A previously healthy 39-year-old presented with fever, weakness, and muscle pain, which began about 6 days after his return from a 3-week safari in Africa. The patient reported being bitten by a tick during the safari.

Physical examination revealed a temperature of 38.2°C, one 0.5 cm eschar on the trunk (figure 1) and non-itchy rashes on his lower limbs (figure 2).

Figure 1 Eschar on the trunk.

Figure 2 Rashes on lower limbs.

Which of the following is the most likely diagnosis?

(Please select 1 option)