Questions on Mediterranean spotted fever a century after its discovery

Abstract

Mediterranean spotted fever (MSF) was first described in 1910. Twenty years later, it was recognized as a rickettsial disease transmitted by the brown dog tick. In contrast to Rocky Mountain spotted fever (RMSF), MSF was thought to be a benign disease; however, the first severe case that resulted in death was reported in France in the 1980s. We have noted important changes in the epidemiology of MSF in the last 10 years, with emergence and reemergence of MSF in several countries. Advanced molecular tools have allowed Rickettsia conorii conorii to be classified as a subspecies of R. conorii. New clinical features, such as multiple eschars, have been recently reported. Moreover, MSF has become more severe than RMSF; the mortality rate was as high as 32% in Portugal in 1997. Whether Rhipicephalus sanguineus is the only vector and reservoir for R. conorii conorii is a question not yet answered.

Figure 1

Rickettsia conorii conorii observed in Vero cells (red rods; magnification ×1,000).

Figure 2

Rickettsia conorii conorii localized in cytoplasm of host cells as seen by electron microscopy (magnification ×100,000).

Figure 3

Fluctuation of incidence of Mediterranean spotted fever (MSF) in Italy and Portugal and of Rocky Mounted spotted fever (RMSF) in the United States, by year.

Figure 4

Distribution of the cases of Mediterranean spotted fever (MSF) in the world and incidence of the disease in countries where MSF is endemic.

Figure 5

Typical eschar and spots on the leg of a patient with Mediterranean spotted fever.

Figure 6

Rhipicephalus sanguineus adult tick, the suspected vector for Rickettsia conorii conorii.