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Rar V, Marchenko V, Suntsova O, Epikhina T, Tikunov A, Meltsov I, Fedorets V, Igolkina Y, Kozlova I, Tikunova N. The first study of the prevalence and genetic diversity of Theileria equi and Babesia caballi in horses in Russia. Parasitol Res 2024; 123:279. [PMID: 39031213 DOI: 10.1007/s00436-024-08300-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Accepted: 07/10/2024] [Indexed: 07/22/2024]
Abstract
Equine piroplasmosis (EP) is a global worldwide infection, which can lead to the death of animals. Despite the causative agents of EP being well studied, there are no data on the distribution and genetic characteristics of EP agents in any region of Russia. In this study, blood samples from 750 horses from Novosibirsk province, Irkutsk province, and Altai region of Russian Siberia were examined for the presence of EP agents. Theileria equi and Babesia caballi were detected in all examined regions, with mean prevalence rates of 60.4% and 7.2%, respectively. The identified pathogens were genetically characterized by the 18S rRNA gene. The determined T. equi sequences were highly conserved and belonged to genotypes A and E, with genotype E being found in 88.6% of genotyped samples. In contrast to T. equi, B. caballi sequences were genetically diverse. Seven sequence variants of B. caballi were identified, and only two of them matched known sequences from the GenBank database. The determined B. caballi sequences belonged to four distinct branches within genotype A. Mixed infections with several variants of B. caballi or with T. equi and B. caballi were common. The conducted phylogenetic analysis based on all available B. caballi sequences of the 18S rRNA gene (> 900 bp) from GenBank and from this study first demonstrated the presence of five monophyletic clusters within genotype A and three clusters within genotype B. Thus, the genetic study of B. caballi from Siberia has significantly expanded the data on the genetic diversity of this pathogen.
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Affiliation(s)
- Vera Rar
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia.
| | - Victor Marchenko
- Federal Altai Scientific Center for Agrobiotechnology, Barnaul, Russia
| | - Olga Suntsova
- Scientific Centre for Family Health and Human Reproduction Problems, Irkutsk, Russia
| | - Tamara Epikhina
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia
| | - Artem Tikunov
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia
| | - Ivan Meltsov
- Irkutsk State Agrarian University Named After A.A. Ezhevsky, Irkutsk Province, Molodezhny Settlement, Russia
| | - Valeria Fedorets
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia
| | - Yana Igolkina
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia
| | - Irina Kozlova
- Scientific Centre for Family Health and Human Reproduction Problems, Irkutsk, Russia
| | - Nina Tikunova
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia
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Nehra AK, Kumari A, Moudgil AD, Vohra S. Revisiting the genotypes of Theileria equi based on the V4 hypervariable region of the 18S rRNA gene. Front Vet Sci 2024; 11:1303090. [PMID: 38560630 PMCID: PMC10978764 DOI: 10.3389/fvets.2024.1303090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 02/27/2024] [Indexed: 04/04/2024] Open
Abstract
Introduction Equine theileriosis, an economically important disease that affects horses and other equids worldwide, is caused by a tick-borne intracellular apicomplexan protozoa Theileria equi. Genotyping of T. equi based on the 18S rRNA gene revealed the presence of two, three, four or five genotypes. In previous published reports, these genotypes have been labelled either alphabetically or numerically, and there is no uniformity in naming of these genotypes. The present study was aimed to revisit the phylogeny, genetic diversity and geographical distribution of T. equi based on the nucleotide sequences of the V4 hypervariable region of the 18S rRNA gene available in the nucleotide databases. Methods Out of 14792 nucleotide sequences of T. equi available in the GenBank™, only 736 sequences of T. equi containing the complete V4 hypervariable region of the 18S rRNA gene (>207 bp) were used in multiple sequence alignment. Subsequently, a maximum likelihood phylogenetic tree was constructed based on the Kimura 2-parameter model (K2+I). Results The phylogenetic tree placed all the sequences into four distinct clades with high bootstrap values which were designated as T. equi clades/ genotypes A, B, C and D. Our results indicated that the genotype B of Nagore et al. and genotype E of Qablan et al. together formed the clade B with a high bootstrap value (95%). Furthermore, all the genotypes probably originated from clade B, which was the most dominant genotype (52.85%) followed by clades A (27.58%), and C (9.78%) and D (9.78%). Genotype C manifested a comparatively higher genetic diversity (91.0-100% identity) followed by genotypes A (93.2-99.5%), and B and D (95.7-100%). The alignment report of the consensus nucleotide sequences of the V4 hypervariable region of the 18S rRNA gene of four T. equi genotypes (A-D) revealed significant variations in one region, between nucleotide positions 113-183, and 41 molecular signatures were recognized. As far as geographical distribution is concerned, genotypes A and C exhibited far-extending geographical distribution involving 31 and 13 countries of the Asian, African, European, North American and South American continents, respectively. On the contrary, the genotypes B and D exemplified limited distribution with confinement to 21 and 12 countries of Asian, African and European continents, respectively. Interestingly, genotypes A and C have been reported from only two continents, viz., North and South America. It was observed that genotypes A and C, and B and D exhibit similar geographical distribution. Discussion The present study indicated the presence of only four previously described T. equi genotypes (A, B, C and D) after performing the molecular analyses of all available sequences of the complete V4 hypervariable region of the 18S rRNA gene of T. equi isolates in the GenBank™.
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Affiliation(s)
- Anil Kumar Nehra
- Department of Veterinary Parasitology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India
| | - Ansu Kumari
- Department of Veterinary Medicine, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India
| | - Aman Dev Moudgil
- Department of Veterinary Parasitology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India
| | - Sukhdeep Vohra
- Department of Veterinary Parasitology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India
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Ahedor B, Otgonsuren D, Zhyldyz A, Guswanto A, Ngigi NMM, Valinotti MFR, Kothalawala H, Kalaichelvan N, Silva SSP, Kothalawala H, Acosta TJ, Sivakumar T, Yokoyama N. Development and evaluation of specific polymerase chain reaction assays for detecting Theileria equi genotypes. Parasit Vectors 2023; 16:435. [PMID: 38007442 PMCID: PMC10675911 DOI: 10.1186/s13071-023-06045-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 11/06/2023] [Indexed: 11/27/2023] Open
Abstract
BACKGROUND Theileria equi causes equine piroplasmosis, an economically significant disease that affects horses and other equids worldwide. Based on 18S ribosomal RNA (18S rRNA sequences), T. equi can be classified into five genotypes: A, B, C, D, and E. These genotypes have implications for disease management and control. However, no conventional polymerase chain reaction (PCR) assays are available to differentiate the genotypes of T. equi. To overcome this limitation, we developed and evaluated PCR assays specific for the detection of each T. equi genotype. METHODS A pair of forward and reverse primers, specifically targeting the 18S rRNA sequence of each genotype, was designed. The genotype-specific PCR assays were evaluated for their specificity using plasmids containing inserts of the 18S rRNA sequence of each genotype. Subsequently, the assays were tested on 270 T. equi-positive equine blood DNA samples (92 from donkeys in Sri Lanka and 178 from horses in Paraguay). 18S rRNA sequences derived from the PCR amplicons were analyzed phylogenetically. RESULTS Each genotype-specific PCR assay accurately targeted the intended genotype, and did not produce any amplicons when 18S rRNA from other T. equi genotypes or genomic DNA of Babesia caballi or uninfected horse blood was used as the template. Previous studies employing PCR sequencing methods identified T. equi genotypes C and D in the Sri Lankan samples, and genotypes A and C in the Paraguayan samples. In contrast, our PCR assay demonstrated exceptional sensitivity by detecting four genotypes (A, C, D, and E) in the Sri Lankan samples and all five genotypes in the Paraguayan samples. All the Sri Lankan samples and 93.3% of the Paraguayan samples tested positive for at least one genotype, further emphasizing the sensitivity of our assays. The PCR assays also had the ability to detect co-infections, where multiple genotypes in various combinations were detected in 90.2% and 22.5% of the Sri Lankan and Paraguayan samples, respectively. Furthermore, the sequences obtained from PCR amplicons clustered in the respective phylogenetic clades for each genotype, validating the specificity of our genotype-specific PCR assays. CONCLUSIONS The genotype-specific PCR assays developed in the present study are reliable tools for the differential detection of T. equi genotypes.
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Affiliation(s)
- Believe Ahedor
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan
- Department of Animal Experimentation, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Davaajav Otgonsuren
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan
| | - Atambekova Zhyldyz
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan
| | - Azirwan Guswanto
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan
| | - Noel Muthoni Mumbi Ngigi
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan
| | | | | | - Nizanantha Kalaichelvan
- Department of Farm Animal Production and Health, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya, Sri Lanka
| | | | | | - Tomás Javier Acosta
- Universidad Nacional de Canendiyu, Salto del Guaira, Paraguay
- Field Center of Animal Science and Agriculture, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Thillaiampalam Sivakumar
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan
| | - Naoaki Yokoyama
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro, Hokkaido, 080-8555, Japan.
- WOAH Reference Laboratory for Equine Piroplasmosis, National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan.
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Zhou B, Yang G, Hu Z, Chen K, Guo W, Wang X, Du C. Development of a Real-Time Quantitative PCR Based on a TaqMan-MGB Probe for the Rapid Detection of Theileria haneyi. Microorganisms 2023; 11:2633. [PMID: 38004645 PMCID: PMC10673206 DOI: 10.3390/microorganisms11112633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 10/20/2023] [Accepted: 10/24/2023] [Indexed: 11/26/2023] Open
Abstract
Equine piroplasmosis (EP) is a parasitic disease caused by Theileria equi (T. equi), Babesia caballi (B. caballi) and Theileria haneyi (T. haneyi). This disease is considered to be reportable by the World Organization for Animal Health (WOAH). Real-time quantitative PCR (qPCR) is regarded as a straightforward, rapid and sensitive diagnostic method to detect pathogens. However, qPCR has not been employed in the various epidemiological investigations of T. haneyi. In this study, we developed a new qPCR method to detect T. haneyi based on the chr1sco (chromosome 1 single-copy open reading frame (ORF)) gene, which has no detectable orthologs in T. equi or B. caballi. A TaqMan MGB probe was used in the development of the qPCR assay. A plasmid containing the chr1sco gene was constructed and used to establish the standard curves. The novel qPCR technique demonstrated great specificity for detecting additional frequent equine infectious pathogens and sensitivity for detecting diluted standard plasmids. This qPCR was further validated by comparison with an optimized nested PCR (nPCR) assay in the analysis of 96 clinical samples. The agreement between the nPCR assay and the established qPCR assay was 85.42%. The newly established method could contribute to the accurate diagnosis of T. haneyi infections in horses.
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Affiliation(s)
| | | | | | | | | | - Xiaojun Wang
- State Key Laboratory of Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (B.Z.); (G.Y.); (Z.H.); (K.C.); (W.G.)
| | - Cheng Du
- State Key Laboratory of Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (B.Z.); (G.Y.); (Z.H.); (K.C.); (W.G.)
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Ahedor B, Kothalawala H, Kanagaratnam R, Vimalakumar SC, Otgonsuren D, Tuvshintulga B, Batmagnai E, Silva SSP, Sivakumar T, Yokoyama N. First detection of Theileria equi in free-roaming donkeys (Equus africanus asinus) in Sri Lanka. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2022; 99:105244. [PMID: 35149223 DOI: 10.1016/j.meegid.2022.105244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/13/2022] [Accepted: 02/07/2022] [Indexed: 06/14/2023]
Abstract
Equine piroplasmosis (EP) is a tick-borne disease caused by Theileria equi and Babesia caballi in equids, including horses, donkeys, zebras, and mules. It is globally endemic with significant economic impact on the equine industry. Infected animals may serve as carriers, and they may be a source of infection for ticks, thereby posing a great challenge for disease management. Sri Lanka is a tropical country, where infections by various tick-borne parasites are common among livestock animals. However, infections by T. equi and B. caballi remain unstudied in Sri Lanka. Therefore, in the present study, we conducted an epidemiological survey to investigate the presence of T. equi and B. caballi in apparently healthy free-roaming donkeys. Blood samples were randomly taken from 111 donkeys in Mannar (n = 100) and Kilinochchi (n = 11) districts in Sri Lanka. Thin blood smears were prepared from the blood samples and subjected to microscopic examination. Additionally, blood DNA samples were prepared and screened for T. equi and B. caballi infections using species-specific PCR assays. Our results showed that 64 (57.7%) and 95 (85.6%) of the donkeys were positive for T. equi by microscopy and PCR, respectively. However, all samples were negative for B. caballi. Phylogenetic analysis of the T. equi 18S rRNA sequences detected two distinct genotypes, namely C and D. To our knowledge, this is the first report of T. equi in Sri Lanka and of genotype C in donkeys. The present study highlights the importance of monitoring the shrinking donkey population in Sri Lanka owing to EP caused by T. equi.
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Affiliation(s)
- Believe Ahedor
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan; Department of Animal Experimentation, Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana
| | | | | | | | - Davaajav Otgonsuren
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Bumduuren Tuvshintulga
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Enkhbaatar Batmagnai
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | | | - Thillaiampalam Sivakumar
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Naoaki Yokoyama
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan; OIE Reference Laboratory for Equine Piroplasmosis, National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan.
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Sears KP, Knowles DP, Fry LM. Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi. Pathogens 2022; 11:pathogens11020254. [PMID: 35215197 PMCID: PMC8879895 DOI: 10.3390/pathogens11020254] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/11/2022] [Accepted: 02/15/2022] [Indexed: 02/01/2023] Open
Abstract
The global importance of the hemoparasite Theileria haneyi to equine health was recently shown by its resistance to imidocarb dipropionate (ID) and its interference with T. equi clearance by ID in some co-infected horses. Genetic characterization of T. haneyi revealed marked genomic reduction compared to T. equi, and initial experiments demonstrated reduced clinical severity in spleen-intact horses. Furthermore, in early experiments, splenectomized horses survived T. haneyi infection and progressed to an asymptomatic carrier state, in stark contrast to the high fatality rate of T. equi in splenectomized horses. Thus, we hypothesized that T. haneyi is less virulent than T. equi. To objectively assess virulence, clinical data from nine splenectomized, T. haneyi-infected horses were evaluated and compared to published data on T. equi-infected, splenectomized horses. Seven of eight splenectomized, T. haneyi-infected horses survived. Further, in six horses co-infected with T. equi and T. haneyi, only horses cleared of T. equi by ID survived splenectomy and became asymptomatic carriers. The reduced virulence of T. haneyi in splenectomized horses instructs why T. haneyi was, until recently, undetected. This naturally occurring comparative reduction in virulence in a natural host provides a foundation for defining virulence mechanisms of theileriosis and Apicomplexa in general.
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Affiliation(s)
- Kelly P. Sears
- Department of Clinical Science, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4801, USA;
- Department of Veterinary Microbiology and Pathology, Washington State University, College of Veterinary Medicine, Pullman, WA 99164-6630, USA;
| | - Donald P. Knowles
- Department of Veterinary Microbiology and Pathology, Washington State University, College of Veterinary Medicine, Pullman, WA 99164-6630, USA;
| | - Lindsay M. Fry
- Department of Veterinary Microbiology and Pathology, Washington State University, College of Veterinary Medicine, Pullman, WA 99164-6630, USA;
- USDA—ARS, Animal Disease Research Unit, Pullman, WA 99164-6630, USA
- Correspondence: ; Tel.: +1-509-595-1822
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Risso A, Campos G, Garcia H, Zerpa H. Insights into equine piroplasmosis in Venezuelan sport horses: Molecular diagnosis, clinical, and cardiovascular findings. Vet Parasitol Reg Stud Reports 2022; 27:100666. [PMID: 35012720 DOI: 10.1016/j.vprsr.2021.100666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 08/28/2021] [Accepted: 11/15/2021] [Indexed: 06/14/2023]
Abstract
Equine piroplasmosis (EP) is a tick-borne infectious disease highly prevalent in tropical and subtropical regions, such as Venezuela. EP affects wild and domestic equids leading to several clinical presentations, from asymptomatic to severely affected animals. In this study, thirty-three (33) sport horses under regular training activities and from endemic regions of north-central Venezuela were submitted to an observational survey, case-control, to describe the presence of clinical signs and natural EP infections. A conventional PCR assay targeting the SSU rRNA gene revealed EP etiologic agents in 13 out of 33 sampled horses (~ 39.4% infections). Nine (9) of these EP-positive samples were confirmed as infected with Babesia caballi (6/9 = 66.7%) or Theileria equi (3/9 = 33.3%) by DNA sequencing and BLASTN analyses. A phylogeny of SSU rRNA gene sequences revealed that these new B. caballi and T. equi sequences clustered within the worldwide distributed phylogenetic genotype A, respectively. No acute EP cases were observed in this study; however, six (6) PCR-positive animals displayed mild clinical signs compatible with EP, including a mild leukocytosis (P < 0.05). The heart rate variability frequency domain analysis in four (4) of these EP-positive infected animals revealed a significant (P < 0.05) higher low-frequency/high-frequency ratio suggesting a sympathovagal imbalance in these chronically infected animals. Other clinical and cardiovascular parameters were similar between the different groups. Sport horses are routinely submitted to intense training programs and sport-related activities that could lead to loss of the host-parasite equilibrium that characterizes enzootic regions, increasing the likelihood of infection reactivation and the risk of transmission. Heart rate variability analysis contributes to evaluate the sympathovagal balance and detecting homeostasis disturbances in sport horses. Molecular diagnostic tests for EP based on the detection of parasite DNA in equine blood samples should be included in the health programs of sport horses in endemic areas.
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Affiliation(s)
- Arnaldo Risso
- Department of Biomedical Sciences, Faculty of Veterinary Sciences, Central University of Venezuela, Maracay, Aragua, Venezuela; Department of Veterinary Pathology, Faculty of Veterinary Sciences, Romulo Gallegos University, Zaraza, Guarico, Venezuela
| | - Gerardo Campos
- Department of Medicine and Surgery, Faculty of Veterinary Sciences, Central University of Venezuela, Maracay, Aragua, Venezuela
| | - Herakles Garcia
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Brazil; Department of Veterinary Pathology, Faculty of Veterinary Sciences, Central University of Venezuela, Maracay, Aragua, Venezuela
| | - Héctor Zerpa
- Anatomy, Physiology, and Pharmacology Department, School of Veterinary Medicine, St. George's University, St. George's, Grenada, West Indies.
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Imidocarb Dipropionate Lacks Efficacy against Theileria haneyi and Fails to Consistently Clear Theileria equi in Horses Co-Infected with T. haneyi. Pathogens 2020; 9:pathogens9121035. [PMID: 33321715 PMCID: PMC7764667 DOI: 10.3390/pathogens9121035] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/05/2020] [Accepted: 12/08/2020] [Indexed: 12/27/2022] Open
Abstract
Control of Theileria equi, the primary cause of equine theileriosis, is largely reliant on acaracide use and chemosterilization with imidocarb dipropionate (ID). However, it is currently unknown if ID is effective against Theileria haneyi, the recently identified second causative agent of equine theileriosis, or if the drug maintains effectiveness against T. equi in the presence of T. haneyi co-infection. The purpose of this study was to address these questions using ID treatment of the following three groups of horses: (1) five T. haneyi infected horses; (2) three T. haneyi-T. equi infected horses; and (3) three T. equi-T. haneyi infected horses. Clearance was first evaluated using nPCR for each Theileria sp. on peripheral blood samples. ID failed to clear T. haneyi in all three groups of horses, and failed to clear T. equi in two of three horses in group two. For definitive confirmation of infection status, horses in groups two and three underwent splenectomy post-treatment. The T. equi-nPCR-positive horses in group two developed severe clinical signs and were euthanized. Remaining horses exhibited moderate signs consistent with T. haneyi. Our results demonstrate that ID therapy lacks efficacy against T. haneyi, and T. haneyi-T. equi co-infection may interfere with ID clearance of T. equi.
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Tirosh-Levy S, Gottlieb Y, Fry LM, Knowles DP, Steinman A. Twenty Years of Equine Piroplasmosis Research: Global Distribution, Molecular Diagnosis, and Phylogeny. Pathogens 2020; 9:E926. [PMID: 33171698 PMCID: PMC7695325 DOI: 10.3390/pathogens9110926] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 11/04/2020] [Accepted: 11/04/2020] [Indexed: 12/26/2022] Open
Abstract
Equine piroplasmosis (EP), caused by the hemoparasites Theileria equi, Theileria haneyi, and Babesia caballi, is an important tick-borne disease of equines that is prevalent in most parts of the world. Infection may affect animal welfare and has economic impacts related to limitations in horse transport between endemic and non-endemic regions, reduced performance of sport horses and treatment costs. Here, we analyzed the epidemiological, serological, and molecular diagnostic data published in the last 20 years, and all DNA sequences submitted to GenBank database, to describe the current global prevalence of these parasites. We demonstrate that EP is endemic in most parts of the world, and that it is spreading into more temperate climates. We emphasize the importance of using DNA sequencing and genotyping to monitor the spread of parasites, and point to the necessity of further studies to improve genotypic characterization of newly recognized parasite species and strains, and their linkage to virulence.
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Affiliation(s)
- Sharon Tirosh-Levy
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot 7610001, Israel; (Y.G.); (A.S.)
| | - Yuval Gottlieb
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot 7610001, Israel; (Y.G.); (A.S.)
| | - Lindsay M. Fry
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164, USA; (L.M.F.); (D.P.K.)
- Animal Disease Research Unit, Agricultural Research Service, US Department of Agriculture, Pullman, WA 99164, USA
| | - Donald P. Knowles
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164, USA; (L.M.F.); (D.P.K.)
| | - Amir Steinman
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot 7610001, Israel; (Y.G.); (A.S.)
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Coultous RM, Leadon DP, Shiels BR, Sutton D, Weir W. Investigating the presence of equine piroplasmosis in Ireland. Vet Rec 2020; 187:e97. [PMID: 32887846 DOI: 10.1136/vr.105937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 08/07/2020] [Accepted: 08/07/2020] [Indexed: 12/18/2022]
Abstract
BACKGROUND Equine piroplasmosis (EP) is a notifiable disease in Ireland and a significant concern to domestic and international equine industries. Information regarding EP presence in Ireland is currently limited. This retrospective surveillance study describes a serological and molecular analysis of blood samples submitted to the Irish Equine Centre for EP testing between January 2013 and April 2016. METHODS Following serological testing, seropositive samples were screened using a PCR targeting the 18S ribosomal RNA gene. Amplicon sequences were bioinformatically analysed to identify the parasite species and to assess genetic diversity. RESULTS From 2099 screened equine blood samples, 2.5 per cent and 1 per cent were seropositive for Theileria equi and Babesia caballi, respectively. T equi DNA was detected in 9 per cent of the seropositive samples while B caballi DNA was not detected in any sample. The T equi DNA sequences displayed no genetic diversity at this locus, in contrast to samples from the UK and from endemic areas. CONCLUSION Detection of EP-seropositive and parasitaemic horses in Ireland indicates a clear and present health risk to the equine population. It is recommended that owners adopt appropriate biosecurity measures and that clinicians are mindful of this disease as a differential diagnosis.
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Affiliation(s)
- Robert M Coultous
- University of Glasgow Institute of Biodiversity, Animal Health and Comparative Medicine, Glasgow, UK
| | | | - Brian R Shiels
- University of Glasgow Institute of Biodiversity, Animal Health and Comparative Medicine, Glasgow, UK
| | - David Sutton
- University of Glasgow School of Veterinary Medicine, Glasgow, UK
| | - William Weir
- University of Glasgow School of Veterinary Medicine, Glasgow, UK
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Tirosh-Levy S, Gottlieb Y, Mazuz ML, Savitsky I, Steinman A. Infection dynamics of Theileria equi in carrier horses is associated with management and tick exposure. Ticks Tick Borne Dis 2020; 11:101508. [PMID: 32993928 DOI: 10.1016/j.ttbdis.2020.101508] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 07/01/2020] [Accepted: 07/04/2020] [Indexed: 01/25/2023]
Abstract
The tick-borne equine hemoparasite, Theileria equi, is endemic in many parts of the world where prevalence may be high, and most infected horses are apparently healthy but serve as life-long carriers. To determine the factors that affect T. equi dynamics, we followed parasitic loads in apparently healthy horses at four time points during one year. A total of 1094 blood samples were collected from 395 horses, along with ticks and demographic and clinical data. Infection and load of T. equi were tested by PCR and qPCR, and for the spring dataset, infection was also tested serologically by IFAT (n = 268). Theileria equi was molecularly detected in 64.8 % of the horses. The agreement between molecular and serological results was 79.8 % (K > 0.674) and positively correlated with parasitic load. Infection was associated with pale mucus membranes, lower packed cell volume and higher total solids (all P < 0.001), although these changes had only minor clinical importance. While parasitic loads in qPCR-positive samples (n = 561) were generally low (mean = 7.9-10-4% parasitized erythrocytes), younger horses showed higher loads, possibly suggesting development of immunity. Infection and parasitic load were associated with housing management and tick exposure, illustrating different patterns of exposure. Endemic stability is suggested in pasture farms with constant exposure to ticks, where parasite prevalence was high (96 %) and associated with T. equi 18S rRNA genotype D, low parasitemia and high antibody titers. Endemic instability can be suggested in case were horses are kept in paddocks (prevalence = 49 %) with intermittent exposure to ticks, where infection was associated with high parasitemia when ticks were present. A steady state is suggested in stabled horses (prevalence = 46 %), with no exposure to ticks; where infection was associated with genotype A, low parasitemia and low antibody titers. The ability to identify different risk groups within endemic areas may improve the administration of suitable treatment and control practices in an effort to reduce the risk of clinical disease.
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Affiliation(s)
- Sharon Tirosh-Levy
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, P.O.B 12, Rehovot 7610001, Israel.
| | - Yuval Gottlieb
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, P.O.B 12, Rehovot 7610001, Israel.
| | - Monica L Mazuz
- Division of Parasitology, Kimron Veterinary Institute, P.O.B 12, Bet Dagan 50250, Israel.
| | - Igor Savitsky
- Division of Parasitology, Kimron Veterinary Institute, P.O.B 12, Bet Dagan 50250, Israel.
| | - Amir Steinman
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, P.O.B 12, Rehovot 7610001, Israel.
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12
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Molecular detection of Theileria species and Babesia caballi from horses in Nigeria. Parasitol Res 2020; 119:2955-2963. [PMID: 32647992 PMCID: PMC7431391 DOI: 10.1007/s00436-020-06797-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 07/02/2020] [Indexed: 02/06/2023]
Abstract
Equine piroplasmosis (EP) is an infectious, tick-borne disease caused by the hemoprotozoan parasites, Theileria equi, Babesia caballi, and a recently reported new species, T. haneyi. Infections by these apicomplexan parasites limit performance and cause economic losses for the horse industry. Equine piroplasmosis is widespread in the northern regions of Nigeria, where an increasing portion of the animal population is composed of horses. This disease has remained epidemiologically challenging, especially as the movement of horses increases across Nigeria. In this study, blood samples from 300 horses were collected in three states of northwestern Nigeria. The presence of piroplasms was screened by nested PCR targeting 18S rDNA and positive samples were analyzed using species-specific-nested PCR-targeting genes including ema1 (T. equi), rap1 (B. caballi), and a gene coding a protein of unknown function (T. haneyi). Species-specific-nPCR results demonstrated that the prevalence of T. equi was 13.0% (39/300), B. caballi was 3.3% (10/300) and T. haneyi was 2.7% (8/300). Mixed infections with T. equi and B. caballi was 2.7% (8/300) while T. equi, B. caballi, and T. haneyi multiple infection prevalence was 0.6% (2/300). We used 18S rDNA sequences to determine close relationships between T. equi by phylogenetic analysis and demonstrated that among 57 sequences of Theileria parasites, 28 samples belonged to clade A (49%), 13 samples were found to be clade C (22%), and 16 were clade D (28%). These results demonstrate the genetic diversity of T. equi circulating in horses from Nigeria.
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