Rickettsia slovaca infection in humans, Portugal

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.

Epidemiological, Clinical, and Microbiological Characteristics in a Large Series of Patients Affected by Dermacentor-Borne-Necrosis-Erythema-Lymphadenopathy from a Unique Centre from Spain

During recent decades, a tick-borne rickettsial syndrome, characterized by eschar and painful lymphadenopathy after Dermacentor marginatus-bite, has been described as an emerging rickettsiosis in Europe. Our group named it DEBONEL (Dermacentor-borne-necrosis-erythema-lymphadenopathy), regarding the vector and the main infection signs. Other groups called it TIBOLA (tick-borne-lymphadenophathy) and, later, SENLAT (scalp-eschar-and-neck-lymphadenopathy-after-tick-bite), expanding, in the latter, the etiological spectrum to other pathogens. Objective: To investigate the etiology of DEBONEL agents in our area, and to compare their epidemiological/clinical/microbiological characteristics. During 2001-2020, 216 patients clinically diagnosed of DEBONEL (the largest series from one center) in La Rioja (northern Spain) were examined. Rickettsia spp. were amplified in 14/104 (13.46%) blood samples, 69/142 (48.59%) eschar swabs, 7/7 (100%) biopsies, and 71/71 (100%) D. marginatus from patients. For samples in which Rickettsia was undetected, no other microorganisms were found. 'Candidatus Rickettsia rioja', Rickettsia slovaca, Rickettsia raoultii, and Rickettsia DmS1 genotype were detected in 91, 66, 4, and 3 patients, respectively. DEBONEL should be considered in patients with clinical manifestations herein described in areas associated to Dermacentor. The most frequently involved agent in our environment is 'Ca. R. rioja'. The finding of Rickettsia sp. DmS1 in ticks attached to DEBONEL patients suggests the implication of other rickettsia genotypes.

Rare Case of Rickettsiosis Caused by Rickettsia monacensis, Portugal, 2021

We report a case of rickettsiosis caused by Rickettsia monacensis in an immunocompetent 67-year-old man in Portugal who had eschar, erythematous rash, and an attached Ixodes ricinus tick. Seroconversion and eschar biopsy led to confirmed diagnosis by PCR. Physicians should be aware of this rare rickettsiosis, especially in geographic regions with the vector.

Molecular Detection of Zoonotic and Non-Zoonotic Pathogens from Wild Boars and Their Ticks in the Corsican Wetlands

Corsica is the main French island in the Mediterranean Sea and has high levels of human and animal population movement. Among the local animal species, the wild boar is highly prevalent in the Corsican landscape and in the island’s traditions. Wild boars are the most commonly hunted animals on this island, and can be responsible for the transmission and circulation of pathogens and their vectors. In this study, wild boar samples and ticks were collected in 17 municipalities near wetlands on the Corsican coast. A total of 158 hunted wild boars were sampled (523 samples). Of these samples, 113 were ticks: 96.4% were Dermacentor marginatus, and the remainder were Hyalomma marginatum, Hyalomma scupense and Rhipicephalus sanguineus s.l. Of the wild boar samples, only three blood samples were found to be positive for Babesia spp. Of the tick samples, 90 were found to be positive for tick-borne pathogens (rickettsial species). These results confirm the importance of the wild boar as a host for ticks carrying diseases such as rickettsiosis near wetlands and recreational sites. Our findings also show that the wild boar is a potential carrier of babesiosis in Corsica, a pathogen detected for the first time in wild boars on the island.

Tick-borne pathogens in ticks (Acari: Ixodidae) collected from various domestic and wild hosts in Corsica (France), a Mediterranean island environment

Corsica is a mountainous French island in the north-west of the Mediterranean Sea presenting a large diversity of natural environments where many interactions between humans, domestic animals and wild fauna occur. Despite this favourable context, tick-borne pathogens (TBPs) have not systematically been investigated. In this study, a large number of TBPs were screened in ticks collected over a period of one year from domestic and wild hosts in Corsica. More than 1,500 ticks belonging to nine species and five genera (Rhipicephalus, Hyalomma, Dermacentor, Ixodes and Haemaphysalis) were analysed individually or pooled (by species, gender, host and locality). A real-time microfluidic PCR was used for high-throughput screening of TBP DNA. This advanced methodology enabled the simultaneous detection of 29 bacterial and 12 parasitic species (including Borrelia, Anaplasma, Ehrlichia, Rickettsia, Bartonella, Candidatus Neoehrlichia, Coxiella, Francisella, Babesia and Theileria). The Crimean-Congo haemorrhagic fever (CCHF) virus was investigated individually in tick species known to be vectors or carriers of this virus. In almost half of the tick pools (48%), DNA from at least one pathogen was detected and eleven species of TBPs from six genera were reported. TBPs were found in ticks from all collected hosts and were present in more than 80% of the investigated area. The detection of DNA of certain species confirmed the previous identification of these pathogens in Corsica, such as Rickettsia aeschlimannii (23% of pools), Rickettsia slovaca (5%), Anaplasma marginale (4%) and Theileria equi (0.4%), but most TBP DNA identified had not previously been reported in Corsican ticks. This included Anaplasma phagocytophilum (16%), Rickettsia helvetica (1%), Borrelia afzelii (0.7%), Borrelia miyamotoi (1%), Bartonella henselae (2%), Babesia bigemina (2%) and Babesia ovis (0.5%). The high tick infection rate and the diversity of TBPs reported in this study highlight the probable role of animals as reservoir hosts of zoonotic pathogens and human exposure to TBPs in Corsica.

Tick-Borne Pathogens in Ixodid Ticks from Poyang Lake Region, Southeastern China

Ticks are the vectors of various pathogens, threatening human health and animal production across the globe. Here, for the first time we detected Ricketssia spp., Borrelia spp. and protozoan in ticks from Poyang Lake region in Ji- angxi Province of eastern China. In 3 habitat categories and on 12 host species, 311 ticks from 11 species were collected. Haemaphysalis longicornis was the predominant species, accounting for 55.63%, followed by Rhipicephalus microplus, Haemaphysalis flava and Ixodes granulatus. Of the collected ticks, 7.07% were positive for tick-borne pathogens, and H. longicornis and H. flava were found to be co-infected with Ricketssia spp. and protozoan. H. flava was the most detected positive for tick-borne pathogens, whereas H. longicornis had the lowest infection rate, and the difference in infection rates between tick species was significant (χ2=61.24, P<0.001). Furthermore, adult ticks demonstrated remarkably greater infection rate than immature ticks (χ2=10.12, P=0.018), meanwhile ticks on Erinaceidae showed significantly higher positivity than ticks collected on other host species (χ2=108.44, P<0.001). Genetic fragment sequencing and analyses showed at least 4 pathogen species presence in ticks, namely Borrelia yangtzensis, Rickettsia slovaca or Rickettsia raoultii related genospecies, Babesia vogeli and Hepatozoon canis or Hepatozoon felis related genospecies. The finding indicates that the abundant ticks can carry diverse pathogens in Poyang Lake region, and pathogen infection is highly related to species, vertebrate hosts and life stages of ticks.

Detection of Anaplasma phagocytophilum, Candidatus Neoehrlichia sp., Coxiella burnetii and Rickettsia spp. in questing ticks from a recreational park, Portugal

Tick-borne agents with medical relevance have been recorded in Portugal but little is known about their occurrence in urban outdoor leisure areas. This study aimed to investigate ticks and tick-borne agents in three public parks of Lisbon's metropolitan area. A total of 234 questing ticks belonging to eight species were found in Parque Florestal de Monsanto (PFM). Ixodes ventalloi represented 40% of collections. Mitochondrial genes confirmed Ixodes morphological identification, evidencing the intraspecific variability of I. ricinus and particularly I. frontalis populations. Regarding tick-borne agents, Rickettsia massiliae DNA were found in 21 (9.0%) ticks, Coxiella burnetii in 15 (6.4%), Anaplasma phagocytophilum in five (2.1%), an agent closely related to Candidatus Neoehrlichia mikurensis in two (0.9%), Rickettsia sibirica mongolitimonae and Rickettsia monacensis each in one (0.4%). Active enzootic cycles were suggested for these agents by the detection of positives in different time periods. Five tick species were founded with C. burnetii, including I. ventalloi which seems to be a new association record. This tick was also the only species found positive for A. phagocytophilum and the Candidatus Neoehrlichia mikurensis-like agent. Two A. phagocytophilum variants were detected in PFM, one of them representing a potentially new ecotype already found in I. ventalloi from another Portuguese area. To the authors´ knowledge, this is also the first report of such a Candidatus Neoehrlichia mikurensis-like microorganism. These data show an interesting diversity of ticks and tick-borne agents with potential public health relevance in PFM, an urban recreational area commonly frequented by humans and their pets.

Molecular Evidence of Rickettsia slovaca in Wild Boar Lice, in Northeastern Algeria

Using molecular assays, Rickettsia slovaca, the agent of a spotted fever group rickettsia was assessed in 92/325 lice collected on 117 wild boars hunted in the far northeast of Algeria. Overall, 7/92 (7.61%) Haematopinus suis were found positive to R. slovaca. The presence of R. slovaca DNA on H. suis questions about the relationship that may exist between R. slovaca and lice.

Prevalence of different Rickettsia spp. in Ixodes ricinus and Dermacentor reticulatus ticks (Acari: Ixodidae) in north-eastern Poland

In two surveys conducted in April and May 2013, a total of 1148 unfed ticks belonging to two species, Ixodes ricinus and Dermacentor reticulatus, were collected by flagging lower vegetation in 15 different localities throughout the Białowieża Primeval Forest (Podlaskie voivodship; north-eastern Poland) and in its buffer zone. In order to establish their infection rate with Rickettsia spp. individual adult ticks and pooled nymphs were tested by real-time PCR targeting the gltA gene. For the further identification of rickettsial species, positive samples were subjected for nested and semi-nested PCR targeting ompA and 16S rRNA genes, respectively, followed by sequencing analysis. Rickettsial DNA was detected in at least 279 ticks (minimum infection rate [MIR], 23.9%), including 52 nymphal and adult I. ricinus (MIR 8.6%) and 222 adult D. reticulatus (41%). Three species of SFG rickettsiae were identified: Rickettsia helvetica and 'Candidatus R. mendelii' in I. ricinus and R. raoultii in D. reticulatus and I. ricinus. Moreover, unidentified Rickettsia spp. which showed 99.4% identity, among others, with the uncultured Rickettsia sp. isolated from Cicadella viridis leafhopper, Rickettsia endosymbiont of Lasioglossum semilucens bee and R. bellii, were detected in I. ricinus, while Rickettsia sp. 98.3-98.4% homologous to Rickettsia secondary endosymbionts of Curculio spp. weevils was found in D. reticulatus. These results confirm the diversity of rickettsiae occurring in Poland. Further studies are needed to expand the knowledge on the species spectrum, prevalence and epidemiology of SFG rickettsiae in the country.

Tick-borne bacteria and protozoa detected in ticks collected from domestic animals and wildlife in central and southern Portugal

Ticks are vectors of many human and animal pathogens. The aim of this study was to screen bacteria and protozoa from ticks infesting domestic animals and wildlife collected in central and southern Portugal. A total of 593 ticks, comprising 465 (78.4%) adults, 122 (20.6%) nymphs, and six (1.0%) larvae, were collected from 283 hosts of 25 different species (4 domestic and 21 wild). Overall, the analysis of DNA extracts prepared from ticks collected from hosts of 11 different species in the districts of Castelo Branco, Portalegre, Lisboa, Setúbal, Beja and Faro, revealed the presence of genomic sequences from Anaplasma sp., A. ovis, Babesia sp., relapsing fever-like Borrelia sp., Ehrlichia spp., Rickettsia aeschlimannii, Ri. helvetica, Ri. massiliae, Ri. raoultii, Ri. slovaca, Candidatus Ri. barbariae, Theileria annulata and T. ovis, in specimens of Dermacentor marginatus, Hyalomma lusitanicum, Hy. marginatum, Rhipicephalus bursa and Rh. sanguineus sensu lato. The obtained results suggest the circulation of a wide variety of infectious agents, some of zoonotic concern, in hard ticks from Portugal. Further studies should be conducted to better characterize (both genetically and phenotypically) the putative novel microorganisms detected, both in what regards their potential pathogenity towards vertebrates, and to assist the implementation of effective control strategies for the management of ticks and human and animal tick-borne pathogens.

Emerging Tick-Borne Bacterial Pathogens

A vast number of novel tick-related microorganisms and tick-borne disease agents have been identified in the past 20 years, and more are being described due to several factors, from the curiosity of clinicians faced with unusual clinical syndromes to new tools used by microbiologists and entomologists. Borrelioses, ehrlichioses, anaplasmosis, and tick-borne rickettsial diseases are some of the emerging diseases that have been described throughout the world in recent years. In this article, we focus on the bacterial agents and diseases that have been recognized in the past 3 years and refer to major recent reviews of other recognized infections.

Kampinos National Park: a risk area for spotted fever group rickettsioses, central Poland?

Ixodid ticks are important vectors of a variety of bacterial and protozoan pathogens which cause infections in humans. In this study, altogether 1041 questing Ixodes ricinus (n = 305) and Dermacentor reticulatus ticks (n = 736), sympatrically occurring in Kampinos National Park (KPN), central-east Poland, were analyzed by PCR for Rickettsia species. Overall, the pathogen prevalence in ticks was 27.5 % for I. ricinus and 42.8 % for D. reticulatus. Sequencing analysis showed that the first tick species was exclusively infected with R. helvetica, whereas the latter was infected with R. raoultii. These organism may pose a threat for populations exposed to ticks. Preliminary results of a serosurvey of 74 KPN employees, inhabitants and visitors from the same area showed a 31.1 % total seroprevalence against SFG rickettsiae compared to 13.3 % seropositive blood donors of the control group. Risk factors significantly associated with IgG seropositivity were: occupational exposure to ticks (p = 0.002), frequency of tick bites (p = 0.02) and male gender (p = 0.005). Seropositive and seronegative individuals occupationally exposed to ticks did not differ significantly with respect to age and years of employment.

Assessment of Domestic Goats as Models for Experimental and Natural Infection with the North American Isolate of Rickettsia slovaca

Rickettsia slovaca is a tick-borne human pathogen that is associated with scalp eschars and neck lymphadenopathy known as tick-borne lymphadenopathy (TIBOLA) or Dermacentor-borne necrosis erythema and lymphadenopathy (DEBONEL). Originally, R. slovaca was described in Eastern Europe, but since recognition of its pathogenicity, human cases have been reported throughout Europe. European vertebrate reservoirs of R. slovaca remain unknown, but feral swine and domestic goats have been found infected or seropositive for this pathogen. Recently, a rickettsial pathogen identical to R. slovaca was identified in, and isolated from, the American dog tick, Dermacentor variabilis. In previous experimental studies, this organism was found infectious to guinea pigs and transovarially transmissible in ticks. In this study, domestic goats (Capra hircus) were experimentally inoculated with the North American isolate of this R. slovaca-like agent to assess their reservoir competence-the ability to acquire the pathogens and maintain transmission between infected and uninfected ticks. Goats were susceptible to infection as demonstrated by detection of the pathogen in skin biopsies and multiple internal tissues, but the only clinical sign of illness was transient fever noted in three out of four goats, and reactive lymphoid hyperplasia. On average, less than 5% of uninfected ticks acquired the pathogen while feeding upon infected goats. Although domestic goats are susceptible to the newly described North American isolate of R. slovaca, they are likely to play a minor role in the natural transmission cycle of this pathogen. Our results suggest that goats do not propagate the North American isolate of R. slovaca in peridomestic environments and clinical diagnosis of infection could be difficult due to the brevity and mildness of clinical signs. Further research is needed to elucidate the natural transmission cycle of R. slovaca both in Europe and North America, as well as to identify a more suitable laboratory model.

Emerging tick-borne infections in mainland China: an increasing public health threat

Since the beginning of the 1980s, 33 emerging tick-borne agents have been identified in mainland China, including eight species of spotted fever group rickettsiae, seven species in the family Anaplasmataceae, six genospecies in the complex Borrelia burgdorferi sensu lato, 11 species of Babesia, and the virus causing severe fever with thrombocytopenia syndrome. In this Review we have mapped the geographical distributions of human cases of infection. 15 of the 33 emerging tick-borne agents have been reported to cause human disease, and their clinical characteristics have been described. The non-specific clinical manifestations caused by tick-borne pathogens present a major diagnostic challenge and most physicians are unfamiliar with the many tick-borne diseases that present with non-specific symptoms in the early stages of the illness. Advances in and application of modern molecular techniques should help with identification of emerging tick-borne pathogens and improve laboratory diagnosis of human infections. We expect that more novel tick-borne infections in ticks and animals will be identified and additional emerging tick-borne diseases in human beings will be discovered.

Mediterranean spotted fever: case series of 24 years (1989-2012)

PURPOSE

Mediterranean spotted fever (MSF) is the most prevalent zoonosis in Portugal. To characterize it's evolution between 1989 and 2012, the authors reviewed the cases diagnosed at their unit during this period.

METHODS

Review of clinical records of patients with MSF diagnosis, between 1989 and 2012.

RESULTS

Data from 250 patients was included, 54% male. Mean age at diagnosis was 58 years (11-92). Mean annual incidence was 10 cases, with clear summer predominance. Most patients, 78% lived in rural areas, 34% had contact with dogs and 10% noticed the tick bite. Most common symptoms were: fever (98%), myo-arthralgia (64%) and headache (48%). Maculopapular rash was noticed in 87%, affecting palms in 77% and soles in 69%. Inoculation eschar was found in 60%, mostly located on the trunk. Treatment included doxycycline in 86% and chloramphenicol in 12%, with a mean duration of 8 days. Most frequent blood test abnormalities were C-reactive protein, lactate dehydrogenase, aspartate aminotransferase and alanine transaminase elevations and thrombocytopenia. First serologic evaluation was positive in 37% (78/212), having seroconversion been documented in 85% (72/85). Most frequent complication was acute renal injury. ICU admission occurred in 5%. Average length of hospital stay was 11.2 days (1-106), with a mortality of 3.6%.

CONCLUSIONS

In our series, there was clear summer predominance of MSF, which had rural origin in 78%. Most common symptoms were fever, myo-arthralgia and headache. Maculopapular rash was noticed in 87% of cases and inoculation eschar in 60%. Most cases had favourable outcome, having 5% been admitted to ICU. Mortality was 3.6%.

Rickettsial infection caused by accidental conjunctival inoculation

The most common transmission route of tick-borne Rickettsia is through tick bite; nevertheless, other transmission routes should also be considered. We report a case of rickettsial infection in a 15-year-old boy caused by accidental contamination of the conjunctiva through the infected fluid of a crushed engorged tick removed from a dog. Right eye pain, conjunctival hyperaemia with mucopurulent exudate, chemosis and eyelid oedema were the first signs and symptoms. Two days later, the boy developed fever, myalgia, headache, abdominal pain and was vomiting; physical examination showed multiple cervical adenopathies but no rash. He was treated with doxycycline (200 mg/day) for 7 days with progressive resolution of clinical signs. Rickettsial infection was confirmed by immunofluorescence assay with serological seroconversion in two consecutive samples. Rickettsia conorii or Rickettsia massiliae were the possible causal agents since they are the Rickettsia spp found in the Rhipicephalus sanguineus dog tick in Portugal.

Syndromic classification of rickettsioses: an approach for clinical practice

Rickettsioses share common clinical manifestations, such as fever, malaise, exanthema, the presence or absence of an inoculation eschar, and lymphadenopathy. Some of these manifestations can be suggestive of certain species of Rickettsia infection. Nevertheless none of these manifestations are pathognomonic, and direct diagnostic methods to confirm the involved species are always required. A syndrome is a set of signs and symptoms that characterizes a disease with many etiologies or causes. This situation is applicable to rickettsioses, where different species can cause similar clinical presentations. We propose a syndromic classification for these diseases: exanthematic rickettsiosis syndrome with a low probability of inoculation eschar and rickettsiosis syndrome with a probability of inoculation eschar and their variants. In doing so, we take into account the clinical manifestations, the geographic origin, and the possible vector involved, in order to provide a guide for physicians of the most probable etiological agent.

Rickettsial meningitis

Rickettsial infections are common in southern Europe and the most frequent and lethal type is Mediterranean spotted fever, caused by Rickettsia conorii. The disease is usually characterised by the classical triad of fever, eschar and rash, and is generally a mild disease in children. Complications including neurological involvement are rarely described. We report an unusual case of meningitis in an 18-year-old man, presenting during summer with fever and persistent headache. The cerebrospinal fluid analysis revealed increased cellularity (107 cells/μL), hypoglycorrhachia (50% of glycaemia) and hyperproteinorrhachia (284 mg/dL). Rickettsial infection was confirmed by serology and the patient was treated with doxycycline, with a favourable outcome. The patient's pet squirrel and/or associated vectors might be involved in the transmission of Rickettsia spp. This case underlines the importance of a high clinical suspicion and the benefits of early empirical treatment when facing compatible epidemiological contexts.