusted scabies)
    • All of the above
crusted scabies
Crusted Scabies

Refer to the HIV Dermatology module for more information on crusted scabies

scabies treatment
Scabies: Treatment
  • As in pediculosis, scabies treatment includes a two-pronged approach. The patient and the environment must both be treated.
  • Environmental care includes washing all clothing and linens in hot water, sealing items which may not be washed in bags for two weeks, and vacuuming.
scabies treatment1
Scabies: Treatment

For difficult to treat or severe scabies, refer to a dermatologist

case three history
Case Three: History
  • HPI: Mrs. Koehler is a 33-year-old woman who presented to clinic with “itchy bumps” which started over the weekend. No one else at home has a similar complaint.
  • PMH: GERD
  • Allergies: none
  • Medications: Omeprazole
  • Family history: not contributory
  • Social history: works in a diner as a waitress
  • ROS: negative
case three skin exam
Case Three: Skin Exam

Edematous papules scattered over the body. Some with signs of excoriation.

case three question 1
Case Three, Question 1
  • What is the most likely diagnosis?
    • Bedbug bites
    • Brown recluse spider bite
    • Chickenpox
    • Methicillin-resistant S. aureusfolliculitis
    • Pediculosiscorporis
case three question 11
Case Three, Question 1

Answer: a

  • What is the most likely diagnosis?
    • Bedbug bites
    • Brown recluse spider bite (normally single site)
    • Chickenpox (presents as dewdrop on a rose petal papules, vesicles, crusts in various stages more common in children)
    • Methicillin-resistant S. aureus folliculitis (follicular-based, may be pustular)
    • Pediculosis corporis (body lice) (normally blue-colored macules or excoriations are seen)
bedbugs the basics
Bedbugs: The Basics
  • Cimex lectularius (most common type) affect people from all racial and socioeconomic groups
  • May be spread via clothing and bedding while traveling, on mattresses, laundry, etc.
  • Stay hidden during the day and feed at night
  • Attracted to the warmth and carbon dioxide emitted by the patient
  • Bites may be multiple in a linear array referred to as “breakfast, lunch, and dinner”
bedbugs pathogenesis
Bedbugs: Pathogenesis
  • Typically have a blood meal every 3-5 days for 4-10 minutes
  • Saliva keeps blood meal flowing due to:
    • Nitrophorin, leading to vasodilation
    • An anticoagulant which prevents conversion of factor X to factor Xa
    • Apyrase, leading to inhibition of platelet aggregation
  • May live over a year without feeding
case three question 2
Case Three, Question 2
  • Which finding favors a diagnosis of bedbug bites?
    • Flecks of blood or feces on the bed sheets
    • Nocturnal assault
    • Sweet, pungent odor in the room
    • All of the above
case three question 21
Case Three, Question 2

Answer: d

  • Which finding favors a diagnosis of bedbug bites?
    • Flecks of blood or feces on the bed sheets
    • Nocturnal assault
    • Sweet, pungent odor in the room
    • All of the above
bedbugs treatment
Bedbugs: Treatment
  • Bites will typically resolve within 1-2 weeks
  • Symptomatic care may include topical. antipruritics such as corticosteroids and/or antibiotics (if secondary infection occurs).
  • Bed linens should be laundered and furniture vacuumed.
  • A professional exterminator may be needed to treat the home.
case four history
Case Four: History
  • HPI: Miss Dean is a 23-year-old woman who presented to clinic with a “painful bump” which started yesterday in the evening. She was cleaning out her attic earlier that day.
  • PMH: Asthma
  • Allergies: Penicillin
  • Medications: Albuterol inhaler
  • Family history: not contributory
  • Social history: college student
  • ROS: malaise
case four skin exam
Case Four: Skin Exam
  • Hemorrhagic bulla with surrounding ischemia and peripheral erythema
case four question 1
Case Four, Question 1
  • What is the most likely diagnosis?
    • Brown recluse spider bite
    • Ecthymagangrenosum
    • MRSA infection
    • Snake bite
case four question 11
Case Four, Question 1

Answer: a

  • What is the most likely diagnosis?
    • Brown recluse spider bite
    • Ecthymagangrenosum
    • MRSA infection
    • Snake bite
arachnid bites the basics
Arachnid Bites: The Basics
  • Only three genera of spiders found in the United States have bites toxic to humans: Latrodectus, Loxosceles, and Tegeneria.
  • Approximately 12,500 spider bites were reported to the American Association of Poison Control Centers and zero deaths secondary to spider bites in 2008.
  • This module will review the characteristics of the Loxoscelesreclusa, or brown recluse spider.
brown recluse the basics
Brown Recluse: The Basics
  • Characteristic violin-shaped dark brown marking on the cephalothorax seen at the left
  • Found in the Midwest and Southeast
brown recluse the basics1
Brown Recluse: The Basics
  • As noted by the name, the spider is typically not aggressive, but is reclusive.
  • Bites frequently occur when patients are disturbing areas where the spiders seek shelter (attics, closets, etc.) or putting on clothing containing the spiders.
  • Cardboard boxes may harbor the spiders as the corrugated structure mimics their natural habitat.
brown recluse clinical presentation
Brown Recluse: Clinical Presentation

This case shows the characteristic

“Red (peripheral erythema),

White (blanching), and

Blue (central violaceous area)”

sign of the brown recluse bite.

brown recluse clinical presentation1
Brown Recluse: Clinical Presentation
  • The initial wound may progress to necrosis and deep ulcer formation.
brown recluse differential
Brown Recluse: Differential

MRSA infections may frequently be mistaken for spider bites. Pyoderma gangrenosum and erythema migrans (Lyme disease) may be considered also.

case four question 2
Case Four, Question 2
  • What leads to tissue destruction in the brown recluse bite?
    • Amylase
    • Keratolytics
    • Solenopsin D
    • Sphingomyelinase D
case four question 21
Case Four, Question 2

Answer: d

  • What leads to tissue destruction in the brown recluse bite?
    • Amylase
    • Keratolytics
    • Solenopsin D
    • Sphingomyelinase D
brown recluse complications
Brown Recluse: Complications
  • Tissue necrosis may occur due to the presence of multiple proteins in the venom.
  • In addition, some patients may develop systemic symptoms including malaise, nausea, vomiting, etc.
  • Uncommonly significant hemolysis, renal failure, anemia, and/or hypotension may occur.
brown recluse management
Brown Recluse: Management
  • Supportive care including cleansing the wound, cold compresses, and pain control is important.
  • Multiple treatments have been suggested, but not consistently shown to be beneficial.
  • The wound at right healed with close monitoring, topical therapy with antibiotic ointment, and nonstick wound dressings without requiring surgical debridement.
take home points
Take Home Points
  • Pediculosis capitis commonly affects school-aged children.
  • Nits and/or adult lice are diagnostic of pediculosis capitis.
  • Pediculosis capitis therapy includes physical removal and over-the-counter or prescription topical therapy.
  • Scabies affects all classes of patients, but those in group settings or in an immunocompromised state are at increased risk of infestation.
  • The primary morphology of scabies is a burrow. Pruritic papules and areas of crusting may be seen as well.
  • The primary diagnostic test for scabies is the skin scraping, or mineral oil prep.
  • First-line treatment for scabies in patients over two months of age who are not pregnant is permethrin 5% cream.
take home points1
Take Home Points
  • Bedbugs infest all populations. They typically feed at night.
  • Bedbug bites cause edematous papules which are frequently arranged in a “breakfast, lunch, and dinner” pattern.
  • Insect bite reactions may be treated with topical corticosteroids and antibiotics if indicated.
  • Brown recluse spiders are only found in the Midwest and Southeast. They have a characteristic violin-shaped marking on their cephalothorax.
  • MRSA infection is frequently misdiagnosed as brown recluse spider bites.
  • The primary therapy for a brown recluse spider bite is supportive care.
acknowledgements
Acknowledgements
  • This module was developed by the American Academy of Dermatology Medical Student Core Curriculum Workgroup from 2008-2012.
  • Primary author: Jennifer Swearingen, MD.
  • Peer reviewers: Susan K. Ailor, MD, FAAD; Cory A. Dunnick, MD, FAAD, Timothy G. Berger, MD, FAAD.
  • Revisions and editing: Jennifer Swearingen, MD; Sarah D. Cipriano, MD, MPH; Jillian W. Wong. Last revised in August 2011.
  • Thank you to Dr. BaharDasgeb, Dr. Steven Daveluy, Dr. Stephanie Diamond,Dr. Dirk Elston, Dr. Darius Mehregan, Dr. David Mehregan, and Dr. Robert Schoenfeld for their assistance in obtaining images for the module.
references
References

Bronstein AC, Spyker DA, Cantilena LR, et al. 2008 Annual Report of the American Association of Poison Control Centers’ National Poison Data System (NPDS): 26th Annual Report. Clinical Toxicology. 2009; 47: 1027.

Chosidow O. Scabies and pediculosis. Lancet. 2000; 355(9206): 819-26.

Epocrates Rx [database for PDA]. Version 9.0. San Mateo (CA): Epocrates, Inc. c2009 [updated 2010 Sept; cited 2010 Sept]. Available from: http://www.epocrates.com.

Goldstein BG, Goldstein AO. Scabies. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA, 2011.

James WD, Berger TG, Elston DM, “Chapter 20. Parasitic Infestations, Stings, and Bites” (chapter). Andrews’ Diseases of the Skin Clinical Dermatology. 10th ed. Philadelphia, Pa: Saunders Elsevier; 2006: 446-448.

Kolb A, Needham GR, Neyman KM, High WA. Bedbugs. Dermatol Ther. 2009; 22 (4):347-52.

references1
References

Meinking TL, Burkhart CN, Burkhart CG, Elgart G. Infestations. In: Bolognia JL, Jorizzo, JL, Rapini RP, eds. Dermatology. 2nd ed. Spain: Elsevier; 2008. MD Consult Web site. Available at http://www.mdconsult.com/books/page.do?eid=4-u1.0-B978-1-4160-2999-1..50088-6&isbn=978-1-4160-2999-1&sid=1055850616&type=bookPage&sectionEid=4-u1.0-B978-1-4160-2999-1..50088-6--cesec2&uniqId=219284186-4#4-u1.0-B978-1-4160-2999-1..50088-6--cesec2 Accessed September 20, 2010.

Steen Christopher J, Schwartz Robert A, "Chapter 210. Arthropod Bites and Stings" (Chapter). Wolff K, Goldsmith LA, Katz SI, Gilchrest B, Paller AS, Leffell DJ: Fitzpatrick's Dermatology in General Medicine, 7e: http://www.accessmedicine.com/content.aspx?aID=3000969.

Stone Stephen P, Goldfarb Jonathan N, Bacelieri Rocky E, "Chapter 208. Scabies, Other Mites, and Pediculosis" (Chapter). Wolff K, Goldsmith LA, Katz SI, Gilchrest B, Paller AS, Leffell DJ: Fitzpatrick's Dermatology in General Medicine, 7e: http://www.accessmedicine.com/content.aspx?aID=2971870.

Wolf R, Davidovici B. Treatment of scabies and pediculosis: facts and controversies. Clin Dermatol. 2010; 28(5): 511-8.