K16 Ectoparasites 2
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K16 Ectoparasites 2

Learn about the biology of ticks, their feeding habits, and the diseases they can transmit to humans and animals, including Lyme disease, Rocky Mountain spotted fever, and more.

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@JoyousAlgebra

Questions and Answers

What is the typical duration of the life cycle of two-host ixodid ticks?

Over two years

What is the stage of the tick life cycle that usually overwinters?

Nymphs

Which host is usually a larger herbivore?

Second host

What is the name of the disease caused by a tick-borne virus of the Bunyaviridae family?

<p>Crimean-Congo hemorrhagic fever</p> Signup and view all the answers

What is the stage of the tick life cycle that seeks out the first host?

<p>Larvae</p> Signup and view all the answers

What is the purpose of the female tick dropping off the second host?

<p>To lay eggs</p> Signup and view all the answers

Can humans serve as both the first and second hosts for ticks with a two-host life cycle?

<p>Yes</p> Signup and view all the answers

What is the typical duration of the life cycle of three-host hard ticks?

<p>Over three years</p> Signup and view all the answers

What is the primary purpose of using permethrin on clothing?

<p>To repel ticks from attaching to the body</p> Signup and view all the answers

What is the most effective way to prevent ticks from attaching to the body while walking in wooded areas?

<p>Wearing long trousers and applying permethrin to clothing</p> Signup and view all the answers

What is the name of the tick-borne encephalitis (TBE) vaccine approved by the U.S. Food and Drug Administration?

<p>TICOVAC</p> Signup and view all the answers

Why should you avoid sleeping on the floors of mud houses?

<p>Because ticks are more likely to be present on floors</p> Signup and view all the answers

What is the purpose of examining the body frequently for ticks?

<p>To remove attached ticks from the body</p> Signup and view all the answers

What is the benefit of using metal beds in areas with high tick infestation?

<p>Ticks have difficulty climbing on metal surfaces</p> Signup and view all the answers

What is the purpose of tucking trousers into boots or socks?

<p>To prevent ticks from crawling up the legs</p> Signup and view all the answers

What is the type of insecticide used to impregnate clothing to prevent tick bites?

<p>Pyrethroid</p> Signup and view all the answers

What is a challenge in diagnosing scabies?

<p>Excoriations may change the appearance of the lesions</p> Signup and view all the answers

Why is it important to decontaminate bedding and clothing?

<p>To kill scabies mites and their eggs</p> Signup and view all the answers

What is a common misdiagnosis of scabies?

<p>All of the above</p> Signup and view all the answers

How can scabies be prevented?

<p>By avoiding skin-to-skin contact with infested persons</p> Signup and view all the answers

What is the habitat of Demodex folliculorum?

<p>Sebum gland on the skin around nose and face</p> Signup and view all the answers

What is a common symptom of Demodex folliculorum infestation?

<p>Blackheads and acne</p> Signup and view all the answers

Why is it important to treat all close contacts of an infested person?

<p>To prevent indirect spread of scabies</p> Signup and view all the answers

How long should lindane 1% lotion be left on the skin?

<p>12 to 24 hours</p> Signup and view all the answers

What type of organisms do ticks feed on?

<p>Reptiles, amphibians, and mammals</p> Signup and view all the answers

What is the primary characteristic of an oblige hematophage?

<p>It feeds on the blood of animals</p> Signup and view all the answers

What is the primary way that ticks can infect humans and animals with diseases?

<p>Through their bite</p> Signup and view all the answers

Which of the following diseases is NOT typically spread by ticks?

<p>Malaria</p> Signup and view all the answers

What is the main difference between the morphology of hard ticks and soft ticks?

<p>Hard ticks have a dorsal shield, while soft ticks do not</p> Signup and view all the answers

What is the typical life cycle of most ticks?

<p>Egg, larva, nymph, adult</p> Signup and view all the answers

What is the advantage of some species of ticks molting on their host?

<p>They do not have to risk finding another host</p> Signup and view all the answers

Why are multiple-host tick species able to exist?

<p>Because they have a great reproduction rate and can survive for a long time without food</p> Signup and view all the answers

What is a common symptom of scabies?

<p>Pruritus</p> Signup and view all the answers

Where are burrows typically noted in scabies infestations?

<p>Hands, wrists, and genitalia</p> Signup and view all the answers

What is the likely representation of erythematous papules in scabies?

<p>An immune response</p> Signup and view all the answers

What is the complication of intense itching in scabies?

<p>Skin sores</p> Signup and view all the answers

Who is at risk for a severe form of scabies called crusted, or Norwegian, scabies?

<p>Immunocompromised, elderly, disabled, or debilitated persons</p> Signup and view all the answers

What is the characteristic of crusted scabies?

<p>Thick crusts of skin that contain large numbers of scabies mites and eggs</p> Signup and view all the answers

How can persons with crusted scabies transmit scabies?

<p>Through both direct skin-to-skin contact and indirect contact with contaminated items</p> Signup and view all the answers

How can scabies be confirmed?

<p>On microscopic examination of scrapings from burrows and papules</p> Signup and view all the answers

Study Notes

Ticks and Tick-Borne Diseases

  • Ticks can feed on reptiles, amphibians, and mammals, and can become larger and more visible after feeding on blood.
  • Tick bites can transmit diseases caused by bacteria, viruses, and protozoans to humans and animals.
  • Some of the diseases spread by ticks include:
    • Lyme disease
    • Colorado tick fever
    • Tularemia
    • Powassan virus
    • Ehrlichiosis
    • Southern tick-associated rash illness (STARI)
    • Rocky Mountain spotted fever
    • Tick paralysis
    • Anaplasmosis
    • Spotted fever
    • Babesiosis
    • Relapsing fever
    • Heartland virus

Morphology of Ticks

  • Hard ticks have a dorsal shield, which covers the entire dorsal surface in males and only a small portion in females.
  • Soft ticks have a leathery body surface and do not have a dorsal shield.
  • Mouthparts of ticks are sub-terminally attached and not visible from the dorsal view.

Life Cycle of Ticks

  • Most ticks go through four life stages: egg, six-legged larva, eight-legged nymph, and adult.
  • Each stage requires a host, and some species can molt on the host.
  • Female ticks drop from the host to lay eggs, and the cycle repeats.
  • Two-host and three-host ticks have different life cycles that can span over two or three years.

Personal Protections and Prophylactic Measures

  • Personal strategies to avoid ticks include:
    • Avoiding grassy areas with shrubs
    • Wearing long trousers and socks
    • Applying permethrin (an insect repellent) to clothing
  • Prophylactic measures include:
    • Vaccines (e.g. TICOVAC for tick-borne encephalitis)
    • Removing attached ticks and examining the body frequently

Clinical Features and Diagnosis of Scabies

  • Scabies causes pruritus, burrows, and erythematous papules on the skin.
  • Burrows typically appear on the hands, wrists, and genitalia, while erythematous papules are seen on the trunk.
  • Scabies can lead to skin sores and bacterial infections.
  • Diagnosis can be confirmed through microscopic examination of scrapings from burrows and papules.

Crusted (Norwegian) Scabies

  • Crusted scabies is a severe form of scabies that affects immunocompromised, elderly, disabled, or debilitated persons.
  • It is characterized by thick crusts of skin containing large numbers of scabies mites and eggs.
  • Crusted scabies is highly contagious and can be transmitted indirectly through contaminated items.

Treatment of Scabies

  • Treatment involves applying a topical cream (e.g. lindane or permethrin) to the entire body, washed off several hours after application.
  • Bedding, clothing, and towels used by infested persons should be decontaminated by washing in hot water and drying in a hot dryer.

Follicle Mites (Demodex folliculorum)

  • Follicle mites cause blackhead, pimples, and acne.
  • They are more prevalent in those with oily skin.
  • Habitat: sebum gland on the skin around the nose and face.
  • Larger numbers of Demodex folliculorum mites can cause unwanted symptoms and skin problems.

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