ANSWER TO PHOTO QUIZ
Philip A. Mackowiak, Section Editor
A Traveler Returning from South Africa with Rash and Genital Ulceration
(See page 881 for Photo Quiz)
Figure 1.
Genital ulceration: tick bite with single eschar
Diagnosis: African tick-bite fever caused by Rickettsia africae.
The diagnosis was suggested because the patient had returned
from an adventure race in South Africa and because we did not
find any sexual risk behaviors. A careful cutaneous examination
did not find any inoculation eschar except for a genital ulceration
(figure 1), which was classified as a tache noire, and a generalized
maculopapular cutaneous rash (figure 2). An ELISA immunofluorescence assay to detect antibodies to Rickettsia species in
serum samples was performed. The acute-phase serum sample
contained no detectable antibodies, but the convalescent-phase
serum sample was positive for IgG antibody (titer, 1:128) and
IgM antibody (titer, 1:16). Serological cross-reactions between
R. africae and Rickettsia coronii were found with equal titers of
antibody. The patient received doxycycline, 200 mg/day for 10
days, and became asymptomatic.
Various rickettsial diseases, of which the spotted fever group
(represented by Mediterranean spotted fever) and African tickbite fever are the principal examples, are endemic in subSaharan Africa. African tick-bite fever is a disease caused by R.
africae and transmitted by cattle ticks in rural areas of southern
Africa. It was first described by Kelly et al. [1] in a patient who
presented with fever, an inoculation eschar, and a regional
908 • CID 2004:38 (15 March) • ANSWER TO PHOTO QUIZ
Figure 2.
Generalized maculopapular cutaneous rash
lymphadenopathy, but no rash. Since then, R. africae has been
implicated in several outbreaks [2–4] and has been recognized
as an emerging health problem for international travelers to
rural sub-Saharan Africa [5, 6]. Clinical features include fever,
headache, myalgia, and maculopapular cutaneous rash. A lesion—the eschar or tache noire—at the site of the tick bite is
a diagnostic criterion and requires a detailed clinical examination, as illustrated in the case we describe. Multiple inoculation eschars are more frequent than single inoculation eschars.
The typical location of eschars is on the legs, but any inoculation site is possible [5]. The inoculation lesion is associated
with regional lymphadenopathy in the region proximal to the
eschar. The duration of time between the tick bite and the onset
of symptoms ranges from 4 to 10 days [3]. The diagnosis is
suggested by epidemiological data and clinical features, and is
confirmed with serological testing. The usual method, namely
microimmunofluorescence assay, which is sometimes completed and other times conducted with cross-adsorption testing
and Western immunoblotting if cross-reactions between R. africae and R. conorii are noted, enabled us to confirm that the
antibodies detected are specific to R. africae. Culture of R. africae from an eschar biopsy specimen or molecular typing with
PCR amplification from eschar biopsy or blood samples is also
possible [3]. The drug of choice for treatment is doxycycline
at a dosage of 200 mg/day for 7 to 15 days.
Pierre Abgueguen, Jean Marie Chennebault, and Eric Pichard
Department of Infectious and Tropical Diseases,
Centre Hospitalier Universitaire d’Angers, Angers, France
References
1. Kelly PJ, Matthewman LA, Beati L, et al. African tick-bite fever—a new
spotted fever group rickettsiosis under an old name. Lancet 1992; 340:
982–3.
2. Fournier PE, Beytout J, Raoult D. Tick-transmitted infections in Transvaal: consider Rickettsia africae. Emerg Infect Dis 1999; 5:178–81.
3. Fournier PE, Roux V, Caumes E, Donzel M, Raoult D. Outbreak of
Rickettsia africae infections in participants of an adventure race in South
Africa. Clin Infect Dis 1998; 27:316–23.
4. Brouqui P, Harle JR, Delmont J, Frances C, Weiller PJ, Raoult D. African
tick-bite fever: an imported spotless rickettsiosis. Arch Intern Med
1997; 157:119–24.
5. Raoult D, Fournier PE, Fenollar F, et al. Rickettsia africae, a tick-borne
pathogen in travelers to sub-saharan Africa. N Engl J Med 2001; 344:
1504–10.
6. Raoult D, Roux V. Rickettsioses as paradigms of new or emerging infectious diseases. Clin Microbiol Rev 1997; 10:694–719.
Reprints or correspondence: Dr. Pierre Abgueguen, Service des Maladies Infectieuses et
Tropicales, Centre Hospitalier Universitaire d’Angers, 4 rue Larrey, 49033 Angers Cedex 01,
France ([email protected]).
Clinical Infectious Diseases 2004; 38:908–9
2004 by the Infectious Diseases Society of America. All rights reserved.
1058-4838/2004/3806-0023$15.00
ANSWER TO PHOTO QUIZ • CID 2004:38 (15 March) • 909