Molecular epidemiology and phylogeny of spotted fever group Rickettsia in camels (Camelus dromedarius) and their infesting ticks from Tunisia

First identification of Brucella melitensis and Rickettsia monacensis in a red fox, Vulpes vulpes

Wild canids, in particular red foxes, serve as potential carriers of zoonotic pathogens. This study aimed to investigate the presence of somepathogenic bacteria relevant to veterinary public health concern. On November 15, 2023, we collected spleen and blood samples from a corpse of a red fox found randomly during a field trip in the El-Jouza district, Beja governorate, northern Tunisia. PCR amplification assays were conducted using specific primers to detect Brucella spp. and major vector-borne bacteria, including Rickettsia, Anaplasma, Borrelia, Bartonella, Coxiella, and hemotropic Mycoplasma. Species identification and genetic characterization were performed through BLAST analysis and phylogenetic studies following the sequencing of the obtained PCR products. DNA of both Brucella melitensis and Rickettsia monacensis was detected in the blood sample. Phylogenetic analysis revealed that the identified B. melitensis isolate was clustered with two strains isolated from humans in Mediterranean countries. The R. monacensis isolate was found to be genetically close to a human strain from a South Korea and several isolates infectingIxodes ticks primarily in Europe. This study revealed for the first time the potential infection of red foxes by B. melitensis and R. monacensis. Further research with larger sample sizes is needed to comprehensively understand the range of zoonotic bacteria in wildlife and to develop effective monitoring and control strategies.

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.

Distribution of different Rickettsia species in countries of the WHO Eastern Mediterranean (WHO-EMRO) region: An overview

SUBJECT

Rickettsia is a zoonotic bacterial pathogen transmitted by vectors and has extensive reservoirs in animal and human populations. Rickettsiosis is a public health problem all over the world. However, comprehensive information on the geographical distribution of different Rickettsia species, infection status of reservoirs, vectors, and human cases is lacking in most parts of the world. Therefore, this study aimed to investigate the geographical distribution of different Rickettsia species and their vectors in countries of the WHO-EMRO region.

METHODS

In this review study, a search was conducted for reports and published studies on Rickettsia species from WHO-EMRO region countries in various databases from 1995 to 2022. Finally, the reported status of human cases, reservoirs, and vectors associated with each species in different countries was documented.

RESULTS

Reports of infections related to the detection of Rickettsia species were only available for 15 out of 22 WHO-EMRO member countries. A total of twenty-four Rickettsia species, including R. sibrica, R. lusitaniae, R. africae, R. prowazekii, R. felis, R. typhi, R. rickettsii, R. aeschlimannii, R. conorii, R. massiliae, R. helvetica, R. monacensis, R. rhipicephali, R. bellii, R. asembonensis, R. hoogstraalii, R. andeanae, R. raoultii, R. asiatica, R. slovaca, R. australis, R. barbariae, Candidatus R. amblyommii, and Candidatus R. goldwasserii, were reported from WHO-EMRO member countries. Furthermore, human cases infected with six different Rickettsia species, including R. sibrica, R. prowazekii, R. felis, R. typhi, R. rickettsii, R. aeschlimannii, R. conorii, R. massiliae, and R. helvetica, were reported from these countries.

CONCLUSION

The vast diversity of Rickettsia vectors has contributed to the ongoing discovery of new Rickettsia species. Therefore, further research on the reservoir hosts of Rickettsia infections in the understudied WHO-EMRO region is crucial. This research sheds light on Rickettsia disease's epidemiology and transmission dynamics in this region.

Tick-borne pathogens in camels: A systematic review and meta-analysis of the prevalence in dromedaries

Published data on tick-borne pathogens (TBPs) in camels worldwide have been collected to provide an overview of the global prevalence and species diversity of camelid TBPs. Several TBPs have been detected in dromedary camels, raising concerns regarding their role as natural or maintenance hosts for tick-borne pathogens. Insubstantial evidence exists regarding the natural infection of camels with Babesia spp., Theileria spp., Anaplasma spp., and Ehrlichia spp., particularly because most of the camels were considered healthy at the time of sampling. Based on polymerase chain reaction (PCR) testing, a pooled prevalence of 35.3% (95% CI: 22.6-48.1%) was estimated for Anaplasma, which was the most frequently tested TBP in dromedaries, and DNA of Anaplasma marginale, Anaplasma centrale, Anaplasma ovis, Anaplasma platys, and A. platys-like were isolated, of which ruminants and dogs are reservoirs. Similarly, the estimated pooled prevalence for the two piroplasmid genera; Babesia and Theileria was approximately equal (10-12%) regardless of the detection method (microscopy or PCR testing). Nevertheless, Babesia caballi, Theileria equi, and Theileria annulata DNA have frequently been detected in camels but they have not yet been proven to be natural hosts. Scarce data detected Babesia microti, Anaplasma phagocytophilum, and Borrelia burgdorferi sensu lato (s.l.) DNA in blood of dromedaries, although ticks of the genus Ixodes are distributed in limited areas where dromedaries are raised. Interestingly, a pooled seroprevalence of 47.7% (26.3-69.2%) was estimated for Crimean-Congo hemorrhagic fever virus, and viral RNA was detected in dromedary blood; however, their contribution to maintain the viral transmission cycles requires further experimental investigation. The substantially low incidence and scarcity of data on Rickettsia and Ehrlichia species could imply that camels were accidentally infected. In contrast, camels may play a role in the spread of Coxiella burnetii, which is primarily transmitted through the inhalation of aerosols emitted by diseased animals and contaminated environments. Bactrian camels showed no symptoms due to the examined TBPs, meanwhile, clinical disease was seen in alpacas infected with A. phagocytophilum. Similar to dromedaries, accidental tick bites may be the cause of TBP DNA found in the blood of Bactrian camels.

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.

Genetic diversity of Hyalomma marginatum in Tunisia is not influenced by the bio-climate

Ticks are important ectoparasites responsible for the transmission of several pathogens with significant medical, veterinary, and economic impacts. Climate and social changes have generated substantial changes in ticks' distribution, abundance, and activity patterns, including ticks belonging to the Hyalomma marginatum species. Knowledge on the genetic structure and dynamics of H. marginatum populations might contribute to a better understanding of their current and future evolution under the effects of anthropogenic factors and eco-climatic changes. In the present study, we investigated the genetic structure and phylogenetic distribution of H. marginatum across three bioclimatic regions in Tunisia using two mitochondrial markers (16S and 12S rRNA). The molecular investigations were based on 47 adult H. marginatum ticks collected from humid, upper semi-arid, and sub-humid regions of Tunisia. Our results revealed a genetic diversity of 0.278% and 0.809% using the 16S and 12S markers, respectively. The low genetic diversity that we observed raises the hypothesis of a bottleneck event occasioned by a reduction in the size of the tick population under the effects of environmental factors and/or human activities. This hypothesis is supported by the population's demographic history analysis, which revealed a clear deviation from neutrality and supports the occurrence of a bottleneck event followed by a demographic expansion. The fact that most 16S and 12S variability was present in the ticks from the humid bioclimatic zone may suggest that those ticks represent the ancestral population. Overall, the analysis has shown that the phylogenetic clusters do not correspond to the bioclimatic zones.

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.

Diversity of Rickettsia spp. in ticks from wild mammals of Morocco and Mauritania

Ticks are known as vectors and reservoirs of rickettsiae and, wildlife vertebrate hosts as suitable dispersers of ticks contributing to the life cycle of rickettsial agents in nature. In the herein study, the presence of rickettsiae was investigated in ticks from wild mammals (Gerbillus and Jaculus, Vulpes rueppellii, Canis anthus, Felis lybica and Felis margarita) in Mauritania and Morocco. Morphological and molecular analysis of ticks allowed their identification as Rhipicephalus sanguineus sensu lato and Hyalomma impeltatum. A total of 126 partially engorged adult ticks, collected from 40 animals, were screened for the presence of rickettsial DNA by conventional PCR targeting the ompB gene, followed by ompA and gltA targets and bidirectional sequencing. As a result of the sequence analyses, that at least three different species of pathogenic spotted fever group rickettsiae were detected. Rickettsia parkeri-like was detected in a R. sanguineus s.l. (n=1) collected from an African wildcat from Morocco. Rickettsia aeschlimannii was detected in a H. impeltatum (n=1) collected from a gerbil rodent. Rickettsia massiliae was detected in R. sanguineus s.l. ticks (n=5) collected from two Ruppells' foxes. The herein study demonstrates that pathogenic Rickettsia species are circulating in Morocco and Mauritania wildlife.

Molecular Detection of Rickettsia hoogstraalii in Hyalomma anatolicum and Haemaphysalis sulcata: Updated Knowledge on the Epidemiology of Tick-Borne Rickettsia hoogstraalii

Ticks are hematophagous ectoparasites that transmit pathogens to animals and humans. Updated knowledge regarding the global epidemiology of tick-borne Rickettsia hoogstraalii is dispersed, and its molecular detection and genetic characterization are missing in Pakistan. The current study objectives were to molecularly detect and genetically characterize Rickettsia species, especially R. hoogstraalii, in hard ticks infesting livestock in Pakistan, and to provide updated knowledge regarding their global epidemiology. Ticks were collected from livestock, including goats, sheep, and cattle, in six districts of Khyber Pakhtunkhwa (KP) Pakistan. Overall, 183 hosts were examined, of which 134 (73.2%), including goats (number = 39/54, 72.2%), sheep (23/40, 57.5%), and cattle (71/89, 80%) were infested by 823 ticks. The most prevalent tick species was Rhipicephalus microplus (number = 283, 34.3%), followed by Hyalomma anatolicum (223, 27.0%), Rhipicephalus turanicus (122, 14.8%), Haemaphysalis sulcata (104, 12.6%), Haemaphysalis montgomeryi (66, 8.0%), and Haemaphysalis bispinosa (25, 3.03%). A subset of 210 ticks was selected and screened for Rickettsia spp. using PCR-based amplification and subsequent sequencing of rickettsial gltA and ompB fragments. The overall occurrence rate of R. hoogstraalii was 4.3% (number = 9/210). The DNA of Rickettsia was detected in Hy. anatolicum (3/35, 8.5%) and Ha. sulcata (6/49, 12.2%). However, no rickettsial DNA was detected in Rh. microplus (35), Rh. turanicus (35), Ha. montgomeryi (42), and Ha. bispinosa (14). The gltA and ompB fragments showed 99-100% identity with R. hoogstraalii and clustered phylogenetically with the corresponding species from Pakistan, Italy, Georgia, and China. R. hoogstraalii was genetically characterized for the first time in Pakistan and Hy. anatolicum globally. Further studies should be encouraged to determine the role of ticks in the maintenance and transmission of R. hoogstraalii in different hosts.

Human-biting ticks and zoonotic tick-borne pathogens in North Africa: diversity, distribution, and trans-Mediterranean public health challenges

North Africa is home to more than 200 million people living across five developing economies (Egypt, Libya, Tunisia, Algeria, and Morocco) and two Spanish exclaves (Ceuta and Melilla), many of whom are impacted by ticks and tick-borne zoonoses. Populations in Europe are also increasingly vulnerable to North African ticks and tick-borne zoonoses due to a combination of climate change and the movement of ticks across the Mediterranean on migratory birds, human travellers, and trafficked wildlife. The human-biting ticks and tick-borne zoonoses in North Africa are reviewed along with their distribution in the region. We also assess present and future challenges associated with ticks and tick-borne zoonoses in North African and highlight opportunities for collaboration and coordination between governments in Europe and North Africa to address public health challenges posed by North African ticks and tick-borne zoonoses.

Diversity and Phylogeny of Cattle Ixodid Ticks and Associated Spotted Fever Group Rickettsia spp. in Tunisia

Tick-borne rickettsioses are mainly caused by obligate intracellular bacteria belonging to the spotted fever group (SFG) of the Rickettsia genus. So far, the causative agents of SFG rickettsioses have not been detected in cattle ticks from Tunisia. Therefore, the aim of this study was to investigate the diversity and phylogeny of ticks associated with cattle from northern Tunisia and their associated Rickettsia species. Adult ticks (n = 338) were collected from cattle in northern Tunisia. The obtained ticks were identified as Hyalomma excavatum (n = 129), Rhipicephalus sanguineus sensu lato (n = 111), Hyalomma marginatum (n = 84), Hyalomma scupense (n = 12) and Hyalomma rufipes (n = 2). After DNA extraction from the ticks, 83 PCR products based on the mitochondrial 16S rRNA gene were sequenced and a total of four genotypes for Rh. sanguineus s.l., two for Hy. marginatum and Hy. excavatum and only one for Hy. scupense and Hy. rufipes were recorded, with the occurrence of one, two and three novel genotypes, respectively, for Hy. marginatum, Hy. excavatum and Rh. sanguineus s.l. mitochondrial 16S rRNA partial sequences. The tick DNA was tested for the presence of Rickettsia spp. by using PCR measurements and sequencing targeting three different genes (ompB, ompA and gltA). Of the 338 analyzed ticks, 90 (26.6%), including 38 (34.2%) Rh. sanguineus s.l., 26 (20.1%) Hy. excavatum, 25 (29.8%) Hy. marginatum and one (50%) Hy. rufipes tick, were positive for Rickettsia spp. Based on 104 partial sequences of the three analyzed genes, the BLAST analysis and phylogenetic study showed the infection of Hy. excavatum, Hy. marginatum and Rh. sanguineus s.l. tick specimens with R. massiliae, R. aeschlimannii and R. sibirica subsp. mongolitimonae and one Hy. rufipes tick specimen with R. aeschlimannii. In addition, coinfection with R. massiliae and R. aeschlimannii was reported in one Hy. marginatum and one Rh. sanguineus s.l. tick specimen, while a coinfection with R. massiliae and R. sibirica subsp. mongolitimonae was recorded in one Rh. sanguineus s.l. tick specimen. In conclusion, our study reports, for the first time in Tunisia, the infection of cattle ticks belonging to Hyalomma and Rhipicephalus genera with zoonotic Rickettsia species belonging to the SFG group.

Distribution and Prevalence of Anaplasmataceae, Rickettsiaceae and Coxiellaceae in African Ticks: A Systematic Review and Meta-Analysis

In Africa, ticks continue to be a major hindrance to the improvement of the livestock industry due to tick-borne pathogens that include Anaplasma, Ehrlichia, Rickettsia and Coxiella species. A systemic review and meta-analysis were conducted here and highlighted the distribution and prevalence of these tick-borne pathogens in African ticks. Relevant publications were searched in five electronic databases and selected using inclusion/exclusion criteria, resulting in 138 and 78 papers included in the qualitative and quantitative analysis, respectively. Most of the studies focused on Rickettsia africae (38 studies), followed by Ehrlichia ruminantium (27 studies), Coxiella burnetii (20 studies) and Anaplasma marginale (17 studies). A meta-analysis of proportions was performed using the random-effects model. The highest prevalence was obtained for Rickettsia spp. (18.39%; 95% CI: 14.23–22.85%), R. africae (13.47%; 95% CI: 2.76–28.69%), R. conorii (11.28%; 95% CI: 1.77–25.89%), A. marginale (12.75%; 95% CI: 4.06–24.35%), E. ruminantium (6.37%; 95% CI: 3.97–9.16%) and E. canis (4.3%; 95% CI: 0.04–12.66%). The prevalence of C. burnetii was low (0%; 95% CI: 0–0.25%), with higher prevalence for Coxiella spp. (27.02%; 95% CI: 10.83–46.03%) and Coxiella-like endosymbionts (70.47%; 95% CI: 27–99.82%). The effect of the tick genera, tick species, country and other variables were identified and highlighted the epidemiology of Rhipicephalus ticks in the heartwater; affinity of each Rickettsia species for different tick genera; dominant distribution of A. marginale, R. africae and Coxiella-like endosymbionts in ticks and a low distribution of C. burnetii in African hard ticks.

Prevalence of Spotted Fever Group Rickettsia and Candidatus Lariskella in Multiple Tick Species from Guizhou Province, China

Rickettsiales (Rickettsia spp., Ehrlichia spp., and Anaplasma spp., etc.) are generally recognized as potentially emerging tick-borne pathogens. However, some bacteria and areas in China remain uninvestigated. In this study, we collected 113 ticks from mammals in Guizhou Province, Southwest China, and screened for the Rickettsiales bacteria. Subsequently, two spotted fever group Rickettsia species and one Candidatus Lariskella sp. were detected and characterized. "Candidatus Rickettsia jingxinensis" was detected in Rhipicephalus microplus (1/1), Haemaphysalis flava (1/3, 33.33%), Haemaphysalis kitaokai (1/3), and Ixodes sinensis (4/101, 3.96%), whereas Rickettsia monacensis was positive in H. flava (1/3), H. kitaokai (2/3), and I. sinensis ticks (74/101, 73.27%). At least two variants/sub-genotypes were identified in the R. monacensis isolates, and the strikingly high prevalence of R. monacensis may suggest a risk of human infection. Unexpectedly, a Candidatus Lariskella sp. belonging to the family Candidatus Midichloriaceae was detected from Ixodes ovatus (1/4) and I. sinensis (10/101, 9.90%). The gltA and groEL gene sequences were successfully obtained, and they show the highest (74.63-74.89% and 73.31%) similarities to "Candidatus Midichloria mitochondrii", respectively. Herein, we name the species "Candidatus Lariskella guizhouensis". These may be the first recovered gltA and groEL sequences of the genus Candidatus Lariskella.

Unraveling the epidemiological relationship between ticks and rickettsial infection in Africa

Tick-borne rickettsioses are emerging and re-emerging diseases of public health concern caused by over 30 species of Rickettsia. Ticks are obligate hematophagous arthropods with over 700 species of Ixodid ticks known worldwide. The escalating geographical dispersal of tick vectors and concomitant increase in the incidences of tick-borne diseases have fueled interest in the ecology of tick-borne pathogens. This review focuses on aspects of the Rickettsia pathogen, including biology, taxonomy, phylogeny, genetic diversity, epidemiology of the disease, and the role of vertebrate host in the perpetuation of rickettsioses in Africa. Our review also highlights some of the species of Rickettsia that are responsible for disease, the role of tick vectors (both hard and soft ticks) and the species of Rickettsia associated with diverse tick species across the continent. Additionally, this article emphasizes the evolutionary perspective of rickettsiae perpetuation and the possible role of amplifying vertebrate host and other small mammals, domestic animals and wildlife in the epidemiology of Rickettsia species. We also specifically, discussed the role of avian population in the epidemiology of SFG rickettsiae. Furthermore, we highlighted tick-borne rickettsioses among travelers due to African tick-bite fever (ATBF) and the challenges to surveillance of rickettsial infection, and research on rickettsiology in Africa. Our review canvasses the need for more rickettsiologists of African origin based within the continent to further research towards understanding the biology, characterization, and species distribution, including the competent tick vectors involved in their transmission of rickettsiae across the continent in collaboration with established researchers in western countries. We further highlighted the need for proper funding to encourage research despite competing demands for resources across the various sectors. We finalize by discussing the similarities between rickettsial diseases around the world and which steps need to be taken to help foster our understanding on the eco-epidemiology of rickettsioses by bridging the gap between the growing epidemiological data and the molecular characterization of Rickettsia species.

Epidemiology and genetic characteristics of tick-borne bacteria in dromedary camels of the world

This review presents updated knowledge on the main tick-borne bacteria infecting one-humped camels (Camelus dromedarius) around the world. Camels are increasingly the subject of several scientific investigations, showing that they are receptive and carriers of several zoonotic bacteria. An appraisal is also given of the relative public health importance of these bacterial infections according to One Health concept. Microscopic, serologic and molecular findings are appropriately generated in order to exploit epidemiological data, and phylogeographic specificities associated to each vector-borne bacterium. Indeed, camels and their ticks harbour similar species and genotypes of pathogenic bacteria commonly identified in other animals, e.g., Anaplasma spp.,Ehrlichia spp., Borrelia spp., Rickettsia spp., Coxiella burnetii, Bartonella spp. and hemotrophic mycoplasmas. This evidence suggests an epidemiological role of camels in the spread of these pathogens in their natural habitats. However, these infections are commonly asymptomatic in camels resulting in underestimation of the impact of these infections. Furthermore, camels have recently been proven to have their own specific unclassified strains, such as Candidatus Anaplasma camelii and Candidatus Bartonella camelii, implying that possible interactions may lead to the emergence of pathogenic and zoonotic bacteria. In camel-rearing areas of the world, spatial and temporal spread of these infections, due to climatic and ecological changes and human activities such as development projects and urbanization, is expected. Hence the data presented herein provides a basis for strategic frameworks for the research and the development of novel diagnosis and control strategies worldwide, which are needed to protect camels, other livestock, and people in contact with dromedaries from threats that arthropod-borne pathogens can pose.

Distribution of Tick-Borne Pathogens in Domestic Animals and Their Ticks in the Countries of the Mediterranean Basin between 2000 and 2021: A Systematic Review

Tick-borne pathogens (TBPs) include a wide range of bacteria, parasites and viruses that cause a large spectrum of animal, human and zoonotic tick-borne diseases (TBDs). The object of this review was to establish an inventory and an analysis of TBPs found in domestic animals in the countries of the Mediterranean Basin. This geographic area occupies a central position between several continents and is an area of movement for animals, humans and pathogens of interest and their vectors, which is important in terms of animal and human health. In this systematic review, we included a total of 271 publications produced between 2000–2021 concerning TBPs in domestic animals. Among this literature, we found a total of 90 pathogen species (known as TBPs) reported in the 20 countries of the area; these were detected in tick species from domestic animals and were also directly detected in domestic animals. In all, 31 tick species were recorded and 12 domestic animal species, the latter comprising nine livestock and three pet species. More than 50% of the publications were from Western Europe. Island data were extracted and assessed, as islands of the Mediterranean Basin were represented in 16% of the publications and 77.8% of the TBPs reported. Our results show the importance of islands in the monitoring of TBPs, despite the low percentage of publications.

Zoonotic vector-borne bacteria in wild rodents and associated ectoparasites from Tunisia

Wild rodents are considered as potential carriers of several zoonotic vector-borne bacteria but their epidemiology is poorly understood in Tunisia. A total of 305 biological samples (100 spleens, 100 livers, 100 kidneys, and 5 pooled ectoparasites (Xenopsylla cheopis, Laelaps echidninus, Ornithonyssus sp., Hoplopleura sp. and eggs of the rat fleas)) were collected from 100 wild rodents from three Tunisian governorates. Molecular screening was performed to reveal infections with main vector-borne bacteria. Captured rodents belonged to three rodent genera and species including Rattus rattus (n = 51, 51%), Meriones shawi (n = 24, 24%) and Mus musculus (n = 25, 25%). Examined rodents were found to be heavily infested by the rat flea X. cheopis (n = 32, 47%) and the rat mite L. echidninus (n = 22, 32.3%). However, the rat mite Ornithonyssus sp. (n = 13, 19.1%) and the rat lice Hoplopleura sp. (n = 1, 1.5%) were rarely identified. Based on 16S rRNA and msp4 genes, infection with Anaplasmataceae bacteria was detected in six specimens of R. rattus and one M. shawi. Pathogenic A. phagocytophilum (n = 1), A. phagocytophilum-like 1 (Anaplasma sp. Japan) (n = 1), and A. ovis (n = 5) were identified. On the basis of ompB, ompA and gltA genes, infection with Rickettsia spp. was identified in three specimens of R. rattus and one of M. shawi. Five Rickettsia species of the spotted fever group, corresponding to R. monacensis, R. helvetica, R. massiliae, R. africae, and R. aeschlimannii, were detected in mixed infections. Bartonella henselae DNA was also found in two R. rattus, based on rpoB partial sequences. All revealed Anaplasma, Rickettsia and Bartonella bacteria were detected in spleen samples. Ehrlichia, Coxiella and Borrelia spp. were not identified in any of the tested samples. In Tunisia, this is the first report indicating infections with Anaplasma, Rickettsia and Bartonella spp. in wild rodents, particularly present alongside domestic livestock and human. This represents a serious risk of potential bacterial transmission. Thus, controlling rodent population in animal herds, residential areas and sensitizing local people to this risk seem absolutely necessary.

Ticks and Tick-Borne Pathogens Associated with Dromedary Camels (Camelus dromedarius) in Northern Kenya

Ticks and tick-borne pathogens (TBPs) are major constraints to camel health and production, yet epidemiological data on their diversity and impact on dromedary camels remain limited. We surveyed the diversity of ticks and TBPs associated with camels and co-grazing sheep at 12 sites in Marsabit County, northern Kenya. We screened blood and ticks (858 pools) from 296 camels and 77 sheep for bacterial and protozoan TBPs by high-resolution melting analysis and sequencing of PCR products. Hyalomma (75.7%), Amblyomma (17.6%) and Rhipicephalus (6.7%) spp. ticks were morphologically identified and confirmed by molecular analyses. We detected TBP DNA in 80.1% of blood samples from 296 healthy camels. "Candidatus Anaplasma camelii", "Candidatus Ehrlichia regneryi" and Coxiella burnetii were detected in both camels and associated ticks, and Ehrlichia chaffeensis, Rickettsia africae, Rickettsia aeschlimannii and Coxiella endosymbionts were detected in camel ticks. We also detected Ehrlichia ruminantium, which is responsible for heartwater disease in ruminants, in Amblyomma ticks infesting camels and sheep and in sheep blood, indicating its endemicity in Marsabit. Our findings also suggest that camels and/or the ticks infesting them are disease reservoirs of zoonotic Q fever (C. burnetii), ehrlichiosis (E. chaffeensis) and rickettsiosis (R. africae), which pose public health threats to pastoralist communities.

Zoonotic Rickettsia Species in Small Ruminant Ticks From Tunisia

Tick-borne rickettsioses present a significant public health threat among emerging tick-borne diseases. In Tunisia, little is known about tick-borne Rickettsia pathogens. Therefore, the aim of this study was to investigate the presence of Rickettsia species in small ruminant ticks from Tunisia. Adult ticks (n = 694) were collected from goats and sheep in northern Tunisia. Obtained ticks were identified as Rhipicephalus turanicus (n = 434) and Rhipicephalus sanguineus sensu lato (n = 260). Selected ticks (n = 666) were screened for the presence of Rickettsia spp. by PCR targeting a partial sequence of the ompB gene followed by sequence analysis. Rickettsial DNA was detected in 122 (18.3%) tested tick samples. The infection rates in Rh. turanicus and Rh. sanguineus s.l. ticks were 23.4 and 9.5%, respectively. The overall prevalence of rickettsial DNA was markedly higher in ticks collected from goats (23.2%) compared to those infesting sheep (7.9%). The detection of rickettsial DNA was significantly higher in ticks from the governorate of Beja (39.0%) than those from the governorate of Bizerte (13.9%). Two additional genes, the outer membrane protein A gene (ompA) and the citrate synthase gene (gltA), were also targeted for further characterization of the detected Rickettsia species. Genotyping and phylogenetic analysis based on partial sequences (n = 106) of the three different genes revealed that positive ticks are infected with different isolates of two Spotted Fever Group (SFG) Rickettsia, namely, Rickettsia massiliae and Rickettsia monacensis, closely related to those infecting camels and associated ticks from Tunisia, and humans and small ruminant ticks from neighboring countries like Italy, France, and Spain.

Phenology and phylogeny of Hyalomma spp. ticks infesting one-humped camels (Camelus dromedarius) in the Tunisian Saharan bioclimatic zone

In this study, we report the results of a survey of Hyalomma ticks infesting one-humped camels in southern Tunisia. Examinations were conducted every second or third month on 406 camels in Tataouine district from April 2018 to October 2019. A total of 1902 ticks belonging to the genus Hyalomma were collected. The ticks were identified as adult H. impeltatum (41.1%; n = 782), H. dromedarii (32.9%; n = 626), H. excavatum (25.9%; n = 493), and H. marginatum for a single specimen. Although the camels were infested by ticks throughout the year, the highest overall infestation prevalence was observed in April 2018 (p < 0.01). The overall infestation intensity varied between 2.7 and 7.4 ticks/animal. There were no statistically significant differences in tick infestation prevalence based on age categories of the camels, and the overall infestation prevalence was between 82.7% and 97.4%. Female camels were significantly more infested with ticks (88.3%) than males (65.5%) (p < 0.01). The infestation prevalence of camels varied significantly according to the region where sampling took place (p < 0.01), but no correlations were found with abiotic factors. The preferred attachment sites for adult Hyalomma ticks were the sternum (38.3%; n = 729/1902), around the anus (36.2%; n = 689/1902), udder (18.4%; n = 350/1902), and inner thigh (6.9%; n = 132/1902). Morphological classification of ticks was corroborated by sequencing the cytochrome c oxidase I (Cox1) and 16S rDNA genes, and these sequences were also used to infer phylogenetic relationships. A single H. dromedarii seemed to be a natural hybrid with H. rufipes. More attention should be devoted by the veterinary services to the infestation of camels by ticks.

Exploring Prokaryotic and Eukaryotic Microbiomes Helps in Detecting Tick-Borne Infectious Agents in the Blood of Camels

Dromedary camels (Camelus dromedarius) are widely distributed in Africa, the Middle East and northern India. In this study, we aimed to detect tick-borne pathogens through investigating prokaryotic and eukaryotic microorganisms in camel blood based on a metagenomic approach and then to characterize potentially pathogenic organisms using traditional molecular techniques. We showed that the bacteria circulating in the blood of camels is dominated by Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria. At the genus level, Sediminibacterium, Hydrotalea, Bradyrhizobium and Anaplasma were the most abundant taxa. Eukaryotic profile was dominated by Fungi, Charophyta and Apicomplexa. At the genus level, Theileria was detected in 10 out of 18 samples, while Sarcocystis, Hoplorhynchus and Stylocephalus were detected in one sample each. Our metagenomic approach was successful in the detection of several pathogens or potential pathogens including Anaplasma sp., Theileria ovis, Th. separata, Th. annulate, Th. mutans-like and uncharacterized Theileria sp. For further characterization, we provided the partial sequences of citrate synthase (gltA) and heat-shock protein (groEL) genes of Candidatus Anaplasma camelii. We also detected Trypanosoma evansi type A using polymerase chain reaction (PCR) targeting the internal transcribed spacer 1 (ITS1) region. This combined metagenomic and traditional approach will contribute to a better understanding of the epidemiology of pathogens including tick-borne bacteria and protozoa in animals.

Lack of detection of the Middle East respiratory syndrome coronavirus (MERS-CoV) nucleic acids in some Hyalomma dromedarii infesting some Camelus dromedary naturally infected with MERS-CoV

Objective

The Middle East respiratory syndrome coronavirus (MERS-CoV) is one of the zoonotic coronaviruses [Hemida Peer J 7:e7556, 2019; Hemida et al. One Health 8:100102, 2019]. The dromedary camels remained the only known animal reservoir for this virus. Several aspects of the transmission cycle of the virus between animals, including arthropod-borne infection, is still largely unknown. The main objective of the current work was to study the possibility of MERS-CoV transmission through some arthropod vectors, particularly the hard ticks. To achieve this objective, we identified a positive MERS-CoV dromedary camel herd using the commercial available real-time PCR kits. We collected some arthropods, particularly the ticks from these positive animals as well as from the animal habitats. We tested these arthropods for the presence of MERS-CoV viral RNAs.

Results

Our results showing the absence of any detectable MERS-CoV-RNAs in these arthropods despite these animals were actively shedding the virus in their nasal secretions. Our results are confirming for the first the failure of detection of the MERS-CoV in ticks infesting dromedary camels. Failure of the detection of MERS-CoV in ticks infesting positive naturally infected MERS-CoV camels is strongly suggesting that ticks do not play roles in the transmission of the virus among the animals and close contact humans.