Read condition-specific symptoms and clinical context for Rickettsia rickettsii. A tick-borne bacterium that lives inside cells and causes Rocky Mountain spotted fever, where treatment delay is the main danger.
PHAC describes R. rickettsii as a small pleomorphic Gram-negative coccobacillus of 0.2 to 0.5 by 0.2 to 0.3 micrometres that is an obligate intracellular bacterium, multiplies by binary fission and has both DNA and RNA. CDC describes Rocky Mountain spotted fever as a bacterial disease spread through the bite of an infected tick, transmitted by the American dog tick, Rocky Mountain wood tick and brown dog tick, with cases occurring throughout the United States. PHAC reports 250 to 1,200 cases reported each year in the USA, making it the most common tick-borne disease there in that account, with 90 to 93% of US cases reported between April and October, and states that 20% of untreated cases are fatal compared to 5% of treated cases.
PHAC gives an incubation period of 2 to 14 days after the bite of an infected tick, and notes the tick normally needs to be attached for a 4 to 6 hour period. CDC states the rash typically emerges 2 to 4 days after fever begins.
Possible symptoms: Fever; Headache; Rash; Malaise; Loss of appetite; Nausea and vomiting.
CDC states that RMSF can be deadly if not treated early and that early treatment with doxycycline can prevent death and severe illness, and notes that untreated severe cases may cause permanent damage including amputations, hearing loss or cognitive impairment resulting from the acute illness. Treatment decisions are clinical.
Most tick bites do not transmit this organism.
The bundled sources give no symptom list for a tick bite that does not lead to infection, and none is invented here. PHAC notes that the tick normally needs to be attached for a 4 to 6 hour period for transmission, and that the host range covers humans, dogs, rodents, small mammals and ticks. PHAC also states that human-to-human transmission has not been confirmed, although aerosols are a potential source of infection in laboratory settings. This profile assigns no human carriage state.
Because RMSF is treated on suspicion rather than after confirmation, any febrile illness following a tick bite in an area where the disease occurs is a clinical question rather than a wait-and-see one. This app gives no bite advice.
Source check: 2026-09-20. Educational content; independent scientific review remains pending.