Reverse Line Blot Hybridization Assay Research Articles

Simultaneous detection of seven bacterial pathogens transmitted by flies using the reverse line blot hybridization assay

BackgroundTraditional methods for detecting insect-borne bacterial pathogens are time-consuming and require specialized laboratory facilities, limiting their applicability in areas without access to such resources. Consequently, rapid and efficient detection methods for insect-borne bacterial diseases have become a pressing need in disease prevention and control.MethodsWe aligned the ribosomal 16S rRNA sequences of seven bacterial species (Staphylococcus aureus, Shigella flexneri, Aeromonas caviae, Vibrio vulnificus, Salmonella enterica, Proteus vulgaris, and Yersinia enterocolitica) by DNASTAR Lasergene software. Using DNASTAR Lasergene and Primer Premier software, we designed universal primers RLB-F and RLB-R, two species-specific probes for each pathogen, and a universal probe (catch-all). The PCR products of seven standard strains were hybridized with specific oligonucleotide probes fixed on the membrane for specific experimental procedures. To evaluate the sensitivity of PCR-RLB, genomic DNA was serially diluted from an initial copy number of 1010 to 100 copies/μl in distilled water. These dilutions were utilized as templates for the PCR-RLB sensitivity analysis. Simultaneous detection of seven fly-borne bacterial pathogens from field samples by the established PCR-RLB method was conducted on a total of 1060 houseflies, collected from various environments in Lanzhou, China.ResultsThe established PCR-RLB assay is capable of detecting bacterial strains of about 103 copies/μl for S. aureus, 103 copies/μl for S. flexneri, 105 copies/μl for A. caviae, 105 copies/μl for V. vulnificus, 100 copies/μl for S. enterica, 105 copies/μl for P. vulgaris, and 100 copies/μl for Y. enterocolitica. The results demonstrate that the detection rate of the established PCR-RLB method is higher (approximately 100 times) compared to conventional PCR. This method was applied to assess the bacterial carrier status of flies in various environments in Lanzhou, China. Among the seven bacterial pathogens carried by flies, S. enterica (34.57%), S. flexneri (32.1%), and Y. enterocolitica (20.37%) were found to be the predominant species.ConclusionsOverall, this research shows that the rapid and efficient PCR-RLB detection technology could be a useful for surveillance and therefore effective prevention and control the spread of insect-borne diseases. Meanwhile, the experimental results indicate that urban sanitation and vector transmission sources are important influencing factors for pathogen transmission.Graphical

Genetic diversity in Babesia bovis from southern Africa and estimation of B. bovis infection levels in cattle using an optimised quantitative PCR assay

Babesia bovis is a causal agent of bovine babesiosis, a disease which leads to mortality and morbidity and impacts the cattle industry worldwide. We amplified, cloned and sequenced the B. bovis merozoite surface antigen-2b (msa-2b) gene (∼940 bp) and the near full-length 18S rRNA gene (∼1600 bp) from cattle samples from South Africa and Mozambique to determine sequence variation between B. bovis parasites in the region. A TaqMan quantitative real-time PCR (qPCR) assay (18S rRNA gene) was optimised for the detection of B. bovis and estimation of parasitaemia in field samples from cattle from southern Africa. Phylogenetic analysis grouped the Msa-2b sequences in six clades and these were 59.7 to 99.6% identical to reference sequences. Sequence variation amongst B. bovis 18S rRNA sequences was found at 2 to 36 positions, and the sequences were 97 to 99% identical to published sequences. Mismatches between the B. bovis 18S rRNA sequences and a previously published qPCR forward primer (BoF) were observed; therefore, we developed a new forward primer (BoF2), and optimised the qPCR assay. Six 10-fold dilution series of B. bovis infected erythrocytes (2 × 108 to 2 × 103 infected red blood cells [iRBC]/ml) were analysed in triplicate in each of six separate qPCR runs, to determine the efficiency of the assay. The qPCR assay amplified the B. bovis 18S rRNA gene with 92.0 to 94.9% efficiency. The detection limit of the qPCR assay was approximately 6 iRBCs/μl. The performance of the optimised assay to diagnose B. bovis in field samples was assessed by testing DNA from 222 field samples of cattle from South Africa and Mozambique using three methods: the optimised qPCR assay, the reverse line blot (RLB) hybridisation assay, and the previously published qPCR assay. The detection rate of B. bovis using the optimised qPCR assay (31.1%, 69/222) was significantly higher (p<0.001) than both that using RLB (20.7%, 46/222) and the previously published qPCR assay (5.4%; 12/222). The B. bovis parasitaemia in samples from infected cattle ranged from 6 iRBCs/μl to 101,852 iRBCs/μl of blood. Our study revealed marked sequence variation between B. bovis parasites from southern Africa. The optimised qPCR assay will be useful in epidemiological studies and clinical diagnosis of B. bovis in southern Africa, and can be used to determine parasitaemia and potential carrier status in cattle populations, which is essential in the control of babesiosis.

Development and validation of a TaqMan® probe- based real-time PCR assay for detection of Ehrlichia canis

Ehrlichiosis is a potentially fatal zoonotic tick-borne disease, caused by a pleomorphic Gram-negative bacterium. It occurs worldwide and affects humans, domestic and wild animals. Dogs infected with Ehrlichia canis develop canine monocytic ehrlichiosis (CME), a significant infectious disease of canines. TaqMan® based real-time PCR assays to detect Ehrlichia spp. affecting dogs were developed and a real-time PCR assay specific for E. canis validated. The efficiency of the assay was 93% and the 95% limit of detection was 33 E. canis plasmid copies/µl of blood (95% confidence interval: 23 - 58). The assay was specific for E. canis when tested against other haemoparasites. Consistent repeatability was observed, with an inter-run standard deviation (SD) range between 0.33 and 1.29 and an intra-run SD range between 0.04 and 1.14. Field samples were tested in parallel by both the E. canis real-time PCR assay and a reverse line blot hybridization assay. The results were in agreement for the two assays, with an exception of two out of 121 samples. Bayesian latent class analysis was used to calculate a diagnostic sensitivity of the E. canis real-time PCR assay of 90% and a specificity of 92%. This assay is a sensitive and reliable molecular detection method for E. canis and will be a useful tool for early diagnosis and timely treatment for this haemoparasite.

Prevalence of Theileria/Babesia Species in Ruminants in Burdur Province of Turkey.

Theileriosis and babesiosis, two tick-borne haemoparasitic diseases (TBHDs) of ruminants, are caused by protozoan parasites of the genus Theileria and Babesia, respectively. Among them, some species are considered to be highly pathogenic causing serious economic losses to livestock holders especially in tropic and subtropic regions. Local and/or general control measures are needed to be applied to reduce economic impact of TBHDs. Prevalence studies are essential for the implementation and/or design of effective prevention and control measures based on true epidemiological data. Therefore, this study aimed to investigate the presence, prevalence and possible cross infections of Theileria/Babesia species between sheep, goat and cattle herds in Burdur province in Turkey. A total of 964 blood samples were collected from sheep (n = 330), goat (n = 300) and cattle (n = 334) from five different districts of Burdur province. The samples were investigated for ovine and bovine Theileria/Babesia species using reverse line blot (RLB) hybridization assay. In small ruminants, T.ovis was the most abundant Theileria species detected in sheep with a rate of 79.69%. Among Babesia species, B.ovis and B.crassa were detected only in blood of goats (0.66%) and sheep (1.12%) as single and mixed infections, respectively. In cattle, T.annulata, B.bovis, Babesiaspp. were detected in rates of 0.59%, 3.29%, 3.59%, respectively. Obtained results clearly indicated that no cross infections with Theileria/Babesia species occurred in small ruminant and cattle herds that use the same grazing area.

First report of Theileria buffeli/Theileria orientalis group and identification of piroplasms via Nested PCR-based RLB Hybridization assay in zebu cattle in the Western Highlands of Cameroon

Piroplasms infections are tick-borne diseases caused by haemoparasite of the genus Theileria or Babesia. They have a great impact on livestock production, especially cattle in sub-Saharan countries. However, data on the prevalence of bovine piroplasms and their genetic diversity are scanty in Cameroon. This study was aimed at highlight the species composition and determine the prevalence of piroplasms infecting cattle in the Western Highlands of Cameroon. To achieve this aim, blood samples from a total of 162 cattle were collected and examined using Reverse Line Blot hybridization (RLB) assay. The amplified hypervariable V4 region of the 18S rRNA gene of bovine piroplasms species, including Theileria parva, T. annulata, T mutans, T. velifera, T. buffeli/T. orientalis, T. taurotragi, Theileria sp (buffalo), Babesia bovis, B. bigemina, B. divergens, B. major and B. occultans was hybridized against species-specific probes. RLB hybridization assay revealed the presence of four piroplasms species with the overall prevalence of infection of 82.1%. Theileria velifera (71.6%) was the most prevalent species followed by Theileria mutans (43.21%), Theileria buffeli/T. orientalis (5.55%) and Babesia bigemina (3.7%). However, the study provided the first molecular evidence for the presence of T. buffeli/T. orientalis group species in cattle in Cameroon. Higher overall prevalence of infection of tick-borne pathogens was observed in this study area as well as the increase in prevalence and widespread of T. velifera and the observance of a new species of piroplasms. These results are an indication that special attention should be given to epizootiological investigations alongside well-adopted control programs.

Ticks on wild boar in the metropolitan area of Barcelona (Spain) are infected with spotted fever group rickettsiae.

Tick-borne pathogens (TBPs) constitute an emerging public health concern favoured by multidimensional global changes. Amongst these, increase and spread of wild boar (Sus scrofa) populations are of special concern since this species can act as a reservoir of zoonotic pathogens and promote tick abundance. Thus, we aimed to make a first assessment of the risk by TBPs resulting from wild boar and ticks in the vicinity of a highly populated area. Between 2014 and 2016, we collected spleen samples and 2256 ticks from 261 wild boars (out of 438 inspected) in the metropolitan area of Barcelona (MAB; northeast Spain). We morphologically identified four tick species: Hyalomma lusitanicum (infestation prevalence: 33.6%), Dermacentor marginatus (26.9%), Rhipicephalus sanguineus sensu lato (18.9%) and R. bursa (0.2%). Ticks were pooled according to species and individual host. A total of 180 tick pools and 167 spleen samples were screened by real-time PCR and/or reverse line blot hybridization assay for Ehrlichia sp., Anaplasma sp., Babesia sp., Rickettsia sp., Borrelia burgdorferi sensu lato and Coxiella burnetii. Seventy-two out of the 180 tick pools were positive to Rickettsia spp. (minimum prevalence of 8.7%), including Rickettsia massiliae, R. slovaca and R. raoultii. We did not detect Rickettsia spp. in wild boar spleens nor other TBPs in ticks or wild boars. Since the ticks identified can bite humans, and the recorded spotted fever group (SFG) rickettsiae are zoonotic pathogens, there is a risk of SFG rickettsiae transmission for MAB inhabitants. Our results suggest a broader distribution of H. lusitanicum, competent vector for the Crimean-Congo haemorrhagic fever virus than previously known. Wild boar is not a Rickettsia spp. reservoir according to the spleen negative results. However, its abundance could favour tick life cycle and abundance, and its proximity to humans could promote the infection risk by Rickettsia spp.

Cross border transhumance involvement in ticks and tick-borne pathogens dissemination and first evidence of Anaplasma centrale in Burkina Faso

In West Africa, cross-border transhumance, also called seasonal migration, is known to be a very important animal production strategy, as it involves about 70 to 90% of cattle. In spite of the cattle movements, some strategic areas of transhumance remain poorly explored regarding ticks and their associated pathogens investigations. The purpose of this study is to evaluate the involvement of transhumance in the spread of cattle ticks and associated pathogens in Burkina Faso (BF) and Benin (BN), in a context of speedy invasion of West African livestock by Rhipicephalus microplus. A longitudinal survey was performed on 210 cattle from BF, monitored for ticks and tick-borne pathogens (TBP) during one seasonal transhumance. The first sampling coded “T0BF” took place in eastern BF, at the transhumance departure. A second sampling “T1BN” was carried out in northern BN, the transhumance arrival zone. A third sampling “T2BF” was done at the return of cattle in eastern BF. Ticks were morphologically identified and TBP detected with reverse line blot hybridization (RLB) assay. A total of 1027 ticks (7 species), 1006 ticks (11 species) and 1211 ticks (9 species) were respectively found at T0BF, T1BN and T2BF. Some species were collected at the three times of sampling without any significant difference in their relative abundances. However, other tick species appeared only at T1BN and/or T2BF. The TBP species found at the three points surveyed were Theileria annulata, Theileria mutans, Theileria velifera, Babesia bigemina and Anaplasma marginale. The most prevalent was T. mutans with 166/210 (79%), 159/210 (75.7%) and 78/210 (37%) cattle positive respectively at T0BF, T1BN and T2BF. Anaplasma centrale was evidenced with 0.5% and 0.9% respectively at T0BF and T2BF. To our knowledge, this represents its first report in the study area.Overall, the TBP prevalences were significantly lower at T2BF, highlighting the effect of tick populations changes induced by transhumance combined with the seasonal variation influence.

Novel Protozoans in Austria Revealed through the Use of Dogs as Sentinels for Ticks and Tick-Borne Pathogens.

We previously isolated and cultivated the novel Rickettsia raoultii strain Jongejan. This prompted us to ask whether this strain is unique or more widely present in Austria. To assess this issue, we retrospectively screened ticks collected from dogs in 2008. Of these collected ticks, we randomly selected 75 (47 females and 28 males) Dermacentor reticulatus, 44 (21 females, 7 males, and 16 nymphs) Haemaphysalis concinna, and 55 (52 females and 3 males) ticks of the Ixodes ricinus complex. Subsequently, these ticks were individually screened for the presence of tick-borne pathogens using the reverse line blot hybridization assay. In our current study, we detected DNA from the following microbes in D. reticulatus: Anaplasma phagocytophilum, Borrelia lusitaniae, Borrelia spielmanii, Borrelia valaisiana, and R. raoultii, all of which were R. raoultii strain Jongejan. In H. concinna, we found DNA of a Babesia sp., Rickettsia helvetica, and an organism closely related to Theileria capreoli. Lastly, I. ricinus was positive for Anaplasma phagocytophilum, Borrelia afzelii, Borrelia burgdorferi sensu stricto, Borrelia garinii/Borrelia bavariensis, B. lusitaniae, B. spielmanii, B. valaisiana, Candidatus Neoehrlichia mikurensis, Rickettsia helvetica, Rickettsia monacensis, and Theileria (Babesia) microti DNA. The detection of DNA of the Babesia sp. and an organism closely related to Theileria capreoli, both found in H. concinna ticks, is novel for Austria.

Molecular detection and characterisation of protozoan and rickettsial pathogens in ticks from cattle in the pastoral area of Karamoja, Uganda

Ticks and tick-borne diseases (TBDs) significantly affect cattle production and the livelihoods of communities in pastoralist areas. Data on protozoan and rickettsial pathogens in ticks infesting cattle in Uganda is scanty; while it is an indicator of the likelihood of disease transmission and occurrence. A cross-sectional study was conducted amongst cattle in the Karamoja Region, northeastern Uganda, from July through September 2017, to determine the tick species diversity, identify protozoan and rickettsial pathogens in the ticks, and characterise pathogenic species by sequence and phylogenetic analyses. About 50 % of the ticks detected from each predilection site on each animal were collected from 100 purposively-selected cattle from 20 randomly-selected herds. Twelve tick species belonging to the genera Amblyomma, Rhipicephalus and Hyalomma were identified, the most abundant being Amblyomma lepidum (93.9 %), followed by Amblyomma variegatum (2.0 %) and Rhipicephalus evertsi evertsi (1.0 %). Tick species that have not been reported in recent studies amongst cattle in Uganda were found, namely Rhipicephalus pravus, Rhipicephalus praetextatus and Rhipicephalus turanicus. The ticks were grouped into 40 pools, by species and location, and the reverse line blot (RLB) hybridisation assay was used to detect pathogens from the ticks. The most frequently detected tick-borne parasites were Theileria mutans, Theileria velifera and Theileria parva, each observed in 25 % (10/40) of the tick pools. Tick-borne pathogens, namely Babesia rossi, Babesia microti and Theileria sp. (sable) that are not common to, or not known to infect, cattle were identified from ticks. The gene encoding Ehrlichia ruminantium pCS20 region, the Ehrlichia and Anaplasma 16S rRNA gene, and T. parva p67 sporozoite antigen gene were amplified, cloned and sequenced. Seven novel E. ruminantium pCS20 variants were identified, and these grouped into two separate clusters with sequences from other parts of Africa and Asia. The T. parva p67 sequences were of the allele type 1, and parasites possessing this allele type are commonly associated with East Coast fever in eastern Africa. Analysis of the Ehrlichia and Anaplasma 16S rRNA gene sequences showed that they were closely related to Rickettsia africae and to a new Ehrlichia species variant recently found in China. Our R. africae 16S rRNA sequences grouped with R. africae isolates from Nigeria, Egypt and Benin. The information on tick species diversity and pathogens in the various tick species provides an indicator of potential transmission amongst cattle populations, and to humans, and can be useful to estimate disease risk and in control strategies.

Tick species identification and molecular detection of tick-borne pathogens in blood and ticks collected from cattle in Egypt

To address the lack of information on ticks infesting cattle in Egypt and the pathogens that they transmit, the current study aimed to (i) provide insight into tick species found on cattle in Egypt, (ii) identify the pathogens in ticks and their cattle hosts and (iii) detect pathogen associations in ticks and cattle. Tick samples and blood from their bovine hosts were collected from three different areas in Egypt (EL-Faiyum Oasis, Assiut Governorate and EL-Kharga Oasis). Tick species were identified by morphology and by sequence analysis of the cytochrome C oxidase subunit 1 (cox1) gene. Tick pools and blood samples from cattle were screened by the Reverse Line Blot hybridization (RLB) assay for the simultaneous detection of tick-borne pathogens, including Babesia, Theileria, Anaplasma, Ehrlichia, and Rickettsia spp., as well as the tick endosymbiont Midichloria mitochondrii. The RLB results were confirmed with specific conventional and semi-nested PCRs followed by sequencing. In total, 570 ticks (males, females and nymphs) were collected from 41 heads of cattle. Altogether 398 ticks belonged to the genus Hyalomma (397 Hyalomma excavatum and one Hyalomma scupense) while 172 ticks were identified as Rhipicephalus annulatus. Pooled H. excavatum ticks tested positive for several protozoa and bacteria with different minimum infection rates (MIRs): Theileria annulata (18.1 %), Babesia occultans (1.8 %), Anaplasma marginale (28.5 %), Anaplasma platys (0.25 %), Midichloria mitochondrii (11.6 %), Ehrlichia chaffeensis-like (1.8 %) and Ehrlichia minasensis (1 %). In R. annulatus, several agents were identified at different MIRs: T. annulata (2.3 %), B. bovis (0.6 %), A. marginale (18.0 %), A. platys (1.2 %), M. mitochondrii (2.9 %), E. minasensis (0.6 %). Pathogens co-detection in tick pools revealed A. marginale and T. annulata in 13.3 % samples followed by the co-detection of A. marginale and M. mitochondrii (8.4 %). In addition, triple co-detection with A. marginale, T. annulata and M. mitochondrii were found in 5.3 % of the tick pools. In cattle, the most common coinfection was with A. marginale and T. annulata (82.9 %) followed by the coinfection between A. marginale, T. annulata and B. bovis (4.9 %), A. marginale and B. bigemina (2.4 %) and finally the coinfection between T. annulata and B. occultans (2.4 %). Anaplasma platys, Babesia occultans, and E. minasensis were detected for the first time in Egypt in both cattle and ticks. These findings should be taken in consideration regarding human and animal wellbeing by the public health and veterinary authorities in Egypt.

Ticks and tick-borne pathogens infecting livestock and dogs in Tchicala-Tcholoanga, Huambo Province, Angola

The diversity of ticks and tick-borne pathogens (TBPs) infesting domestic animals in Tchicala-Tcholoanga, Angola, in 2016 was investigated. Seventeen tick species were recorded, Amblyomma pomposum being the most abundant on cattle (40%), goats (38%) and sheep (35%); Rhipicephalus turanicus was the most abundant on dogs (46%). This study presents new records of Haemaphysalis paraleachi, R. compositus, R. kochi and R. sulcatus in Angola, the first georeferenced population of Ha. leachi in southern Africa and the second record of R. microplus in Angola. Using the reverse line blot (RLB) hybridisation assay, fifteen TBP species were detected in blood samples from cattle (n = 88), goats (n = 82), sheep (n = 85) and dogs (n = 85). F The most frequently detected species were Theileria velifera in cattle (78%), Theileria ovis in sheep (80%) and Babesia vogeli in dogs (35%). Species-specific quantitative PCR assays detected Babesia bigemina in 43% (35/80) of blood samples of cattle, while E. ruminantium was detected in 4% (3/70) of blood samples and in 7% of A. pomposum ticks. Anaplasma platys was detected from cattle (18%) and sheep (6%) during RLB analysis. These findings constitute pioneering research in Angola.

Babesia bicornis, Theileria bicornis and Theileria equi in metapopulations of two black rhinoceros (Diceros bicornis) subspecies in South Africa and their potential impact on conservation

The two black rhinoceros subspecies (Diceros bicornis bicornis and D. b. minor) in South African conservation areas are managed as separate metapopulations. Since infection with Babesia bicornis can be fatal in black rhinoceroses, occurrence of this and other piroplasms in the two metapopulations was determined to assess possible risk. Blood specimens were collected from 156 black rhinoceroses: 80 from D. b. bicornis and 76 from D. b. minor. DNA was extracted; the V4 hypervariable region of the parasite 18S rRNA gene was amplified and subjected to the Reverse Line Blot (RLB) hybridization assay. There was a significant difference in occurrence of piroplasms: 18/80 (23%) in D. b. bicornis and 39/76 (51%) in D. b. minor. Theileria bicornis occurred in significantly more of the D. b. minor population (36/76; 47%) than the D. b. bicornis population (1/80; 1%); with B. bicornis the difference was not significant: D. b. bicornis 5/80 (6%) and D. b. minor 9/76 (11%). Three individuals were infected with Theileria equi. Results were confirmed using molecular characterization of the near full-length parasite 18S rRNA gene of 13 selected specimens. We identified four (Tb1, Tb2, Tb3 and Tb4) 18S rDNA sequence types for T. bicornis, two for B. bicornis (Bb1 and Bb2) and one for T. equi (Teq1). We furthermore identified T. bicornis haplotypes H1, H3 and H4 in 10 rhinoceroses; H3 was the most common haplotype identified. Rhinoceroses inhabiting more arid areas are apparently free of T. bicornis and B. bicornis, probably due to the absence or scarcity of vectors. When individuals are relocated for metapopulation management purposes, appropriate prophylactic action should be taken to minimise the risk of babesiosis, which could be fatal.

Prevalence of Piroplasma in Ticks Collected from Dogs and Cattle in Guangxi, South China Determined by Reverse Line Blot Hybridization Assay

Piroplasmosis is a disease of domestic and wild animals caused by tick-borne protozoa of the genera Theileria and Babesia. Piroplasmosis leads to substantial economic losses in the livestock industry. This disease has been frequently reported in subtropical and tropical regions worldwide. However, information regarding the prevalence of piroplasma in ticks collected from dogs and cattle is lacking in most areas. To assess the potential threat of piroplasmosis in South China, 671 ticks were collected in Guangxi Province. Deoxyribonucleic acid (DNA) was extracted from these ticks to evaluate the presence of piroplasma through a reverse line blot (RLB) hybridization assay using the hypervariable V4 region of the piroplasmic 18S ribosomal ribonucleic acid (r)RNA genes as probes to detect Theileria and Babesia species. The RLB results indicated that 144/671 (21.46%) ticks were infected with piroplasma species belonging to the genera Theileria or Babesia. Theileria buffeli, Babesia vogeli, Theileria annulata, and Theileria luwenshuni were present in the ticks at frequencies of 60/671 (8.94%), 21/671 (3.13%), 6/671 (0.89%), and 6/671 (0.89%), respectively. Mixed infections with 2 or more piroplasma species were present in 8/671 (1.19%) tick samples. The hypervariable V4 region of the piroplasmic 18S rRNA genes from 6 tick DNA samples with single infections was cloned, sequenced, and aligned to related sequences from GenBank. The Theileria and Babesia sequences were analyzed separately. 18S rRNA gene fragment sequences of T. annulata and T. buffeli were compared with previously reported homologous sequences. All 3 B. vogeli sequences examined in this study were grouped into the same cluster and belonged to the same genotype. The present study provides important epidemiological information regarding piroplasmosis occurrence in China. The existence of tick-borne piroplasma likely leads to high infection risks among the local animals in the studied areas.

A Retrospective Epidemiological Study: The Prevalence of Ehrlichia canis and Babesia vogeli in Dogs in the Aegean Region of Turkey

Abstract Among tick-borne diseases, Ehrlichia canis and Babesia piroplasm cause important diseases in dogs where the distributions of the pathogen, vector and host overlap. The primary aim of the present study was to detect the prevalence of Babesia spp. and E. canis using PCR and reverse line blot (RLB) hybridization assay in a total of 379 samples comprising stray and owned dogs and to compare the diagnostic sensitivity of the two tests. Overall, 41.4% of dogs were infected with B. vogeli and/or E. canis as single (35.4%) and mixed (6.1%) infections. The majority of Babesia positive dogs (74.1%) were co-infected with E. canis. PCR detected a higher (P= 0.000) number of positivity in some provinces compared to RLB. To the best of our knowledge, these findings provide the first molecular evidence for the existence of B. vogeli in the Aegean Region, Turkey. The present study pinpoints the distribution and prevalence of E. canis and B. vogeli in the Aegean region of Turkey as of 2004 and as such establishes a baseline. This is of pivotal importance for future studies aimed to demonstrate changes in the dynamics of E. canis and B. vogeli infections in the region.

Epidemiology of tick-borne pathogens in the semi-arid and the arid agro-ecological zones of Punjab province, Pakistan.

Tick-borne diseases (TBDs) have a large impact on animal health and the livelihood of livestock owners, particularly in developing countries. Although climatic and ecological conditions in Pakistan may favour the transmission of tick-borne pathogens (TBPs), only a few systematic studies have been carried out on TBPs and the diseases that they cause in this country. To improve our understanding of the distribution of TBPs, 3,807 ticks were collected from ruminants (n=369) on 108 livestock farms (semi-arid zone=36, arid zone=72) in Punjab Province. After morphological identification ticks were pooled into 405 pools (Hyalomma anatolicum=300, Rhipicephalus microplus=89, Hyalomma dromedarii=9, Rhipicephalus turanicus=7) based on their species, locality of collection, and the host. DNA from each pool was screened by a Reverse Line Blot (RLB) hybridization assay for the presence of Anaplasma, Ehrlichia, Rickettsia, Babesia, and Theileria species. DNA from at least one TBP was found in 142 (35.1%) pools. Among the positive pools, 91 (64.1%) had a mixed infection with two or more TBPs, whereas 51 (35.9%) pools were infected with a single TBP. The detected pathogens not only included species that were known to be endemic in Pakistan, such as Theileria annulata (6.7%), Theileria orientalis (3.5%), Anaplasma marginale (5.7%), Anaplasma centrale (2.7%), Anaplasma ovis (1.5%), Babesia bigemina (0.7%), and Babesia bovis (0.2%), but also several TBPs that had not been reported to occur in Pakistan before. This included Ehrlichia minasensis (3.2%), an Anaplasma platys-like organism (1.2%), Babesia occultans (0.2%), and Rickettsia massiliae (0.2%), as well as two previously uncharacterized species: Ehrlichia sp. Multan (18.0%) and Anaplasma sp. (BL099-6) (2.22%). The pathogenicity of these novel species remains to be examined. This study shows that a much broader spectrum of TBPs is present in Pakistan than previously thought, including several zoonotic pathogens.

Identification of chromoblastomycosis agents by PCR based reverse line blot (PCR-RLB) hybridization assay

Chromoblastomycosis is one of the most prevalent implantation fungal infections caused by melanized fungi, affecting individuals with certain risk factors with high morbidity due to its recalcitrant nature. It is difficult to identify the etiological agents and thus a suitable reproductive molecular identification method applicable in developing countries has been investigated.We report the identification of four different fungal causative agents of chromoblastomycosis by reverse line blotting hybridization (RLB) based on biotin-labeled PCR products and amine labeled probes to hybridize. Sixty five reference strains, including type strains, i.e. Fonsecaea pedrosoi, F. monophora, F. nubica, and Phialophora verrucosa, obtained from the CBS-KNAW were included in this study.Internal transcribed spacer 1 (ITS1) regions of relevant species were aligned and adjusted using BIONUMERICS v. 4.61 in order to design four specific probes to identify informative nucleotide polymorphisms. The final identification of these species by RLB assay was concordant with ITS sequencing and showed 100% specificity with no cross hybridization, able to identify all tested strains. The time and cost were less compare to other routine identification methods such as sequencing.This assay allows sensitive and specific simultaneous detection and identification of a different fungal species.

Occurrence of Hepatozoon canis (Adeleorina: Hepatozoidae) and Anaplasma spp. (Rickettsiales: Anaplasmataceae) in black-backed jackals (Canis mesomelas) in South Africa

BackgroundDomestic dogs are not native to sub-Saharan Africa, which may account for their susceptibility to Babesia rossi, of which endemic black-backed jackals (Canis mesomelas) are natural reservoirs. There is virtually no information on the occurrence of potentially pathogenic haemogregarines (e.g. Hepatozoon canis) or even rickettsial bacteria (e.g. Ehrlichia spp. and Anaplasma spp.) in indigenous canids in sub-Saharan Africa. Such organisms could pose a risk to domestic dogs, as well as to populations of endangered indigenous canid species.ResultsGenomic DNA extracted from blood samples taken from 126 free-ranging and 16 captive black-backed jackals was subjected to reverse line blot (RLB) hybridization assay; 82 (57.8%) specimens reacted only with the Ehrlichia/Anaplasma genera-specific probe. Full-length bacterial 16S rRNA gene of five of these specimens was cloned and the recombinants sequenced. The ten 16S rDNA sequences obtained were most closely related, with approximately 99% identity, to Anaplasma sp. South African Dog, various uncultured Anaplasma spp., as well as various Anaplasma phagocytophilum genotypes. Ninety-one specimens were screened for haemogregarines through PCR amplification using the 18S rRNA gene; 20 (21.9%) specimens reacted positively, of which 14 (15.4%) were confirmed positive for Hepatozoon genotypes from within H. canis. Two (2.2%) specimens were found positive for two different Hepatozoon genotypes.ConclusionsSequence analyses confirmed the presence of 16S rDNA sequences closely related to A. phagocytophilum and Anaplasma sp. South African Dog as well as two H. canis genotypes in both free-ranging and captive black-backed jackals. Distinguishing between closely related lineages may provide insight into differences in pathogenicity and virulence of various Anaplasma and H. canis genotypes. By building up a more comprehensive understanding of the range and diversity of the bacteria and eukaryotic organisms (piroplasms and haemogregarines) in the blood of indigenous canids, we may gain insight to such infections in these often-endangered species and the potential for horizontal transmission to and from domestic dogs via ticks where favourable conditions exist.

Detection and Characterisation of Anaplasma marginale and A. centrale in South Africa.

Bovine anaplasmosis is endemic in South Africa and it has a negative economic impact on cattle farming. An improved understanding of Anaplasma marginale and Anaplasma marginale variety centrale (A. centrale) transmission, together with improved tools for pathogen detection and characterisation, are required to inform best management practices. Direct detection methods currently in use for A. marginale and A. centrale in South Africa are light microscopic examination of tissue and organ smears, conventional, nested, and quantitative real-time polymerase chain reaction (qPCR) assays, and a reverse line blot hybridisation assay. Of these, qPCR is the most sensitive for detection of A. marginale and A. centrale in South Africa. Serological assays also feature in routine diagnostics, but cross-reactions prevent accurate species identification. Recently, genetic characterisation has confirmed that A. marginale and A. centrale are separate species. Diversity studies targeting Msp1a repeats for A. marginale and Msp1aS repeats for A. centrale have revealed high genetic variation and point to correspondingly high levels of variation in A. marginale outer membrane proteins (OMPs), which have been shown to be potential vaccine candidates in North American studies. Information on these OMPs is lacking for South African A. marginale strains and should be considered in future recombinant vaccine development studies, ultimately informing the development of regional or global vaccines.

Occurrence of tick-borne haemoparasites in cattle in the Mungwi District, Northern Province, Zambia

Little is known about the occurrence of haemoparasites in cattle in communal grazing areas of Mungwi District of Northern Province, Zambia. Clinical signs and post mortem lesions are pathognomonic of mixed tick-borne infections especially babesiosis, anaplasmosis and East Coast fever. The main objective of this study was to screen selected communal herds of cattle for tick-borne haemoparasites, and identify the tick vectors associated with the high cattle mortalities due to suspected tick-borne diseases in the local breeds of cattle grazing along the banks of the Chambeshi River in Mungwi District, Northern Province, Zambia. A total of 299 cattle blood samples were collected from July to September 2010 from Kapamba (n = 50), Chifulo (n = 102), Chisanga (n = 38), Kowa (n = 95) and Mungwi central (n = 14) in the Mungwi District. A total of 5288 ticks were also collected from the sampled cattle from April to July 2011. DNA was extracted from the cattle blood and the hypervariable region of the parasite small subunit rRNA gene was amplified and subjected to the reverse line blot (RLB) hybridization assay. The results of the RLB assay revealed the presence of tick-borne haemoparasites in 259 (86.6%) cattle blood samples occurring either as single (11.0%) or mixed (75.6%) infections. The most prevalent species present were the benign Theileria mutans (54.5%) and T. velifera (51.5%). Anaplasma marginale (25.7%), Babesia bovis (7.7%) and B. bigemina (3.3%) DNA were also detected in the samples. Only one sample (from Kapamba) tested positive for the presence of T. parva. This was an unexpected finding; also because the tick vector, Rhipicephalus appendiculatus, was identified on animals from Kowa (14.0%), Chisanga (8.5%), Chifulo (6.0%) and Kapamba (1.4%). One sample (from Kapamba) tested positive for the presence of Ehrlichia ruminantium even though Amblyomma variegatum ticks were identified from 52.9% of the sampled animals from all study areas. There was significant positive association between T. mutans and T. velifera (p < 0.001) infections, and between A. marginale and B. bovis (p = 0.005). The presence of R. microplus tick vectors on cattle was significantly associated with B. bovis (odds ratio, OR = 28.4, p < 0.001) and A. marginale (OR = 42.0, p < 0.001) infections, while A. variegatum presence was significantly associated with T. mutans (OR = 213.0, p < 0.001) and T. velifera (OR = 459.0, p < 0.001) infections. Rhipicephalus decoloratus was significantly associated with B. bigemina (OR = 21.6, p = 0.004) and A. marginale (OR = 28.5, p < 0.001). Multivariable analysis showed a significant association between location and tick-borne pathogen status for A. marginale (p < 0.001), T. mutans (p = 0.004), T. velifera (p = 0.003) and T. taurotragi (p = 0.005). The results of our study suggest that the cause of cattle mortalities in Mungwi during the winter outbreaks is mainly due to A. marginale, B. bovis and B. bigemina infections. This was confirmed by the clinical manifestation of the disease in the affected cattle and the tick species identified on the animals. The relatively low prevalence of T. parva, B. bigemina, B. bovis and E. ruminantium could indicate the existence of endemic instability with a pool of susceptible cattle and the occurrence of disease outbreaks.

Molecular detection of tick-borne pathogens in cattle from Southwestern Ethiopia.

Tick-borne diseases (TBDs) cause significant losses among livestock and impact the livelihoods of resource-poor farming communities worldwide. In Ethiopia, detailed studies on the epidemiology of tick-borne pathogens (TBPs) in cattle using sensitive molecular detection methods are scarce. The objective of this study was to determine the prevalence and species composition of bovine TBPs of veterinary significance in local cattle populations. A comprehensive cross-sectional epidemiological study was conducted in cattle populations of Illubabor zone in Southwestern Ethiopia from June to August 2013. For this purpose, blood samples were collected from 392 cattle. A combination of polymerase chain reaction (PCR) and a Reverse Line Blot (RLB) hybridization assay was employed for the detection of TBPs in these samples. The PCR/RLB results of the 392 blood samples indicated a high overall prevalence of 96.9% for TBPs, including Theileria mutans (66.1%), Theileria orientalis (51.8%), Anaplasma sp. Omatjenne (25.5%), Anaplasma marginale (14.5%), Babesia bigemina (14.0%) and Theileria velifera (13.0%) and minor occurrences of Ehrlichia ruminantium (0.5%) and Ehrlichia minasensis (0.26%). Moreover, three novel Anaplasma genotypes were detected in bovine blood samples. A phylogenetic analysis revealed that they most likely represent three, but at least two, new species. The prevalence of the three novel Anaplasma species, preliminary designated as Anaplasma sp. Hadesa, Anaplasma sp. Saso and Anaplasma sp. Dedessa, was 12.5%, 14.3% and 5.6%, respectively. Overall, a total of 227 cattle (57.9%) were found to be co-infected with two or more TBPs simultaneously and 86 different species combinations were observed. The findings show a very high burden of infection of cattle with TBPs in Ethiopia. The high frequency of co-infections suggests that clinical manifestations might be complex. Further research is required to determine the pathogenicity, host cell types and vector of the three novel Anaplasma species identified in this study.