An 85-year-old man arrives one summer morning at the clinic of his Florida retir

Question

An 85-year-old man arrives one summer morning at the clinic of his Florida retirement community with severe headache, chills, muscle pain, and nausea. He reports that the symptoms developed quite suddenly. He has had no rash. During the interview the man states that he is a World War II veteran of the battle for Guadalcanal in the South Pacific, a golfer, and an avid bird watcher who spends many hours in the woods near his home. He had not noticed any fleas, ticks, or lice on his body, but he had been almost “eaten alive” by chiggers. His cat had a few fleas, but he had “gotten the little buggers.” He had not been out of the United States in 40 years.

Part A

What disease is this man most likely to have?

Part B

What vector is implicated in the spread of the disease in this clinical case?

Part C

What is the treatment of choice for this disease?

Part D

What diagnostic test could be used to verify the diagnosis?

Part E

How would you know if you were “eaten alive” by chiggers?

Explanation / Answer

Part A

scrub typhus

Justification:

Scrub typhus is a mite-borne disease caused by Orientia tsutsugamushi. Symptoms are fever, a primary lesion, a macular rash, and lymphadenopathy. Scrub typhus is related to rickettsial diseases. Scrub typhus is transmitted by some species of trombiculid mites ("chiggers") which are found in areas of heavy scrub vegetation. The bite of this mite leaves a characteristic black eschar that is useful to the doctor for making the diagnosis.

Part B

Ixodes tick

Explanation:

The louse, flea, tick, or mite becomes infected with the bacteria when they feed on the blood of an infected person or an infected rodent (in the case of endemic typhus). If you come in contact with these infected arthropods, their feces may be deposited on your skin when the louse, flea, tick, or mite feeds on your blood. If you scratch the bite, the bacteria can enter your bloodstream through the tiny wound on your skin.

Part C

doxycycline

Justification:

Antibiotics most commonly used to treat typhus include:

Part D

immunofluorescent antibody stain of a blood smear from this patient

Justification:

Diagnostic tests for the presence of typhus include:

Part E

intense swelling and blue discoloration of the lower legs

Justification:

Symptoms in people with scrub typhus include:

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