Ticks and tick-borne rickettsiae from dogs in El Salvador,with report of the human pathogen Rickettsia parkeri

Twelve tick species have been reported in El Salvador; however, information regarding ticks infesting domestic dogs is lacking, and pathogenic tick-borne Rickettsia species have never been reported in El Salvador. This work evaluated ticks infesting 230 dogs from ten municipalities in El Salvador from July 2019 to August 2020. A total of 1,264 ticks were collected and identified into five species: Rhipicephalus sanguineus sensu lato (s.l.), Rhipicephalus microplus, Amblyomma mixtum, Amblyomma ovale, and Amblyoma cf. parvum. The tick R. sanguineus s.l. was the most frequent species in all localities (81.3% of sampled dogs), followed by Amblyomma mixtum (13.0%), Amblyomma ovale (10.9%) and Amblyomma cf. parvum (10.4%). The overall mean intensity of tick infestation was 5.5 ticks/dog. The highest specific mean intensity value was for R. sanguineus s.l. (4.8 ticks/dog), varying from 1.6 to 2.7 ticks/dog for the three Amblyomma species. From a random sample of 288 tick specimens tested molecularly for the presence of rickettsial agents, three spotted fever group Rickettsia were detected: Rickettsia amblyommatis in 90% (36/40) A. mixtum, 46% (11/24) A. cf. parvum, 4% (7/186) R. sanguineus s.l., and 17% Amblyomma spp.; Rickettsia parkeri strain Atlantic rainforest in 4% (1/25) A. ovale; and an unnamed rickettsia agent, designated as ‘Rickettsia sp. ES-A.cf.parvum’, in 4% (1/24) A. cf. parvum. Our finding of R. parkeri strain Atlantic rainforest in A. ovale is highly relevant because this agent has been associated to spotted fever illness in other Latin American countries, where A. ovale is implicated as its main vector. These findings suggest that spotted fever cases caused by R. parkeri strain Atlantic rainforest could be occurring in El Salvador.     

The inoculation eschar of Rickettsia parkeri rickettsiosis in Brazil: Importance and cautions

Two well characterized tick-borne rickettsioses occur in Brazil. Rickettsia rickettsii caused spotted-fever, transmitted by Amblyomma sculptum and Amblyomma aureolatum, is a severe disease with a high case-fatality rate in the southeastern region of the country. Rickettsia parkeri strain Atlantic rainforest infections transmitted by adult Amblyomma ovale ticks cause a milder non-lethal febrile disease with an eschar (necrosis) at the tick bite site. Clinical diagnosis of rickettsiosis is challenging, particularly during the early stages of the illness when signs and symptoms are non-specific. Since eschar at the tick bite site has emerged as the main clinical feature of mild R. parkeri infections and used to differentiate it from severe R. rickettsii infection, its proper recognition, distinction from other tick bite lesions, and boundaries as a clinical tool must be highlighted. Of importance, eschars induced by Rickettsia must be differentiated from dermatoses caused by other tick-borne skin infections as well from lesions caused by the tick bite itself. We herein highlight information on eschar in rickettsial diseases in Brazil and discuss the need for further research on its clinical relevance and application in the diagnosis of spotted fever caused by R. parkeri strain Atlantic rainforest. In particular, we draw attention to diagnosis of other febrile diseases in the presence of concomitant tick bites.     

Tick fauna in non-anthropogenic areas in Mato Grosso do Sul,Brazil, with the presence of the Rickettsia parkeri strain Atlantic rainforest in Amblyomma ovale

The aim of this study was to evaluate tick fauna and identify the possible presence of Rickettsia spp. in ticks of the genus Amblyomma from two environmental preservation areas in different regions of Mato Grosso do Sul state, Brazil. CO₂ traps, visual observation and cloth dragging were used to capture ticks. Three hundred ticks were submitted to the hemolymph test, and samples that showed organisms morphologically compatible with Rickettsia were used for rickettsial DNA detection by PCR. DNA was extracted using guanidine-phenol isothiocyanate, and the primers CS78 and CS323 were used for PCR, which amplified a 401-base pair fragment of the citrate synthase (gltA) gene. If positive, the DNA sample was tested by primers Rr190.70p and Rr190.602n that produce a 530 bp amplicon of the ompA gene that is present only in rickettsiae of the spotted fever group. A total of 1,745 adult ticks were collected, including 1,673 specimens of Amblyomma sculptum, 63 of Amblyomma coelebs, five of Amblyomma naponense and four of Amblyomma ovale. Thirteen ticks of the species A. ovale, A. coelebs and A. sculptum showed structures compatible with Rickettsia inside the hemocytes; after DNA extraction, the presence of Rickettsia spp. in a sample of A. ovale was confirmed by PCR in both analyzed fragments. In the sequencing analysis, 100% identity for the Rickettsia parkeri strain Atlantic rainforest was obtained according to GenBank. The two environmental preservation areas showed A. sculptum as the predominant species, as well as the presence of marked seasonality for this species. This paper is the first report of the R. parkeri strain Atlantic rainforest in A. ovale ticks in the state of Mato Grosso do Sul, Brazil.     

Detection of Rickettsia tamurae-like and other spotted fever group rickettsiae in ticks (Acari: Ixodidae) associated with wild birds in the Western Amazon,Brazil

Ticks are vectors for several pathogens, including bacteria belonging to the Rickettsia genus, such as Rickettsia rickettsii and Rickettsia parkeri, the causative agents of spotted fever. The aim of the present study was to investigate the tick species richness and rickettsial agents associated with wild birds captured in the Humaita Forest Reserve, Acre, in the Western Amazon region. Wild birds were captured with ornithological nets for visual inspection with the purpose of collecting ticks, which were identified through morphological analyses and molecular tests for several genes (12S rDNA, 16S rDNA, gltA, ompA, and sca4). A total of 607 wild birds were captured, 12% of which were parasitized by 268 ticks of the Amblyomma genus, with new host-parasite associations reported for Amblyomma calcaratum, Amblyomma geayi, Amblyomma longirostre, Amblyomma naponense, Amblyomma nodosum, and Amblyomma varium. Of the total ticks collected, 113 were tested for the presence of rickettsial DNA fragments, with 19 testing positive for R. parkeri in A. geayi, Rickettsia tamurae-like in Amblyomma sp., and Rickettsia amblyommatis in A. geayi, A. longirostre, and Amblyomma sp. We detected R. tamurae-like in Amblyomma larvae for the first time in the Western Brazilian Amazon biome, and registered spotted fever group rickettsiae, although the relevance of the detected species in a public health context should be further explored in South America, as well as new host-parasite interactions in this underexplored region.     

Epidemiological aspects of Rickettsia parkeri in the Atlantic forest biome of Espírito Santo state,Brazil

Since 2010, a new rickettsiosis caused by Rickettsia parkeri, a species included in the spotted fever group (SFG) and transmitted by the tick Amblyomma ovale, has been described in Brazil. Considering that A. ovale does occur in the Espírito Santo state (ES), the present study aimed at preliminarily describing the epidemiology of R. parkeri in the Atlantic forest of this state. Between June 2016 and September 2018, 33 villages from nine municipalities of the ES were included in a study for the molecular detection and isolation of SFG rickettsiae from adult Amblyomma ticks collected on dogs with free access to the forest. Serologic screenings against SFG rickettsiae in these animals and their owners (humans) were performed through immunofluorescence assay (IFA) using antigens of Rickettsia rickettsii and R. parkeri. Additionally, local health secretariats were informed on clinical manifestations of R. parkeri infection and told to communicate any suspected case. A total of 280 adult ticks were collected and taxonomically classified as A. ovale (n = 152), Amblyomma aureolatum (n = 127) and Amblyomma sculptum (n = 1). Overall, Rickettsia DNA was detected in 12/266 ticks. The sequencing of PCR products revealed that 0.7% (1/144) and 0.8% (1/121) of the analyzed A. ovale and A. aureolatum ticks were infected by R. parkeri strain Atlantic rainforest, respectively, and 8.3% (10/121) of the A. aureolatum ticks infected by Rickettsia bellii. Among the above PCR-positive ticks, only one isolate from one A. aureolatum tick was successfully established in the laboratory. DNA extracted from the third passage of this isolate was designated as strain M9A and molecularly characterized using primers targeting the Rickettsia gltA gene, whose sequence matched 100% the corresponding sequences of R. bellii. Seroprevalence against SFG rickettsiae in sampled dogs (n = 83) was 41% or 57%, depending on the rickettsial antigen (R. rickettsii strain Taiaçu or R. parkeri strain Atlantic rainforest, respectively). A total of 37 (45%) canine sera showed titers to R. parkeri at least fourfold higher than to R. rickettsii antigen. Among humans, 10% (4/41) of the samples reacted to at least one rickettsial antigen, with the highest endpoint titer varying from 64 to 128 for R. rickettsii and R. parkeri; no human serum showed ≥4-fold difference between the highest endpoint titers. Finally, during the study period, suspicions on cases of R. parkeri-rickettsiosis were not informed by the health secretariats. Our results confirm the presence and exposure to R. parkeri strain Atlantic rainforest, associated with two anthropophilic tick species (A. ovale and A. aureolatum) parasitizing domestic dogs with unrestrained access to forest areas. Consequently, the occurrence of R. parkeri infection in humans inhabiting the Atlantic forests of ES should not be discarded.     

Spotted Fever Group Rickettsioses in Israel, 2010–2019

In a multicenter, nationwide, retrospective study of patients hospitalized with spotted fever group rickettsiosis in Israel during 2010–2019, we identified 42 cases, of which 36 were autochthonous. The most prevalent species was the Rickettsia conorii Israeli tick typhus strain (n = 33, 79%); infection with this species necessitated intensive care for 52% of patients and was associated with a 30% fatality rate. A history of tick bite was rare, found for only 5% of patients; eschar was found in 12%; and leukocytosis was more common than leukopenia. Most (72%) patients resided along the Mediterranean shoreline. For 3 patients, a new Rickettsia variant was identified and had been acquired in eastern, mountainous parts of Israel. One patient had prolonged fever before admission and clinical signs resembling tickborne lymphadenopathy. Our findings suggest that a broad range of Rickettsia species cause spotted fever group rickettsiosis in Israel.     

Records of ticks (Acari: Ixodidae) on humans and distribution of spotted-fever cases and its tick vectors in Paraná State,southern Brazil

Brazilian spotted fever (BSF) is the deadliest rickettsiosis in the world. Although the epidemiology of the disease has been established in Brazil, there are still limited data available on distribution of tick vectors and tick species parasitizing humans in the country, particularly in Paraná State. The State of Paraná is located in the southern region of the country and is covered by two biomes: Atlantic rainforest and Cerrado. Thus, the aims of this study were i) to map the distribution of SF tick vectors, ii) to describe and map the distribution of human parasitism by ticks, and iii) to map the distribution of fatal and non-fatal spotted fever (SF) cases in Paraná State, southern Brazil. Data were reviewed and compiled from previous published reports, and also from two scientific collections of Paraná State. SF cases were retrieved from the Brazilian Notifiable Diseases Information System. A total of 50 cases of human parasitism by ticks were recorded, with a total of 64 (22 males, 12 females, 30 nymphs) ticks collected. The following 12 tick species were identified: Amblyomma aureolatum, Amblyomma brasiliense, Amblyomma calcaratum, Amblyomma dubitatum, Amblyomma incisum, Amblyomma longirostre, Amblyomma ovale, Amblyomma parkeri, Amblyomma scalpturatum, Amblyomma sculptum, Haemaphysalis juxtakochi and Rhipicephalus sanguineus sensu lato (s.l.). The most prevalent tick species associated to cases of human parasitism were A. sculptum (13/50; 26 %), A. aureolatum (10/50; 20 %), A. brasiliense (5/50; 10 %), A. ovale (5/50; 10 %) and A. parkeri (4/50; 8%). A total of 51 non-fatal and five fatal SF cases were recorded. Data from this study highlights the need for monitoring ticks parasitizing humans aiming early detection of tick-borne diseases cases, particularly BSF in Paraná State, southern Brazil.     

Novel PCR exclusion assay to detect spotted fever group rickettsiae in the lone star tick (Amblyomma americanum)

The lone star tick (Amblyomma americanum) is the most common and abundant human-biting tick in the southeastern United States where spotted fever rickettsioses frequently occur. However, the role of this tick in transmitting and maintaining pathogenic and non-pathogenic spotted fever group rickettsiae (SFGR) remains poorly defined. This is partially due to the high prevalence and abundance of Rickettsia amblyommatis in most populations of A. americanum. Many molecular assays commonly employed to detect rickettsiae use PCR primers that target highly conserved regions in the SFGR so low abundance rickettsia may not be detected when R. amblyommatis is present. It is costly and inefficient to test for low abundance rickettsial agents with multiple individual specific assays even when they are multiplexed, as most samples will be negative. Real time PCR assays may also be hampered by inadequate limits of detection (LODs) for low abundance agents. We exploited the absence of an otherwise relatively SFGR-conserved genome region in R. amblyommatis to design a hemi-nested PCR-assay which has a sensitivity of 10 copies in detecting the presence of most SFGR, but not R. amblyommatis in DNA of infected lone star ticks. This deletion is conserved in 21 isolates of R. amblyommatis obtained from multiple states. We demonstrated the assay’s utility by detecting a pathogenic SFGR, Rickettsia parkeri, in 15/50 (30 %) of field collected A. americanum ticks that were previously screened with conventional assays and found to be positive for R. amblyommatis. These co-infected ticks included 1 questing female, 6 questing nymphs, and 8 attached males. The high prevalence of R. parkeri among host-attached ticks may be due to several variables and does not necessarily reflect the risk of disease transmission from attached ticks to vertebrate hosts. This novel assay can provide accurate estimates of the prevalence of less common SFGR in A. americanum and thus improve our understanding of the role of this tick in the maintenance and transmission of the SFGR commonly responsible for human rickettsioses.     

A surrogate life cycle of Amblyomma ovale Koch, 1844

As ticks spend most of their time off-host, the environment is a major selective force of these parasites. In fact, human impact on landscapes has favored a minority of tick species which became well-known pests. However, this is an ongoing process and novel pests may arise. We herein report a surrogate life cycle of a neotropical tick species, Amblyomma ovale, and which may be related to an increased risk of human rickettsiosis. Under natural conditions, adults of this tick species feed on carnivores and exhibit non-nidicolous ambush behavior, whereas larvae and nymphs feed on small rodents and birds. In an anthropized spot within an Atlantic rainforest reserve of Brazil, an A. ovale population exhibited a nidicolous behavior with all 3 tick stages feeding on the dog. This dog's infestation was outstandingly high, and it displayed the highest anti-Rickettsia titers and harbored Rickettsia-infected ticks.     

Rickettsia spp. in ticks from a tropical dry forest reserve on Mexico's Pacific Coast

The present study analyzes the diversity of bacteria of the genus Rickettsia in ticks collected from wild mammals and vegetation at the Chamela Biological Station (EBCh), Jalisco, Mexico, a core area in the Chamela-Cuixmala Biosphere Reserve, which is characterized by the presence of tropical dry forest, one of the most threatened ecosystems in the world. Ticks were collected during April and November 2018 and 2019, determined to species, and subsequently processed for rickettsiae. Genomic DNA was extracted from each of 349 ticks (198 from mammals, 151 from vegetation) and screened for Rickettsia by targeting the gltA and ompA genes. Overall, 75 ticks (21.5%) were positive for rickettsiae (46 from mammals, 29 from vegetation). Through BLASTn and maximum likelihood analysis, four Rickettsia taxa were identified. Only Rickettsia amblyommatis had been previously recorded in the vicinity of the EBCh, and we confirm its presence in this reserve, associated with Amblyomma mixtum, Amblyomma cf. oblongoguttatum and Amblyomma parvum. Additionally, we record for the first time at EBCh the taxa Rickettsia parkeri strain Atlantic rainforest, which is known to cause spotted fever illness in humans, detected in Amblyomma ovale; Rickettsia bellii in A. parvum and Ornithodoros talaje; and an undescribed Rickettsia sp. in Ixodes sinaloa.     

Human Rickettsiosis Caused by Rickettsia parkeri Strain Atlantic Rainforest,Urabá, Colombia

We describe the clinical, serologic, and molecular findings of a new human rickettsiosis in Colombia. Antibodies against Rickettsia spp. were detected. PCR showed amplification of genes for R. parkeri strain Atlantic Rainforest. This new rickettsiosis of minor virulence could explain some of the undifferentiated acute febrile diseases in Colombia.     

Survey of bacterial and protozoan agents in ticks and fleas found on wild animals in the state of Rio de Janeiro,Brazil

This study evaluates the presence of bacterial and protozoan agents in ticks and fleas found on wild animals in the state of Rio de Janeiro, Brazil. These ectoparasites were collected on mammal species Hydrochoerus hydrochaeris, Tapirus terrestris, Dicotyles tajacu, Didelphis aurita, Cuniculus paca, Cerdocyon thous, and Coendou prehensilis, and on the terrestrial bird Dromaius novaehollandiae. Ticks and fleas were identified morphologically using specific taxonomic keys. A total of 396 ticks and 54 fleas were tested via polymerase chain reaction (PCR) for the presence of Rickettsia spp., Borrelia spp., microorganisms of the order Piroplasmida and Anaplasmataceae family. This total is distributed among nine tick species of the genus Amblyomma and one flea species. Rickettsia bellii was detected in Amblyomma dubitatum and Amblyomma pacae; Rickettsia sp. strain AL was found in Amblyomma longirostre; Rickettsia parkeri strain Atlantic rainforest was found in Amblyomma ovale; and “Candidatus Rickettsia senegalensis” and Rickettsia felis were detected in Ctenocephalides felis felis. Wolbachia sp. was detected in C. f. felis, and Borrelia sp. was detected in Amblyomma calcaratum (here named Borrelia sp. strain Acalc110). All tested samples were negative for Ehrlichia spp. and microorganisms of the Piroplasmida order. This study detected a new bacterial strain, Borrelia sp. strain Acalc 110 (which is genetically close to B. miyamotoi and B. venezuelensis) and the Rickettsia sp. strain 19P, which is 100% similar to “Ca. R. senegalensis”, a bacterium recently discovered and now being reported for the first time in Brazil.     

Immature hard ticks infected with Rickettsia amblyommatis on breeding birds from Pantanal

Immature hard ticks from the genus Amblyomma feed on blood from a wide range of Neotropical avian hosts. They serve as vectors for pathogens of medical and veterinary importance, such as Rickettsia agents of the spotted fever group (SFG). Hence, determining ecological factors that increase encounter rates between immature ticks and their avian hosts may contribute to the understanding of tick-borne diseases transmission. Here, we used 720 individual birds from 96 species surveyed in the Brazilian Pantanal to test whether host breeding season influenced tick infestation probabilities. Additionally, collected ticks were screened for Rickettsia agents to describe new avian-tick-bacteria associations. Our models revealed that the probability of an individual bird being infested with immature ticks was similar during the breeding and pre-breeding season, but higher loads of immature tick stages were found during the breeding season. Host sex did not predict infestation probability, but Rickettsia agents recovered from ticks were more prevalent during the pre-breeding season. The new records of host usage by larvae and nymphs of Amblyomma in Pantanal and the growing body of tick surveys in Neotropical avian communities, suggest that immature ticks may benefit from avian blood sources during their annual cycle. The low number of infected ticks with Rickettsia agents on Pantanal birds suggest that this vertebrate group are likely not acting as reservoirs for these microorganisms. However, long-term surveys at the same site are imperative to determine which tick species are acting as reservoirs for Rickettsia agents in Pantanal and determine whether birds are playing a role in dispersing ticks and tick-borne pathogens.     

Rickettsia parkeri Rickettsiosis, Argentina

Rickettsia parkeri, a recently identified cause of spotted fever rickettsiosis in the United States, has been found in Amblyomma triste ticks in several countries of South America, including Argentina, where it is believed to cause disease in humans. We describe the clinical and epidemiologic characteristics of 2 patients in Argentina with confirmed R. parkeri infection and 7 additional patients with suspected R. parkeri rickettsiosis identified at 1 hospital during 2004–2009. The frequency and character of clinical signs and symptoms among these 9 patients closely resembled those described for patients in the United States (presence of an inoculation eschar, maculopapular rash often associated with pustules or vesicles, infrequent gastrointestinal manifestations, and relatively benign clinical course). Many R. parkeri infections in South America are likely to be misdiagnosed as other infectious diseases, including Rocky Mountain spotted fever, dengue, or leptospirosis.Rickettsia parkeri, a tick-borne bacterium discovered in 1937, was considered nonpathogenic until 2004. Since 2004, >25 cases of R. parkeri rickettsiosis have been reported in persons living within the recognized range of the tick vector, Amblyomma maculatum, in the United States (1–4; Centers for Disease Control and Prevention, unpub. data). The clinical features of this newly recognized disease appear less severe than those produced by R. rickettsii bacteria, the agent of Rocky Mountain spotted fever (RMSF). For many years, investigators in several countries of South America, including Argentina, Brazil, and Uruguay, have recognized eschar-associated infections that clinically resemble R. parkeri rickettsiosis (5–7). These reports, and the discoveries of R. parkeri in A. triste ticks collected from these same countries, suggest that human infections with R. parkeri also occur in South America (8–10); to our knowledge, no confirmed cases of disease caused by this Rickettsia species have been reported from this continent.The Paraná Delta, situated in the provinces of Buenos Aires and Entre Ríos in Argentina, represents the terminus of the Paraná River as it approaches and drains into the Uruguay River and subsequently into the Río de la Plata. This alluvial ecosystem, where braided river branches create a network of islands and wetlands, covers ≈14,000 km² (5,405 mi²) and extends for ≈320 km (200 mi). This region also contains abundant populations of A. triste ticks (10). The Paraná Delta has always been a major agricultural and farming region. Recently, this area has become increasingly developed; roads have been built to allow greater access for tourism and recreational activities by many of the ≈14 million inhabitants of nearby Buenos Aires. In 2005, an eschar-associated febrile infection was diagnosed in a male beekeeper from the Paraná Delta; the infection was later confirmed as a spotted fever group (SFG) rickettsiosis by serology and immunohistochemistry (5). He had been bitten by a tick not far from several sites where R. parkeri was subsequently detected in A. triste ticks (10). We report confirmed cases of R. parkeri rickettsiosis in 2 patients in Argentina and describe additional suspected cases of this disease, or similar infections, in patients from the provinces of Buenos Aires, Chaco, and Entre Ríos.     

A putative novel strain of Ehrlichia infecting Amblyomma tigrinum associated with Pampas fox (Lycalopex gymnocercus) in Esteros del Iberá ecoregion,Argentina

The current work evaluated road-killed Pampas foxes (Lycalopex gymnocercus) and their ticks for the presence of vector-borne agents in the ecoregion Esteros del Iberá in northeastern Argentina. Spleen, lung and blood samples and Amblyomma tigrinum adult ticks collected from the foxes were tested by polymerase chain reaction (PCR) assays targeting bacteria of the genera Ehrlichia, Anaplasma, and Rickettsia. All foxes tested were negative for the three genera, but evidence of Ehrlichia and Rickettsia infection was detected in the ticks. One A. tigrinum (out of 12 tested) was infected by an ehrlichial agent, here named Ehrlichia sp. strain Iberá, related to ehrlichial agents recently detected in platypuses in Tasmania (Ornithorhynchus anatinus) and in voles (Myodes rutilus and Myodes rufocanus) and shrews (Sorex araneus) in the Russian Far East. Regarding Rickettsia, all A. tigrinum ticks (100%) were infected by ´Candidatus Rickettsia andeanae´, a member of the spotted fever group rickettsia of unknown pathogenicity. Further research is necessary to unveil the ecology of Ehrlichia sp. strain Iberá as well as its zoonotic relevance. The species of the genus Ehrlichia are known to be pathogenic to mammals, including humans and domestic animals, thus the presence of this ehrlichial agent in A. tigrinum is a potential risk for veterinary and public health, as the adults of A. tigrinum are common parasites of dogs in rural and peri-urban environments, and humans are also frequently bitten by this tick species.     

Molecular epidemiology of Rickettsia sp. and Coxiella burnetii collected from Hyalomma asiaticum in Bactrian camels (Camelus bactrianus) in inner Mongolia of China

The purpose of the present study was to determine the presence of Rickettsia sp. and Coxiella burnetii in Hyalomma asiaticum collected from Bactrian camels (Camelus bactrianus) in Inner Mongolia of China. A total of 385 H. asiaticum adults collected from Bactrian camels from Alxa in Inner Mongolia from 2017 to 2018 were examined using PCR combined with sequencing. The results indicated that 18 (4.7 %) and 5 (1.3 %) samples tested positive for Rickettsia and C. burnetii, respectively. The corresponding nucleotide identities among detected genes ranged between 99.7 % and 100 % for the sequences of 17 kD and ompB from Rickettsia and 16S rRNA and FtsX from C. burnetii. Two representative strains—Rickettsia IMA-1 strain and C. burnetii IMA-1 strain—were used for subsequent analysis. NCBI BLAST and phylogenetic analyses demonstrated that the detected strain Rickettsia IMA-1 may represent a novel species of spotted fever group (SFG) rickettsiae. The C. burnetii IMA-1 strain was grouped with Coxiella burnetii str. RSA439 (GenBank: CP040059.1). In addition, the Rickettsia sp. was successfully isolated from the ticks in Vero cells incubated at 28 °C. These findings indicate that the H. asiaticum collected off Bactrian camels in Inner Mongolia carried SFG Rickettsia species and C. burnetii and could contribute to the etiology of febrile illness in animals and humans.     

Detection of tick-borne pathogens in Rhipicephalus sanguineus sensu lato and dogs from different districts of Portugal

Dogs are highly exposed to pathogens transmitted by ectoparasites. The Mediterranean climate of Southern Europe, together with the presence of stray and/or neglected pets in close proximity with humans, contribute for tick expansion and stand for increased risk to infections in humans due to the zoonotic potential of many of these agents.The aim of this study was to perform a molecular survey in dogs (suspected of tick-borne disease and/or infested with ticks), as well as in ticks collected from those animals, from 12 districts of Portugal to investigate the occurrence of Rickettsia spp. and other tick-borne pathogens (Babesia, Ehrlichia, Anaplasma and Hepatozoon). Additionally, a serological survey of spotted fever group Rickettsia in Portuguese dogs was performed using an in-house immunofluorescence assay (IFA).A total of 200 whole-blood samples and 221 Rhipicephalus sanguineus s. l. ticks were collected from dogs.A total of 14 (7 %) blood samples and 10 (4.5 %) ticks yielded presumptively positive 420-bp amplicons using the Rickettsia spp. partial ompB nested PCR. Screening of the ompB-positive samples using the gltA gene showed 8 positive ticks. All Rickettsia ompB and gltA sequences had the highest identity with R. massiliae. The Rickettsia-positive dogs were further tested for other tick-borne pathogens and were found to be infected with Babesia spp. (n = 5), but not with Ehrlichia, Anaplasma or Hepatozoon.Of the 149 dog serum specimens tested in the serological assay, 103 (69 %) were positive for IgG antibodies against spotted fever group Rickettsia. Antibodies were found in dogs from all the studied districts, in 55 (53 %) of the stray and in 48 (47 %) of the owned dogs.Our study detected and characterized for the first time R. massiliae in dogs from Portugal, broadening the geographical range of this canine pathogen and adding knowledge to the impact of this disease in dogs.     

First detection of “Candidatus Rickettsia wissemanii” in Ornithodoros hasei (Schulze, 1935) (Acari: Argasidae) from Argentina

The aim of this study was to assess the presence of Rickettsia in soft ticks (Acari: Argasidae) collected from insectivorous bats (Chiroptera) in Santa Fe province, Argentina. First, a subset of ticks were mounted in Hoyer’s medium to be determined by morphological characters and then confirmed by sequencing the mitochondrial 16S rRNA gene. Also ticks were processed by PCR assays using primers CS-78 and CS-323, which amplify a fragment of the Rickettsia spp. gltA gene. Positive ticks were subjected to a second PCR round with primers Rr190.70p and Rr190.701n of the spotted fever group rickettsiae ompA gene. A phylogenetic analysis was performed with Maximum-likelihood method, and the best fitting substitution models were determined with the Akaike Information Criterion. Five bats of the species Eptesicus diminutus Osgood, 1915, Eptesicus furinalis (d’Orbigny and Gervais, 1847), Eptesicus spp. (Vespertilionidae), and Molossops temminckii Burmeister, 1854 (Molossidae) were parasitized with Ornithodoros hasei (Schulze, 1935) larvae. One E. diminutus ticks’ tested positive to “Candidatus Rickettsia wissemanii”, a spotted fever group rickettsiae. The association O. hasei –“Ca. R. wissemanii” detected in this study represents the first evidence of a Rickettsia in Ornithodoros ticks in Argentina and the third report of this association in America. Also, this finding constitutes the first record of “Ca. R. wissemanii” in Argentina. Finally, we found for the first time the insectivorous bats E. diminutus and E. furinalis parasitized with O. hasei larvae. These findings add two new hosts and a new location, the southernmost recorded to date, for O. hasei.     

Novel Rickettsia Species Infecting Dogs,United States

In 2018 and 2019, spotted fever was suspected in 3 dogs in 3 US states. The dogs had fever and hematological abnormalities; blood samples were Rickettsia seroreactive. Identical Rickettsia DNA sequences were amplified from the samples. Multilocus phylogenetic analysis showed the dogs were infected with a novel Rickettsia species related to human Rickettsia pathogens.     

Serosurvey among Mediterranean spotted fever patients of a new spotted fever group rickettsial strain (Bar29)

Mediterranean spotted fever is an endemic disease in Catalonia, Spain. A new spotted fever group (SFG) rickettsial strain (Bar29) of unknown pathogenicity for humans was isolated by our group, in 1996, from the dog brown tick, Rhipicephalus sanguineus. Interestingly, Rickettsia conorii was not isolated in this study. The aim of the present study was to assess the possible pathogenic role of the Bar29 strain. To this purpose, serum samples from 15 patients with Mediterranean spotted fever were obtained and tested by immunofluorescence for antibodies against four related rickettsial strains (R. conorii, R. africae, R. massiliae, and Bar29). Eight of the studied sera reacted at high titers with only R. conorii and Bar29 antigens. For five of the eight sera, the titers against Bar29 were clearly higher than for R. conorii. Four of these sera were also studied by Western blot immunoassay to confirm a specific response. Two of these sera reacted with the high-molecular-mass specific proteins of Bar29 as well as with the low-molecular-mass region (LPS antigen) whereas their reactions with R. conorii were located only on bands of the LPS. This specific response would support the possible pathogenic role of the Bar29 strain for humans. According to this finding, spotted fever caused by R. conorii and rickettsial strain Bar29 may be present in our area. The epidemiological implications of spotted fever caused by R. conorii and by rickettsial strain Bar29 in the Catalonia deserve further studies with isolation and characterization of more rickettsial strains.