In vitro quantitation of Theileria parva sporozoites for use - TropMed ...

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Chapter 1: Quantitation of Theileria parva sporozoites: Review of literature 19 ______________________________________________________________________________________________ "There came large, handsome oxen from the interior to Sena on the River Cuama, sixty miles form the coast. The oxen died suddenly, though fine and in good condition, and were given to the soldiers for food" - Father Monclaro in 1569 (Theal, 1916) cited by Henning (1932) who wrote that this was "probably the first record of a disease that can be identified as East Coast fever" 1.1. Introduction This chapter reviews available literature on aspects of quantitating Theileria parva sporozoite stabilates for immunisation and related fields of research. Immunisation by the Infection and Treatment (I & T) method is currently the only technique for protecting susceptible cattle against East Coast fever, a disease of economic importance in eastern central and southern Africa. The history, epidemiology and control options of the disease are presented in brief. Survival of T. parva in the natural hosts and in vitro is re-visited as it pertains to quality of immunising stabilates. The survival of the parasite is currently assessed by titrating selected doses of stabilates in groups of cattle. Available information is examined on other techniques of quantitating this survival and their suitability for vaccine dose determination reviewed. 1.1.1. The history of East Coast fever East Coast fever (ECF) is considered the most economically important tick-borne disease of cattle in affected areas (McInerney et al., 1992). The disease was endemic along the coast of East Africa "for generations" (Mettam and Carmichael, 1936 - cited by Norval et al. (1992f) and is believed to have originated in buffalo populations (Norval et al., 1992f). Notwithstanding the opening quote to this chapter, which refers to a "probable" outbreak of the disease, scientific records describe the disease as having been introduced into southern Africa through Zimbabwe (then Southern Rhodesia) in 1902 by a consignment of cattle shipped from Tanzania to Beira, Mozambique for restocking after the rinderpest epidemic of 1896-97 (Gray and Robertson, 1902 - cited by (Dolan, 1999). High mortalities in both local and imported cattle ensued and the disease was initially wrongly diagnosed as Rhodesian redwater (babesiosis) by Theiler (1903). From this focus, the disease spread to other parts of central and southern Africa where the vector was already present. A causative agent for East Coast fever was first described by Koch in 1898 (Norval et al., 1992e) who mistook it for young forms of Babesia bigemina while investigating Texas fever in East Africa. The organism was first named Piroplasma kochi by Stephens and Christophers (1903) and a few years later called Piroplasma parvum by Theiler (1905), both cited by Norval et al. (1992e).
20 Chapter 1: Quantitation of Theileria parva sporozoites: Review of literature ______________________________________________________________________________________________ It was subsequently called Theileria parva when Bettencourt, Franca and Borges (1907) cited by Norval et al. (1992d), created a new genus comprising 26 species of Theileria. 1.1.2. Biology of T. parva 1.1.2.1. Classification of Theileria species The taxonomy of T. parva according to Levine (1988): Kingdom: Protista Subkingdom: Protozoa Phylum: Class: Subclass: Order: Family: Genus: Apicomplexa Sporozea Piroplasmia Piroplasmida Theileriidae Theileria The species of economic importance that infect domesticated animals are: Theileria parva, Theileria annulata, Theileria taurotragi, Theileria mutans, Theileria velifera, Theileria orientalis in cattle; Theileria ovis, Theileria hirci in sheep and goats and Theileria equi in horses. Two former Babesia spp are now commonly described as T. equi and Theileria microti (Uilenberg, 2006). The latter causes human theileriosis (= human babesiosis) and is therefore of zoonotic importance. Based on clinical manifestations and for convenience, T. parva was classified trinomially in the 1980's as 1) T. parva parva, that causes classical ECF, 2) T. parva lawrencei responsible for "Corridor disease" transmitted from buffalo to cattle and 3) T. parva bovis implicated in "January disease" unique to Zimbabwe (Uilenberg et al., 1982). With improved molecular characterization techniques, it was decided to drop this form of classification and revert to single taxonomy as T. parva since there was no molecular basis for the distinction (Anon.1989). It is known that within T. parva, stocks with distinct antigenic characteristics exist (Radley, 1981; Irvin, 1987; Nambota et al., 1997; Geysen et al., 1999). This poses complications for immunisation as protection is strain specific (Goddeeris et al., 1986) and therefore, vaccine stocks have to be carefully matched to prevailing local stocks in particular regions. A few examples of stocks with antigenic differences that are relevant to immunisation are given in Table 1.
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Page 6 and 7: V ACKNOWLEDGEMENTS This work was ma
Page 8 and 9: VII TABLE OF CONTENTS ACKNOWLEDGEME
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Page 14 and 15: General Introduction 13 ___________
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Chapter 6: Storage of Theileria par
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Chapter 7: Lyophilisation of Theile
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Chapter 8: SNA and refinement of ti
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APPENDICES
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SUMMARY
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Curriculum Vitae
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