heartwater disease

Summary

Summary: A tick-borne septicemic disease of domestic and wild ruminants caused by EHRLICHIA RUMINANTIUM.

Top Publications

  1. Faburay B, Geysen D, Munstermann S, Bell Sakyi L, Jongejan F. Longitudinal monitoring of Ehrlichia ruminantium infection in Gambian lambs and kids by pCS20 PCR and MAP1-B ELISA. BMC Infect Dis. 2007;7:85 pubmed
    ..Thus in this study, we monitored the onset (age at first infection) and kinetics of E. ruminantium infection and antibody response in extensively managed newborn lambs and kids at three sites in The Gambia...
  2. O Callaghan C, Medley G, Peter T, Perry B. Investigating the epidemiology of heartwater (Cowdria ruminantium infection) by means of a transmission dynamics model. Parasitology. 1998;117 ( Pt 1):49-61 pubmed
    ..Model limitations and future developments are discussed. The essential role of a transmission dynamics model in assessing the impact of new vaccines in conjunction with vector control programmes is highlighted...
  3. Postigo M, Bell Sakyi L, Paxton E, Sumption K. Kinetics of experimental infection of sheep with Ehrlichia ruminantium cultivated in tick and mammalian cell lines. Exp Appl Acarol. 2002;28:187-93 pubmed
    ..ruminantium (Gardel isolate). The method and initial results are described, and the significance of the findings is discussed in relation to the clinical responses of the sheep. ..
  4. Esteves I, Vachiery N, Martinez D, Totte P. Analysis of Ehrlichia ruminantium-specific T1/T2 responses during vaccination with a protective killed vaccine and challenge of goats. Parasite Immunol. 2004;26:95-103 pubmed
    ..ruminantium-specific T1 responses will be valuable to develop cellular tools for the identification of potential protective antigens...
  5. Martinez D, Vachiery N, Stachurski F, Kandassamy Y, Raliniaina M, Aprelon R, et al. Nested PCR for detection and genotyping of Ehrlichia ruminantium: use in genetic diversity analysis. Ann N Y Acad Sci. 2004;1026:106-13 pubmed
    ..These genes may allow better predictions on cross-protection, given the recent completion of the sequence of the full genome of two E. ruminantium strains...
  6. Peter T, O Callaghan C, Medley G, Perry B, Semu S, Maha S. Population-based evaluation of the Ehrlichia ruminantium MAP 1B indirect ELISA. Exp Appl Acarol. 2001;25:881-97 pubmed
    ..Although the reasons for this low response in field cattle are not fully understood, this study illustrates the need for field validation of the performance of new diagnostic tests prior to their use for epidemiological purposes...
  7. Martinez D, Swinkels J, Camus E, Jongejan F. [Comparison between 3 antigens for the serodiagnosis of heartwater disease by indirect immunofluorescence]. Rev Elev Med Vet Pays Trop. 1990;43:159-66 pubmed
  8. Bell Sakyi L, Koney E, Dogbey O, Sumption K, Walker A, Bath A, et al. Detection by two enzyme-linked immunosorbent assays of antibodies to Ehrlichia ruminantium in field sera collected from sheep and cattle in Ghana. Clin Diagn Lab Immunol. 2003;10:917-25 pubmed
    ..ruminantium seroprevalence of at least 70% in Ghanaian sheep; levels of exposure among Amblyomma variegatum-infested Ghanaian cattle are likely to be higher than the seroprevalence value of 66% obtained with the PC-ELISA...
  9. Allsopp M, Dorfling C, Maillard J, Bensaid A, Haydon D, Van Heerden H, et al. Ehrlichia ruminantium major antigenic protein gene (map1) variants are not geographically constrained and show no evidence of having evolved under positive selection pressure. J Clin Microbiol. 2001;39:4200-3 pubmed

More Information

Publications90

  1. Bell Sakyi L, Koney E, Dogbey O, Walker A. Ehrlichia ruminantium seroprevalence in domestic ruminants in Ghana; I. Longitudinal survey in the Greater Accra Region. Vet Microbiol. 2004;100:175-88 pubmed
    ..E. ruminantium was detected in brains of 14, 36 and 4% of cattle, sheep and goats submitted for post mortem at the Accra Veterinary Laboratory, indicating that sheep were most at risk from heartwater disease.
  2. Semu S, Peter T, Mukwedeya D, Barbet A, Jongejan F, Mahan S. Antibody responses to MAP 1B and other Cowdria ruminantium antigens are down regulated in cattle challenged with tick-transmitted heartwater. Clin Diagn Lab Immunol. 2001;8:388-96 pubmed
    ..ruminantium via ticks. Significantly, serological responses to the MAP 1B antigen may not be a reliable indicator of C. ruminantium exposure in cattle in areas of endemic heartwater infection...
  3. Faburay B, Munstermann S, Geysen D, Bell Sakyi L, Ceesay A, Bodaan C, et al. Point seroprevalence survey of Ehrlichia ruminantium infection in small ruminants in The Gambia. Clin Diagn Lab Immunol. 2005;12:508-12 pubmed
    ..These findings need to be taken into consideration when future livestock-upgrading programs are implemented...
  4. Allsopp M, Louw M, Meyer E. Ehrlichia ruminantium: an emerging human pathogen?. Ann N Y Acad Sci. 2005;1063:358-60 pubmed
  5. Allsopp M, Van Heerden H, Steyn H, Allsopp B. Phylogenetic relationships among Ehrlichia ruminantium isolates. Ann N Y Acad Sci. 2003;990:685-91 pubmed
    ..Sequence variation within this clade is greater than that within the western African clade, suggesting that E. ruminantium originated in southern Africa...
  6. Van Heerden H, Steyn H, Allsopp M, Zweygarth E, Josemans A, Allsopp B. Characterization of the pCS20 region of different Ehrlichia ruminantium isolates. Vet Microbiol. 2004;101:279-91 pubmed
    ..These results facilitated the design of a short pCS20 probe and a large PCR target that improved the sensitivity of the E. ruminantium detection assay...
  7. Camus E, Barre N. Epidemiology of heartwater in Guadeloupe and in the Caribbean. Onderstepoort J Vet Res. 1987;54:419-26 pubmed
    ..The possible evolution of heartwater in the Caribbean and in the United States in considered...
  8. Allsopp M, Allsopp B. Extensive genetic recombination occurs in the field between different genotypes of Ehrlichia ruminantium. Vet Microbiol. 2007;124:58-65 pubmed
    ..It also appears likely that the Gardel genotype, isolated in the Caribbean, originally came from west central Africa, not from west Africa as had long been assumed...
  9. Waghela S, Rurangirwa F, Mahan S, Yunker C, Crawford T, Barbet A, et al. A cloned DNA probe identifies Cowdria ruminantium in Amblyomma variegatum ticks. J Clin Microbiol. 1991;29:2571-7 pubmed
    ..ruminantium in nymphs and adults was confirmed by transmission of heartwater to goats. The DNA sequences of both probes were determined; synthetic oligonucleotides from pCS20 are recommended as DNA probes for C. ruminantium...
  10. Jongejan F. Protective immunity to heartwater (Cowdria ruminantium infection) is acquired after vaccination with in vitro-attenuated rickettsiae. Infect Immun. 1991;59:729-31 pubmed
    ..This is the first report of vaccination with live attenuated C. ruminantium. These attenuated organisms may replace vaccination with virulent blood currently in use in areas where heartwater is endemic...
  11. Allsopp M, van Strijp M, Faber E, Josemans A, Allsopp B. Ehrlichia ruminantium variants which do not cause heartwater found in South Africa. Vet Microbiol. 2007;120:158-66 pubmed
    ..Infection levels in both animals and ticks were too low to generate a marked response when a blood stabilate was sub-passaged in a clean sheep, preventing the subsequent establishment of any of the organisms in culture...
  12. Burridge M, Simmons L, Peter T, Mahan S. Increasing risks of introduction of heartwater onto the American mainland associated with animal movements. Ann N Y Acad Sci. 2002;969:269-74 pubmed
    ..Measures to control importation of infected animals from the Caribbean must be based on knowledge of the islands that are infected with C. ruminantium so that the risk of dissemination of heartwater can be established...
  13. Kakono O, Hove T, Geysen D, Mahan S. Detection of antibodies to the Ehrlichia ruminantium MAP1-B antigen in goat sera from three communal land areas of Zimbabwe by an indirect enzyme-linked immunosorbent assay. Onderstepoort J Vet Res. 2003;70:243-9 pubmed
    ..The highest corresponded with the period January to February (peak tick activity) and the lowest with the period July to September (minimal tick activity)...
  14. Steyn H, Pretorius A, McCrindle C, Steinmann C, Van Kleef M. A quantitative real-time PCR assay for Ehrlichia ruminantium using pCS20. Vet Microbiol. 2008;131:258-65 pubmed publisher
    ..Thus, because this new quantitative pCS20 real-time PCR TaqMan probe assay was the most sensitive and can be performed within 2h it is an effective assay for epidemiological surveillance and monitoring of infected animals...
  15. Peixoto C, Marcelino I, Vachiery N, Bensaid A, Martinez D, Carrondo M, et al. Quantification of Ehrlichia ruminantium by real time PCR. Vet Microbiol. 2005;107:273-8 pubmed
  16. Jongejan F, Uilenberg G, Franssen F, Gueye A, Nieuwenhuijs J. Antigenic differences between stocks of Cowdria ruminantium. Res Vet Sci. 1988;44:186-9 pubmed
    ..The Senegalese stock of C ruminantium is the first stock outside South Africa against which the reference Ball 3 stock does not fully immunise...
  17. Louw M, Allsopp M, Meyer E. Ehrlichia ruminantium, an emerging human pathogen--a further report. S Afr Med J. 2005;95:948, 950 pubmed
  18. Faburay B, Geysen D, Munstermann S, Taoufik A, Postigo M, Jongejan F. Molecular detection of Ehrlichia ruminantium infection in Amblyomma variegatum ticks in The Gambia. Exp Appl Acarol. 2007;42:61-74 pubmed
    In West Africa, losses due to heartwater disease are not known because the incidence/prevalence has not been well studied or documented...
  19. Simbi B, Peter T, Burridge M, Mahan S. Comparing the detection of exposure to Ehrlichia ruminantium infection on a heartwater-endemic farm by the pCS20 polymerase chain reaction assay and an indirect MAP1-B enzyme linked immunosorbent assay. Onderstepoort J Vet Res. 2003;70:231-5 pubmed
    ..Comparison of the two tests indicated that the pCS20 PCR assay was more reliable because it detected more infections than the indirect MAP-1B ELISA and would therefore be the method of choice for detection of E. ruminantium infection...
  20. Walker J, Olwage A. The tick vectors of Cowdria ruminantium (Ixodoidea, Ixodidae, genus Amblyomma) and their distribution. Onderstepoort J Vet Res. 1987;54:353-79 pubmed
    ..marmoreum) have proved to be capable of transmitting heartwater in the laboratory, as have 2 American species (A. maculatum and A. cajennense), but none of these ticks have been implicated in field outbreaks of the disease...
  21. Pascucci I, Capobianco Dondona A, Cammà C, Marcacci M, Di Domenico M, Lelli R, et al. Survey of ixodid ticks and two tick-borne pathogens in African buffaloes, Syncerus caffer, from the Caprivi Strip, Namibia. J Zoo Wildl Med. 2011;42:634-40 pubmed
  22. Zweygarth E, Josemans A. In vitro infection by Ehrlichia ruminantium of baby hamster kidney (BHK), Chinese hamster ovary (CHO-K1) and Madin Darby bovine kidney (MDBK) cells. Onderstepoort J Vet Res. 2003;70:165-8 pubmed
    ..ruminantium. Growth of the Welgevonden stock in BHK and CHO-K1 cells could lead to the development of suspension cultures suitable for the mass production of E. ruminantium for an inactivated elementary body vaccine. ..
  23. Gunter N, Esteves I, Kandassamy Y, Martinez D, Bensaid A, Van Kleef M, et al. Cowdria ruminantium antigens of around 15 kDa are potent inducers of IFN-gamma. Ann N Y Acad Sci. 2002;969:135-40 pubmed
    ..These pilot experiments pave the way towards the identification of proteins/genes that have potential for the development of a recombinant vaccine against heartwater. ..
  24. Schröder J. Heartwater insights. Aust Vet J. 2005;83:29 pubmed
  25. O Callaghan C, Medley G, Peter T, Mahan S, Perry B. Predicting the effect of vaccination on the transmission dynamics of heartwater (Cowdria ruminantium infection). Prev Vet Med. 1999;42:17-38 pubmed
    ..Our results suggest that where relatively high tick challenge can be achieved and consistently maintained, vaccination may be used in susceptible herds to minimise losses in a policy of transition to endemic stability. ..
  26. Vachiery N, Lefrancois T, Esteves I, Molia S, Sheikboudou C, Kandassamy Y, et al. Optimisation of the inactivated vaccine dose against heartwater and in vitro quantification of Ehrlichia ruminantium challenge material. Vaccine. 2006;24:4747-56 pubmed
  27. Collins N, Allsopp M, Allsopp B. Molecular diagnosis of theileriosis and heartwater in bovines in Africa. Trans R Soc Trop Med Hyg. 2002;96 Suppl 1:S217-24 pubmed
    ..Routine application of these tests has led to the discovery of new genotypes that are probably not E. ruminantium but are probably new species of Ehrlichia. ..
  28. Ahmadu B, Lovelace C, Samui K, Mahan S. Some observations on the sero-prevalence of heartwater and tick infestation in Zambian goats. Onderstepoort J Vet Res. 2004;71:161-4 pubmed
    ..4% of the tick species, identified. The overall tick infestation rate was 10% while the tick:goat ratio was 2.1:1. Amblyomma variegatum appears to be widespread throughout the study area, as are antibodies to E. ruminantium. ..
  29. Collins N, Pretorius A, Van Kleef M, Brayton K, Zweygarth E, Allsopp B. Development of improved vaccines for heartwater. Ann N Y Acad Sci. 2003;990:474-84 pubmed
    ..This suggests that the local E. ruminantium genotypes were different from any which were administered by needle challenge, or that needle challenge is not a good model for tick challenge in the field. ..
  30. Allsopp B. Natural history of Ehrlichia ruminantium. Vet Parasitol. 2010;167:123-35 pubmed publisher
    ..ruminantium, at a time when the prospects for the development of an effective vaccine against the organism seem better than at any time since its discovery 83 years ago...
  31. Peter T, Mahan S, Burridge M. Resistance of leopard tortoises and helmeted guineafowl to Cowdria ruminantium infection (heartwater). Vet Parasitol. 2001;98:299-307 pubmed
    ..However, leopard tortoises are efficient hosts of A. marmoreum and A. hebraeum and are likely to be important epidemiologically in the transport and maintenance of these tick vector species. ..
  32. Marcelino I, Vachiery N, Amaral A, Roldão A, Lefrancois T, Carrondo M, et al. Effect of the purification process and the storage conditions on the efficacy of an inactivated vaccine against heartwater. Vaccine. 2007;25:4903-13 pubmed
  33. Mbengue M, Gueye A, Faye O, Toguebaye B, Konte M. [Sero-epidemiological study of cowdriosis in Moorish zebu cattle from Senegal]. Parasite. 2007;14:169-71 pubmed
  34. Vachiery N, Raliniaina M, Stachurski F, Adakal H, Molia S, Lefrancois T, et al. Understanding the mechanisms of transmission of Ehrlichia ruminantium and its influence on the structure of pathogen populations in the field. Ann N Y Acad Sci. 2006;1078:495-7 pubmed
    ..During a dual infection, the timing of Ehrlichia ruminantium circulation of the two stocks in hosts influenced their selection by ticks. ..
  35. Nefefe T, Liebenberg J, Van Kleef M, Steyn H, Pretorius A. Innate immune transcriptomic evaluation of PBMC isolated from sheep after infection with E. ruminantium Welgevonden strain. Mol Immunol. 2017;91:238-248 pubmed publisher
    ..This data indicates that innate immune activation, perhaps by using adjuvants, should be an important component for consideration during future heartwater recombinant vaccine development...
  36. du Plessis J, Van Gas L, Olivier J, Bezuidenhout J. The heterogenicity of Cowdria ruminantium stocks: cross-immunity and serology in sheep and pathogenicity to mice. Onderstepoort J Vet Res. 1989;56:195-201 pubmed
  37. Adakal H, Stachurski F, Konkobo M, Zoungrana S, Meyer D, Pinarello V, et al. Efficiency of inactivated vaccines against heartwater in Burkina Faso: impact of Ehrlichia ruminantium genetic diversity. Vaccine. 2010;28:4573-80 pubmed publisher
    ..Map1 genotyping of strains detected in brains from control sheep showed that genotype distribution varied according to time and study areas, which could explain the difference in efficacy of the vaccine...
  38. Scott G. The taxonomic status of the causative agent of heartwater. Onderstepoort J Vet Res. 1987;54:257-60 pubmed
    ..Cowdria is classified as a genus along with Chlamydia, Coxiella and Anaplasma in the tribe Chlamydieae in the family Phagosomaphilaceae. ..
  39. du Plessis J, Van Gas L. Immunity of tick-exposed seronegative and seropositive small stock challenged with two stocks of Cowdria ruminantium. Onderstepoort J Vet Res. 1989;56:185-8 pubmed
    ..The fact that only 74% of the seropositive sheep and goats were immune to challenge can probably be ascribed to the poor cross-protection between stocks of C. ruminantium and not to false positive serological reactions. ..
  40. Marcelino I, Veríssimo C, Sousa M, Carrondo M, Alves P. Characterization of Ehrlichia ruminantium replication and release kinetics in endothelial cell cultures. Vet Microbiol. 2005;110:87-96 pubmed
  41. De Villiers E, Brayton K, Zweygarth E, Allsopp B. Genome size and genetic map of Cowdria ruminantium. Microbiology. 2000;146 ( Pt 10):2627-34 pubmed
    ..ruminantium DNA fragments were mapped to specific KSP:I, RSR:II and SMA:I fragments, including the major antigenic protein gene, map-1. ..
  42. El Hussein A, Majid A, Shawgi M. Present status of tick-borne diseases in Sudan. Arch Inst Pasteur Tunis. 2004;81:31-4 pubmed
    ..The large number of tick species, the multplicity of transmitted agents and the diverse ecoclimatic zones of the Sudan provide a unique opportunity to host diverse research activities that could benefit other regions in Africa. ..
  43. Bryson N, Horak I, Venter E, Yunker C. Collection of free-living nymphs and adults of Amblyomma hebraeum (Acari: Ixodidae) with pheromone/carbon dioxide traps at 5 different ecological sites in heartwater endemic regions of South Africa. Exp Appl Acarol. 2000;24:971-82 pubmed
    ..This study confirmed that the traps could be used in a variety of ecological areas to locate populations of free-living adult A. hebraeum. ..
  44. Wesonga F, Mukolwe S, Grootenhuis J. Transmission of Cowdria ruminantium by Amblyomma gemma from infected African buffalo (Syncerus caffer) and eland (Taurotragus oryx) to sheep. Trop Anim Health Prod. 2001;33:379-90 pubmed
    ..No nymphs that had fed on the waterbuck transmitted the disease. This is the first report of transmission of heartwater by Amblyomma gemma from infected wild ruminant species to a susceptible domestic ruminant species...
  45. Peter T, Burridge M, Mahan S. Ehrlichia ruminantium infection (heartwater) in wild animals. Trends Parasitol. 2002;18:214-8 pubmed
    ..The host range of Ehrlichia ruminantium in wildlife is reviewed here and the role played by these species in the epidemiology and spread of heartwater is discussed...
  46. Zweygarth E, Josemans A, Van Strijp M, Lopez Rebollar L, Van Kleef M, Allsopp B. An attenuated Ehrlichia ruminantium (Welgevonden stock) vaccine protects small ruminants against virulent heartwater challenge. Vaccine. 2005;23:1695-702 pubmed
  47. Totte P, Nyanjui J, Bensaid A, McKeever D. Bovine CD4+ T-cells lines reactive with soluble and membrane antigens of Cowdria ruminantium. Vet Immunol Immunopathol. 1999;70:269-76 pubmed
    ..Given their high sensitivity and specificity, these short-term CD4+ T-cell lines will be valuable tools for the identification of Cowdria antigens for incorporation in a subunit vaccine. ..
  48. Vachiery N, Maganga G, Lefrancois T, Kandassamy Y, Stachurski F, Adakal H, et al. Differential strain-specific diagnosis of the heartwater agent: Ehrlichia ruminantium. Infect Genet Evol. 2008;8:459-66 pubmed
    ..The target genes identified by bacterial comparative genomics are shown to be highly efficient for strain-specific PCR diagnosis of E. ruminantium and further vaccine management tools...
  49. Nakao R, Stromdahl E, Magona J, Faburay B, Namangala B, Malele I, et al. Development of loop-mediated isothermal amplification (LAMP) assays for rapid detection of Ehrlichia ruminantium. BMC Microbiol. 2010;10:296 pubmed publisher
    ..This report describes the development of two different loop-mediated isothermal amplification (LAMP) assays for sensitive and specific detection of E. ruminantium...
  50. Adakal H, Meyer D, Carasco Lacombe C, Pinarello V, Allègre F, Huber K, et al. MLST scheme of Ehrlichia ruminantium: genomic stasis and recombination in strains from Burkina-Faso. Infect Genet Evol. 2009;9:1320-8 pubmed publisher
    ..This work also shows that the MLST scheme developed can discriminate between these two kinds of strains...
  51. Kiel J, Gonzalez Y, Parker J, Andrews C, Martinez D, Vachiery N, et al. Viral association with the elusive rickettsia of viper plague from Ghana, West Africa. Ann N Y Acad Sci. 2008;1149:318-21 pubmed publisher
    ..The virus and rickettsia infection was associated with transfer of cytopathic effect, regardless of cell species. Close association of virus and rickettsia may indicate a dual infection etiology of viper plague...
  52. Norval R, Andrew H, Yunker C. Infection rates with Cowdria ruminantium of nymphs and adults of the bont tick Amblyomma hebraeum collected in the field in Zimbabwe. Vet Parasitol. 1990;36:277-83 pubmed
    ..Depending on the date of collection and locality, these rates were in the range 0.0-44.9% for males, 20.0-36.1% for females and 0.0-13.4% for nymphs. Most of these rates are considerably higher than those previously believed to occur...
  53. Mwangi D, McKeever D, Nyanjui J, Barbet A, Mahan S. Immunisation of cattle against heartwater by infection with Cowdria ruminantium elicits T lymphocytes that recognise major antigenic proteins 1 and 2 of the agent. Vet Immunol Immunopathol. 2002;85:23-32 pubmed
    ..Our findings indicate that immunisation of cattle by infection with C. ruminantium results in generation of MAP1- and MAP2-specific T cell responses that may play a role in protection against the pathogen...
  54. Camus E, Barre N. Diagnosis of heartwater in the live animal: experiences with goats in Guadeloupe. Onderstepoort J Vet Res. 1987;54:291-4 pubmed
    ..Ticks that have engorged on a suspect animal can be allowed to moult and then fed on a susceptible animal to test their infectivity. These methods are time consuming but useful for heartwater surveys...
  55. du Plessis J, Malan L, Kowalski Z. The pathogenesis of heartwater. Onderstepoort J Vet Res. 1987;54:313-8 pubmed
    ..Complement, and the products of arachidonic acid metabolism, possibly play a role in the release of the vaso-active substances...
  56. Kiel J, Alarcon R, Parker J, Vivekananda J, Gonzalez Y, Stribling L, et al. Emerging tick-borne disease in African vipers caused by a Cowdria-like organism. Ann N Y Acad Sci. 2006;1081:434-42 pubmed
  57. Simuunza M, Weir W, Courcier E, Tait A, Shiels B. Epidemiological analysis of tick-borne diseases in Zambia. Vet Parasitol. 2011;175:331-42 pubmed publisher
    ..A negative association was observed between the number of co-infecting pathogens and the erythrocyte packed cell volume (PCV) of carrier cattle...
  58. Uilenberg G. Methods currently used for the control of heartwater: their validity and proposals for future control strategies. Parassitologia. 1990;32:55-62 pubmed
    ..More research is also needed on the immunology and diagnosis of the disease and the factors involved in the resistance of young animals...
  59. Esemu S, Besong W, Ndip R, Ndip L. Prevalence of Ehrlichia ruminantium in adult Amblyomma variegatum collected from cattle in Cameroon. Exp Appl Acarol. 2013;59:377-87 pubmed publisher
    ..ruminantium in the GenBank. This report represents the first molecular evidence of E. ruminantium infection in A. variegatum ticks in Cameroon and suggests possible exposure of cattle to this pathogen in our environment...
  60. Jongejan F, Thielemans M, Briere C, Uilenberg G. Antigenic diversity of Cowdria ruminantium isolates determined by cross-immunity. Res Vet Sci. 1991;51:24-8 pubmed
    Antigenic diversity in five stocks of the tick-borne rickettsia Cowdria ruminantium, the causal agent of heartwater disease of ruminants, was studied by cross-immunity trials in goats and sheep...
  61. Steyn H, Van Heerden H, Allsopp M, Allsopp B. Variability of pCS20 gene sequences among different Ehrlichia ruminantium isolates. Ann N Y Acad Sci. 2003;990:723-5 pubmed
  62. Mahan S, Simbi B, Burridge M. The pCS20 PCR assay for Ehrlichia ruminantium does not cross-react with the novel deer ehrlichial agent found in white-tailed deer in the United States of America. Onderstepoort J Vet Res. 2004;71:99-105 pubmed
    ..Since the pCS20 PCR assay also does not amplify any DNA products from E. chaffeensis or Ehrlichia canis DNA, it is therefore the method of choice for the detection of E. ruminantium in these deer and other animal hosts...
  63. Uilenberg G. General review of tick-borne diseases of sheep and goats world-wide. Parassitologia. 1997;39:161-5 pubmed
    ..A commented list of tick-borne diseases and their vectors is presented. It is stressed that large gaps remain in our knowledge of the real importance in the field of many of these diseases, especially in local stock...
  64. Mondry R, Martinez D, Camus E, Liebisch A, Katz J, Dewald R, et al. Validation and comparison of three enzyme-linked immunosorbent assays for the detection of antibodies to Cowdria ruminantium infection. Ann N Y Acad Sci. 1998;849:262-72 pubmed
    ..In addition, the competitive ELISA is useful for studies in wildlife for which species-specific conjugates do not exist...
  65. Kivaria F. Estimated direct economic costs associated with tick-borne diseases on cattle in Tanzania. Trop Anim Health Prod. 2006;38:291-9 pubmed
    ..Despite the inadequacies of the data used, the results give evidence that tick-borne diseases inflict substantial economic losses on cattle production and resource use in Tanzania...
  66. Wagner G, Holman P, Waghela S. Babesiosis and heartwater: threats without boundaries. Vet Clin North Am Food Anim Pract. 2002;18:417-30, vi-vii pubmed
    ..Most importantly, you, whether as a small animal or large animal practitioner, are the first line of defense against such exotic diseases and their vectors...
  67. Knopf L, Komoin Oka C, Betschart B, Jongejan F, Gottstein B, Zinsstag J. Seasonal epidemiology of ticks and aspects of cowdriosis in N'Dama village cattle in the Central Guinea savannah of Côte d'Ivoire. Prev Vet Med. 2002;53:21-30 pubmed
    ..Most of the animals typically carried low tick burdens. N'Dama cattle seem well adapted to their environment and can resist the tick burdens under this traditional farming system...
  68. Tshikhudo N, Pretorius A, Putterill J, Van Kleef M. Preparation and in vitro characterisation of Ehrlichia ruminantium plasmid DNA and proteins encapsulated into and DNA adsorbed onto biodegradable microparticles. Ticks Tick Borne Dis. 2010;1:186-93 pubmed publisher
    ..In contrast, PLGA 50:50 microparticles had low (15-65%) initial burst release followed by (25-80%) release by days (days 28-42). A cocktail of these microparticles could therefore be used as single-dose auto-booster vaccine...
  69. Gilfoyle D. Science and popular participation in the investigation of heartwater in South Africa, c. 1870-1950. Parassitologia. 2008;50:291-304 pubmed
    ..Dipping in arsenic solutions to attack the tick on the animal thus remained the most important means of controlling disease in the first half of the twentieth century...
  70. Wassink L, Jongejan F, Gruys E, Uilenberg G. Observations on mouse-infective stocks of Cowdria ruminantium: microscopical demonstration of the Kwanyanga stock in mouse tissue and the carrier-status of the Senegal stock in mice. Res Vet Sci. 1990;48:389-90 pubmed
    ..However, the Senegal stock could not be demonstrated microscopically in mice. These results indicate the possible role of rodents in the epidemiology of heartwater...
  71. Mahan S, Kumbula D, Burridge M, Barbet A. The inactivated Cowdria ruminantium vaccine for heartwater protects against heterologous strains and against laboratory and field tick challenge. Vaccine. 1998;16:1203-11 pubmed
  72. Mahan S, McGuire T, Semu S, Bowie M, Jongejan F, Rurangirwa F, et al. Molecular cloning of a gene encoding the immunogenic 21 kDa protein of Cowdria ruminantium. Microbiology. 1994;140 ( Pt 8):2135-42 pubmed
    ..The antigenic conservation of the 21 kDa protein and its immunogenic nature are reasons for further testing of this recombinant protein in subunit diagnostic tests...
  73. Prozesky L. Diagnosis of heartwater at post-mortem in ruminants and the confirmation of Cowdria ruminantium in mice. Onderstepoort J Vet Res. 1987;54:301-3 pubmed
    ..The effect of specific chemotherapy on the morphology of heartwater organisms in vivo is outlined. A severe nephrosis in heartwater-infected Angora goats, treated after the first day of the febrile reaction, is described...
  74. Mahan S, Allsopp B, Kocan K, Palmer G, Jongejan F. Vaccine strategies for Cowdria ruminantium infections and their application to other ehrlichial infections. Parasitol Today. 1999;15:290-4 pubmed
    ..Given the antigenic similarities between the related ehrlichial agents, common strategies of vaccine development could be applied against these agents that cause infections of importance in animals and humans...
  75. Shkap V, de Vos A, Zweygarth E, Jongejan F. Attenuated vaccines for tropical theileriosis, babesiosis and heartwater: the continuing necessity. Trends Parasitol. 2007;23:420-6 pubmed
    ..As a result, there is a continuing necessity to use available live vaccines in tick and tick-borne disease-control strategies adapted to conditions prevailing in many parts of the world...
  76. Bigalke R. Future prospects and goal setting regarding research on heartwater. Onderstepoort J Vet Res. 1987;54:543-6 pubmed
    ..The development of a tissue culture vaccine offers the greatest chance of immediate success and should be actively pursued. Studies on a recombinant vaccine should, however, be initiated because of the potential long term advantages...
  77. Nakao R, Morrison L, Zhou L, Magona J, Jongejan F, Sugimoto C. Development of multiple-locus variable-number tandem-repeat analysis for rapid genotyping of Ehrlichia ruminantium and its application to infected Amblyomma variegatum collected in heartwater endemic areas in Uganda. Parasitology. 2012;139:69-82 pubmed publisher
    ..ruminantium genotypes and phenotypes such as pathological outcome in the ruminant host...
  78. Pretorius A, Van Strijp F, Brayton K, Collins N, Allsopp B. Genetic immunization with Ehrlichia ruminantium GroEL and GroES homologues. Ann N Y Acad Sci. 2002;969:151-4 pubmed
    ..None of the mice inoculated with the genetic vaccine survived. Immunological memory was also tested in these mice and a correlation between splenocyte proliferation and the survival rate was observed...
  79. Pretorius A, Collins N, Steyn H, Van Strijp F, Van Kleef M, Allsopp B. Protection against heartwater by DNA immunisation with four Ehrlichia ruminantium open reading frames. Vaccine. 2007;25:2316-24 pubmed
    ..Each individual 1H12 ORF provided protection, but all the animals vaccinated with the other cocktails succumbed to the challenge...
  80. Barbet A, Byrom B, Mahan S. Diversity of Ehrlichia ruminantium major antigenic protein 1-2 in field isolates and infected sheep. Infect Immun. 2009;77:2304-10 pubmed publisher
    ..by immune T and B cells from infected animals or from animals that were infected and have recovered from heartwater disease (although still remaining infected carriers)...
  81. Bell Sakyi L, Paxton E, Munderloh U, Sumption K. Growth of Cowdria ruminantium, the causative agent of heartwater, in a tick cell line. J Clin Microbiol. 2000;38:1238-40 pubmed
    ..Infection of the tick cells was confirmed by PCR, karyotyping, electron microscopy, and reinfection of bovine cells...