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?

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

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

Leptotrombidium deliense Signup and view all the answers

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

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

What is the typical color of the chigger mite?

Bright red Signup and view all the answers

What are the typical hosts of the chigger mites?

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

What is the diameter of chigger larvae?

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

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

To break down skin cells for digestion Signup and view all the answers

How do chigger larvae typically find a host?

By crawling on soil or up grass blades Signup and view all the answers

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

To suck up partially-digested skin cells Signup and view all the answers

How is scrub typhus fever typically transmitted?

Through the bite of an infected chigger Signup and view all the answers

What is the role of the dermatologist in diagnosing scabies?

To remove some skin to examine under a microscope Signup and view all the answers

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

Larva Signup and view all the answers

What is the shape of chigger eggs?

Globular Signup and view all the answers

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

A week or more Signup and view all the answers

What is the primary method of preventing scrub typhus?

Avoiding areas with high vegetation and brush Signup and view all the answers

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

They usually recover quickly Signup and view all the answers

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

To kill chiggers Signup and view all the answers

What is the potential consequence of scratching a chigger bite?

It may result in secondary infections Signup and view all the answers

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

It has a hard, white central area Signup and view all the answers

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

Soon after symptoms begin 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?

To prevent bites from infected chiggers 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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