Molecular Detection of Tick-Borne Pathogen Diversities in Ticks from Livestock and Reptiles along the Shores and Adjacent Islands of Lake Victoria and Lake Baringo, Kenya

New insights into the systematics of the afrotropical Amblyomma marmoreum complex (Acari: Ixodidae) and the genome of a novel Rickettsia africae strain using morphological and metagenomic approaches

The Amblyomma marmoreum complex includes afrotropical species, such as Amblyomma sparsum, a three-host tick that parasitizes reptiles, birds, and mammals, and is a recognized vector of Ehrlichia ruminantium. However, the lack of morphological, genetic and ecological data on A. sparsum has caused considerable confusion in its identification. In this study, we used microscopy and metagenomic approaches to analyze A. sparsum ticks collected from a puff adder snake (Bitis arietans) in southwest Senegal (an endemic rickettsioses area) in order to supplement previous morphological descriptions, provide novel genomic data for the A. marmoreum complex, and describe the genome of a novel spotted fever group Rickettsia strain. Based on stereoscope and scanning electron microscopy (SEM) morphological evaluations, we provide high-quality images and new insights about punctation and enameling in the adult male of A. sparsum to facilitate identification for future studies. The metagenomic approach allowed us assembly the complete mitochondrial genome of A. sparsum, as well as the nearly entire chromosome and complete plasmid sequences of a novel Rickettsia africae strain. Phylogenomic analyses demonstrated a close relationship between A. sparsum and Amblyomma nuttalli for the first time and confirmed the position of A. sparsum within the A. marmoreum complex. Our results provide new insights into the systematics of A. sparsum and A. marmoreum complex, as well as the genetic diversity of R. africae in the Afrotropical region. Future studies should consider the possibility that A. sparsum may be a vector for R. africae.

Tissue-specific localization of tick-borne pathogens in ticks collected from camels in Kenya: insights into vector competence

Background

Tick-borne pathogen (TBP) surveillance studies often use whole-tick homogenates when inferring tick-pathogen associations. However, localized TBP infections within tick tissues (saliva, hemolymph, salivary glands, and midgut) can inform pathogen transmission mechanisms and are key to disentangling pathogen detection from vector competence.

Methods

We screened 278 camel blood samples and 504 tick tissue samples derived from 126 camel ticks sampled in two Kenyan counties (Laikipia and Marsabit) for Anaplasma, Ehrlichia, Coxiella, Rickettsia, Theileria, and Babesia by PCR-HRM analysis.

Results

Candidatus Anaplasma camelii infections were common in camels (91%), but absent in all samples from Rhipicephalus pulchellus, Amblyomma gemma, Hyalomma dromedarii, and Hyalomma rufipes ticks. We detected Ehrlichia ruminantium in all tissues of the four tick species, but Rickettsia aeschlimannii was only found in Hy. rufipes (all tissues). Rickettsia africae was highest in Am. gemma (62.5%), mainly in the hemolymph (45%) and less frequently in the midgut (27.5%) and lowest in Rh. pulchellus (29.4%), where midgut and hemolymph detection rates were 17.6% and 11.8%, respectively. Similarly, in Hy. dromedarii, R. africae was mainly detected in the midgut (41.7%) but was absent in the hemolymph. Rickettsia africae was not detected in Hy. rufipes. No Coxiella, Theileria, or Babesia spp. were detected in this study.

Conclusions

The tissue-specific localization of R. africae, found mainly in the hemolymph of Am. gemma, is congruent with the role of this tick species as its transmission vector. Thus, occurrence of TBPs in the hemolymph could serve as a predictor of vector competence of TBP transmission, especially in comparison to detection rates in the midgut, from which they must cross tissue barriers to effectively replicate and disseminate across tick tissues. Further studies should focus on exploring the distribution of TBPs within tick tissues to enhance knowledge of TBP epidemiology and to distinguish competent vectors from dead-end hosts.

Data release: targeted systematic literature search for tick and tick-borne pathogen distributions in six countries in sub-Saharan Africa from 1901 to 2020

BACKGROUND

Surveillance data documenting tick and tick-borne disease (TBD) prevalence is needed to develop risk assessments and implement control strategies. Despite extensive research in Africa, there is no standardized, comprehensive review.

METHODS

Here we tackle this knowledge gap, by producing a comprehensive review of research articles on ticks and TBD between 1901 and 2020 in Chad, Djibouti, Ethiopia, Kenya, Tanzania, and Uganda. Over 8356 English language articles were recovered. Our search strategy included 19 related MeSH terms. Articles were reviewed, and 331 met inclusion criteria. Articles containing mappable data were compiled into a standardized data schema, georeferenced, and uploaded to VectorMap.

RESULTS

Tick and pathogen matrixes were created, providing information on vector distributions and tick-pathogen associations within the six selected African countries.

CONCLUSIONS

These results provide a digital, mappable database of current and historical tick and TBD distributions across six countries in Africa, which can inform specific risk modeling, determine surveillance gaps, and guide future surveillance priorities.

First report of dog ticks and tick-borne pathogens they are carrying in Malawi

Ticks are vectors for transmitting tick-borne pathogens (TBPs) in animals and humans. Therefore, tick identification is necessary to understand the distribution of tick species and the pathogens they carry. Unfortunately, data on dog ticks and the TBPs they harbor in Malawi are incomplete. This study aimed to identify dog ticks and the TBPs they transmit in Malawi. One hundred thirty-two ticks were collected from 87 apparently healthy but infested domestic dogs in four districts of Malawi, which were pooled into 128 tick samples. The ticks were morphologically identified under a stereomicroscope using identification keys, and species identification was authenticated by polymerase chain reaction (PCR) through the amplification and sequencing of 12S rRNA and cytochrome c oxidase subunit I (CO1) genes. The tick species identified were Rhipicephalus sanguineus sensu lato (58.3%), Haemaphysalis elliptica (32.6%), and Hyalomma truncatum (9.1%). Screening for TBPs using species-specific PCR assays revealed that 48.4% of the ticks were infected with at least one TBP. The TBP detection rates were 13.3% for Anaplasma platys, 10.2% for Babesia rossi, 8.6% for B. vogeli, 6.3% for Ehrlichia canis, 3.9% for A. phagocytophilum, 3.1% for B. gibsoni, 2.3% for B. canis and 0.8% for Hepatozoon canis. Co-infections of up to three pathogens were observed in 48.4% of the positive samples. This is the first study to identify dog ticks and the TBPs they harbor in Malawi. These findings provide the basis for understanding dog tick distribution and pathogens they carry in Malawi. This study necessitates the examination of ticks from more study locations to have a better picture of tick challenge, and the development of ticks and tick-borne disease control methods in Malawi.

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.

Effects of cattle on vector-borne disease risk to humans: A systematic review

Vector-borne pathogens (VBPs) causing vector-borne diseases (VBDs) can circulate among humans, domestic animals, and wildlife, with cattle in particular serving as an important source of exposure risk to humans. The close associations between humans and cattle can facilitate the transmission of numerous VBPs, impacting public health and economic security. Published studies demonstrate that cattle can influence human exposure risk positively, negatively, or have no effect. There is a critical need to synthesize the information in the scientific literature on this subject, in order to illuminate the various ecological mechanisms that can affect VBP exposure risk in humans. Therefore, the aim of this systematic review was to review the scientific literature, provide a synthesis of the possible effects of cattle on VBP risk to humans, and propose future directions for research. This study was performed according to the PRISMA 2020 extension guidelines for systematic review. After screening 470 peer-reviewed articles published between 1999-2019 using the databases Web of Science Core Collection, PubMed Central, CABI Global Health, and Google Scholar, and utilizing forward and backward search techniques, we identified 127 papers that met inclusion criteria. Results of the systematic review indicate that cattle can be beneficial or harmful to human health with respect to VBDs depending on vector and pathogen ecology and livestock management practices. Cattle can increase risk of exposure to infections spread by tsetse flies and ticks, followed by sandflies and mosquitoes, through a variety of mechanisms. However, cattle can have a protective effect when the vector prefers to feed on cattle instead of humans and when chemical control measures (e.g., acaricides/insecticides), semio-chemicals, and other integrated vector control measures are utilized in the community. We highlight that further research is needed to determine ways in which these mechanisms may be exploited to reduce VBD risk in humans.

Hard ticks (Acari: Ixodidae) and tick-borne diseases of sheep and goats in Africa: A review

Ticks are leading vectors of economically important pathogens that affect small ruminants due to favourable climatic conditions across different regions of the African continent. They are responsible for both direct and indirect economic losses in the livestock industry. This review focuses on the species diversity of hard ticks, their biology, tick-borne diseases of sheep and goats including non-infectious disease, and risk factors to tick infestation in Africa. Furthermore, our review provides recent updates on distribution of ticks and tick-borne pathogens of small ruminants in Africa. It was observed that several species and subspecies of hard ticks belonging to the genera Hyalomma (Hy), Rhipicephalus (Rh), Ixodes (I) and Amblyomma (Am) were found infesting small ruminants across the different regions of the continent. Of these genera, Rhipicephalus ticks accounts for the majority of the registered species, with exactly 27 different species infesting small ruminant stocks comprising of different developmental instars and adults of the tick. Rhipicephalus decolaratus, Rh. e. evertsi and Rh. appendiculatus were the three most common Rhipicephalus species reported. Both protozoal (Babesia and Theileria) and bacterial (Anaplasma, Rickettsia, Ehrlichia, Coxiella and Mycoplasma) pathogens have being reported to be amplified in several hard tick species and/or small ruminant hosts. Furthermore, tick paralysis and lameness were non-infectious conditions attributed to tick infestations. Amblyomma hebraeum and Rh. glabroscutatum may cause lameness in goats, while Hy. rufipes is responsible for the same condition in Merino sheep. Host paralysis due to a neurotoxin released by female Rh. e. evertsi and I. rubicundus has been documented within the continent. We therefore advocate for the need of integrated control measures against tick-borne pathogens (TBPs) including their arthropod vectors, to be performed simultaneously to ease the burden of vector-borne diseases in small ruminant production.

Anaplasma Species in Africa-A Century of Discovery: A Review on Molecular Epidemiology, Genetic Diversity, and Control

Anaplasma species, belonging to the family Anaplasmataceae in the order Rickettsiales, are obligate intracellular bacteria responsible for various tick-borne diseases of veterinary and human significance worldwide. With advancements in molecular techniques, seven formal species of Anaplasma and numerous unclassified species have been described. In Africa, several Anaplasma species and strains have been identified in different animals and tick species. This review aims to provide an overview of the current understanding of the molecular epidemiology and genetic diversity of classified and unclassified Anaplasma species detected in animals and ticks across Africa. The review also covers control measures that have been taken to prevent anaplasmosis transmission on the continent. This information is critical when developing anaplasmosis management and control programs in Africa.

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.

Molecular survey of Anaplasma and Ehrlichia species in livestock ticks from Kassena-Nankana, Ghana; with a first report of Anaplasma capra and Ehrlichia minasensis

Tick-borne pathogens harm livestock production and pose a significant risk to public health. To combat these effects, it is necessary to identify the circulating pathogens to create effective control measures. This study identified Anaplasma and Ehrlichia species in ticks collected from livestock in the Kassena-Nankana Districts between February 2020 and December 2020. A total of 1550 ticks were collected from cattle, sheep and goats. The ticks were morphologically identified, pooled and screened for pathogens using primers that amplify a 345 bp fragment of the 16SrRNA gene and Sanger sequencing. The predominant tick species collected was Amblyomma variegatum (62.98%). From the 491 tick pools screened, 34 (6.92%) were positive for Ehrlichia and Anaplasma. The pathogens identified were Ehrlichia canis (4.28%), Ehrlichia minasensis (1.63%), Anaplasma capra (0.81%) and Anaplasma marginale (0.20%). This study reports the first molecular identification of the above-mentioned Ehrlichia and Anaplasma species in ticks from Ghana. With the association of human infections with the zoonotic pathogen A. capra, livestock owners are at risk of infections, calling for the development of effective control measures.

Phlebovirus diversity in ticks from livestock in arid ecologies in Kenya

Phleboviruses are emerging pathogens of public health importance. However, their association with ticks is poorly described, particularly in Africa. Here, adult ticks infesting cattle, goats and sheep were collected in two dryland pastoralist ecosystems of Kenya (Baringo and Kajiado counties) and were screened for infection with phleboviruses. Ticks mainly belonged to the species Rhipicephalus appendiculatus, Hyalomma impeltatum, and Hyalomma rufipes. A fragment of the RNA-dependent RNA polymerase (RdRp) gene was identified in thirty of 671 tick pools, of which twenty-nine were from livestock sampled in Baringo county. Phylogenetic analyses revealed that twenty-five sequences were falling in three clades within the group of tick-associated phleboviruses. The sequences of the three clades showed nucleotide distances 8%, 19% and 22%, respectively, to previously known viruses suggesting that these sequence fragments may belong to three distinct viruses. Viruses of the group of tick-associated phleboviruses have been found in several countries and continents but so far have not been associated with disease in humans or animals. In addition, five sequences were found to group with the sandfly-associated phleboviruses Bogoria virus, Perkerra virus and Ntepes virus recently detected in the same region. Further studies are needed to investigate the transmission and maintenance cycles of these viruses, as well as to assess their potential to infect vertebrates.

PREVALENCE AND PARASITE INTENSITY OF HAEMOGREGARINES IN AFRICAN BELL HINGE-BACK (KINIXYS BELLIANA) AND AFRICAN HOME'S HINGE-BACK (KINIXYS HOMEANA) TORTOISES IN IBADAN, NIGERIA

Haemogregarines are a group of intracellular blood parasites reported in reptiles, other vertebrate taxa including mammals and fish, and haematophagous invertebrates. Information on prevalence, biodiversity, and host-specificity of haemogregarines of tortoises in Nigeria are scarce. A total of 120 African hinge-back tortoises (Kinixys belliana, n=70, and K. homeana, n=50) were bought from the Wildlife and Herbal Market in Ibadan, Nigeria. Blood was withdrawn via the subcarapacial sinuses of each tortoise. The prevalence and parasite intensity of haemogregarine infection was determined using a light microscope, and parasite species were determined by PCR using HepF300 and HepR900 primers. A sequence of 654 base pairs (bp; Hepatozoon cf. fitzsimonsi) from the study aligned with published 18SrRNA and closely related with a similarity of 97.38% to Hepatozoon fitzsimonsi sequenced from Kinixys zobensis in South Africa. Overall prevalence of haemogregarines was 53.33% from light microcopy and 75.83% from PCR, which is considered very high. Higher prevalence and mean±SD parasite intensity were recorded for K. belliana (82.89%, 0.29%) than for K. homeana (66.00%, 0.26%). Prevalence rates and parasite intensities of haemogregarines were significantly higher in wet than in dry seasons. The differences in prevalence and intensity between and within species may be due to habitat characteristics, feeding habits of vectors and hosts, seasons, and vector abundance.

Molecular Detection of Tick-Borne Bacteria from Amblyomma (Acari: Ixodidae) Ticks Collected from Reptiles in South Africa

Reptiles are hosts for various tick species and tick-associated organisms, many of which are zoonotic. However, little is known about the presence and diversity of tick-borne bacteria infecting reptiles and their ticks in South Africa. Amblyomma ticks (n = 253) collected from reptiles were screened for the presence of Coxiella, Anaplasma, Rickettsia, and Borrelia species by amplification, sequencing and phylogenetic analysis of the 16S rRNA, 23S rRNA, gltA, OmpA, and Flagellin genes, respectively. This study recorded the presence of reptile associated Borrelia species and Coxiella-like endosymbiont in South Africa for the first time. Furthermore, a spotted fever group Rickettsia species was observed in 7 Amblyomma marmoreum and 14 Amblyomma sylvaticum from tortoises of genera Kinixys and Chersina. Francisella-like endosymbiont was observed from 2 Amblyomma latum collected from the Mozambique spitting cobra, Naja mossambica. Coxiella burnetii and Anaplasma spp., were not detected from the current samples. Although the direct evidence that reptiles can act as reservoir hosts remains to be determined, observations from this study provide indications that reptilian ticks may play a role in the transmission of pathogenic bacteria to homothermic animals. Furthermore, the absence of Anaplasma spp., and C. burnetii does not mean that these pathogens should be completely neglected.

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.

Molecular survey for tick-borne pathogens and associated risk factors in sheep and goats in Kano Metropolis, Nigeria

Tick-borne pathogens (TBPs) pose an increased health and productivity risk to livestock in sub-Saharan Africa. Information regarding TBPs infecting small ruminants in Kano metropolis is scarce. Therefore, we investigated the molecular epidemiology of tick-borne pathogens of economic importance from sheep and goats in Kano, Nigeria using Polymerase chain reaction (PCR). A total of 346 blood DNA samples were collected from small ruminants and analyzed for TBPs using PCR and sequencing. Risk of infection was determined for age, sex, breed and animal species. Our results indicate the absence of piroplasmids (Babesia/Theileria) and Rickettsia spp. infections. The overall prevalence for Anaplasma spp. was 9.25% (32/346) with a higher prevalence in goats 13.59% (25/184) compared with sheep 4.32% (7/162). With respect to age of animals, goats >4 years had the highest prevalence of 32.45% (11/37) which differs significantly (P = 0.0059) compared with other age categories. Cross breed goats had a prevalence of 15.63% (5/32) compared with Kano brown breed 14.08 (20/142). Sex significant difference (P = 0.029) was observed in the goats with females having the highest prevalence 20.89% (14/67) compared with males 9.40% (11/117). Furthermore, with regards to sheep, no significant difference (P > 0.05) was observed with respect to age and breed. Finally, no significant difference (P > 0.05) was observed with the prevalence of Anaplasma spp. due to Body condition score (BCS) in both sheep and goats. Conclusively, the occurrence of TBPs in small ruminants is low. Continuous efforts in tick control must be sustained to ensure high productive yield and reduced disease burden associated with TBPs of sheep and goats in Kano metropolis.

Metagenomic Investigation of Ticks From Kenyan Wildlife Reveals Diverse Microbial Pathogens and New Country Pathogen Records

Focusing on the utility of ticks as xenosurveillance sentinels to expose circulating pathogens in Kenyan drylands, host-feeding ticks collected from wild ungulates [buffaloes, elephants, giraffes, hartebeest, impala, rhinoceros (black and white), zebras (Grévy’s and plains)], carnivores (leopards, lions, spotted hyenas, wild dogs), as well as regular domestic and Boran cattle were screened for pathogens using metagenomics. A total of 75 host-feeding ticks [Rhipicephalus (97.3%) and Amblyomma (2.7%)] collected from 15 vertebrate taxa were sequenced in 46 pools. Fifty-six pathogenic bacterial species were detected in 35 pools analyzed for pathogens and relative abundances of major phyla. The most frequently observed species was Escherichia coli (62.8%), followed by Proteus mirabilis (48.5%) and Coxiella burnetii (45.7%). Francisella tularemia and Jingmen tick virus (JMTV) were detected in 14.2 and 13% of the pools, respectively, in ticks collected from wild animals and cattle. This is one of the first reports of JMTV in Kenya, and phylogenetic reconstruction revealed significant divergence from previously known isolates and related viruses. Eight fungal species with human pathogenicity were detected in 5 pools (10.8%). The vector-borne filarial pathogens (Brugia malayi, Dirofilaria immitis, Loa loa), protozoa (Plasmodium spp., Trypanosoma cruzi), and environmental and water-/food-borne pathogens (Entamoeba histolytica, Encephalitozoon intestinalis, Naegleria fowleri, Schistosoma spp., Toxoplasma gondii, and Trichinella spiralis) were detected. Documented viruses included human mastadenovirus C, Epstein-Barr virus and bovine herpesvirus 5, Trinbago virus, and Guarapuava tymovirus-like virus 1. Our findings confirmed that host-feeding ticks are an efficient sentinel for xenosurveillance and demonstrate clear potential for wildlife-livestock-human pathogen transfer in the Kenyan landscape.

Jingmen Tick Virus in Ticks from Kenya

Jingmen tick virus (JMTV) is an arbovirus with a multisegmented genome related to those of unsegmented flaviviruses. The virus first described in Rhipicephalus microplus ticks collected in Jingmen city (Hubei Province, China) in 2010 is associated with febrile illness in humans. Since then, the geographic range has expanded to include Trinidad and Tobago, Brazil, and Uganda. However, the ecology of JMTV remains poorly described in Africa. We screened adult ticks (n = 4550, 718 pools) for JMTV infection by reverse transcription polymerase chain reaction (RT-PCR). Ticks were collected from cattle (n = 859, 18.88%), goats (n = 2070, 45.49%), sheep (n = 1574, 34.59%), and free-ranging tortoises (Leopard tortoise, Stigmochelys pardalis) (n = 47, 1.03%) in two Kenyan pastoralist-dominated areas (Baringo and Kajiado counties) with a history of undiagnosed febrile human illness. Surprisingly, ticks collected from goats (0.3%, 95% confidence interval (CI) 0.1-0.5), sheep (1.8%, 95% CI 1.2-2.5), and tortoise (74.5%, 95% CI 60.9-85.4, were found infected with JMTV, but ticks collected from cattle were all negative. JMTV ribonucleic acid (RNA) was also detected in blood from tortoises (66.7%, 95% CI 16.1-97.7). Intragenetic distance of JMTV sequences originating from tortoise-associated ticks was greater than that of sheep-associated ticks. Phylogenetic analyses of seven complete-coding genome sequences generated from tortoise-associated ticks formed a monophyletic clade within JMTV strains from other countries. In summary, our findings confirm the circulation of JMTV in ticks in Kenya. Further epidemiological surveys are needed to assess the potential public health impact of JMTV in Kenya.

Identification of Pseudomonas aeruginosa From the Skin Ulcer Disease of Crocodile Lizards (Shinisaurus crocodilurus) and Probiotics as the Control Measure

The crocodile lizard (Shinisaurus crocodilurus) is an endangered ancient reptile species. Captive breeding is an important conservation measure for the potential restoration and recovery of their wild populations. However, a skin ulcer disease caused by an unknown pathogen has become a serious threat to captive breeding individuals. In the current study, based on microbial isolation, we identified Pseudomonas aeruginosa as the dominant pathogen in skin ulcer disease. Chinese skinks (Plestiodon chinensis) were used to verify the pathogenicity of P. aeruginosa in skin ulcer disease in vivo. As expected, subcutaneous inoculation of P. aeruginosa induced skin disease in healthy skinks and P. aeruginosa was re-isolated from the induced skin ulcers. Therefore, P. aeruginosa, an opportunistic and ubiquitous pathogen that causes a wide range of infections, appears to be the main pathogen of the skin disease affecting crocodile lizards. In the aquaculture industry, probiotics are widely used in the prevention and control of animal diseases caused by such pathogens. Here, we administered probiotics to the breeding crocodile lizards for 6 months. The three experiment groups treated with different kinds of probiotics showed significance at controlling case incidence. Three of the four groups treated with probiotics showed significant disease prevention (Effective Microorganisms mixed probiotics P = 0.0374; Double-dose Effective Microorganisms, P = 0.0299; Bacillus subtilis, P = 0.0140, T-test), and CFUs in the water of the breeding enclosures were also inhibited after probiotics usage (P < 0.001, T-test). Our study demonstrated the role of Pseudomonas aeruginosa in development of skin ulcer disease of crocodile lizards in a local zoo and offered the probiotic-based method for control measurements, which would be of benefit for the conservation of endangered reptiles.

Molecular Characterization of Rickettsial Agents in Ticks (Acari: Ixodidae) from Sri Lanka

Because the majority of spotted fever group rickettsiae are transmitted to humans by tick bites, it is important to understand which ticks might play a role in transmission of rickettsial pathogens in Sri Lanka. The purpose of our study was to conduct molecular surveillance of 847 ticks collected in different locations in central Sri Lanka to determine which were infected with Rickettsia and Anaplasmataceae. Molecular methods were used to identify the ticks and the agents detected. Most ticks (Amblyomma, Haemaphysalis, and Rhipicephalus) were collected by flagging, and lower number was collected from dogs, cattle, pigs, a pangolin, and tortoises. Five spotted fever genotypes were identified: a Rickettsia africae-like agent in Amblyomma larvae, Rhipicephalus massiliae and a related genotype identified in association with the tropical type of Rhipicephalus sanguineus from dogs and Rhipicephalus haemaphysaloides from dogs and cattle, and Candidatus R. kellyi and another novel genotype (SL94) in R. haemaphysaloides. Twenty-three ticks were positive for Anaplasmataceae, including one Anaplasma and two Ehrlichia genotypes. Because the sequence database for both ticks and rickettsial agents from Sri Lanka and southern India is not extensive, additional molecular characterization of the tick species of Sri Lanka and their rickettsial agents is required to understand their pathogenic potential more completely. However, several of the agents we identified in this survey may well be pathogenic for humans and domestic animals, and should be considered as a part of epidemiological surveillance and patient management.

Geographical distribution of ixodid ticks and tick-borne pathogens of domestic animals in Ethiopia: a systematic review

BACKGROUND

In Ethiopia, ixodid ticks and associated tick-borne pathogens (TBPs) are of great importance from both a veterinary and public health point of view. This review aimed at compiling available published data on the distribution of ixodid tick species and TBPs in the country.

METHODS

A standard review approach was employed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Published peer-reviewed articles and theses/dissertations reporting on ixodid ticks and TBPs in Ethiopia were searched using different keywords in many electronic databases including PubMed, Scopus, Web of Science, Google Scholar, African Journals OnLine, and institutional repositories. Articles were screened based on inclusion and exclusion criteria using the PRISMA flowchart. Data were retrieved from eligible articles and recorded in a preformed data record sheet. Descriptive statistics were employed to present data using graphs. QGIS (Quantum GIS) software version 3.4.5 was used to show the distribution of ixodid tick species and TBPs.

RESULTS

Overall, 35 articles that met the inclusion criteria were included in this review. Of these, 24 articles report only on ixodid ticks of domestic animals, six articles report only on TBPs in livestock or ticks, and five articles report on both ticks and TBPs in either animals or ticks. Of these studies, 54% were in the Oromia region, while only 3% of studies were in the Benishangul-Gumuz region. The Gambela region lacked studies on ticks and TBPs. At least 19 ixodid tick species have been recorded from different domestic animals including cattle, small ruminants, donkeys, horses, camels, dogs, and cats. Morphological characterization appears to be the sole method of tick species identification in the country. The distribution and abundance of specific tick species depend on geographical locations and agroecological factors. Sixteen molecularly confirmed TBPs have been identified in animal and tick tissue using molecular methods from only four administrative regions, despite the wide distribution of ticks. Among TBPs, five Anaplasma, two Ehrlichia, two Rickettsia, five Theileria, two Babesia, and one Coxiella species are the major pathogens in both livestock and humans.

CONCLUSIONS

Many ixodid ticks circulate in a wide geographical zone of Ethiopia. However, the limited reports on TBPs at the country level in general, and the absence of either tick or TBP reports around the border region with neighboring countries in particular, highlights the need for further study.

Prevalence of Ticks Infesting Dairy Cattle and the Pathogens They Harbour in Smallholder Farms in Peri-Urban Areas of Nairobi, Kenya

This study aimed at determining the tick species infesting dairy cattle in Nairobi, Kenya, and the pathogens they harbour. While ticks are well-known vectors of major bacterial pathogens of both veterinary importance and public health importance, few studies have investigated the range of the tick species and the associated pathogens, especially present in unique dairy production systems, which compromise animal welfare, such as those in peri-urban areas. A cross-sectional study was undertaken involving 314 randomly selected dairy cattle in 109 smallholder farms. Each animal was examined for attached ticks followed by morphological tick identification at the species level. Genomic DNA was extracted from each of the ticks, and 16S rDNA gene was amplified for pathogen identification. Sequencing of the amplicons and subsequent BLASTn analysis, multiple sequence alignment, and phylogenetic reconstruction were performed to confirm the species of the pathogens. Sixty-six (21.0%) of the cattle examined had ticks. A total of 94 adult ticks were found on the cattle, and of these, 63 (67.0%), 18 (19.1%), and 13 (13.8%) were in the genera Rhipicephalus, Amblyomma, and Hyalomma, respectively. Twelve tick species in Rhipicephalus genus and two in Amblyomma and Hyalomma genera were identified. Although Rh. decoloratus was the most prevalent tick (24.5% (23/94)), the emerging Rh. microplus (6.4% (6/94)) was also identified. The DNA of Rickettsia was detected in the ticks, with Rickettsia conorii in H. rufipes and A. variegatum, and Rickettsia aeschlimannii in Rh. microplus and H. rufipes, while Ehrlichia ruminantium and E. canis were in A. variegatum. In conclusion, the study reported a wide range of tick species present in the study area including Rhipicephalus microplus, which is an emerging tick species in parts of Kenya. The ticks harboured DNA of Rickettsia and Ehrlichia, highlighting possible animal and human health concerns. Hence, effective tick control strategies remain paramount to prevent potential diseases associated with the harboured pathogens.

Molecular screening of ticks of the genus Amblyomma (Acari: Ixodidae) infesting South African reptiles with comments on their potential to act as vectors for Hepatozoon fitzsimonsi (Dias, 1953) (Adeleorina: Hepatozoidae)

In South Africa, the role of reptilian ticks in the transmission of haemoparasites is lacking, in part, due to limited information on tick diversity and their associated haemoparasites. The aim of this research was to identify tick species parasitizing reptiles and to molecularly screen these ectoparasites for species of the blood apicomplexan genus Hepatozoon. Samples were collected from Ndumo Game Reserve, KwaZulu-Natal, and the Cape Columbine region, Western Cape. Reptiles collected included 2 snakes, 2 monitor lizards of a single species respectively, as well as 17 tortoises of four species. Ticks collected from these were morphologically identified as Amblyomma latum (n = 2) and Amblyomma marmoreum (n = 98), this identification was molecularly confirmed using 16S rRNA and CO1 genes. Screening for Hepatozoon was done by amplifying the 18S rRNA gene. A species of Hepatozoon, Hepatozoon fitzsimonsi, was identified from A. marmoreum ticks, with an overall prevalence of 10%. This Hepatozoon species, has been described parasitizing tortoises from southern Africa, and has been reported from ticks infesting tortoises from Kenya, East Africa. Even though ticks have been suggested to be the likely vector of this Hepatozoon species, with this supported by the findings of Hepatozoon-like developmental stages in ticks collected off of infected tortoises, a recent systematic revision placed this species in a newly erected genus Bartazoon, a genus vectorised by biting insects. The present study thus provides further support for ticks acting as the potential vectors of H. fitzsimonsi.

Molecular prevalence and risk factors associated with tick-borne pathogens in cattle in western Kenya

Background

Tick-borne pathogens (TBPs) are of global importance, especially in sub-Saharan Africa where they represent a major constraint to livestock production. Their association with human disease is also increasingly recognized, signalling their zoonotic importance. It is therefore crucial to investigate TBPs prevalence in livestock populations and the factors associated with their presence. We set out to identify TBPs present in cattle and to determine associated risk factors in western Kenya, where smallholder livestock production is important for subsistence and market-driven income.

Results

Tick-borne pathogen infections in blood samples collected from cattle at livestock markets and slaughterhouses between May 2017 and January 2019 were identified by high-resolution melting analysis and sequencing of PCR products of genus-specific primers. Of the 422 cattle sampled, 30.1% (127/422) were infected with at least one TBP, while 8.8% (37/422) had dual infections. Anaplasma spp. (19.7%) were the most prevalent, followed by Theileria (12.3%), Ehrlichia (6.6%), and Babesia (0.2%) spp. Sequence analysis of the TBPs revealed them to be Anaplasma platys-like organisms (13.5%), Theileria velifera (7.4%), Anaplasma marginale (4.9%), Theileria mutans (3.1%), Theileria parva (1.6%), and Babesia bigemina (0.2%). Ehrlichia ruminantium, Rickettsia spp., and arboviruses were not detected. Exotic breeds of cattle were more likely to be infected with A. marginale compared to local breeds (OR: 7.99, 95% CI: 3.04–22.02, p <  0.001). Presence of ticks was a significant predictor for Anaplasma spp. (OR: 2.18, 95% CI: 1.32–3.69, p = 0.003) and Ehrlichia spp. (OR: 2.79, 95% CI: 1.22–7.23, p = 0.022) infection. Cattle sampled at slaughterhouses were more likely to be positive for Anaplasma spp. (OR: 1.64, 95% CI: 1.01–2.70, p = 0.048) and A. marginale (OR: 3.84, 95% CI: 1.43–12.21, p = 0.012), compared to those sampled at livestock markets.

Conclusion

This study reports TBP prevalence and associated risk factors in western Kenya, factors which are key to informing surveillance and control measures.

Reptile vector-borne diseases of zoonotic concern

Reptile vector-borne diseases (RVBDs) of zoonotic concern are caused by bacteria, protozoa and viruses transmitted by arthropod vectors, which belong to the subclass Acarina (mites and ticks) and the order Diptera (mosquitoes, sand flies and tsetse flies). The phyletic age of reptiles since their origin in the late Carboniferous, has favored vectors and pathogens to co-evolve through millions of years, bridging to the present host-vector-pathogen interactions. The origin of vector-borne diseases is dated to the early cretaceous with Trypanosomatidae species in extinct sand flies, ancestral of modern protozoan hemoparasites of zoonotic concern (e.g., Leishmania and Trypanosoma) associated to reptiles. Bacterial RVBDs are represented by microorganisms also affecting mammals of the genera Aeromonas, Anaplasma, Borrelia, Coxiella, Ehrlichia and Rickettsia, most of them having reptilian clades. Finally, reptiles may play an important role as reservoirs of arborivuses, given the low host specificity of anthropophilic mosquitoes and sand flies. In this review, vector-borne pathogens of zoonotic concern from reptiles are discussed, as well as the interactions between reptiles, arthropod vectors and the zoonotic pathogens they may transmit.

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.

Multi-country investigation of the diversity and associated microorganisms isolated from tick species from domestic animals, wildlife and vegetation in selected african countries

In many areas of Africa, recent studies highlighted the great impact of ticks on animal and human health throughout the continent. On the other hand, very limited information on the bacterial endosymbionts of the African ticks and their pattern of co-infections with other bacteria are found in literature, notwithstanding their pivotal role in tick survival and vector efficiency. Thus, we investigated the distribution of selected pathogenic and symbiotic bacteria in hard ticks collected from wild, domestic animals and from vegetation in various ecological zones in Africa and their co-occurrence in the same tick host. Overall, 339 hard ticks were morphologically identified as belonging to the genera Amblyomma, Dermacentor, Hyalomma, Haemaphysalis, Ixodes and Rhipicephalus. Molecular screening provided information on pathogens circulation in Africa, detecting spotted fever group rickettsiae, Anaplasma spp., Ehrlichia ruminantium, Borrelia garinii, Babesia spp., Theileria spp. and Coxiella burnetii. Furthermore, our work provides insights on the African scenario of tick-symbiont associations, revealing the presence of Coxiella, Francisella and Midichloria across multiple tick populations. Coxiella endosymbionts were the most prevalent microorganisms, and that with the broadest spectrum of hosts, being detected in 16 tick species. Francisella was highly prevalent among the Hyalomma species tested and correlated negatively with the presence of Coxiella, showing a potential competitive interaction. Interestingly, we detected a positive association of Francisella with Rickettsia in specimens of Hy. rufipes, suggesting a synergistic interaction between them. Finally, Midichloria was the most prevalent symbiont in Rhipicephalus sanguineus sensu lato from Egypt.

Ehrlichia spp. close to Ehrlichia ruminantium, Ehrlichia canis, and "Candidatus Ehrlichia regneryi" linked to heartwater-like disease in Kenyan camels (Camelus dromedarius)

We present findings from an outbreak of a heartwater-like disease in camels that killed at least 2000 adult animals in Kenya in 2016. Clinical signs included excitability, head pressing, aimless wandering, recumbency, and fast breathing followed by death after about 4 days. The observed morbidity in one herd was 40% with an average mortality of 7.5% in animals that received early antibiotic treatments. In untreated adults, the case fatality rate reached 100%. Gross pathology showed pulmonary edema, pleural exudate, hydrothorax, hydropericardium, ascites, enlarged "cooked" liver, nephrosis, and blood in the abomasum and intestine. Using established PCR-based protocols for tick-borne pathogens, a sequence close to Ehrlichia regneryi and Ehrlichia canis amplified in blood from two sick camels. We also amplified an Ehrlichia sp. sequence close to Ehrlichia ruminantium Welgevonden from a pool of Amblyomma spp. ticks collected from a sick camel and in a pool of Rhipicephalus spp. ticks from healthy camels.

Effect of housing improvement and other factors on the growth of heifer calves on Kenyan smallholder dairy farms

This trial evaluated average daily gain (ADG) effects of heifer calves (< 1 year old) from affordable housing improvements to the roof and flooring on 150 randomly allocated smallholder dairy farms. During the 16-month data collection period, bimonthly farm visits were used to measure weight and other animal- and farm-level factors on the 187 study calves. Multivariable linear regression was used to model ln ADG and ADG during pre-weaning and post-weaning periods, respectively. Median pre-weaning and post-weaning ADGs were 0.307 (interquartile range (IQR): 0.227-0.398) and 0.487 (IQR: 0.354-0.675) kg/d, respectively. In the final pre-weaning model (p<0.050), factors positively associated with ln ADG were calf age at first acaricide application, and total number of calf pens, while factors negatively associated with ln ADG included calf mortality risk over the last 5 years and calf age at first ad lib access to water. In an interaction term, for calves from parity 3+ dams, ADG was lower when milk was fed twice/day than thrice/day, with no difference in calves of lower parity dams. In the final post-weaning model, housing improvements increased ADG by 5.6%. Other factors positively associated with post-weaning ADG were feeding of calf pellets, wheat bran, maize bran, and hay. Calf age at first introduction of concentrate and calf mortality risk over the last 5 years were negatively associated with ADG. In an interaction term, ADG was high when there were faecal coccidia oocysts and when calves had visual or physical contact with their dams, but low when faecal coccidia cysts were present, and these dam-calf connections were absent. In a second interaction term, ADG increased with more calf pens for female principal farmers, while remaining low for male principal farmers. In conclusion, while controlling for other factors of ADG, making affordable calf housing improvements enhanced ADG, particularly during the post-weaning period.

Tick-borne pathogens, including Crimean-Congo haemorrhagic fever virus, at livestock markets and slaughterhouses in western Kenya

Vectors of emerging infectious diseases have expanded their distributional ranges in recent decades due to increased global travel, trade connectivity and climate change. Transboundary range shifts, arising from the continuous movement of humans and livestock across borders, are of particular disease control concern. Several tick-borne diseases are known to circulate between eastern Uganda and the western counties of Kenya, with one fatal case of Crimean-Congo haemorrhagic fever (CCHF) reported in 2000 in western Kenya. Recent reports of CCHF in Uganda have highlighted the risk of cross-border disease translocation and the importance of establishing inter-epidemic, early warning systems to detect possible outbreaks. We therefore carried out surveillance of tick-borne zoonotic pathogens at livestock markets and slaughterhouses in three counties of western Kenya that neighbour Uganda. Ticks and other ectoparasites were collected from livestock and identified using morphological keys. The two most frequently sampled tick species were Rhipicephalus decoloratus (35%) and Amblyomma variegatum (30%); Ctenocephalides felis fleas and Haematopinus suis lice were also present. In total, 486 ticks, lice and fleas were screened for pathogen presence using established molecular workflows incorporating high-resolution melting analysis and identified through sequencing of PCR products. We detected CCHF virus in Rh. decoloratus and Rhipicephalus sp. cattle ticks, and 82 of 96 pools of Am. variegatum were positive for Rickettsia africae. Apicomplexan protozoa and bacteria of veterinary importance, such as Theileria parva, Babesia bigemina and Anaplasma marginale, were primarily detected in rhipicephaline ticks. Our findings show the presence of several pathogens of public health and veterinary importance in ticks from livestock at livestock markets and slaughterhouses in western Kenya. Confirmation of CCHF virus, a Nairovirus that causes haemorrhagic fever with a high case fatality rate in humans, highlights the risk of under-diagnosed zoonotic diseases and calls for continuous surveillance and the development of preventative measures.

Anaplasma and Theileria Pathogens in Cattle of Lambwe Valley, Kenya: A Case for Pro-Active Surveillance in the Wildlife-Livestock Interface

Tick-borne pathogens (TBPs) are major constraints to livestock production and a threat to public health in Africa. This cross-sectional study investigated the risk of infection with TBPs in cattle of Lambwe Valley, Kenya. Blood samples of 680 zebu cattle from 95 herds in six geospatial clusters within 5 km of Ruma National Park were screened for bacterial and protozoan TBPs by high-resolution melting analysis and sequencing of PCR products. We detected Anaplasma bovis (17.4%), Anaplasma platys (16.9%), Anaplasma marginale (0.6%), Theileria velifera (40%), and Theileria mutans (25.7%), as well as an Anaplasma sp. (11.6%) that matched recently reported Anaplasma sp. sequences from Ethiopia. Babesia, Rickettsia, and Ehrlichia spp. were not detected. The animal and herd-level prevalences for TBPs were 78.5% (95% confidence intervals (CI): 75.3, 81.5) and 95.8% (95% CI: 91.8, 99.8), respectively. About 31.6% of cattle were co-infected with 13 combinations of TBPs. The prevalence of TBPs differed between clusters and age, but the risk of infection was not associated with sex, herd size, or the distance of homesteads from Ruma. This study adds insight into the epidemiology of TBPs around Ruma and highlights the need for proactive surveillance of TBPs in livestock–wildlife interfaces.

Molecular prevalence of emerging Anaplasma and Ehrlichia pathogens in apparently healthy dairy cattle in peri-urban Nairobi, Kenya

Background

Anaplasma and Ehrlichia species are tick-borne pathogens of both veterinary and public health importance. The current status of these pathogens, including emerging species such as Ehrlichia minasensis and Anaplasma platys, infecting cattle in Kenya, remain unclear, mainly because of limitation in the diagnostic techniques. Therefore, we investigated the Anaplasma and Ehrlichia species infecting dairy cattle in Nairobi, Kenya using molecular methods.

Results

A total of 306 whole blood samples were collected from apparently healthy dairy cattle. Whole blood DNA was extracted and tested for presence of Anaplasma and Ehrlichia DNA through amplification and sequencing of the 16S rDNA gene. Sequence identity was confirmed using BLASTn analysis while phylogenetic reconstruction was performed to determine the genetic relationship between the Kenyan isolates and other annotated genotypes available in GenBank. Anaplasma and Ehrlichia species were detected in 19.9 and 3.3% of all the samples analyzed, respectively. BLASTn analysis of the sequences against non-redundant GenBank nucleotide database revealed infections with A. platys (44.8%), A. marginale (31%) and A. bovis (13.8%). All four sequenced Ehrlichia spp. were similar to Ehrlichia minasensis. Nucleotide polymorphism was observed for A. platys, A. bovis and E. minasensis. The Anaplasma species clustered in four distinct phylogenetic clades including A. marginale, A. platys, A. bovis and some unidentified Anaplasma spp. The Kenyan Ehrlichia minasensis clustered in the same clade with isolates from America and Australia but distant from E. ruminantium.

Conclusion

This study provides the first report of infection of dairy cattle in Kenya with A. platys and E. minasensis, which are emerging pathogens. We conclude that cattle in peri-urban Nairobi are infected with various species of Anaplasma and E. minasensis. To understand the extent of these infections in other parts of the country, large-scale screening studies as well as vector identification is necessary to inform strategic control.

Development of a practical framework for sustainable surveillance and control of ticks and tick-borne diseases in Africa

A workshop on ticks and tick-borne diseases (T&TBDs) was held on June 25 and 26, 2019, at the Tropical Pesticides Research Institute, Division of Livestock and Human Diseases Vector Control, Arusha, Tanzania. The objectives of the workshop were to discuss the current situation and to formulate actionable strategies to improve surveillance and control of T&TBDs in Africa. The workshop was funded by the National Research Foundation and the Cape Peninsula University of Technology and attended by livestock health providers, farmers, and researchers from East, West, and Southern African countries. During the workshop, experts presented recent surveillance data focused on T&TBDs; participants discussed research opportunities and community engagement. The primary outcome of the workshop was the creation of a new research consortium known as The African Consortium for T&TBDs. The consortium is intended to function as a community for researchers, students, farmers, policymakers, extension workers, and community members who are interested in the advancement of T&TBD control. The consortium will engage in research activities that focus on comprehensive surveillance of T&TBDs, developing tick acaricide resistance, alternative tick control programs, and policy development and education. These areas were identified as top priorities to be developed to improve T&TBD control on the continent.

Pathogens, endosymbionts, and blood-meal sources of host-seeking ticks in the fast-changing Maasai Mara wildlife ecosystem

The role of questing ticks in the epidemiology of tick-borne diseases in Kenya's Maasai Mara National Reserve (MMNR), an ecosystem with intensified human-wildlife-livestock interactions, remains poorly understood. We surveyed the diversity of questing ticks, their blood-meal hosts, and tick-borne pathogens to understand potential effects on human and livestock health. By flagging and hand-picking from vegetation in 25 localities, we collected 1,465 host-seeking ticks, mostly Rhipicephalus and Amblyomma species identified by morphology and molecular analysis. We used PCR with high-resolution melting (HRM) analysis and sequencing to identify Anaplasma, Babesia, Coxiella, Ehrlichia, Rickettsia, and Theileria pathogens and blood-meal remnants in 231 tick pools. We detected blood-meals from humans, wildebeest, and African buffalo in Rh. appendiculatus, goat in Rh. evertsi, sheep in Am. gemma, and cattle in Am. variegatum. Rickettsia africae was detected in Am. gemma (MIR = 3.10) that had fed on sheep and in Am. variegatum (MIR = 250) that had fed on cattle. We found Rickettsia spp. in Am. gemma (MIR = 9.29) and Rh. evertsi (MIR = 200), Anaplasma ovis in Rh. appendiculatus (MIR = 0.89) and Rh. evertsi (MIR = 200), Anaplasma bovis in Rh. appendiculatus (MIR = 0.89), and Theileria parva in Rh. appendiculatus (MIR = 24). No Babesia, Ehrlichia, or Coxiella pathogens were detected. Unexpectedly, species-specific Coxiella sp. endosymbionts were detected in all tick genera (174/231 pools), which may affect tick physiology and vector competence. These findings show that ticks from the MMNR are infected with zoonotic R. africae and unclassified Rickettsia spp., demonstrating risk of African tick-bite fever and other spotted-fever group rickettsioses to locals and visitors. The protozoan pathogens identified may also pose risk to livestock production. The diverse vertebrate blood-meals of questing ticks in this ecosystem including humans, wildlife, and domestic animals, may amplify transmission of tick-borne zoonoses and livestock diseases.

Ticks and Associated Pathogens From Rescued Wild Animals in Rainforest Fragments of Northeastern Brazil

The Ixodidae family comprises ticks that are hematophagous ectoparasites and are considered vectors of several hemoparasites from the Anaplasmataceae family and the genus Hepatozoon, Babesia, and Rickettsia. These ectoparasites parasitize domestic and wild animals belonging to several vertebrate groups. Ticks are highly adapted to different biomes and thus possess a wide geographical distribution. In the Brazilian state of Bahia, localized in the Northeast region, there are large rainforest fragments. Studies have rarely been carried out on ticks, and their hemoparasites, that parasitize wild animals in this region. Thus, this study aimed to identify the tick species parasitizing wild animals rescued in rainforest fragments of Bahia and investigate the presence of hemoparasites in tick tissues. During a 2-year period, 238 ticks were collected from 41 wild mammalians, reptiles, and amphibians. These ectoparasites were taxonomically classified according to their morphological characteristics. The ticks identified belonged to five different species from the Ixodidae family: Amblyomma varium, Amblyomma rotundatum, Amblyomma nodosum, Ixodes loricatus, and Rhipicephalus sanguineus. For the first time, an A. rotundatum parasitizing the Mesoclemmys tuberculata turtle was described. PCR assays using DNA extracted from salivary glands or midgut of the ticks were performed to detect specific DNA fragments of hemoparasites from the genus Rickettsia, Ehrlichia, Babesia, Hepatozoon, and from the Anaplasmataceae family. The results showed positive detection of the Rickettsia genus (7.9%), Anaplasmataceae family (15.8%), and Hepatozoon genus (15.8%). Specific DNA from the Ehrlichia and Babesia genera were not detected in these samples. Specific DNA from members of the Anaplasmataceae family was detected in A. varium for the first time. The present work showed that amphibians, reptiles, and mammals from Bahia's Atlantic Forest areparasitized by different tick species, and that these ectoparasites present pathogens in their tissues that impact both humans and animals due to their zoonotic potential.

Molecular detection and genetic characterisation of pathogenic Theileria, Anaplasma and Ehrlichia species among apparently healthy sheep in central and western Kenya

Tick-borne diseases (TBDs) caused by Theileria, Babesia, Anaplasma and Ehrlichia species are common in tropical and subtropical regions. In this study, we investigated the presence and genetic diversity of Theileria spp., Anaplasma ovis, B. ovis, E. ruminantium and Anaplasma spp. in sheep from the Machakos and Homa Bay counties of Kenya. In order to improve the diagnosis and control of ovine TBDs, a total of 76 blood samples from apparently healthy sheep were screened using a polymerase chain reaction (PCR). The assays were conducted using primers based on Theileria spp. 18S rRNA, Anaplasma ovis Major surface protein-4 (AoMSP4), B. ovis 18S rRNA, E. ruminantium pCS20 and Anaplasma spp. 16S rRNA. The overall infection rates for Theileria spp., A. ovis, E. ruminantium and Anaplasma spp. were 39/76 (51.3%), 26/76 (34.2%), 6/76 (7.9%) and 31/76 (40.8%), respectively. The overall co-infection was 47/76 (61.8%). All Theileria spp. positive samples were confirmed to be of Theileria ovis on sequencing. A phylogenetic analysis of the 18S rRNA gene sequences of T. ovis revealed that all isolates of this study clustered with T. ovis sequences extracted from the GenBank suggesting this gene is highly conserved. E. ruminantium pCS20 sequences were in the same clade on the phylogenetic tree. However, three AoMSP4 sequences from this study appeared in the same clade, while one sequence formed a separate branch revealing genetic divergence. The 16S rRNA sequencing revealed uncharacterised Anaplasma spp. and A. ovis. The phylogenetic analyses of the uncharacterised Anaplasma spp. revealed that the two sequences from this study appear in an independent clade from other sequences extracted from the GenBank. This study provides important information regarding the occurrence of tick-borne pathogens and their degree of genetic diversity among sheep in Kenya, which is useful for the diagnosis and control of TBDs.

Hyalomma rufipes on an untraveled horse: Is this the first evidence of Hyalomma nymphs successfully moulting in the United Kingdom?

During September 2018, a tick was submitted to Public Health England's Tick Surveillance Scheme for identification. The tick was sent from a veterinarian who removed it from a horse in Dorset, England, with no history of overseas travel. The tick was identified as a male Hyalomma rufipes using morphological and molecular methods and then tested for a range of tick-borne pathogens including; Alkhurma virus, Anaplasma, Babesia, Bhanja virus, Crimean-Congo Haemorrhagic fever virus, Rickettsia and Theileria. The tick tested positive for Rickettsia aeschlimannii, a spotted fever group rickettsia linked to a number of human cases in Africa and Europe. This is the first time H. rufipes has been reported in the United Kingdom (UK), and the lack of travel by the horse (or any in-contact horses) suggests that this could also be the first evidence of successful moulting of a Hyalomma nymph in the UK. It is postulated that the tick was imported into the UK on a migratory bird as an engorged nymph which was able to complete its moult to the adult stage and find a host. This highlights that passive tick surveillance remains an important method for the detection of unusual species that may present a threat to public health in the UK. Horses are important hosts of Hyalomma sp. adults in their native range, therefore, further surveillance studies should be conducted to check horses for ticks in the months following spring bird migration; when imported nymphs may have had time to drop off their avian host and moult to adults. The potential human and animal health risks of such events occurring more regularly are discussed.

Detection of zoonotic agents and a new Rickettsia strain in ticks from donkeys from South Africa: Implications for travel medicine

BACKGROUND

In rural South Africa, people are in close contact with tick-infested donkeys. This study aimed to investigate the presence of spotted fever group Rickettsia, Anaplasma, Ehrlichia and Coxiella species in these arthropods.

METHOD

376 ticks (7 species) from donkeys from Limpopo Province (South Africa) were pooled and analyzed using PCR assays for the bacterium detection.

RESULTS

Rickettsia africae was amplified in 6 Amblyomma hebraeum, 1 Rhipicephalus appendiculatus and 5 Rhipicephalus evertsi evertsi pools. Rickettsia aeschlimannii was found in 1 Hyalomma rufipes, 1 Rh. appendiculatus and 2 Rh. e. evertsi pools. Three Rhipicephalus simus specimens were infected with a new Rickettsia strain that showed low identity with any validated Rickettsia species. Ehrlichia canis was detected in 2 Rh. e. evertsi pools and in one of them Anaplasma bovis was amplified. An Am. hebraeum pool showed infection with Anaplasma ovis and another with Coxiella burnetii.

CONCLUSION

South African donkeys are involved in the epidemiology of tick-borne pathogens and other associated agents such as C. burnetii with Health importance. A potential new Rickettsia species, with unknown pathogenic potential, has been detected in the anthropophilic Rh. simus.

MALDI-TOF MS identification of ticks of domestic and wild animals in Algeria and molecular detection of associated microorganisms

Recent studies have reported the reliability of MALDI-TOF MS for arthropod identification, including fresh or alcohol-preserved ticks based on leg-derived mass spectra. The aim of this study was to evaluate the performance of MALDI-TOF MS for the identification of alcohol-preserved Algerian ticks collected from different domestic and wild hosts. Secondly, we conducted a molecular survey to detect the presence of bacterial DNA in all ticks that were previously subjected to MALDI-TOF MS. A total of 2635 ixodid and 1401 argasid ticks belonging to 9 distinct species were collected in nine different regions of northeastern Algeria. The legs of 230 specimens were subjected to MALDI-TOF MS assays. Spectral analysis revealed intra-species similarity and inter-species specificity for the MS spectra, which was consistent with the morphological identification. Blind tests against the in-lab database revealed that 93.48% of the tested specimens were correctly identified. The accuracy of the morphological and MALDI-TOF MS identifications was validated by sequencing the 12S ribosomal RNA gene (rRNA) for 33 specimens and all the ticks were correctly identified. The quantitative PCR screening showed that for 219 tested ticks, 15 were positive for Rickettsia spp., 8 for Borrelia spp. and 17 for Anaplasmataceae. The PCR tests were negative for Coxiella burnetii and Bartonella spp. This study supports MALDI-TOF MS being a reliable tool for the identification of arthropods and brings new data that sheds light on tick species diversity and tick-borne diseases in Algeria.