K17 SCRUB TYPHUS
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Questions and Answers

What is the name of the bacteria that causes scrub typhus?

  • Orientia tsutsugamushi
  • Rickettsia tsutsugamushi
  • Both a and b (correct)
  • Leptotrombidium deliense
  • What is the primary mode of transmission of scrub typhus?

  • Through bites of infected mosquitoes
  • Through bites of infected chiggers (larval mites) (correct)
  • Through contaminated food and water
  • Through direct contact with infected animals
  • What are the common symptoms of scrub typhus?

  • Cough, fever, and sore throat
  • Rash, fever, and diarrhea
  • Fever, headache, body aches, and sometimes rash (correct)
  • Fever, headache, and body aches
  • What is the typical size of a chigger?

    <p>About 1/20 inch long</p> Signup and view all the answers

    What is the name of the mite vector that transmits scrub typhus?

    <p>Leptotrombidium deliense</p> Signup and view all the answers

    What is the typical characteristics of the larval stage of the chigger?

    <p>Three pairs of legs and no constriction in the front part of the body</p> Signup and view all the answers

    What is the typical color of the chigger mite?

    <p>Bright red</p> Signup and view all the answers

    What are the typical hosts of the chigger mites?

    <p>A wide variety of animals such as snakes, turtles, birds, and small mammals as well as humans</p> Signup and view all the answers

    What is the diameter of chigger larvae?

    <p>1/150 to 1/120 inch</p> Signup and view all the answers

    What is the purpose of the salivary secretion injected into the host by chigger larvae?

    <p>To break down skin cells for digestion</p> Signup and view all the answers

    How do chigger larvae typically find a host?

    <p>By crawling on soil or up grass blades</p> Signup and view all the answers

    What is the purpose of the straw-like feeding tube formed by chigger larvae?

    <p>To suck up partially-digested skin cells</p> Signup and view all the answers

    How is scrub typhus fever typically transmitted?

    <p>Through the bite of an infected chigger</p> Signup and view all the answers

    What is the role of the dermatologist in diagnosing scabies?

    <p>To remove some skin to examine under a microscope</p> Signup and view all the answers

    What stage of the chigger's life cycle is responsible for transmitting scrub typhus fever?

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

    What is the shape of chigger eggs?

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

    What is the typical duration of symptoms after exposure to a chigger bite?

    <p>A week or more</p> Signup and view all the answers

    What is the primary method of preventing scrub typhus?

    <p>Avoiding areas with high vegetation and brush</p> Signup and view all the answers

    What is the typical outcome for people who are treated early with doxycycline for scrub typhus?

    <p>They usually recover quickly</p> Signup and view all the answers

    What is the purpose of treating clothing and gear with 0.5% permethrin?

    <p>To kill chiggers</p> Signup and view all the answers

    What is the potential consequence of scratching a chigger bite?

    <p>It may result in secondary infections</p> Signup and view all the answers

    What is the characteristic of the red welt that develops after a larva is fully fed?

    <p>It has a hard, white central area</p> Signup and view all the answers

    What is the most effective time to administer antibiotics for scrub typhus?

    <p>Soon after symptoms begin</p> Signup and view all the answers

    What is the purpose of dressing children in clothing that covers arms and legs or covering their gear with mosquito netting?

    <p>To prevent bites from infected chiggers</p> Signup and view all the answers

    Study Notes

    Background on Scrub Typhus

    • Scrub typhus, also known as bush typhus, is a disease caused by the bacterium Orientia tsutsugamushi (formerly known as Rickettsia tsutsugamushi).
    • The disease is spread to humans through the bites of infected chiggers (larval mites).

    Life Cycle of Chiggers

    • The life cycle of chiggers consists of several stages: egg, deutovum, larva, protonymph, deutonymph, tritonymph, and adult.
    • Only the larval stage bites humans.
    • Eggs are laid in damp soil during the first warm spring weather.

    Symptoms of Scrub Typhus

    • Common symptoms include fever, headache, body aches, and sometimes a rash.
    • A dark, scab-like region at the site of the chigger bite (eschar) may form.
    • Enlarged lymph nodes and rash may also occur.
    • In severe cases, organ failure and bleeding can occur, which can be fatal if left untreated.

    Transmission

    • Scrub typhus fever is not spread from person-to-person.
    • The disease is spread through the bite of an infected chigger.

    Diagnosis

    • Diagnosis is made by examining a skin scraping under a microscope to detect the presence of chiggers or their eggs.

    Pathogenesis

    • Chigger larvae pierce the skin and inject a salivary secretion containing powerful digestive enzymes that break down skin cells.
    • The digestive fluid causes surrounding tissues to harden, forming a straw-like feeding tube.

    Treatment and Prevention

    • Scrub typhus should be treated with the antibiotic doxycycline.
    • No vaccine is available to prevent scrub typhus.
    • Prevention measures include avoiding contact with infected chiggers, using EPA-registered insect repellents, and wearing protective clothing.
    • Treating clothing and gear with 0.5% permethrin can also help prevent chigger bites.

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