A previously healthy 24-year-old man comes to the physician because of a 4-day history of fever, headache, myalgias, and abdominal pain. He developed a new rash this morning. He returned from a backpacking trip in Arkansas. 5 days ago. He was camping outdoors, drank only filtered water, and used sunscreen. He is sexually active and uses condoms for contraception. He appears ill and fatigued. His temperature is 39.5°C (103.1°F). Physical examination shows conjunctival injection in both eyes without exudate or pus. There is a diffuse blanching, macular rash. Laboratory testing reveals leukopenia, thrombocytopenia, and elevated aminotransferase levels. Microscopic evaluation of the blood demonstrates mulberry-shaped, intracytoplasmic inclusions in monocytes. Which of the following is the most likely pathogen responsible for this patient's condition?

Question

A previously healthy 24-year-old man comes to the physician because of a 4-day history of fever, headache, myalgias, and abdominal pain. He developed a new rash this morning. He returned from a backpacking trip in Arkansas.  5 days ago. He was camping outdoors, drank only filtered water, and used sunscreen. He is sexually active and uses condoms for contraception. He appears ill and fatigued. His temperature is 39.5°C (103.1°F). Physical examination shows conjunctival injection in both eyes without exudate or pus. There is a diffuse blanching, macular rash. Laboratory testing reveals leukopenia, thrombocytopenia, and elevated aminotransferase levels.  Microscopic evaluation of the blood demonstrates mulberry-shaped, intracytoplasmic inclusions in monocytes.  Which of the following is the most likely pathogen responsible for this patient's condition?

Quizplus · Accepted Answer

Eductional Objective: Ehrlichia chaffeensis is harbored in white-tailed deer and transmitted to humans by tick bite.  It replicates in vacuoles within monocytes and forms mulberry-shaped, intraleukocytic inclusions (morulae).  Manifestations usually include nonspecific symptoms (eg, fever, chills, myalgia), maculopapular rash, and significant laboratory abnormalities, particularly lymphopenia.

A Previously Healthy 24-Year-Old Man Comes to the Physician Because