Rocky Mountain spotted fever

Rocky Mountain spotted fever (RMSF), also known as Brazilian spotted fever, is an infectious disease caused by the Gram negative coccobacillus Rickettsia rickettsii which is usually transmitted by the bite of infected ticks.

Epidemiology

Rocky Mountain spotted fever distribution correlates with the presence of its vectors, and has been diagnosed in the United States of America and in many parts of both Central and South Americas, and generally is a notifiable disease in most of the affected countries .

Clinical presentation

There is a classical triad of non-specific symptoms which are not always present :

• fever
• headache 
• rash

The symptoms are in general similar to viral syndromes and the epidemiological features are essential to better direct the diagnosis .

Diagnosis

Serological analysis by an immunofluorescence reaction can be used as a sensitive method to diagnosis rickettsioses, however the PCR (polymerase chain reaction) method is known to be more useful as it can discriminate between the different species of Rickettsia .

Pathology

Etiology 

Rickettsia rickettsii is a Gram-negative coccobacillus and is an obligate intracellular bacterium .

Transmission

Infected ticks act as the biological vector, whilst humans are an accidental host.