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K15 Ectoparasites 1

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40 Questions

What is the typical length of a Pediculus humanus capitis (Head Lice)?

2-3 mm

What is the main mode of transmission of body lice infestations?

Through close person-to-person contact

What is a common symptom of body lice infestation?

Intense itching and rash

What is the primary characteristic of ectoparasites?

They remain on the skin for relatively long periods.

Which of the following statements about head lice is true?

Head lice are known to cause intense itching

Which class does Fleas, Lice, and Bedbugs belong to?


What is the primary habitat of body lice?

On clothing

What is the order of Lice?


What is a potential complication of body lice infestation?

Secondary bacterial infection of the skin

What is the main difference between head lice and body lice?

Their habitat

What is a characteristic of insects?

Chitinous exoskeleton and three pairs of legs

How long does it take for itching to appear after a person gets head lice for the first time?

4-6 weeks

What is the body structure of insects?

Three-part body

Why are body lice infestations more common in certain populations?

Due to poor hygiene

What is the primary way head lice infestation is spread?

Through close person-to-person contact

How long can head lice survive if they fall off a person and cannot feed?

Less than 1-2 days

What is a characteristic of Arachnida?

Four pairs of legs

What is the classification of Lice?

Kingdom: Animalia

What is the nickname of pubic lice?


How are pubic lice typically spread?

Through close personal contact

What is a characteristic of Lice?

Small and wingless

What is the typical symptom of pubic lice infestation?

Itching in the pubic and groin area

What is unique about the front legs of pubic lice?

They are very large and resemble pincher claws

What is NOT a way that head lice can be spread?

Through contaminated food and water

What is the primary method of treating body lice?

Improving the personal hygiene of the infested person

What is the minimum temperature required to kill lice and eggs when washing clothes?


What is the purpose of using a magnifying lens when checking for lice?

To distinguish lice eggs from other particles found in hair

What is the function of some pediculicides?

To kill both lice and eggs

What is a characteristic of adult bed bugs that have recently fed?

They are balloon-like and reddish-brown.

Why is it important to wash and dry hats, scarves, pillowcases, bedding, clothing, and towels?

To destroy lice and eggs

What is unique about the antennae of true bugs?

They have four parts.

What is the recommended frequency for changing clean clothes worn by the infested person?


What is the name of the medicinal ingredient used in some lice-killing lotions?


What is the purpose of Integrated Pest Management (IPM)?

To use pesticides judiciously and carefully.

What is the recommended action after vacuuming to reduce bed bug populations?

Immediately seal and dispose of the vacuum bag.

What is the name of the FDA-approved medicinal ingredient for treating lice?

Ivermectin lotion

What is the characteristic of young bed bugs (nymphs) when they have not fed recently?

They are smaller and nearly invisible.

What is the purpose of installing bed bug interceptors?

To prevent bed bugs from climbing up furniture legs.

What is a characteristic of bed bug eggs?

They are pearl-white in color.

What is essential for all stages of Cimex spp.?

Blood meals from warm-blooded hosts.

Study Notes


  • Ectoparasites are pathogens that infect only the superficial layers of the skin, attaching or burrowing into the skin and remaining there for relatively long periods of time.

Classification of Ectoparasites

  • Class: Insecta (Fleas, Lice, and Bedbugs)
  • Class: Arachnida (Ticks and Mites)

Characteristics of Insecta

  • Chitinous exoskeletons
  • Three-part bodies (divided into head, thorax, and abdomen)
  • Three pairs of legs
  • Two antennae


  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Phthiraptera

Biology of Lice

  • Small, wingless, blood-sucking ectoparasites of mammals and birds
  • Prevalence: Low standard hygiene
  • Infestation: Pediculosis
  • Have humans as their only host
  • Have similar life cycles
  • Morphology: Body Dorso-ventrally flattened, 3 parts: Head - Thorax - Abdomen

Types of Lice

  • Head lice: Pediculus humanus capitis (2-3 mm long)
  • Body lice: Pediculus humanus corporis (2.3-3.6 mm long)
  • Pubic lice (crabs): Pthirus pubis (1.1-1.8 mm long)

Body Lice

  • Also known as Pediculus humanus humanus
  • Adult body lice are 2.3–3.6 mm in length
  • Live and lay eggs on clothing and only move to the skin to feed
  • Symptoms: Intense itching and rash caused by an allergic reaction to louse bites
  • Can transmit disease (epidemic typhus, Bartonella quintana infection, and epidemic relapsing fever)

Head Lice

  • Not known to transmit any disease
  • Symptoms: Itching (“pruritus”) - caused by an allergic reaction to louse bites
  • Infestation: Pediculosis
  • Spread: Close person-to-person contact
  • Not transmitted by animals

Pubic Lice

  • Pubic (“crab”) lice: Dorsoventrally-flattened
  • Adults are much broader in comparison to head and body lice
  • Second and third legs have a large modified claw with a thumb-like projection, used for grasping on to hair shafts
  • Symptoms: Itching (“pruritus”) in the pubic and groin area
  • Spread: Through sexual contact, close personal contact, or contact with materials used by an infested person

Treatment of Lice

  • Body Lice: Improve personal hygiene, assure regular change of clean clothes
  • Head Lice: Use pediculicides (medicines that kill lice), routine retreatment recommended
  • Pubic Lice: Use lice-killing lotion containing 1% permethrin or a mousse containing pyrethrins and piperonyl butoxide


  • Adult bed bugs: About the size of an apple seed (5-7 mm or 3/16 - 1/4 inch long), brown, with a flat, oval-shaped body
  • Young bed bugs (nymphs): Smaller, translucent or whitish-yellow in color
  • Bed bug eggs: Tiny, pearl-white in color, marked by an eye spot if more than five days old

Life Cycle of Bedbugs

  • Two species of bed bugs (Insecta: Hemiptera: Cimicidae) implicated in human infestations: Cimex lectularius and C. hemipterus
  • Adults and all nymphal stages need to take blood meals from warm-blooded hosts, typically humans

Control Measures for Bedbugs

  • Integrated Pest Management (IPM): Environmentally sensitive approach to pest management that relies on knowledge of the pest and a combination of common-sense practices
  • Environmental Modification: Vacuuming, sealing cracks, using barriers, and judicious use of pesticides if needed

Learn about ectoparasites, including lice, fleas, and bedbugs, and their impact on human health. This quiz covers the general introduction to ectoparasites and their types.

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