A 34-year-old man - pacemaker

[ArchivalUser]

A 34-year-old man is evaluated because of fever, mild headache, and malaise that began while on a flight to the United States from South Africa. One day later, he developed a slight rash and swelling in the right axilla. The patient had been on a hunting safari. His group lived in tents and often walked through fields with low scrub. He had taken appropriate antimalarial prophylaxis and did not skin the animals or dress the meat. Medical history is unremarkable.

On physical examination 2 days after the flight, temperature is 38 °C (100.4 °F), pulse rate is 82/min, respiration rate is 16/min, and blood pressure is 132/88 mm Hg. There is a firm swelling in the right axilla without fluctuance or erythema. No edema is noted. Approximately 15 to 20 small pruritic vesicles on erythematous bases are seen on the anterior chest and upper arms, and one vesicle appears on the left cheek. A 1-cm red-brown eschar is present over the right lateral clavicle. Neurologic examination is normal.

Laboratory Studies
Hemoglobin

14.9 g/dL (149 g/L)
Hematocrit

44%
Leukocyte count

6500/μL (6.5 × 109/L)
Platelet count

270,000/μL (270 × 109/L)
Blood urea nitrogen

Normal
Serum creatinine

Normal
Serum electrolytes

Normal
Liver chemistry studies

Normal
Urinalysis

Normal

Which of the following is the most likely diagnosis?

A Herpes zoster virus
B Dengue fever
C African tick bite fever
D Cutaneous leishmaniasis

[ArchivalUser]

C African tick bite fever..!

[ArchivalUser]

Correct Answer = C)
Key Points

* African tick bite fever is the most common rickettsial infection in humans.
* Symptoms of African tick bite fever are relatively mild and are characterized by a vesicular rash with an inoculation eschar.

The patient has characteristic features of African tick bite fever, which is probably the most common rickettsial infection in humans. He has just returned from a highly endemic area, and his signs and symptoms developed within the known incubation period of 1 to 2 weeks. The relatively mild symptoms and vesicular rash with one or two inoculation eschars (presumed to be in the area of the original tick bite) are also characteristic. A definitive diagnosis is made by serologic studies or, if available, by polymerase chain reaction. Without treatment, the disease is self-limited. However, administration of doxycycline causes prompt resolution of symptoms in most patients.

The patient's mild symptoms, speed of onset of infection, presence of a rash, and normal laboratory findings preclude dengue fever. Leishmaniasis does not occur in South Africa, and the clinical presentation of cutaneous leishmaniasis is typically that of slowly progressing cutaneous ulcers rather than vesicles.

Although not listed in the options, varicella (chickenpox) should be considered initially. This infection is difficult to rule out based on clinical presentation alone because mild forms may occur in adults who had been immunized earlier in life. If facilities are available, the presence of varicella virus can be detected by direct immunofluorescent assay of vesicle scrapings.