Heartwater in sheep and goats: A review

Onderstepoort Journal of Veterinary Research

Volumn 63, Issue 2, 1996, Pages 159-170

  Yunker, Conrad ^a,b  

^a ONDERSTEPOORT VETERINARY INSTITUTE   (South Africa)

^b Tickconsult   (United States)

Author keywords

Cowdria ruminantium; Cowdriosis; Goats; Heartwater; Rickettsia; Sheep

Indexed keywords

ACARI; ANIMALIA; CAPRA HIRCUS; EHRLICHIA; EHRLICHIA RUMINANTIUM; OVIS ARIES; RICKETTSIA;

TETRACYCLINE DERIVATIVE;

ANIMAL; ANIMAL DISEASE; ARTICLE; CATTLE; CATTLE DISEASE; CLASSIFICATION; DISEASE CARRIER; DNA PROBE; DRUG EFFECT; EHRLICHIA RUMINANTIUM; ENZYME LINKED IMMUNOSORBENT ASSAY; FLUORESCENT ANTIBODY TECHNIQUE; HEARTWATER DISEASE; ISOLATION AND PURIFICATION; METHODOLOGY; POLYMERASE CHAIN REACTION; SOUTH AFRICA; TICK BORNE DISEASE; WESTERN BLOTTING;

ANIMALS; BLOTTING, WESTERN; CATTLE; CATTLE DISEASES; DISEASE VECTORS; DNA PROBES; EHRLICHIA RUMINANTIUM; ENZYME-LINKED IMMUNOSORBENT ASSAY; FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT; HEARTWATER DISEASE; POLYMERASE CHAIN REACTION; SOUTH AFRICA; TETRACYCLINES; TICK-BORNE DISEASES;

EID: 0030158583     PISSN: 00302465     EISSN: None     Source Type: Journal    
DOI: None     Document Type: Article

References (107)

1. ALEXANDER, R.A. 1931. Heartwater: The present state of our knowledge. 17th Report of the Director of Veterinary Services and Animal Industry, Union of South Africa: 89-150.
2. ALEXANDER, R.A., NEITZ, W.O. & ADELAAR, T.F. 1946. Heartwater. Farming in South Africa, August: 548-552.
3. ALLSOPP, B.A. & VISSER, E.S. 1994. Genetic heterogeneity of the causative agent of heartwater. Proceedings of the 9th International Veterinary Hemoparasite Diseases Conference, Merida, Mexico, 6-9 October 1993 (in press).
4. AMBROSIO, R., DU PLESSIS, J.L & BEZUIDENHOUT, J.D. 1987. The construction of genomic libraries of Cowdria ruminantium in an expression vector, Lambda gt11. Onderstepoort Journal of Veterinary Research, 54:255-256.
5. ANDREW, H.R. & NORVAL, R.A.I. 1989. The carrier status of sheep, cattle and African buffalo recovered from heartwater. Veterinary Parasitology, 34:261-266.
6. ANONYMOUS, 1877. (Testimony of J. Webb) Report of the Colonial Veterinary Surgeon, Sheep & Cattle Diseases. Colony Cape of Good Hope. Appendix: 108-111.
7. ANONYMOUS. 1898. Spread of ticks and prevalence of heartwater. Agricultural Journal of the Cape of Good Hope, 13:594-595.
8. ANONYMOUS. 1965. The blackhead Persian in South Africa. Farming in South Africa. January: 34-39.
9. ASSELBERGS, M., JONGEJAN, F., LANGA, A., NEVES, L. & AFONSO, S. 1993. Antibodies to Cowdria ruminantium in Mozambican goats and cattle detected by immunofluorescence using endothelial cell culture antigen. Tropical Animal Health and Production, 25:144-150.
10. BARBET, A., MAHAN, S., ALLRED, D., McGUIRE, T.C., PALMER, G.H. & YUNKER, C.E. 1992. Recent Developments in the Control of Anaplasmosis, Babesiosis and Cowdriosis. Publication: ILRAD, Nairobi: 87-91.
11. BARBET, A.,TEBELE, N., SEMU, S., PETER J., WASSINK, L. & MAHAN, S. 1993. Serological diagnosis of heartwater in Zimbabwe. Problems and perspectives. Revue d'Élevage et de Médecine Vétérinaire des Pays Tropicaux, 46:121 (Abstract only).
12. BEZUIDENHOUT, J.D., PATTERSON, C.L. & BARNARD, B.H.J. 1985. In vitro cultivation of Cowdria ruminantium. Onderstepoort Journal of Veterinary Research, 52:113-120.
13. BEZUIDENHOUT, J.D. & BIGALKE, R.D. 1987. The control of heartwater by means of tick control. Onderstepoort Journal of Veterinary Research, 54:525-528.
14. BIGALKE, R. 1985. Onderstepoort today, yesterday and tomorrow. Commemorative lecture. Onderstepoort Journal of Veterinary Research, 52:121-132.
15. CAMUS, E. 1992. Le portage asymptomatique de bovins et chèvres Créole guéris de la cowdriose en Guadeloupe. Revue d'Élevage et de Médecine Vétérinaire des Pays Tropicaux, 45: 133-135.
16. CAMUS, E. 1994. Application and uses of specific methods for diagnosis of cowdriosis in developing countries. Present and future trends. Proceedings of a FAO Expert Consultancy, Use of Applicable Biotechnological Methods for Diagnosing Haemoparasites, Merida, Mexico, 4-6 October 1993 (in press).
17. CAMUS, E. & BARRÉ, N. 1982. La cowdriose (heartwater). Revue General des connaissances. Institut d'Élevage et de Médécine Vétérinaire des Pays Tropicaux, Maisons-Mort, France.
18. CAMUS, E. & BARRÉ, N. 1987. Epidemiology of heartwater in Guadeloupe and in the Caribbean. Onderstepoort Journal of Veterinary Research, 54:419-426.
19. CAMUS, E. & BARRÉ, N. 1988. Heartwater. A review. (A translation of Camus & Barré 1982.) Publications of the Office International des Epizooties Bulletin, Paris.
20. COWDRY, E.V. 1925. Studies of the etiology of heartwater. I. Observation of a rickettsia. Rickettsia ruminantium (n. sp.), in the tissues of infected animals. Journal of Experimental Medicine, 42:231-252.
21. DAME, J.B., MAHAN, S.M. & YOWELL, C.A. 1992. Phylogenetic relationship of Cowdria ruminantium, agent of heartwater, to Anaplasma marginale and other members of the order Rickettsiales determined on the basis of 16S rRNA sequence. International Journal of Systematic Bacteriology, 42:270-274.
22. DIXON, R.W. 1898. Heartwater experiments. Agricultural Journal of the Cape of Good Hope, 12:754-762.
23. DONKIN, E.F., STEWART, C.G., MACGREGOR, R.G., ELS, H.C. & BOYAZOGLU, P.A. 1992. Resistance of indigenous and cross-bred goats to heartwater (Cowdria ruminantium). Recent Advances in Goat Production. (Proceedings of the fifth International Conference on Goats), New Delhi, India, 2-8 March. 1992: 1716-1719
24. DU PLESSIS, J.L. 1981 .The application of the indirect fluorescent antibody test to the serology of heartwater. in: Proceedings of an International Conference on Tick Biology and Control, Rhodes University, Grahamstown, Republic of South Africa, edited by G.B. Whitehead & J.P. Gibson: 47-52.
25. DU PLESSIS, J.L. & KUMM, N.A.L. 1971. The passage of Cowdria ruminantium in mice. Journal of the South African Veterinary Medical Association, 42:217-221.
26. DU PLESSIS, J.L. & MALAN, L. 1987a. The application of the indirect fluorescent antibody test in research on heartwater. Onderstepoort Journal of Veterinary Research, 54:319-325.
27. DU PLESSIS, J.L. & MALAN, L. 1987b.The block method of vaccination against heartwater. Onderstepoort Journal of Veterinary Research, 54: 493-495.
28. DU PLESSIS, J.L., JANSEN, B.C. & PROZESKY, L. 1983. Heartwater in Angora goats. I. Immunity subsequent to infection and treatment. Onderstepoort Journal of Veterinary Research, 50: 137-153.
29. DU PLESSIS, J.L. VAN GAS, L., OLIVIER, J.A. & BEZUIDENHOUT, J.D. 1989. The heterogenicity of Cowdria ruminantium stocks: cross-immunity and serology in sheep and pathogenicity to mice. Onderstepoort Journal of Veterinary Research, 56: 195-201.
30. DU PLESSIS, J.L., BEZUIDENHOUT, J.D., BRETT, M.S., CAMUS, E., JONGEJAN, F., MAHAN, S.M. & MARTINEZ, D. 1993. The sero-diagnosis of heartwater: a comparison of 5 tests. Revue d'Élevage et de Médecine Vétérinaire des Pays Tropicaux, 46: 123-129.
31. DU PLESSIS, J.L., DEWAAL, D.T. & STOLTSZ, W.H. 1994. A survey of the incidence and importance of the tick-borne diseases heartwater, redwater and anaplasmosis in the heartwater endemic regions of South Africa. Onderstepoort Journal of Veterinary Research, 61:295-301.
32. EDINGTON, A. 1898, Heartwater. Agricultural Journal of the Cape of Good Hope, 12:749-754.
33. FULLER, C. 1924. Tsetse in the Transvaal and surrounding territories. An historical review. 9th & 10th Reports of the Director of Veterinary Educational Research, Department of Agriculture, April 1923:315-379.
34. GRUSS, B. 1983. The danger of immunizing Boer goats against heartwater. Journal of the South African Veterinary Medical Association, 54:67-68.
35. HOWELL, C.J., DE VOS, A.J., BEZUIDENHOUT, J.D., POTGIE-TER, F.T. & BARROWMAN, P.R. 1981. The role of chemical tick eradication in the control or prevention of tick-transmitted diseases of cattle, in Proceedings of an International Conference on Tick Biology and Control, Rhodes University, Grahamstown, Republic of South Africa, edited by G.B. Whitehead & J.D. Gibson: 61-66.
36. HUTCHEON, D. 1900. The history of heartwater. Agricultural Journal of the Cape of Good Hope, 17:410-417.
37. IMMELMAN, A. & DREYER, G. 1982. The use of doxycycline to control heartwater in sheep. Journal of the South African Veterinary Association, 53:23-24.
38. JONGEJAN, F., THIELEMANS, M.J.C., BRIERE, C. & UILENBERG, G. 1991a. Antigenic diversity of Cowdria ruminantium isolates determined by cross-immunity. Research in Veterinary Science, 44:186-189.
39. JONGEJAN, F., THIELEMANS, M.J.C., VAN KOOTEN, P.J.S., DE GROOT, M. & VAN DER ZEIJST, B.A.M. 1991b. Competitive enzyme-linked immunosorbent assay for heartwater using monoclonal antibodies to a Cowdria ruminantium-specitic 32-kilodalton protein. Veterinary Microbiology, 28:199-211.
40. JONGEJAN, F. 1992a. Experimental transmission of Cowdria ruminantium (Rickettsiales) by the American reptile tick Amblyomma dissimile Koch, 1844. Experimental Applied Acarology, 15:117-121.
41. JONGEJAN, F. 1992b. Serodiagnosis of Cowdria ruminantium: current status. Recent Developments in the Control of Anaplasmosis, Babesiosis and Cowdriosis. Publication: ILRAD, Nairobi: 67-77.
42. JONGEJAN, F., VAN VLIET, A.H.M. & VAN DER ZEIST, B.A.M. 1994. Molecular cloning and expression of the gene encoding the immunodominant 32 kilodalton protein of Cowdria ruminantium. Proceedings of a FAO Expert Consultancy, Use of Applicable Biotechnological Methods for Diagnosing Haemoparasites, Merida, Mexico, 4-6 October 1993 (in press).
43. LAWRENCE, J.A., WHITELAND, A.P., MALIKA, J., KAFUWA, P.T. & JONGEJAN, F. 1993. Use of serological response to evaluate heartwater immunization of cattle. Revue d'Élevage et de Médecine Vétérinaire des Pays Tropicaux, 46:211-215.
44. LOGAN, L.L., HOLLAND, C.J., MEBUS, C.A. & RISTIC, M. 1986. Letters: Serological relationship between Cowdria ruminantium and certain ehrlichia. Veterinary Record, 119:458-459.
45. LOGAN, L.L., WHYARD, T.C.,QUINTERO, J.C. & MEBUS, C.A. 1987. The development of Cowdria ruminantium in neutrophils. Onderstepoort Journal of Veterinary Research, 54:197-204.
46. LOGAN, L.L., BIRNIE, E.F. & MEBUS, C.A. 1987. Cross-immunity between isolates of Cowdria ruminantium. Onderstepoort Journal of Veterinary Research, 54:345 (Abstract only).
47. LOUNSBURY, C.P. 1900. Tick heartwater experiments. Agricultural Journal of the Cape of Good Hope, 16:682-687.
48. LOUNSBURY, C.P. 1902. Heartwater in calves. Agricultural Journal of the Cape of Good Hope, 21:165-169.
49. LOUNSBURY, C.P. & ROBERTSON, W. 1904. Persian sheep and heartwater. Agricultural Journal of the Cape of Good Hope, 25:175-186.
50. MACKENZIE, P.K.I. & McHARDY, N. 1987. Cowdria ruminantium infection in the mouse: a review. Onderstepoort Journal of Veterinary Research, 54:257-269.
51. MAHAN, S.M., WAGHELA, S.D., McGUIRE, T.C., RURANGIRWA, F.R., WASSINK, L.A. & BARBET, A.F. 1992a. A cloned DNA probe for Cowdria ruminantium hybridizes with eight heartwater strains and detects infected sheep. Journal of Clinical Microbiology, 30:981-986.
52. MAHAN, S.M., WAGHELA, S.D., RURANGIRWA, F.R., YUNKER, C.E., CRAWFORD, T.B., BARBET, A.F., BURRIDGE, M.J. & McGUIRE, T.C. 1992b DNA probes for Cowdria ruminantium. Recent Developments in the Control of Anaplasmosis, Babesiosis and Cowdriosis. Publication: ILRAD, Nairobi: 79-83.
53. MAHAN, S.M., McGUIRE, T.C., JONGEJAN, F., RURANGIRWA, F.R. & BARBET, A.F. 1993a. Molecular cloning of a Cowdria ruminantium gene spectator an immunodominant 21 Kd protein. Abstract. 2nd Biennial Meeting of the American Society for Tropical Veterinary Medicine, Guadeloupe, West Indies, 2-6 February: 23.
54. MAHAN, S.M., TEBELE, N., MUKWEDEYA, D., SEMU, S., NYATHI, C.B., WASSINK, L.A., KELLEY, P.J., PETER, T. & BARBET, A.F. 1993b. An immunoblotting diagnostic assay for heartwater based on the immunodominant 32-kilodalton protein of Cowdria ruminantium detects false positives in field sera. Journal of Clinical Microbiology, 31:2729-2737.
55. MAMMERICKX, M. 1961. Les buffles domestiques d'Asie importés au Congo. I.N.E.A.C. Série technique, 24:50-51.
56. MARE, C.J. 1984. Heartwater. Foreign Animal Diseases. Their Prevention, Diagnosis and Control. Publication United States Animal Health Association, Richmond, VA, USA: 186-194.
57. MARTINEZ, D., SWINKELS, J.T., CAMUS, E. & JONGEJAN, F. 1990. Comparaison de trois antigènes pour le sérodiagnostique de la cowdriose. Revue Élevage et de Médecine Vétérinaire des Pays Tropicaux, 43:159-166.
58. MATHERON, G., BARRÉ, N., CAMUS, E. & GOGUE, J. 1987. Genetic resistance of Guadeloupe native goats to heartwater. OnderstepoortJournal of Veterinary Research, 54:337-340.
59. MULLER KOBOLD, A., MARTINEZ, D., CAMUS, E. & JONGEJAN, F. 1992. Distribution of heartwater in the Caribbean determined on the basis of detection of antibodies to the conserved 32-kilodalton protein of Cowdria ruminantium. Journal of Clinical Microbiology, 30:1870-1873.
60. NEITZ, W.O. 1940. Uleron in the treatment of heartwater. Journal of the South African Veterinary Medical Association, 11:15.
61. NEITZ, W.O. & ALEXANDER, R.A. 1941. The immunization of calves against heartwater. Journal of the South African Veterinary Medical Association, 12:103-111.
62. NEITZ, W.O. & ALEXANDER, R.A. 1945. Immunization of cattle against heartwater and the control of the tick-borne diseases, redwater, gallsickness and heartwater. Onderstepoort Journal of Veterinary Science and Animal Industry, 20:137-158.
63. NEITZ, W.O. 1947. Die oordraging van hartwater deur Amblyomma pomposum Dönitz 1909. South African Journal of Science, 1: 83.
64. NEITZ, W.O. 1968. Heartwater. Bulletin. Office International des Epizooties, 70:329-336.
65. NORVAL, R.A.I., ANDREW, H.R. & YUNKER, C.E. 1990. Infection rates with Cowdria ruminantium of nymphs and adults of the bont tick Amblyomma hebraeum collected in the field in Zimbabwe. Veterinary Parasitology, 36:277-283.
66. NORVAL, R.A.I., ANDREW, H.R.,YUNKER, C.E. & BURRIDGE, M.J. 1992. Biological processes in the epidemiology of heartwater, in Tick Vector Biology. Medical and Veterinary Aspects, edited by B. Fivaz, T. Petney & I. Horak. New York: Springer-Verlag: 71-86.
67. OBEREM, P.T. & BEZUIDENHOUT, J.D. 1987. Heartwater in hosts other than domestic ruminants. Onderstepoort Journal of Veterinary Research, 54:271-275.
68. PEPIN, L., CAMUS, E., MATHERON, G. & BENSAID, A. 1993. Use of microsatelites as genomic markers to study resistance to cowdriosis. Revue d'Élevage et de Médecine Vétérinaire des Pays Tropicaux, 46:209 (Abstract only).
69. PERREAU, P., MOREL, P.C., BARRÉ, N. & DURAND, P. 1980. Existence de la cowdriose (heartwater) àCowdria ruminantium chez la petit ruminants des Antilles françaises (la Guadeloupe) et des Mascareignes (la Reunion et l'lle Maurice). Revue d'Élevage et de Médecine Vétérinaire des Pays Tropicaux, 33: 21-22.
70. PETNEY, T.N., HORAK, I.G. & RECHAV, Y. 1987. The ecology of the African vectors of heartwater, with particular reference to Amblyomma hebraeum and Amblyomma variegatum. Onderstepoort Journal of Veterinary Research, 54:381-395.
71. PIENAAR, J.G., BASSON, P.A. & VAN DER MERWE, J.L. DEB. 1966. Studies on the pathology of heartwater [Cowdria (Rickettsia) ruminantium (Cowdry 1926)]. I. Neuropathological changes. Onderstepoort Journal of Veterinary Research, 33: 115-138.
72. POISSON, H. & GEOFFROY (_) 1925. [Cited by Provost, A. and Bezuidenhout, J.D. 1987, fide Curasson, G. 1936. Heartwater. Traité de pathologie éxotique vétérinaire comparée. Paris: Vigot, 2:316-353.]
73. PRELLER, G.S. 1938. Dagboek van Louis Trichardt (1836-1838). Met inleiding en aantekeninge. Cape Town: Nasionale Pers: 273-274; 288-289.
74. PROVOST, A. & BEZUIDENHOUT, J.D. 1987. The historical background and global importance of heartwater. Onderstepoort Journal of Veterinary Research, 54:165-169.
75. PROZESKY, L. 1987. The pathology of heartwater. III. A review. Onderstepoort Journal of Veterinary Research, 54:281-286.
76. PURCHASE, H.S. 1945. A simple and rapid method for demonstrating Rickettsia ruminantium (Cowdry 1925) in heartwater brains. Veterinary Record, 57:413-414.
77. PURNELL, R.E. 1984. Control of heartwater in cattle in southern Africa using Terramycin/LA. Preventive Veterinary Medicine, 2: 239-254.
78. PURNELL, R.E. 1987. Development of a prophylactic regime using terramycin/LA to assist in the introduction of susceptible cattle into heartwater endemic areas of Africa. 54:509-512.
79. RISTIC, M. & HUXSOLL, D.L. 1984. Tribe II. Ehrlichieae Philip 1957, 948, in Bergey's Manual of Systematic Bacteriology, edited by N.R. Krieg & J.G. Holt. Baltimore: Williams & Wilkins, 1:704-711.
80. RUFF, G., MAILLARD, J.C., CAMUS, E., DEPRES, E. & MATHERON, G. 1993. Occurrence of caprine leucocyte antigens (CLA) in Creole goats susceptible/resistant to heartwater. Revue d' Élevage et de Médecine Vétérinaire des Pays Tropicaux, 46: 205-207.
81. SCOTT, G.R. 1987. The taxonomic status of the causative agent of heartwater. Onderstepoort Journal of Veterinary Research, 54:257-260.
82. SEMU, S., MAHAN, S.M.,YUNKER, C.E. & BURRIDGE, M.J. 1992. Development and persistence of Cowdria ruminantium antibodies following experimental infection of cattle, as detected by the indirect fluorescent antibody test. Veterinary Immunology and Immunopathology, 33:339-352.
83. SOLDAN, A.W., NORMAN, T.L. MASAKA, S., PAXTON, E.A., EDELSTEN, R.M. & SUMPTION, K.J. 1993. Seroconversion to Cowdria ruminantium of Malawi zebu calves, reared under different tick control strategies. Revue d'Elevage et de Médecine Vétérinaire des Pays Tropicaux, 46:171-177.
84. SPREULL, J. 1922. Heartwater. Agricultural Journal of the Union of South Africa, 4:236-255.
85. STECK, W. 1928. Pathological studies on heartwater. 13th & 14th Reports of the Director of Veterinary Education and Research, Department of Agriculture, October: 283-309.
86. STILLER, D. 1990. Application of biotechnology for the diagnosis and control of ticks and tickborne diseases. Parassitologia, 32:87-111.
87. SYNGE, B.A. 1978. Brain biopsy in the diagnosis of heartwater. Tropical Animal Health and Production, 10:45-48.
88. THOMAS, A.D. & MANSVELT, P.R. 1957. The immunization of goats against heartwater. Journal of the South African Veterinary Medical Association, 28:163-168.
89. UILENBERG, G. 1971a. Études sur la cowdriose à Madagascar. Première partie. Revue d'Élevage et de Médecine Vétérinaire des Pays Tropicaux, 24:239-249.
90. UILENBERG, G. 1971b. Études sur la cowdriose à Madagascar. Deuxième partie. Revue d'Elevage et de Médecine Vétérinaire des Pays Tropicaux, 24:355-364.
91. UILENBERG, G. 1981. Heartwater disease in Diseases of cattle in the tropics, edited by M. Ristic & I. McIntyre.The Hague, The Netherlands: Nijhoff Publication: 345-360.
92. UILENBERG, G. 1982. Experimental transmission of Cowdria ruminantium by the Gulf Coast tick Amblyomma maculatum: danger of introducing heartwater and benign African theileriosis onto the American mainland. American Journal of Veterinary Research, 43:1279-1282.
93. UILENBERG, G. 1983. Heartwater (Cowdria ruminantium infection): Current status. Advances in Veterinary Science and Comparative Medicine, 27:427-480.
94. UILENBERG, G. 1989. La cowdriose caprine, in African small ruminant research and development, edited by R.T. Wilson & A. Melaku. African Small Ruminant Research Network: Addis Ababa: ILCA: 427-435.
95. UILENBERG, G. 1990a. Extension de la tique Amblyomma variegatum dans les Antilles: comment expliquer cette grave menace et que faire? Revue d'Élevage et de Médicine Vétérinaire des Pays Tropicaux, 43:297-299.
96. UILENBERG, G. 1990b. Methods currently used for the control of heartwater: Their validity and proposals for future control strategies. Parassitologia, 32:55-62.
97. UILENBERG, G. 1994. Recent advances in the diagnosis of heartwater. Proceedings of a FAO Expert Consultancy, Use of Applicable Biotechnological Methods for Diagnosing Haemoparasites. Merida, Mexico, 4-6 October 1993 (in press).
98. VAN AMSTEL, S.R. & OBEREM, P.T. 1987. The treatment of heartwater. Onderstepoort Journal of Veterinary Research, 54:475-479.
99. VAN DE PYPEKAMP, H. & PROZESKY, L. 1987. Heartwater. An overview of the clinical signs, susceptibility and differential diagnoses of the disease in domestic ruminants. Onderstepoort Journal of Veterinary Research, 54:263-266.
100. VANVLIET, A.M., JONGEJAN, F. & VAN DER ZEIJST, B.A. 1992. Phylogenetic position of Cowdria ruminantium (Rickettsiales) determined by analysis of amplified 16S ribosomal DNA sequences. Internationa/Journal of Systematic Bacteriology, 42: 494-498.
101. WAGHELA, S.D., RURANGIRWA, F.R., MAHAN, S.M.,YUNKER, C.E., CRAWFORD, T.G., BARBET, A.F., BURRIDGE, M.J. & Mc GUIRE, T.C. 1991. A cloned DNA probe identifies Cowdria ruminantium in Amblyomma variegatum ticks. Journal of Clinical Microbiology, 29:2571-2577.
102. WALKER, J.B. & OLWAGE, A. 1987. The tick vectors of Cowdria ruminantium (Ixodoidea, Ixodidae, genus Amblyomma) and their distribution. Onderstepoort Journal of Veterinary Research, 54: 353-379.
103. WHITE, F. 1983. The Vegetation of Africa, Paris: UNESCO.
104. YUNKER, C.E., BYROM, B. & SEMU, S. 1988. Cultivation of Cowdria ruminantium in bovine vascular endothelial cells. Kenya Veterinarian, 12:12-16.
105. YUNKER, C.E. 1991. The epidemiology, diagnosis and control of heartwater, in Cowdriosis and Dermatophilosis of Livestock in the Caribbean Region. Trinidd and Tobago: Caribbean Agricultural Research Development Institute, St. Augustine: 87-96.
106. YUNKER, C.E., MAHAN, S.M., WAGHELA, S.D., McGUIRE, T.C., RURANGIRWA, F.R., BARBET, A.F. & WASSINK, L.A. 1993. Detection of Cowdria ruminantium by means of a DNA probe, pCS20, in infected bont ticks, Amblyomma hebraeum, the major vector of heartwater in Southern Africa. Epidemiology and Infection, 110:95-104.
107. YUNKER, C.E. & ALLSOPP, B.A. 1994. Modern biotechnological methods for diagnosis of cowdriosis - present and future trends. Proceedings of a FAO Expert Consultancy, Use of Applicable Biotechnological Methods for Diagnosing Haemoparasites, Merida, Mexico, 4-6 October 1993. FAO Publication, Rome, Italy: 143-155.