Cardiac involvement in a patient with clinical and serological evidence of African tick-bite fever
© Bellini et al; licensee BioMed Central Ltd. 2005
Received: 29 April 2005
Accepted: 20 October 2005
Published: 20 October 2005
Myocarditis and pericarditis are rare complications of rickettsiosis, usually associated with Rickettsia rickettsii and R. conorii. African tick-bite fever (ATBF) is generally considered as a benign disease and no cases of myocardial involvement due to Rickettsia africae, the agent of ATBF, have yet been described.
The patient, that travelled in an endemic area, presented typical inoculation eschars, and a seroconversion against R. africae, was admitted for chest pains and increased cardiac enzymes in the context of an acute myocarditis.
Our findings suggest that ATBF, that usually presents a benign course, may be complicated by an acute myocarditis.
Rickettsia africae, the causative agent of African tick-bite fever, an emerging disease transmitted by Amblyomma ticks in rural sub-Saharan Africa, has been recently described . Symptoms usually includes abrupt appearance of fever (59–100% of cases), headache (62–83%), myalgia (63–87%), prominent neck muscle myalgia (81%), regional lymphadenitis (43–100%), cutaneous rash (15–46%) and inoculation eschar (53–100%), typically present in multiple sites (21–54%) . The time lag from tick bite to symptom onset is usually 5 to 7 days but may be as long as 10 days [2–4].
Several case reports of ATBF in travellers from Europe and elsewhere have been published [1–5] and recently, ATBF have also been reported in autochthonous Africans . However, no cases of myocardial involvement have yet been described. Here, we report the first evidence that ATBF may be complicated by an acute myocarditis.
Contrarily to R. rickettsii and R. conorii that are considered potential agents of myocarditis and pericarditis [1–3], R. africae usually present a benign, uncomplicated course, and has never been yet associated with cardiac complications. Our findings suggest that R. africae, the agent of ATBF, may lead to myocarditis.
In this report, the grouped cases, the presence of multiple inoculation eschars and the serologic seroconversion for R. africae, strongly supported the diagnosis of ATBF. To confirm the diagnosis, we could also perform PCR and/or culture on the biopsy of the eschar bite, since both techniques are good tools to diagnose acute rickettsial infection . However, no skin biopsy was performed for ethical reasons since the diagnosis of ATBF was evident.
In presence of highly specific pathologic cardiac enzymes (troponin I) and ECG alteration, and in absence of coronary stenosis at coronarography, and despite the absence of morphological abnormalities at echocardiography, the more likely cause of the chest pain is a myocarditis with or without pericardial involvement. Indeed, myocarditis that is defined as an acute inflammatory syndrome involving the heart and related structures is typically characterized by increased troponin and normal coronary arteries [13–15]. Since the pathogenesis of rickettsial disease is generally associated with endothelium damage , unstable angina might occur in patients with spotted fever Rickettsiosis. However, in this case, the normal coronarography does not support the occurrence of a peripheric, transitory thrombotic event. A myocarditis is much more likely in this setting.
To our knowledge, there are no described case of cardiac involvement associated with a R. africae infection. Although a serological cross reaction with another rickettsial infection can not be formally excluded, the endemic presence of R.africae in Swaziland and South Africa [2–4], the presence of multiple inoculation eschars and the simultaneous infection of both travellers , strongly support the diagnosis of ATBF.
In conclusion, if ATBF usually presents a benign course, rare complications such as myocardial involvement may occur. Travellers to endemic areas should be informed of the risk of contracting ATBF and be encouraged to take personal protective measures against tick bites [5, 7].
List of abbreviations
african tick bite fever
creatine phosphokinase muscle-brain isoform
polymerase chain reaction
We thank the "Unité des Rickettsies, Marseille, France" for performing the serologies.
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