Spotted fever group Rickettsia infection kinetics and cutaneous host response during single tick feeding events.

Rickettsia parkeri transmits to host skin within 1 hour of tick attachment, with bacterial loads increasing rapidly over 144 hours.

• Why it matters: Understanding early transmission and immune responses at the tick bite site is crucial for developing effective prevention strategies against tick-borne rickettsial diseases, which are often studied using needle inoculation that overlooks vector effects.
• What they did: A single tick feeding model was used to track transmission and dissemination of R. parkeri from 1 to 144 hours, combined with immunophenotyping, cytokine profiling, and histopathology to analyze host immune responses.
• The result: Transmission occurs swiftly, with bacterial loads rising significantly over time, and delayed pro-inflammatory responses characterized by macrophage dominance and cytokine shifts, informing potential intervention points.