Wingless b dorsoventrally flattened

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Lice and typhus

March 5, 2008, Pages 202-210

1. List four morphological characteristics that characterize lice

a. wingless b. dorsoventrally flattened c. heavily sclerotized d. reduced sensory apparatus, haustellate mouthparts, equipped with claws for “holding on”

2. Because of differences in mouthpart structure and feeding behavior, the Anoplura are known as the sucking lice and the Mallophaga as the biting lice; both belong to the order Phthiraptera
3. What group is intermediate between the Anoplura and Mallophaga? Rhyncophthirina

What are its intermediate characteristics? Elongate mouthparts

4. A nit is:

a. mark on the skin made by louse feeding c. an immature louse

b. a louse egg d. a louse dropping
5. Human infestation by body or head lice is known as pediculiasis; infestation by crab lice is phthiriasis. The “disease” of being infested with lice is known as pediculosis.
6. Match the scientific name with the common name

Pediculus humanus humanus Crab louse Phthirus pubis

Pediculus humanus capitis Body louse Pediculus humanus humanus

Phthirus pubis Head louse Pediculus humanus capitis
What is the evidence that head lice and body lice are actually the same species?

Molecular evidence (DNA) shows that they are the same species

Which came first—head lice or body lice?

Which came first—gorilla lice or crab lice?
How can you distinguish crab lice from head or body lice?

Crab lice has a wider body and has bigger “claws” that grasp thicker hairs.

7. True or false: Head lice have not yet shown resistance to permethrin-based insecticides.

8. What is a cootie?

Pediculus humanus humanus

9. Exanthematous typhus is caused by Rickettsia prowazekii, a

a. virus b. rickettsia c. protozoan d. nematode
10. In what year was the genome of Rickettsia prowazekii sequenced? How many genes does it have? 1998, 834 genes
11. T or F:: Lice inject the pathogens that cause typhus into the feeding site along with saliva.
12. Typhus is/is not always fatal to a louse.

13. List four symptoms of typhus:

a. headache b. macular/papulomacular rash on trunk c. mental disorientation d. uremia, circulatory collapse
14. True or false: Crab lice are important vectors of typhus.
15. More people died of typhus than of battle wounds in which war(s)?

a. Napoleon’s march on Moscow b. Crimean War c. World War II d. Korean War

16. Describe the contributions of the following people to the history of typhus:

a. Florence Nightingale-cleaned up the hospitals

b. Stanislaus von Prowazek-studied transmission of typhus

c. H.T. Ricketts-described rickettsia as the pathogen

d. Charles Nicolle-discovered transmission by the louse

e. H. da Rocha Lima-identified rickettsia in louse guts

e. Hans Zinsser-developed a vaccine

17. Today, deaths from typhus worldwide number in the

a. hundreds

b. thousands

c. tens of thousands

d. hundreds of thousands

18. When was the Rickettsia prowazekii genome sequenced?

a. 1998 b. 2000 c. 2005 d. 2007
19. When was the first draft of the Pediculus humanus genome completed?

a. 1998 b. 2000 c. 2005 d. 2007

20. True or false: The genome of the body louse is enormous compared with the genomes of other insects
21. Which of the following diseases are also vectored by lice?

a. Rocky Mountain spotted fever c. epidemic relapsing fever

b. trench fever d. dengue
22. What is the vector of murine typhus?

a. rat flea c. lice

b. chiggers d. ticks

23. What is the vector of scrub typhus?

a. rat flea c. lice

b. chiggers d. ticks
24. Tsutsugamushi is caused by scrub typhus;

murine typhus is caused by rat flea.

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