Rickettsialpox Differential Diagnoses

Updated: Jun 30, 2017
  • Author: Pradeep Kumar Mada, MD, MRCP(UK); Chief Editor: Mark R Wallace, MD, FACP, FIDSA  more...
  • Print
DDx

Diagnostic Considerations

Human spotted fever secondary to Rickettsia parkeri infection

African tick bite fever secondary to Rickettsia africae infection

Mediterranean Spotted Fever

Scrub Typhus [16, 17]

Anthrax

Smallpox

Table 1. Characteristics of Similar Conditions (Open Table in a new window)

Disease Rash/Eschar Generalized Rash Clinical Features Geography
Rickettsialpox secondary to R akari infection A red papule with a vesicle in the center dries and forms a black eschar with surrounding induration. Multiple eschars are possible. The papulovesicular rash is usually on the trunk and extremities; the palms, soles, and oral mucosa may also be involved. The papule precedes the febrile illness and mild systemic symptoms. Regional lymphadenopathy may develop. See Frequency
Chickenpox secondary to varicella zoster infection The papule turns into a vesicle on an erythematous base and resembles a "dew drop on a rose petal." The rash begins on the head and progresses to the trunk, arms, and then legs; vesicles are present in all stages. It is common in children. No black eschar is present. Worldwide
Mediterranean spotted fever secondary to Rickettsia conorii infection At the site of a tick bite, a single eschar with a red halo forms. The rash is generalized, involves the palms and soles, and is often maculopapular, occasionally petechial. Fever, headache, myalgias may develop. The onset is abrupt. The disease may be severe in context of comorbidity. North Africa, Middle East, Southern Europe
African tick bite fever secondary to R africae infection Single or multiple eschars with regional lymphadenopathy A scant generalized rash, vesicular or maculopapular, may be present. Conversely, the rash may be absent. Fever, headache, myalgias, regional lymphadenopathy; associated with reports of subacute neuropathy Sub-Saharan Africa, Caribbean
Human spotted fever secondary to R parkeri infection Single or multiple eschars develop from erythematous papules. Scant nonpruritic papules Fever, headache, myalgias, arthralgias United States
Scrub typhus secondary to Orientia tsutsugamushi infection A vesicle or black scab appears on an erythematous base at the bite site. Vesicles are usually on the trunk or extremities. The rash fades within a few days; pneumonitis is common. Asia-Pacific rim

Differential Diagnoses