How deadly is Rocky Mountain spotted fever in São Paulo this year?

Between January and July 2026, São Paulo state recorded 19 confirmed cases of Rocky Mountain spotted fever (febre maculosa) and 18 deaths — a fatality rate of nearly 95%. The deaths were concentrated in the regions of Piracicaba, Americana, Sorocaba, Campinas, São José dos Campos, Santo André and São Bernardo do Campo.

What causes it and how is it transmitted?

The disease is caused by the bacterium Rickettsia rickettsii, transmitted through the bite of infected ticks. Dogs are a key vector: they can pick up ticks in forests, farms or tall grass and bring them indoors — where ticks may also hide in bedding and clothing.

What are the warning symptoms?

Early symptoms are non-specific and are frequently confused with dengue, common viral infections or leptospirosis:

  • High fever, body aches, headache and general malaise in the first days.
  • Reddish skin spots from around day three, followed by purplish lesions on hands and feet — a sign the disease is progressing to a severe stage.
  • Advanced stages can include gangrene of the fingers and ears, and a paralysis that starts in the legs and moves up to the lungs.

Why is early treatment so critical?

Infectologist Jean Gorinchteyn of Hospital Israelita Albert Einstein warns that mortality can reach 80% when antibiotic treatment is not started quickly. The disease triggers vascular inflammation that can damage the kidneys, liver and brain. Crucially, laboratory confirmation can take up to two weeks — so doctors should start treatment immediately based on symptoms and exposure history, without waiting for test results.

How can you protect yourself?

  • Avoid entering forests, farms, eco-trails or areas of tall grass whenever possible.
  • If exposure is unavoidable, wear long trousers, boots and light-coloured clothing.
  • Inspect your body and clothes thoroughly after outdoor activities.
  • Protect dogs with tick collars and repellent products.
  • If you develop a fever after visiting any of these environments, tell your doctor immediately and mention where you have been.
Key Facts:
  • 18 deaths out of 19 confirmed cases in São Paulo, January–July 2026.
  • Regions affected: Piracicaba, Americana, Sorocaba, Campinas, São José dos Campos, Santo André, São Bernardo do Campo.
  • Caused by Rickettsia rickettsii, spread by tick bites.
  • Mortality can reach 80% without prompt antibiotic treatment.
  • Lab results can take up to two weeks — do not wait to begin treatment.
  • Dogs can carry ticks into the home environment.