Rickettsiales in Italy

First Evidence of Rickettsia conorii Infection in Dogs in Northern Tunisia

A cross-sectional study was carried out, between April 2021 and June 2022, to understand the role of dogs in the circulation of rickettsiosis in Tunisia. The presence of specific IgG antibodies against Rickettsia conorii was analyzed by indirect immunofluorescence test. By qPCR, blood and ticks were collected from 136 dogs examined at the Canine Department of National School for Veterinary Medicine of Tunisia. These dogs were also analyzed to detect Rickettsia DNA. The rate of Rickettsia seropositivity in 136 dogs was 55.14%. A total of 51 (53%) seropositive dogs showed clinical and biological signs such as fever and anorexia as well as thrombocytopenia and anemia. By qPCR, targeting the mitochondrial 16S rRNA gene, no Rickettsia DNA was detected in the blood. On the other hand, qPCR followed by sequencing revealed the presence of R. conorii subsp. raoultii in 7 tick pools of the 51 pools composed of the 227 ticks collected. A One Health approach to raise the awareness of dog owners to control tick infestations is imperative, given the dangers of canine zoonoses.

Ticks and Tick-Borne Pathogens: Occurrence and Host Associations over Four Years of Wildlife Surveillance in the Liguria Region (Northwest Italy)

Tick-borne diseases (TBDs) are a considerable public health problem worldwide. The occurrence of Anaplasma spp., Borrelia burgdorferi s.l., Coxiella burnetii, Rickettsia spp., and tick-borne encephalitis virus (TBEv) was investigated via PCR and sequencing in 683 ticks collected from 105 roe deer, 61 wild boars, 49 fallow deer, and 2 chamois, in the Liguria region, northwest Italy, between 2019 and 2022. The ticks were morphologically identified. Four different tick species were found: Ixodes ricinus (66.8% of the collected ticks), Dermacentor marginatus (15.8%), Rhipicephalus sanguineus s.s. (15.7%), and Haemaphysalis punctata (0.9%). Six ticks (0.9%) were only identified as Rhipicephalus spp. Of the 222 pools analyzed, 27.9% were positive. Most pools (n = 58, 26.1% of pools analyzed) were positive for Rickettsia spp., and several species were found: Rickettsia slovaca was the dominant species (15.3%), followed by R. monacensis (8.1%), while R. helvetica (1.8%), R. massiliae (0.5%), and R. raoultii (0.5%) were found only sporadically. Anaplasma phagocytophilum was identified in three pools and B. burgdorferi s.l. in one pool. All samples were negative for C. burnetii and TBEv. Significant associations were found between I. ricinus and roe deer, D. marginatus and wild boar, and between R. monacensis and I. ricinus. The prevalence of Rickettsia spp. differed significantly between tick and host species. This updated picture of tick species and TBPs in wild ungulates in Liguria, where the population of these animals is increasing, shows a widespread presence of potentially zoonotic Rickettsia spp. Continuous monitoring and public information on preventive measures are needed.

Identification of Rickettsia spp. in Ticks Removed from Tick-Bitten Humans in Northwestern Spain

Tick-borne rickettsioses (TBRs) are distributed worldwide and are recognized as important emerging vector-borne zoonotic diseases in Europe. The aim of this study was to identify tick-associated Rickettsia among ticks removed from humans, and to track how tick populations and their associated pathogens have changed over the years. For this purpose, we conducted a tick surveillance study in northwestern Spain between 2018 and 2022. Ticks were morphologically identified and analyzed for the presence of rickettsial pathogens through the amplification of the citrate synthase (gltA) and the outer membrane protein A (ompA) genes. PCR products were sequenced and subjected to phylogenetic analyses. We collected 7397 ticks, with Ixodes ricinus being the species most frequently isolated. Based on the PCR results, Rickettsia DNA was detected in 1177 (15.91%) ticks, and 10 members of Rickettsia were identified: R. aeschlimannii, R. conorii subsp. conorii, R. conorii subsp. raoultii, R. massiliae, R. monacensis, R. sibirica subsp. mongolitimonae, R. slovaca, R. helvetica, Candidatus R. barbariae, and Candidatus R. rioja. Some of these Rickettsia have gone previously undetected in the study region. There is clear geographic and seasonal expansion not only of tick populations, but also of the associated Rickettsia. The comparison of our data with those obtained years ago provides a clear idea of how the spatiotemporal distributions of ticks and their associated Rickettsiae have changed over the years.

Key molecules regulating the blood meals of Rhipicephalus sanguineus (Acari: Ixodidae) revealed by transcriptomics

Rhipicephalus sanguineus, a repulsive obligate blood feeder, is a three-host tick inflicting tremendous damage. Blood-sucking initiates tick-pathogen-host interactions along with alterations in the expression levels of numerous bioactive ingredients. Key molecules regulating blood meals were identified using the transcriptomic approach. A total number of 744 transcripts showed statistically significantly differential expression including 309 significantly upregulated transcripts and 435 significantly downregulated transcripts in semiengorged female ticks compared to unfed ticks, all collected in 2021. The top 10 differentially upregulated transcripts with explicit functional annotations included turripeptide OL55-like protein, valine tRNA ligase-like protein and ice-structuring glycoprotein-like protein. The top 10 differentially down-regulated transcripts were uncharacterized proteins. Gene Ontology (GO) enrichment analysis revealed four associated terms in the cellular component category and 16 in the molecular function category among the top 20 terms. Differentially expressed genes (DEGs) were enriched in GO terms ID 0000323 (lytic vacuole) and ID 0005773 (vacuole). The top 20 enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways included metabolism, cellular processes, organismal systems and human diseases. The DEGs were enriched in the KEGG term ID: ko-04142 (lysosome pathway) associated with intracellular digestion in the tick midgut epithelium. Molecular markers annotated via comparative transcriptomic profiling were expected to be candidate markers for the purpose of tick control.

Grazing system and Hyalomma marginatum tick infestation in cattle with high prevalence of SFG Rickettsia spp

Tick-borne diseases (TBDs) represent a significant portion of infectious diseases of global public health interest. In Italy, knowledge about the occurrence of tick-borne pathogens (TBPs) in ticks parasitizing cattle is scarce. In this research, we focused on ticks infesting Maremmana cattle grazing in open pasture and silvopasture systems. After being morphologically identified, ticks were molecularly tested for the presence of pathogens of the genus Rickettsia. Of the 794 ticks detected, 117 were collected, being the majority Hyalomma marginatum (72.6%), followed by other Hyalomma species (23%), Rhipicephalus turanicus (1.7%), Rh. bursa (0.9%), Hy. lusitanicum (0.9%) and Dermatocentor marginatus (0.9%). All ticks were adults, 58.1% males and 41.8% females. The highest tick prevalence was noted in April for silvopasture system cattle (90%), and in May for open pasture ones (85%). TBPs were detected only in Hy. marginatum, and all belong to Rickettsia spp. of zoonotic interest. In particular, 21/40 (52.5%) ticks scored positive for Rickettsia spp. by gltA gene and of these 15/21 (71.4%) also to spotted fever group (SFG) rickettsiae by ompA gene. Of the total positive specimens, 19 were successfully sequenced and scored Rickettsia aeschilimannii (17/19, 89.5%), R. slovaca (1/19, 5%), and R. massiliae (1/19, 5%). This research highlights the potential impact of grazing systems on cattle parasitization by hard ticks. The molecular investigation of TBPs in ticks collected from Maremmana cattle shed light on the presence of pathogenic bacteria of SFG Rickettsia spp., pointing out the potential risk of TBPs transmission between livestock and humans.

High-throughput screening of pathogens in Ixodes ricinus removed from hosts in Lombardy, northern Italy

Ticks are important vectors of many pathogens in Europe, where the most impactful species is Ixodes ricinus. Recently, the geographical distribution of this tick species has been expanding, resulting in an increased risk of human exposure to tick bites. With the present study, we aimed to screen 350 I. ricinus specimens collected from humans and wild animals (mainly ungulates), to have a broader understanding of the tick-borne pathogens circulating in the Lombardy region, in northern Italy. To do so, we took advantage of a high-throughput real-time microfluidic PCR approach to screen ticks in a cost-effective and time-saving manner. Molecular analysis of the dataset revealed the presence of four genera of bacteria and two genera of protozoa: in ungulates, 77 % of collected ticks carried Anaplasma phagocytophilum, while the most common pathogen species in ticks removed from humans were those belonging to Borrelia burgdorferi sensu lato group (7.6 %). We also detected other pathogenic microorganisms, such as Rickettisa monacensis, Rickettsia helvetica, Neoehrlichia mikurensis, Babesia venatorum, and Hepatozoon martis. Besides, we also reported the presence of the pathogenic agent Borrelia miyamotoi in the area (1.4 % overall). The most common dual co-infection detected in the same tick individual involved A. phagocytophilum and Rickettsia spp. Our study provided evidence of the circulation of different tick-borne pathogens in a densely populated region in Italy.

Detection of Rickettsia spp. and Anaplasma ovis in Melophagus ovinus from southern Xinjiang, China

Melophagus ovinus is a hematophagous insect that is distributed worldwide and plays a crucial role in transmitting disease-causing pathogens. From June 2021 to March 2022, a total of 370 M. ovinus were collected from 11 sampling points in southern Xinjiang, China. The specimens were identified using morphological and molecular analyses. Rickettsia spp. and Anaplasma ovis were detected from all the samples using seven Rickettsia-specific genetic markers and the msp-4 gene of A. ovis. Approximately 11% of the M. ovinus specimens were positive for Rickettsia spp., and Candidatus Rickettsia barbariae was the most predominant species (35/41; 85.4%), while R. massiliae was least prevalent (6/41; 14.6%). Approximately 10.5% (39/370) of the M. ovinus specimens were positive for A. ovis of genotype III, which was co-detected with Candidatus R. barbariae in M. ovinus (3/370; 0.8%). To the best of our knowledge, this is the first report of the detection of R. massiliae and Candidatus R. barbariae in M. ovinus globally. The detection and control of insect-borne diseases originating from M. ovinus should be strengthened in southern Xinjiang, an area important to animal husbandry and production.

Rickettsial Infection in the COVID-19 Era: The Correlation between the Detection of Rickettsia aeschlimannii in Ticks and Storytelling Photography of a Presumable Human Rickettsiosis Case

Rickettsia aeschlimannii infection is an emerging human tick-borne disease with only a few recorded cases. We reported a presumable autochthonous case of rickettsiosis in an Italian cattle breeder associated with a Hyalomma marginatum bite. Rickettsia aeschlimannii DNA was detected in both the tick specimen from the patient and the grazing cattle close to his farm.

Wild ungulates as sentinels of flaviviruses and tick-borne zoonotic pathogen circulation: an Italian perspective

BACKGROUND

Vector-borne zoonotic diseases are a concerning issue in Europe. Lyme disease and tick-borne encephalitis virus (TBEV) have been reported in several countries with a large impact on public health; other emerging pathogens, such as Rickettsiales, and mosquito-borne flaviviruses have been increasingly reported. All these pathogens are linked to wild ungulates playing roles as tick feeders, spreaders, and sentinels for pathogen circulation. This study evaluated the prevalence of TBEV, Borrelia burgdorferi sensu lato, Rickettsia spp., Ehrlichia spp., and Coxiella spp. by biomolecular screening of blood samples and ticks collected from wild ungulates. Ungulates were also screened by ELISA and virus neutralization tests for flaviviral antibody detection.

RESULTS

A total of 274 blood samples were collected from several wild ungulate species, as well as 406 Ixodes ricinus, which were feeding on them. Blood samples tested positive for B. burgdorferi s.l. (1.1%; 0-2.3%) and Rickettsia spp. (1.1%; 0-2.3%) and showed an overall flaviviral seroprevalence of 30.6% (22.1-39.2%): 26.1% (17.9-34.3%) for TBEV, 3.6% (0.1-7.1%) for Usutu virus and 0.9% (0-2.7%) for West Nile virus. Ticks were pooled when possible and yielded 331 tick samples that tested positive for B. burgdorferi s.l. (8.8%; 5.8-11.8%), Rickettsia spp. (26.6%; 21.8-31.2%) and Neoehrlichia mikurensis (1.2%; 0-2.4%). TBEV and Coxiella spp. were not detected in either blood or tick samples.

CONCLUSIONS

This research highlighted a high prevalence of several tick-borne zoonotic pathogens and high seroprevalence for flaviviruses in both hilly and alpine areas. For the first time, an alpine chamois tested positive for anti-TBEV antibodies. Ungulate species are of particular interest due to their sentinel role in flavivirus circulation and their indirect role in tick-borne diseases and maintenance as Ixodes feeders and spreaders.

Touching Base with Some Mediterranean Diseases of Interest from Paradigmatic Cases at the "Magna Graecia" University Unit of Infectious Diseases: A Didascalic Review

Among infectious diseases, zoonoses are increasing in importance worldwide, especially in the Mediterranean region. We report herein some clinical cases from a third-level hospital in Calabria region (Southern Italy) and provide a narrative review of the most relevant features of these diseases from epidemiological and clinical perspectives. Further, the pathogenic mechanisms involved in zoonotic diseases are reviewed, focusing on the mechanisms used by pathogens to elude the immune system of the host. These topics are of particular concern for individuals with primary or acquired immunodeficiency (e.g., people living with HIV, transplant recipients, patients taking immunosuppressive drugs). From the present review, it appears that diagnostic innovations and the availability of more accurate methods, together with better monitoring of the incidence and prevalence of these infections, are urgently needed to improve interventions for better preparedness and response.

Tick Species Diversity and Molecular Identification of Spotted Fever Group Rickettsiae Collected from Migratory Birds Arriving from Africa

The role of migratory birds in the spread of ticks and tick-borne pathogens along their routes from Africa to Europe is increasingly emerging. Wild birds can host several tick species, often infected by bacteria responsible for zoonoses. The aim of the study is to assess the possible introduction of exotic ticks carried by migratory birds into Italy from Africa and to detect the presence of Rickettsia species and Coxiella burnetii they may harbor. During a two-year survey, we collected ticks from migratory birds captured during their short stop-over on Ventotene Island. Specimens were first identified by morphology or sequencing molecular targets when needed, and then tested by real-time PCR for the presence of selected pathogens. A total of 91% of the collection consisted of sub-Saharan ticks, more than 50% of which were infected by Rickettsia species belonging to the spotted fever group, mainly represented by R. aeschlimannii. In contrast, the suspected C. burnetii detected in two soft ticks were confirmed as Coxiella-like endosymbionts and not the pathogen. Although there are still gaps in the knowledge of this dispersal process, our findings confirm the role of migratory birds in the spread of ticks and tick-borne pathogens, suggesting the need for a continuous surveillance to monitor the potential emergence of new diseases in Europe.

Rickettsiales in the WHO European Region: an update from a One Health perspective

BACKGROUND

The availability of molecular techniques has significantly increased our understanding of bacteria of the order Rickettsiales, allowing the identification of distinct species in both vector and host arthropods. However, the literature lacks studies that comprehensively summarize the vast amount of knowledge generated on this topic in recent years. The purpose of this study was to conduct a comprehensive analysis of the distribution of Rickettsiales in arthropod vectors, animals and humans in the WHO European Region in order to provide useful information to predict the emergence of certain diseases in specific geographical areas and to formulate hypotheses regarding the possible pathogenetic role of some rickettsial species in the etiology of human pathological conditions.

METHODS

A systematic review of the literature in the PubMed and EMBASE databases was conducted following the PRISMA methodology using the search terms "Spotted fever" OR "rickettsiosis" OR "ricketts*" AND all the countries of the WHO European Region, from 1 January 2013 to 12 February 2022. Only studies that identified rickettsiae in human, animal or arthropod samples using molecular techniques were included in the review.

RESULTS

A total of 467 articles considering 61 different species of Rickettsiales with confirmed or suspected human pathogenicity were analyzed in the review. More than 566 identifications of Rickettsiales DNA in human samples were described, of which 89 cases were assessed as importation cases. A total of 55 species of ticks, 17 species of fleas, 10 species of mite and four species of lice were found infected. Twenty-three species of Rickettsiales were detected in wild and domestic animal samples.

CONCLUSION

The routine use of molecular methods to search for Rickettsiales DNA in questing ticks and other blood-sucking arthropods that commonly bite humans should be encouraged. Molecular methods specific for Rickettsiales should be used routinely in the diagnostics of fever of unknown origin and in all cases of human diseases secondary to an arthropod bite or animal contact.

Co-Infection of Potential Tick-Borne Pathogens of the Order Rickettsiales and Borrelia burgdorferi s. l. and Their Link to Season and Area in Germany

The prevalence of potential human pathogenic members of the order Rickettsiales differs between Borrelia burgdorferi sensu lato-positive and -negative tick microbiomes. Here, co-infection of members of the order Rickettsiales, such as Rickettsia spp., Anaplasma phagocytophilum, Wolbachia pipientis, and Neoehrlichia mikurensis as well as B. burgdorferi s.l. in the tick microbiome was addressed. This study used conventional PCRs to investigate the diversity and prevalence of the before-mentioned bacteria in 760 nucleic acid extracts of I. ricinus ticks detached from humans, which were previously tested for B. burgdorferi s.l.. A gltA gene-based amplicon sequencing approach was performed to identify Rickettsia species. The prevalence of Rickettsia spp. (16.7%, n = 127) and W. pipientis (15.9%, n = 121) were similar, while A. phagocytophilum was found in 2.8% (n = 21) and N. mikurensis in 0.1% (n = 1) of all ticks. Co-infection of B. burgdorferi s. l. with Rickettsia spp. was most frequent. The gltA gene sequencing indicated that Rickettsia helvetica was the dominant Rickettsia species in tick microbiomes. Moreover, R, monacensis and R. raoultii were correlated with autumn and area south, respectively, and a negative B. burgdorferi s. l. finding. Almost every fifth tick carried DNA of at least two of the human pathogenic bacteria studied here.

Emerging tick-borne spotted fever group rickettsioses in the Balkans

The impact of tick-borne pathogens (TBPs) on human health has increased in the last decades, since the incidence of emerging and re-emerging infectious and zoonotic tick-borne diseases has increased worldwide. Tick-borne rickettsiae of the Spotted Fever group (SFGR) are considered as emerging pathogens that can infect humans and cause a variety of non-specific clinical symptoms. Here, we report nine cases of atypical tick-borne diseases (9/460; 1.95%) that occurred over a period of four months (from 15 April 2021 to 16 August 2021) in Serbia, from which five cases were classified as confirmed SFGR infection, two cases as probable SFGR infection and two cases as suspected SFGR infection. Within cases of confirmed SFGR infection, R. helvetica was detected as the causative agent in two cases. The most common clinical finding was non-expanding persistent circular redness, followed by eschar and enlargement of regional lymph nodes, and pain at lesion site. Rickettsia outer membrane protein B (ompB) and citrate synthase (gltA) gene fragments were amplified from clinical samples and ticks attached to patients and IgG reacting with Rickettsia conorii antigen were detected in sera samples of patients, which are highly suggestive of exposure to SFGR. Surveillance and monitoring of rickettsial diseases in Serbia should continue and extended to new areas due to the increasing trend of clinical infections caused by SFGR in the country.

High Prevalence of Tick-Borne Zoonotic Rickettsia slovaca in Ticks from Wild Boars, Northeastern Italy

Simple Summary

Tick-borne rickettsioses are emerging diseases that have become widespread in many European countries, particularly in those facing the Mediterranean basin. Although Rickettsia conorii was traditionally thought to be the most threatening species, in recent decades, thanks to the improvements in biomolecular tools, other zoonotic species have been identified, such as Rickettsia slovaca, the etiological agent of scalp eschar and neck lymphadenopathy after tick bite (SENLAT), as well as other neglected species. These pathogens are present in Italy, but few data are available. This research aimed to improve the epidemiological knowledge of rickettsial infections in tick and wild boar populations in the Euganean Hills Regional Park, an enclosed area in northeastern Italy. Both tick and wild boar blood samples were tested using biomolecular methods to detect and identify Rickettsia species. Only ticks tested positive, and Rickettsia slovaca was the most frequently detected species, showing a high prevalence, followed by Rickettsia monacensis and Rickettsia helvetica. These data highlight a non-negligible presence of these pathogens in northern Italy and outline that rickettsial infections deserve further investigation.

Abstract

Tick-borne rickettsiae are emerging pathogens that are becoming widespread in Europe. Rickettsiae are endemic in Italy, but epidemiological data are currently scarce. This study aimed to improve our knowledge about rickettsial infections in tick and wild boar populations. Blood and ticks were collected from 102 wild boars in 2010 and 2018. Ticks were also collected from the vegetation in the area. All of the samples were examined using real-time PCR targeting the gltA gene to detect Rickettsia DNA. Positivity was confirmed by PCR amplifying the gltA and/or ompB genes. A total of 254 ticks and 89 blood samples were analyzed. Zoonotic rickettsiae were detected in the ticks but not in the blood samples. Rickettsia slovaca (R. slovaca) was the most prevalent in ticks and was found in 23.7% of Dermacentor marginatus (D. marginatus) and in 3.4% of Ixodes ricinus (I. ricinus). Other zoonotic species were identified, such as Rickettsia monacensis, which was detected in 12% of I. ricinus ticks, and Rickettsia helvetica which was found in 3.4% of questing I. ricinus ticks and in 1.1% of D. marginatus collected from wild boars. This study highlights a high prevalence of zoonotic rickettsiae, particularly that of R. slovaca, in northeastern Italy. As rickettsioses are underreported and underdiagnosed in human medicine, both clinicians and researchers should pay more attention to this topic.

Clinical, epidemiological, and laboratory features of Rickettsia africae infection, African tick-bite fever: A systematic review

African tick-bite fever (ATBF), caused by Rickettsia africae, is the main tick-borne rickettsiosis and the second most frequent cause of fever after malaria in travelers returning from sub-Saharan Africa. General descriptions on ATBF were made in the first two decades after recognized as a new infectious entity, and since then, many authors have contributed to the knowledge of the disease by reporting clinical cases in scientific literature. We developed a systematic review that evaluated all available evidence in the literature regarding clinical, epidemiological, and laboratory features of confirmed R. africae rickettsiosis cases. We followed the recommendations made by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guide. A total of 48 scientific publications (108 confirmed cases) were analyzed in order to extract data for developing this review. Overall, our results show that R. africae rickettsiosis is more frequent in males in the age group of 18-64 years, more than 80% of the cases occurred in European travelers, South Africa was the country where most infections were acquired, and almost 40% of cases occurred in clusters. Clinically, more than 80% of the cases had fever and eschar (55% developed multiple eschars), rash was present in less than the half of cases, and lymphangitis was not a common sign (11%). Headache, myalgia and regional lymphadenopathy were predominant nonspecific clinical manifestation (mean of 60%, 49% and 51%, respectively). Our results show that at least 70% of R. africae cases had altered laboratory parameters, most often showing an increase in transaminases and C-reactive protein. Tetracycline-class antibiotics, as monotherapy, were used in most (>90%) of the patients. Overall, only 4% of cases had complications, 12% required hospitalization, and there was a 100% rate of clinical recovery.

Rickettsiosis with Pleural Effusion: A Systematic Review with a Focus on Rickettsiosis in Italy

Background: Motivated by a case finding of Mediterranean spotted fever (MSF) associated with atypical pneumonia and pleural effusion in which Rickettsia conorii subsp. israelensis was identified by molecular methods in the pleural fluid, we wanted to summarize the clinical presentations of rickettsiosis in Italy by systematic research and to make a systematic review of all the global cases of rickettsiosis associated with pleural effusion. Methods: For the literature search, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was followed. We chose to select only the studies published in last 25 years and confirmed both with serological and molecular assays. Results: Human cases of rickettsiosis in Italy were reported in 48 papers describing 2831 patients with very different clinical presentations; the majority was MSF accounted to R. conorii and was reported in Sicily. Pleural effusion associated with infection with microorganisms belonging to Rickettsiales was described in 487 patients. It was rarely associated with microorganisms different from O. tsutsugamushi; also rarely, cases of scrub typhus were reported outside Southeast Asia and in the largest majority, the diagnosis was achieved with serology. Conclusions: MSF, especially when caused by R. conorii subsp. israelensis, may be a severe disease. A high index of suspicion is required to promptly start life-saving therapy. Pleural effusion and interstitial pneumonia may be part of the clinical picture of severe rickettsial disease and should not lead the physician away from this diagnosis

One Health Approach to Rickettsiosis: A Five-Year Study on Spotted Fever Group Rickettsiae in Ticks Collected from Humans, Animals and Environment

The spotted fever group of Rickettsiae is a heterogeneous group of Rickettsiae transmitted by ticks, causing similar diseases in humans (spotted fever). Until recently, it was supposed that a single pathogenic tick-borne SFG Rickettsia circulated in each different geographic area and that R. conorii subsp. conorii was the SFG Rickettsiae circulating in Italy, but in the last decade, thanks to molecular diagnostic, several different Rickettsia species, previously not considered pathogenic for decades, have been isolated from ticks and definitively associated to human disease, also in Italy. The present survey was carried out with the aim of investigating the presence of different SFG Rickettsia species in a geographic area where no information was available. Ticks collected from animals submitted to necropsy, removed from humans in local hospitals and collected from the environment were identified and tested by PCR for Rickettsia spp. based on the gltA gene, and positive PCR products were sequenced. A total of 3286 ticks were collected. Fifteen tick species were recognized, the most represented (79.52%) species in the collection was Ixodes ricinus, followed by Rhipicephalus sanguineus (9.13%). The overall prevalence of Rickettsia infection was 7.58%. Eight species of Rickettsia were identified, the most frequent was R. monacensis (56%), followed by R. helvetica (25.50%). Noteworthy, is the detection in the present study of Rrhipicephali, detected only twice in Italy. These are the first data available on SFG Rickettsiae circulation in the study area and they can be considered as starting point to assess the possible risk for humans.

Mediterranean Spotted Fever: Current Knowledge and Recent Advances

Mediterranean spotted fever (MSF) is an emerging tick-borne rickettsiosis of the spotted fever group (SFG), endemic in the Mediterranean basin. By virtue of technological innovations in molecular genetics, it has been determined that the causative agent of MSF is Rickettsia conorii subspecies conorii. The arthropod vector of this bacterium is the brown dog tick Rhipicephalus sanguineus. The true nature of the reservoir of R. conorii conorii has not been completely deciphered yet, although many authors theorize that the canine population, other mammals, and the ticks themselves could potentially contribute as reservoirs. Typical symptoms of MSF include fever, maculopapular rash, and a characteristic eschar (“tache noire”). Atypical clinical features and severe multi-organ complications may also be present. All of these manifestations arise from the disseminated infection of the endothelium by R. conorii conorii. Several methods exist for the diagnosis of MSF. Serological tests are widely used and molecular techniques have become increasingly available. Doxycycline remains the treatment of choice, while preventive measures are focused on modification of human behavior and vector control strategies. The purpose of this review is to summarize the current knowledge on the epidemiology, pathogenesis, clinical features, diagnosis, and treatment of MSF.

A severe case of Israeli spotted fever with pleural effusion in Italy

Background

The most common Italian rickettsiosis is Mediterranean Spotted Fever (MSF). MSF is commonly associated with a symptom triad consisting of fever, cutaneous rash, and inoculation eschar. The rash is usually maculopapular but, especially in severe presentations, may be petechial. Other typical findings are arthromyalgia and headache. Herein, we describe for the first time an unusual case of Israeli spotted fever (ISF) associated with interstitial pneumonia and pleural effusion in which R. conorii subsp. israelensis was identified by molecular methods in the blood, as well as in the pleural fluid.

Case presentation

A 72-year-old male presented with a 10-day history of remittent fever. On admission, the patient’s general condition appeared poor with confusion and drowsiness; the first assessment revealed a temperature of 38.7°, blood pressure of 110/70 mmHg, a blood oxygen saturation level of 80% with rapid, frequent, and superficial breathing using accessory muscles (28 breaths per minute), and an arrhythmia with a heart rate of 90 beats per minute. qSOFA score was 3/3. Chest CT revealed ground-glass pneumonia with massive pleural effusion. Petechial exanthema was present diffusely, including on the palms and soles, and a very little eschar surrounded by a violaceous halo was noted on the dorsum of the right foot. Awaiting the results of blood cultures, broad-spectrum antibiotic therapy with meropenem 1 g q8h, ciprofloxacin 400 mg q12h, and doxycycline 100 mg q12h was initiated. Doxycycline was included in the therapy because of the presence of petechial rash and fever, making us consider a diagnosis of rickettsiosis. This suspicion was confirmed by the positivity of polymerase chain reaction on whole blood for R. conorii subsp. israelensis. Thoracentesis was performed to improve alveolar ventilation. R. conorii subsp. israelensis was again identified in the pleural fluid by PCR technique. On day 4 the clinical condition worsened. Blood exams showed values suggestive of secondary hemophagocytic lymphohistiocytosis; 4 out of 8 diagnostic criteria were present and empirical treatment with prednisone was started resulting in a gradual improvement in general condition.

Conclusions

Israeli spotted fever may be a severe disease. A high index of suspicion is required to promptly start life-saving therapy. Pleural effusion and interstitial pneumonia may be part of the clinical picture of severe rickettsial disease and should not lead the physician away from this diagnosis.