Image 22:
A visitor to South Africa noted an "insect bite" like lesion on the upper posterior chest wall, a day after lying in the grass in a game park. It was not itchy or particularly tender and had a 0.5 cm dark centre, without a breathing hole, when seen here 10 days later. There was no fever but there was a mild headache and a tender axilla (2 cm. lymphnode) on the same side.
Diagnosis:
This is an eschar of tick typhus. The incubation period can be 1-2 weeks and the development of the eschar can be well advanced before the onset of systemic symptoms. When seen initially, doxycycline was given for a possible rickettsial infection in the pre-febrile (pre-systemic) phase. Fatigue and axillary tenderness resolved over 2-3 days. Acute and convalescent serology for Rickettsia conorii and Rickettsia rickettsii were <32 and 128.
