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Letter
Israeli Spotted Fever Rickettsia
in Sicilian Rhipicephalus sanguineus Ticks
Giovanni M. Giammanco,* Serafino Mansueto,* Pietro Ammatuna,* and
Giustina Vitale*
*Università di Palermo, Palermo, Italy
Suggested citation for this article: Giammanco
GM, Mansueto S, Ammatuna P, Vitale G. Israeli spotted fever Rickettsia
in Sicilian Rhipicephalus sanguineus ticks. Emerg Infect Dis
[serial online] 2003 Jul [date cited]. Available from: URL: http://www.cdc.gov/ncidod/EID/vol9no7/03-0109.htm
To the Editor: Mediterranean spotted fever (MSF) is endemic in
Italy, where it is a reportable disease. From 1992 to 1998, the Italian
Ministry of Health was notified of approximately 8,500 cases of human
rickettsioses presumed to be MSF. MSF occurs more commonly in some central
(Lazio) and southern (Sardinia, Sicily, and Calabria) regions (1,2);
in 1998, an average of 8.8 cases occurred for every 100,000 persons in
Sicily, compared with the national average of 1.6 cases per 100,000 persons.
Rickettsia conorii has been thought to be the only pathogenic Rickettsia
of the spotted fever group in Sicily (3,4) or the western
Mediterranean area. Recently, three different spotted fever group rickettsiae,
including R. helvetica, were detected in Ixodes ricinus
ticks from central and northern Italy. This finding suggests that bacteria
other than R. conorii are involved in rickettsial diseases in Italy
(5).
To investigate whether unusual tick-transmitted rickettsiae are also
present in Sicily, we used molecular-sequence–based identification techniques
to study two strains isolated from the hemolymph of Rhipicephalus sanguineus
ticks collected in 1990 in western Sicily. These isolates had been previously
identified by serologic tests as belonging to the spotted fever group
rickettsiae. We obtained bacterial DNA and performed polymerase chain
reaction (PCR) for ompA gene and restriction analysis under conditions
previously described by Roux et al. (6). Our observation
of a peculiar PstI profile allowed a presumptive identification
of one of the two tick isolates as belonging to the Israeli spotted fever
rickettsiae, while the other showed a restriction profile corresponding
to that of R. conorii strain Seven. To confirm the identification
of the Israeli spotted fever Rickettsia isolate, we sequenced the
PCR-amplified fragment of ompA gene (MWG-Biotech AG, Ebersberg,
Germany) and aligned sequence data with homologous sequences of reference
strains of the spotted fever group rickettsiae retrieved from the GenBank
database. Sequence analysis showed 100% similarity with the homologous
sequence of Israeli spotted fever Rickettsia reference strain ISTT
CDC1 (GenBank accession no. U43797). The Israeli spotted fever Rickettsia
belongs to the R. conorii complex (7,8) and was
first isolated in 1974 from ticks and humans. Initially, Israeli spotted
fever rickettsiae distribution appeared to be restricted to Israel (9),
but more recently the organism has also been isolated from patients with
MSF in Portugal (10). Our finding of Israeli spotted
fever Rickettsia infection in a R. sanguineus tick, the
main vector for MSF in Sicily, also suggests that the geographic distribution
of Israeli spotted fever might be wider than previously thought, including
not only Israel and the Iberian Peninsula but also Italy.
Molecular analysis of spotted fever group Rickettsia isolates
from Sicilian MSF patients is under way to verify this hypothesis. Because
initial signs and symptoms of Israeli spotted fever are particularly uncharacteristic,
awareness of the presence of Israeli spotted fever Rickettsia in
our geographic area may hasten provision of the appropriate treatment.
The Sicilian ompA gene sequence described in this study has been
deposited in the GenBank database (accession no. AY197565).
References
- Scaffidi V. Current
endemic expansion of boutonneuse fever in Italy. Minerva Med 1981;72:2063–70.
- Tringali G, Intonazzo V, Perna AM, Mansueto S, Vitale G, Walker DH.
Epidemiology
of Boutonneuse fever in western Sicily. Distribution and prevalence
of spotted fever group rickettsial infection in dog ticks (Rhipicephalus
sanguineus). Am J Epidemiol 1986;123:721–7.
- Mansueto S, Vitale G, Lavagnino A, Di Rosa S, Merulla R. Rickettsiae
of the spotted fever group in dog fleas (Ctenocephalides spp.)
in western Sicily. Ann Trop Med Parasitol 1989;83:325.
- Vitale G, Di Stefano R, Damiani G, Mansueto S. Characterization
of Sicilian strains of spotted fever group rickettsiae by using monoclonal
antibodies. J Clin Microbiol 1989;27:1081–5.
- Beninati T, Lo N, Noda H, Esposito F, Rizzoli A, Favia G, et al. First
detection of spotted fever group Rickettsiae in Ixodes ricinus
from Italy. Emerg Infect Dis 2002;8:983–6.
- Roux V, Fournier PE, Raoult D. Differentiation
of spotted fever group Rickettsiae by sequencing and analysis
of restriction fragment length polymorphism of PCR-amplified DNA of
the gene encoding the protein rOmpA. J Clin Microbiol 1996;34:2058–65.
- Regnery RL, Spruill CL, Plikaytis BD. Genotypic
identification of Rickettsiae and estimation of interspecies
sequence divergence for portions of two rickettsial genes. J Bacteriol
1991;173:1576–89.
- Fournier PE, Roux V, Raoult D. Phylogenetic
analysis of spotted fever group Rickettsiae by study of the outer
surface protein rOmpA. Int J Syst Bacteriol 1998;48:839–49.
- Roux V, Raoult D. Phylogenetic analysis and taxonomic relationships
among the genus Rickettsia. In: Raoult D, Brouqui P, editors.
Rickettsiae and rickettsial diseases at the turn of the third
millennium. Paris: Elsevier; 1999. p. 52–66.
- Bacellar F, Beati L, Franca A, Pocas J, Regnery R, Filipe A. Israeli
spotted fever rickettsia (Rickettsia conorii complex) associated
with human disease. Emerg Infect Dis 1999;5:835–6.
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