Rickettsia aeschlimannii in Spain: molecular evidence in Hyalomma marginatum and five other tick species that feed on humans

First report of spotted fever group Rickettsia aeschlimannii in Hyalomma turanicum, Haemaphysalis bispinosa, and Haemaphysalis montgomeryi infesting domestic animals: updates on the epidemiology of tick-borne Rickettsia aeschlimannii

Tick-borne Rickettsia spp. have long been known as causative agents for zoonotic diseases. We have previously characterized Rickettsia spp. in different ticks infesting a broad range of hosts in Pakistan; however, knowledge regarding Rickettsia aeschlimannii in Haemaphysalis and Hyalomma ticks is missing. This study aimed to obtain a better understanding about R. aeschlimannii in Pakistan and update the knowledge about its worldwide epidemiology. Among 369 examined domestic animals, 247 (66%) were infested by 872 ticks. Collected ticks were morphologically delineated into three genera, namely, Rhipicephalus, Hyalomma, and Haemaphysalis. Adult females were the most prevalent (number ₌ 376, 43.1%), followed by nymphs (303, 34.74%) and males (193, 22.13%). Overall, genomic DNA samples of 223 tick were isolated and screened for Rickettsia spp. by the amplification of rickettsial gltA, ompA, and ompB partial genes using conventional PCR. Rickettsial DNA was detected in 8 of 223 (3.58%) ticks including nymphs (5 of 122, 4.0%) and adult females (3 of 86, 3.48%). The rickettsial gltA, ompA, and ompB sequences were detected in Hyalomma turanicum (2 nymphs and 1 adult female), Haemaphysalis bispinosa (1 nymph and 1 adult female), and Haemaphysalis montgomeryi (2 nymphs and 1 adult female). These rickettsial sequences showed 99.71-100% identity with R. aeschlimannii and phylogenetically clustered with the same species. None of the tested Rhipicephalus microplus, Hyalomma isaaci, Hyalomma scupense, Rhipicephalus turanicus, Hyalomma anatolicum, Rhipicephalus haemaphysaloides, Rhipicephalus sanguineus, Haemaphysalis cornupunctata, and Haemaphysalis sulcata ticks were found positive for rickettsial DNA. Comprehensive surveillance studies should be adopted to update the knowledge regarding tick-borne zoonotic Rickettsia species, evaluate their risks to humans and livestock, and investigate the unexamined cases of illness after tick bite among livestock holders in the country.

Co-Occurrence of Francisella, Spotted Fever Group Rickettsia, and Midichloria in Avian-Associated Hyalomma rufipes

The migratory behavior of wild birds contributes to the geographical spread of ticks and their microorganisms. In this study, we aimed to investigate the dispersal and co-occurrence of Francisella and spotted fever group Rickettsia (SFGR) in ticks infesting birds migrating northward in the African-Western Palaearctic region (AWPR). Birds were trapped with mist nests across the Mediterranean basin during the 2014 and 2015 spring migration. In total, 575 ticks were collected from 244 birds. We screened the ticks for the species Francisella tularensis, the genus Francisella, and SFGR by microfluidic real-time PCR. Confirmatory analyses and metagenomic sequencing were performed on tick samples that putatively tested positive for F. tularensis during initial screenings. Hyalomma rufipes was the most common tick species and had a high prevalence of Francisella, including co-occurrence of Francisella and SFGR. Metagenomic analysis of total DNA extracted from two H. rufipes confirmed the presence of Francisella, Rickettsia, and Midichloria. Average nucleotide identity and phylogenetic inference indicated the highest identity of the metagenome-assembled genomes to a Francisella-like endosymbiont (FLE), Rickettsia aeschlimannii, and Midichloria mitochondrii. The results of this study suggest that (i) FLE- and SFGR-containing ticks are dispersed by northbound migratory birds in the AWPR, (ii) H. rufipes likely is not involved in transmission of F. tularensis in the AWPR, and (iii) a dual endosymbiosis of FLEs and Midichloria may support some of the nutritional requirements of H. rufipes.

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 and Diseases in Greece

Tick-borne diseases (TBDs) are recognized as a serious and growing public health epidemic in Europe, and are a cause of major losses in livestock production worldwide. This review is an attempt to present a summary of results from studies conducted over the last century until the end of the year 2020 regarding ticks, tick-borne pathogens, and tick-borne diseases in Greece. We provide an overview of the tick species found in Greece, as well as the most important tick-borne pathogens (viruses, bacteria, protozoa) and corresponding diseases in circulation. We also consider prevalence data, as well as geographic and climatic conditions. Knowledge of past and current situations of TBDs, as well as an awareness of (risk) factors affecting future developments will help to find approaches to integrated tick management as part of the ‘One Health Concept’; it will assist in avoiding the possibility of hotspot disease emergencies and intra- and intercontinental transmission. Increased surveillance in Greece is required to ensure clear and effective policies for TBD control.

Epidemiological Aspects of Crimean-Congo Hemorrhagic Fever in Western Europe: What about the Future?

Crimean-Congo hemorrhagic fever virus (CCHFV) is an arthropod-borne virus (arbovirus), mainly transmitted by ticks, belonging to the genus Orthonairovirus (family Nairoviridae, order Bunyavirales). CCHFV causes a potentially severe, or even fatal, human disease, and it is widely distributed in Africa, Asia, eastern Europe and, more recently, in South-western Europe. Until a few years ago, no cases of Crimean-Congo hemorrhagic fever (CCHF) had been reported in western Europe, with the exception of several travel-associated cases. In 2010, the CCHFV was reported for the first time in South-western Europe when viral RNA was obtained from Hyalomma lusitanicum ticks collected from deer in Cáceres (Spain). Migratory birds from Africa harboring CCHFV-infected ticks and flying to Spain appear to have contributed to the establishment of the virus (genotype III, Africa-3) in this country. In addition, the recent findings in a patient and in ticks from deer and wild boar of viral sequences similar to those from eastern Europe (genotype V, Europe-1), raise the possibility of the introduction of CCHFV into Spain through the animal trade, although the arrival by bird routes cannot be ruled out (Africa-4 has been also recently detected). The seropositive rates of animals detected in regions of South-western Spain suggest an established cycle of tick-host-tick in certain areas, and the segment reassortment detected in the sequenced virus from one patient evidences a high ability to adaptation of the virus. Different ixodid tick genera can be vectors and reservoirs of the virus, although Hyalomma spp. are particularly relevant for its maintenance. This tick genus is common in Mediterranean region but it is currently spreading to new areas, partly due to the climate change and movement of livestock or wild animals. Although to a lesser extent, travels with our pets (and their ticks) may be also a factor to be considered. As a consequence, the virus is expanding from the Balkan region to Central Europe and, more recently, to Western Europe where different genotypes are circulating. Thus, seven human cases confirmed by molecular methods have been reported in Spain from 2016 to August 2020, three of them with a fatal outcome. A One Health approach is essential for the surveillance of fauna and vector populations to assess the risk for humans and animals. We discuss the risk of CCHFV causing epidemic outbreaks in Western Europe.

High-Throughput Microfluidic Real-Time PCR for the Detection of Multiple Microorganisms in Ixodid Cattle Ticks in Northeast Algeria

Ixodid ticks are hematophagous arthropods considered to be prominent ectoparasite vectors that have a negative impact on cattle, either through direct injury or via the transmission of several pathogens. In this study, we investigated the molecular infection rates of numerous tick-borne pathogens in ticks sampled on cattle from the Kabylia region, northeastern Algeria, using a high-throughput microfluidic real-time PCR system. A total of 235 ticks belonging to seven species of the genera Rhipicephalus, Hyalomma, and Ixodes were sampled on cattle and then screened for the presence of 36 different species of bacteria and protozoans. The most prevalent tick-borne microorganisms were Rickettsia spp. at 79.1%, followed by Francisella-like endosymbionts (62.9%), Theileria spp. (17.8%), Anaplasma spp. (14.4%), Bartonella spp. (6.8%), Borrelia spp. (6.8%), and Babesia spp. (2.5%). Among the 80.4% of ticks bearing microorganisms, 20%, 36.6%, 21.7%, and 2.1% were positive for one, two, three, and four different microorganisms, respectively. Rickettsia aeschlimannii was detected in Hyalomma marginatum, Hyalomma detritum, and Rhipicephalus bursa ticks. Rickettsia massiliae was found in Rhipicephalus sanguineus, and Rickettsiamonacensis and Rickettsia helvetica were detected in Ixodesricinus. Anaplasma marginale was found in all identified tick genera, but Anaplasma centrale was detected exclusively in Rhipicephalus spp. ticks. The DNA of Borrelia spp. and Bartonella spp. was identified in several tick species. Theileria orientalis was found in R. bursa, R. sanguineus, H. detritum, H. marginatum, and I. ricinus and Babesia bigemina was found in Rhipicephalus annulatus and R. sanguineus. Our study highlights the importance of tick-borne pathogens in cattle in Algeria.

Zingiber officinalis and Eucalyptus globulus, Potent Lethal/Repellent Agents against Rhipicephalus bursa, Probable Carrier for Zoonosis

BACKGROUND

Rhipicephalus bursa is a hard tick with importance in transmission of tick-borne diseases and zoonosis. Natural products are excellent alternative to pesticides. In this study for the first time, lethal and repellent activity of Zingiber officinalis and Eucalyptus globulus against Rh. bursa were studied.

METHODS

In July till September of 2017, essential oils were extracted in Shahrekord University, Iran from fresh plant materials and engorged mature ticks were collected from infested sheep herd located in Saman, Iran. Ticks were challenged by different concentrations of essential oils including 300, 500 and 800µl/ml and 1 (pure) singly and/or in combination. Percentages of killed and repellent ticks as efficacy of acaricidal and repellent activity of essential oils against Rh. bursa were calculated and analyzed statistically.

RESULTS

Efficacy of eucalyptus essential oils was more in whole concentrations and its highest performance was observed in concentration 1 (pure). Efficacies of ginger and combined essential oils were different for each concentration but their highest efficacies were observed in concentration 1 (pure), too.

CONCLUSION

This study showed considerable values of acaricidal and repellent activity against Rh. bursa for both essential oils singly and in combination, so they can be considered as potent lethal/repellent agents for control of ticks, but more studies need for this purpose, study on lethal/repellent activity of these essential oils and/or other plants against other important arthropods can be considered as subjects for next experiments.

Rickettsia species in human-parasitizing ticks in Greece

BACKGROUND

Ticks serve as vectors and reservoirs for a variety of bacterial, viral and protozoan pathogens affecting humans and animals. Unusual increased tick aggressiveness was observed in 2008-2009 in northeastern Greece. The aim of the study was to check ticks removed from persons during 2009 for infection with Rickettsia species.

METHODS

A total of 159 ticks were removed from 147 persons who sought medical advice in a hospital. Tick identification was performed morphologically using taxonomic keys. DNA was extracted from each individual tick and a PCR assay targeting the rickettsial outer membrane protein A gene of Rickettsia spp. was applied.

RESULTS

Most of the adult ticks (132/153, 86.3%) were Rhipicephalus sanguineus. Rickettsiae were detected in 23 of the 153 (15.0%) adult ticks. Five Rickettsiae species were identified: R. aeschlimannii, R. africae (n=6), R. massilae (4), R. monacensis (1), and Candidatus R. barbariae (1). To our knowledge, this is the first report of R. africae, R. monacensis, and Candidatus R. barbariae in Greece.

CONCLUSIONS

Several Rickettsia species were identified in ticks removed from humans in Greece, including those that are prevalent in northern and southern latitudes.

The first detection of Rickettsia aeschlimannii and Rickettsia massiliae in Rhipicephalus turanicus ticks, in northwest China

Background

Rickettsia spp. belonging to the spotted fever group (SFG) cause infections in humans, domestic animals and wildlife. At least five SFG rickettsial species have been reported in China, but the occurrence of Rickettsia aeschlimannii and R. massiliae in ticks has not been characterized to date.

Findings

A total of 114 adult ticks were collected from sheep in Yining County, Xinjiang Uygur Autonomous Region, in northwest China. The ticks were identified from morphological and molecular characteristics. All samples were examined by polymerase chain reaction (PCR), and six genetic markers were used to determine the Rickettsia spp. in the ticks. The ticks collected were identified as Rhipicephalus turanicus. Three different lineages of Rh. turanicus from Yining County were discovered on phylogenetic analysis of 16S rDNA and cox1. Twenty-one of the 114 samples (18.42%) were positive for rickettsial agents. Phylogenetic analysis based on six genetic sequences showed that three rickettsial species were present, namely: R. aeschlimannii (19.05%, 4/21), R. massiliae (19.05%, 4/21) and R. sibirica variant (61.90%, 13/21), which is clustered in the clade of R. sibirica subsp. sibirica.

Conclusions

This is the first description of R. aeschlimannii and R. massiliae in China. R. massiliae, R. aeschlimannii and R. sibirica variant co-circulate in the region of the China-Kazakhstan border, in northwest China. Rickettsial agents in ticks of the genus Rhipicephalus from migrant birds, transported livestock, wildlife and human beings should be investigated further in the region of the China–Central Asian border.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-015-1242-2) contains supplementary material, which is available to authorized users.

Tick-borne pathogens and the vector potential of ticks in China

Ticks, as obligate blood-sucking ectoparasites, attack a broad range of vertebrates and transmit a great diversity of pathogenic microorganisms. They are considered second only to mosquitoes as vectors of human disease, and the most important vector of pathogens of domestic and wild animals. Of the 117 described species in the Chinese tick fauna, 60 are known to transmit one or more diseases: 36 species isolated within China and 24 species isolated outside China. Moreover, 38 of these species carry multiple pathogens, indicating the potentially vast role of these vectors in transmitting pathogens. Spotted fever is the most common tick-borne disease, and is carried by at least 27 tick species, with Lyme disease and human granulocytic anaplasmosis ranked as the second and third most widespread tick-borne diseases, carried by 13 and 10 species, respectively. Such knowledge provides us with clues for the identification of tick-associated pathogens and suggests ideas for the control of tick-borne diseases in China. However, the numbers of tick-associated pathogens and tick-borne diseases in China are probably underestimated because of the complex distribution and great diversity of tick species in this country.

Spotted fever group rickettsiae in ticks collected from wild animals in Israel

We report molecular evidence for the presence of spotted fever group rickettsiae (SFGR) in ticks collected from roe deer, addax, red foxes, and wild boars in Israel. Rickettsia aeschlimannii was detected in Hyalomma marginatum and Hyalomma detritum while Rickettsia massiliae was present in Rhipicephalus turanicus ticks. Furthermore, a novel uncultured SFGR was detected in Haemaphysalis adleri and Haemaphysalis parva ticks from golden jackals. The pathogenicity of the novel SFGR for humans is unknown; however, the presence of multiple SFGR agents should be considered when serological surveillance data from Israel are interpreted because of significant antigenic cross-reactivity among Rickettsia. The epidemiology and ecology of SFGR in Israel appear to be more complicated than was previously believed.

Spotted fever group Rickettsia in ticks from southeastern Spain natural parks

During an 8-years study, we collected from vegetation or domestic and wild mammals 1246 ticks (624 males, 511 females and 111 nymphs) belonging to 13 species in Jaen province (Andalusia) and we analyzed these ticks by PCR and sequencing for the presence of rickettsiae. Specific rickettsiae DNA was detected in 243 (19.5%) of the ticks tested. Sequence analysis of amplicons of gltA, ompA and ompB genes revealed that Ixodes ricinus were infected with R. monacensis, including strain IRS3, and R. helvetica (prevalences of 27.0% and 2.7%, respectively), while in I. ventalloi we found only this last species (12.5%). Moreover, Dermacentor marginatus presents R. slovaca (24.7%) and R. raoultii (59.9%). In Rhipicephalus sanguineus group ticks (Rh. sanguineus, Rh. turanicus and Rh. pusillus) only R. massiliae (15.2%) was found. Haemaphysalis punctata and Ha. sulcata were infected with a Rickettsia sp. near R. hoogstraalii (prevalence of 3.1% and 16.1%, respectively). In addition, Ha. punctata appeared infected with R. monacensis-like Rickettsia (1.0%) and R. raoultii (9.3%). None of I. hexagonus, Hyalomma lusitanicum, Hyalomma sp., Ha. hispanica or Rh. bursa studied ticks contained rickettsiae.

Detection of a questing Hyalomma marginatum marginatum adult female (Acari, Ixodidae) in southern Germany

The first finding of a questing Hyalomma marginatum marginatum female tick in Germany is described. The tick was found in May 2006 on the clothing of a person who had spent the preceding day in rural surroundings in southern Germany. As the infested person had also been visiting Spain where H. m. marginatum is known to occur some weeks prior to finding the tick, it is not clear whether the tick had been imported by him as a female or by another host in a preimaginal stage and succeeded to develop to an adult in Germany. H. m. marginatum is a thermophilic tick species usually occurring in relatively dry and warm regions of southern Europe, northern Africa and some parts of Asia. It is a vector of several disease agents of human relevance including Crimean-Congo hemorrhagic fever virus. Although, by PCR examination, the female was found neither infected with this virus nor with Rickettsia aeschlimannii, another human pathogen which has been found in Spanish Hyalomma ticks, its mere finding should be taken seriously and draw further attention to the increasing problem of the import and spread of putatively tropical vectors of disease to central Europe.

Emerging zoonoses and vector-borne infections affecting humans in Europe

The purpose of this study was to assess and describe the current spectrum of emerging zoonoses between 2000 and 2006 in European countries. A computerized search of the Medline database from January 1966 to August 2006 for all zoonotic agents in European countries was performed using specific criteria for emergence. Fifteen pathogens were identified as emerging in Europe from 2000 to August 2006: Rickettsiae spp., Anaplasma phagocytophilum, Borrelia burgdorferi, Bartonella spp., Francisella tularensis, Crimean Congo Haemorrhagic Fever Virus, Hantavirus, Toscana virus, Tick-borne encephalitis virus group, West Nile virus, Sindbis virus, Highly Pathogenic Avian influenza, variant Creutzfeldt-Jakob disease, Trichinella spp., and Echinococus multilocularis. Main risk factors included climatic variations, certain human activities as well as movements of animals, people or goods. Multi-disciplinary preventive strategies addressing these pathogens are of public health importance. Uniform harmonized case definitions should be introduced throughout Europe as true prevalence and incidence estimates are otherwise impossible.

Tick-borne rickettsioses around the world: emerging diseases challenging old concepts

During most of the 20th century, the epidemiology of tick-borne rickettsioses could be summarized as the occurrence of a single pathogenic rickettsia on each continent. An element of this paradigm suggested that the many other characterized and noncharacterized rickettsiae isolated from ticks were not pathogenic to humans. In this context, it was considered that relatively few tick-borne rickettsiae caused human disease. This concept was modified extensively from 1984 through 2005 by the identification of at least 11 additional rickettsial species or subspecies that cause tick-borne rickettsioses around the world. Of these agents, seven were initially isolated from ticks, often years or decades before a definitive association with human disease was established. We present here the tick-borne rickettsioses described through 2005 and focus on the epidemiological circumstances that have played a role in the emergence of the newly recognized diseases.

Suicide PCR on skin biopsy specimens for diagnosis of rickettsioses

As rickettsioses may be severe diseases and Rickettsia prowazekii is a potential agent of bioterrorism, highly efficient diagnostic techniques are required to detect rickettsiae in patients. We developed a nested PCR assay using single-use primers targeting single-use gene fragments present in the genomes of both Rickettsia conorii and R. prowazekii. We used this "suicide" PCR with DNA from 103 skin biopsy specimens from patients who definitely had a rickettiosis, 109 skin biopsy specimens from patients who possibly had a rickettsiosis, and 50 skin biopsy specimens from patients with nonrickettsial diseases. The suicide PCR detected "R. conorii conorii" in 38 biopsy specimens, R. africae in 28 biopsy specimens, R. slovaca in 12 biopsy specimens, "R. sibirica mongolotimonae" in 5 biopsy specimens, R. aeschlimannii in 2 biopsy specimens, and "R. conorii caspia" and "R. sibirica sibirica" in 1 biopsy specimen each. The technique had a specificity of 100% and a sensitivity of 68%. It was 2.2 times more sensitive than culture (P < 10(-2)) and 1.5 times more sensitive than regular PCR (P < 10(-2)). The efficacy of the suicide PCR was reduced by antibiotic therapy prior to biopsy (P < 10(-2)) and was increased when it was performed with eschar biopsy specimens (P = 0.03). We propose the use of the suicide PCR as a sensitive, specific, and versatile technique for improving the diagnosis of rickettsioses, especially when it is used on eschar biopsy specimens taken prior to antibiotic therapy.