Lecture 12

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Questions and Answers

What is the main cause of Cutaneous Larva Migrans (CLM)?

Insect venom exposure

Direct contact with infected animals

Exposure to cold, icy conditions

Contact with contaminated warm, sandy soil (correct)

How does the eruption of Cutaneous Larva Migrans typically present?

A rash that spreads uniformly without blisters

Small red bumps without significant itching

An extensive red rash covering the entire body

A red, itchy, serpiginous line with possible blisters (correct)

Which organism is primarily responsible for causing Cutaneous Larva Migrans?

Dermatobia hominis

Anopheles gambiae

Ancylostoma braziliense (correct)

Aedes aegypti

What type of reactions do insect bites usually provoke immediately?

Immediate reactions due to insect venom Signup and view all the answers

Which of the following types of reactions may occur after several hours to days from an insect bite?

Delayed allergic reactions Signup and view all the answers

What is the typical appearance of delayed allergic reactions to insect bites?

Itchy, red papules Signup and view all the answers

What are the systemic reactions typically associated with a black widow spider bite?

Muscle spasms and pain Signup and view all the answers

Which treatment is commonly used for Cutaneous Larva Migrans?

Ivermectin or albendazole Signup and view all the answers

What distinguishes immediate reactions from delayed toxic reactions in insect bites?

Immediate reactions occur right away; delayed reactions can take time to develop Signup and view all the answers

Which of the following insects are known to cause immediate reactions as a defense mechanism?

Bees Signup and view all the answers

What is considered the most effective insect repellent?

DEET Signup and view all the answers

How should anaphylaxis from insect stings be treated?

Epinephrine and systemic steroids Signup and view all the answers

What is a common symptom of Seabather’s Eruption?

Itchy red papules Signup and view all the answers

What action is recommended to prevent insect bites from blood-feeding insects?

Using insect repellents Signup and view all the answers

What is the recommended concentration of DEET for daily use?

10% Signup and view all the answers

What is a typical reaction time for Seabather’s Eruption to occur?

Within 24 hours of swimming Signup and view all the answers

What is the typical time frame in which sunburn becomes noticeable after exposure?

4 to 24 hours Signup and view all the answers

What is a common characteristic of severe sunburns?

They may lead to permanent lentigines. Signup and view all the answers

How does melanin provide protection against UV radiation?

By absorbing UV radiation. Signup and view all the answers

Which type of UV rays is considered to be the 'burning rays'?

UVB rays Signup and view all the answers

What should be applied every 6-8 hours to minimize sunburn symptoms?

Medium- to high-potency topical steroid Signup and view all the answers

What is one of the main differences between UVA and UVB rays?

UVA penetrates deeper into the skin than UVB. Signup and view all the answers

What can be done to help relieve symptoms of sunburn?

Keeping the skin moisturized Signup and view all the answers

What is a primary method for preventing sunburn?

Using sunscreens and protective clothing Signup and view all the answers

What is the primary cause of the rash associated with poison ivy and oak?

Urushiol present in the sap of the plant Signup and view all the answers

During which phase does a rash typically occur after initial exposure to poison ivy or oak?

Elicitation phase Signup and view all the answers

How long after exposure can a rash develop in a sensitized individual?

6 hours to 6 days Signup and view all the answers

What is the recommended action if exposed to poison ivy or oak?

Wash the affected area within 30 minutes Signup and view all the answers

What happens to the urushiol after the plant has died?

It remains allergenic for weeks or months Signup and view all the answers

What is the typical reaction mechanism of lymphocytes during re-exposure to urushiol?

Memory T-cells react to the presented antigen Signup and view all the answers

What primarily causes swimmer's itch?

Schistosome larvae Signup and view all the answers

Which type of dermatitis is caused by poison ivy and oak?

Allergic contact dermatitis Signup and view all the answers

What is the factor that influences the severity of the allergic reaction?

Magnitude of exposure and sensitivity of the patient Signup and view all the answers

Which condition is characterized by a foreign body reaction in the skin?

Swimmer's itch Signup and view all the answers

What is the typical time frame for hot tub folliculitis to develop after exposure?

1 to 3 days Signup and view all the answers

Which of the following would most likely cause seabather's eruption?

Contact with thimble jellyfish larvae Signup and view all the answers

What is the typical treatment for swimmer's itch?

Topical steroids and antihistamines Signup and view all the answers

What can be a rare symptom associated with hot tub folliculitis?

Low grade fever Signup and view all the answers

Which demographic is more likely to experience sunburn?

Younger and more lightly pigmented individuals Signup and view all the answers

What is the likely duration for hot tub folliculitis to resolve in immunocompetent patients?

10-14 days Signup and view all the answers

What is the primary reason that tanning beds do not provide the same level of sunburn protection as natural sunlight?

Tanning beds emit only UVA radiation. Signup and view all the answers

Which plant substance is most commonly associated with phytophotodermatitis?

Lime juice Signup and view all the answers

What type of skin change is typically observed in cases of phytophotodermatitis?

Asymptomatic brown hyperpigmentation Signup and view all the answers

How long after exposure to a photosensitizing substance can discoloration from phytophotodermatitis appear?

1-2 weeks Signup and view all the answers

What causes the clinical manifestations of phytophotodermatitis at a molecular level?

Non-oxidative DNA cross-linking and oxidative DNA damage Signup and view all the answers

Which of the following symptoms is least likely to be remembered by patients experiencing phytophotodermatitis?

Erythema with stinging Signup and view all the answers

What is the common allergic reaction associated with poison ivy exposure?

50% - 70% of individuals are allergic. Signup and view all the answers

What is the typical timeframe for the pigmentation from phytophotodermatitis to normalize?

Up to 2 years Signup and view all the answers

Study Notes

Vacation Dermatoses

Cutaneous Larva Migrans (CLM) is caused by skin exposure to warm, sandy soil contaminated with cat or dog feces.
The eruption is reddish, itchy, and serpiginous, sometimes with blisters.
It most commonly affects the feet and extends 1-2 cm daily.
CLM is caused by a hookworm ( Ancylostoma braziliense or Ancylostoma caninum) that infects dogs and cats.
The hookworm can't penetrate the basement membrane, remaining in the epidermis until death.
CLM usually resolves spontaneously as the organism dies off.
Treatment includes anti-helminthic agents like ivermectin or albendazole.

Insect Bites and Stings

Reactions can be immediate, delayed allergic, or delayed toxic.
Immediate reactions: Occur immediately and result from insect venom. Symptoms include pain, stinging, itching, swelling, and skin redness.
Delayed allergic reactions: Appear hours to days later. Symptoms are usually itchy, reddish papules.
Delayed toxic reactions: Also appear hours to days later. Can be localized (like an ulcer) or systemic reactions like pain and paralysis, possibly due to toxins from spiders.

Seabather's Eruption and Swimmer's Itch

Seabather's eruption develops within 24 hours of swimming in saltwater.
It presents as itchy, red papules and macules.
Swimmer's itch develops within a few hours of swimming in freshwater.
It also presents as itchy, red skin lesions in areas of skin not covered by the bathing suit.
Seabather's eruption is caused by immature jellyfish larvae and other stinging larvae that penetrate the skin.
Swimmer's itch is caused by schistosome larvae.
Both conditions resolve spontaneously within a few weeks.

Hot Tub Folliculitis

It appears days after exposure to an inadequately chlorinated hot tub that is contaminated.
Symptoms are red, follicular based papules, possibly itchy.
Lesions may appear on skin covered by the bathing suit, or exposed skin in contact with the hot tub.
Treatment usually isn't necessary, and resolves within a few weeks.
In immunosuppressed patients, it might become a significant infection.

Sunburn

Symptoms are erythema and pain of the affected skin.
It can develop 4-24 hours after exposure to UV rays.
Severe sunburn may include blistering.
Recovery time varies depending on the severity of the burn.
Severe cases can lead to skin desquamation and permanent lentigines.

Phytophotodermatitis

Manifests as brown hyperpigmentation on areas of skin exposed to sunlight.
Caused by photosensitizing substances, such as those found in lime juice.
Symptoms can appear 1-2 weeks after exposure and may persist for up to two years.

Poison Ivy and Poison Oak

Contact with these plants can cause an allergic contact dermatitis, triggering an immune response.
The first exposure often doesn't cause symptoms, leading to sensitization.
On subsequent exposure, there is a rash that may be itchy and appear in a streaky pattern, and vesicles.
The allergen, urushiol, is highly potent and can remain active for weeks.
Treatment involves symptomatic management with topical steroids and anti-histamines.

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Description

Explore the causes and treatments of vacation dermatoses such as Cutaneous Larva Migrans. This quiz covers the reactions from insect bites and stings, including immediate and delayed allergic responses. Test your knowledge on common skin issues encountered during vacations.