Bite site (child’s scalp), season and location of the encounter with the questing tick (early April/countryside near Florence) and duration of feeding activity (10 days) are consistent with
D. marginatus ecology. Indeed, this species is widely distributed in prairies and steppes of central Italy up to 2500 m above sea level. The adults are active from autumn to spring, parasitizing wild or domestic ungulates and they can occasionally feed on humans [
5,
7].
D. marginatus can feed for several days, increasing the risk of pathogen transmission, and it is considered the main vector of SENLAT in our country [
6]. The tendency of
Dermacentor spp. to bite children or women on the scalp can be explained by the host preference for hairy animals and the questing height of 1–1.5 m on vegetation, typical of this genus [
9]. Unfortunately, as described in this report, the diagnosis of SENLAT can often be delayed, because the bite lesion is usually hidden by hair and the symptoms are usually non-specific [
2,
6,
10]. In our patient, the tick had been feeding for 10 days before being removed from the child’s scalp, thus having enough time to transmit the pathogen. Moreover, during this time no symptoms were evidenced, since the incubation period of the syndrome ranges from 1 to 55 days after the tick bite (typically between 5 and 10 days) [
1]. Although the suspected diagnosis of tick-borne rickettsioses is based on epidemiological and clinical findings, serological tests are useful to confirm the exposure to a specific pathogen, as different agents (i.e.,
B. burgdorferi s.l.,
F. tularensis,
B. hensalae,
C. burnetii) could sometimes emerge with the same symptoms [
6]. However, an antibiotic therapy needs to be started while waiting for laboratory confirmation, in order to prevent severe forms [
5,
6]. IFAT is the reference serological method for SFG rickettsiae, but it could lack diagnostic sensitivity in the case of SENLAT, probably due to the local diffusion of bacteria. Thus, the identification of the specific agent on clinical samples (skin swabs or biopsies, crusts, blood or sera) or ticks by PCR or culture is required [
1]. In this report an increase in IgG antibody titer (1:1024) against
R. conorii was revealed by IFAT, confirming the low specificity of this technique, due to the frequent cross-reactions among SFG rickettsiae. In case of positive IFAT results a Western blot with cross-adsorption should be performed to discriminate the species involved [
1]. The diagnosis of MSF was unlikely in our patient, as this syndrome is typically associated with other specific symptoms like acute fever, chills, headache, photophobia, arthralgia, muscular pain and maculopapular rash on palms and soles or less frequently on trunk. Moreover,
R. slovaca DNA was successfully amplified and sequenced from the tick vector.
This case emphasizes the importance of collaboration between experts who, through a multidisciplinary approach including epidemiological information, clinical evaluations, entomological identification and molecular investigations on tick, can allow for a proper diagnosis and therapy of SENLAT and other tick-borne diseases. In absence of the tests performed on tick, diagnosis would not have been confirmed, since Western blot for discriminating SFG rickettsiae is not available in our centre.
Hence, in case of tick bite, patients should be advised to preserve the vector for further analysis in the event of developing symptoms and collaboration between different experts should be implemented.