What is spotted fever?

Brazilian Spotted Fever (BSF) is an acute febrile infectious disease caused by different species of the genus Rickettsia sp., with Rickettsia rickettsii being the most commonly involved. It is a gram-negative spirochete bacterium.

Types

There are different types of Rickettsia sp. that can cause conditions of varying severity. Rickettsia rickettsii, for example, can cause disease with high mortality (20–40% of cases). Additionally, some species, although currently known, have not yet had their potential to cause disease in humans established.

Human diseases caused by these bacteria include: BSF, African tick bite fever, Queensland tick typhus, Boutonneuse fever, and Japanese spotted fever

Transmission

The disease is transmitted by arthropod vectors. BSF is associated with the following vectors: the star tick (Amblyomma sculptum), found on capybaras, horses, and tapirs in warm regions, and the yellow dog tick (Amblyomma aureolatum), where domestic dogs and human occupation in degraded Atlantic Forest areas play a key role in transmission.

Symptoms

Cases may present with few symptoms or even severe manifestations that can lead to death. It is generally a disease with abrupt onset, fever, and nonspecific initial symptoms. The most common are: high fever, headache, muscle pain, malaise, nausea, and vomiting, possibly with a history of tick bite and/or contact with areas known for disease transmission.

A maculopapular rash may occur, especially on the palms and soles. Pulmonary, renal, gastrointestinal, and hemorrhagic manifestations may also occur, as the bacterium can cause significant systemic vasculitis.

Diagnosis

New technologies, such as molecular techniques, haves improved the diagnosis of rickettsioses and the identification of new species. However, serology is still widely used in clinical practice.

Epidemiological history related to tick exposure and contact with disease transmission areas is also important, as definitive tests do not provide immediate results.

Treatment

Treatment is carried out with antibiotics, with doxycycline being the first-choice drug.

Rapid diagnosis and the initiation of appropriate therapy are essential for a good disease prognosis.

Prevention

The main form of prevention is to avoid contact with ticks and also avoid areas where disease transmission (cases) is established.

Incidence

According to Health Surveillance Bulletins, from 2007 to 2012, 9,644 cases of BSF were reported in 10 Brazilian states. Of these, 734 were confirmed, most by laboratory criteria.

In the state of São Paulo, in 2017, according to data from the Epidemiological Surveillance Center, 65 cases of the disease were confirmed.

By Einstein Editorial Board