Mediterranean spotted fever (MSF) is a rickettsial disease caused by Rickettsia conorii, transmitted by brown dog ticks, and endemic in the Mediterranean region. Its incidence is increasing, with varied presentations and potential complications because of delayed diagnosis. This study retrospectively included 173 adult patients hospitalized for MSF at La Rabta University Hospital, Tunis, from 2000 to 2020. Patients, predominantly male (67.6%) and averaging 40 years of age, mostly resided in urban areas (82.7%). Animal exposure was reported in 74.6%, and cases peaked during the hot season (68.8%), with no cases in winter months. The classic triad of fever, rash, and eschar was observed in 69.9%, with maculopapular lesions affecting palms and soles in 83.8%. Headache (64.5%), myalgia (60.7%), and arthralgia (57.2%) were also common. Laboratory findings included elevated white blood cell count (36.4%), thrombocytopenia (48%), and increased aspartate aminotransferase (50.9%). Treatment with doxycycline (n = 161) resolved fever within 2.8±1.3 [1–5] days. Complications, including encephalitis, chorioretinitis, anterior uveitis and vasculitis, occurred in 2.3% of cases, but all patients recovered without relapse. No significant risk factors for severe forms were identified. Improved awareness of MSF’s clinical features may be the key to an early diagnosis and successful treatment.

The incidence of Mediterranean spotted fever (MSF) in Catalonia (Spain) has decreased in the last two decades. The prevalence of antibodies to Rickettsia conorii in human beings and dogs in the region of Vallès Occidental (Catalonia) was assessed by indirect immunofluorescence, and the results compared with those obtained in a similar study from 1987. Nineteen (5·0%) out of 383 human serum samples had antibodies to R. conorii. This seroprevalence was significantly lower (11·5%) (P = 0·003) than that recorded in the 1987 survey. Forty-two out (42·0%) of 100 canine serum samples had antibodies to R. conorii. A high proportion of the studied dogs (91·0%) were receiving anti-tick treatment, mainly with permethrin-imidacloprid spot-on (Advantix, Bayer, Germany). The current canine seroprevalence was not significantly different from that recorded in the 1987 survey (36.9%). In conclusion, this study shows a significant decrease in the prevalence of antibodies to R. conorii in the human population of Catalonia in the last 20 years, which corresponds with a decrease in the number of cases of MSF. We suggest that the widespread use of anti-tick treatment in dogs could limit the introduction of ticks to humans due to a reduction of infestation duration in dogs, thus contributing to the decrease in MSF incidence.