First Confirmed Human Case of Rickettsia parkeri Strain Atlantic Rainforest Infection on the North Coast of São Paulo State, Brazil

Rickettsia parkeri strain Atlantic rainforest is an emerging pathogen in Brazil, but human infections remain rarely reported. We report the first confirmed case in the municipality of Caraguatatuba on the northern coast of São Paulo State, Brazil. A 37-year-old man was bitten by an Amblyomma ovale tick while visiting a forested area. Six days later, he developed a papular skin lesion with a necrotic center at the tick bite site, accompanied by regional lymphadenopathy, myalgia, and flu-like symptoms. Ticks parasitizing both the patient and his dog were collected, along with the eschar. Two ticks were analyzed for Rickettsia isolation, and R. parkeri was successfully isolated from one infected specimen. The patient’s infection was confirmed by molecular testing through the PCR amplification of the gltA and ompA genes from an eschar inoculation sample. This represents the sixth confirmed case of rickettsiosis caused by R. parkeri in Brazil, and it reinforces the need for increased epidemiological surveillance in endemic regions for spotted fever caused by this pathogen. With the increasing recognition of R. parkeri in South America, further research is needed to better understand its transmission dynamics, clinical manifestations, and potential public health impact.