Parasitic Protozoa (eBook)

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2012 | 2. Auflage
323 Seiten
Elsevier Science (Verlag)
978-0-08-092413-7 (ISBN)

Infos

Updated and much expanded, the Second Edition of Parasitic Protozoa is designed to be useful to physicians, veterinarians, and research scientists concerned with diseases caused by protozoa in man, and in domestic and wild animals including fish, mollusks and insects, as well as the more commonly considered vertebrate animals. Each section contains information on disease pathogens, treatment, diagnosis, and epidemiology of the diseases caused by the various protozoans. The book is not limited to these medically-oriented subjects, but treats taxonomy, morphology, and metabolism of the organisms in such a way as to be of interest to scientists and graduate students working in the field of protozoology. The entire edition, published in ten volumes, is arranged so that subjects of common interest occupy individual volumes.

Inhalt

Front Cover 1
Parasitic Protozoa 4
Copyright Page 5
Table of Contents 6
Contributors 14
Preface to the Second Edition 16
Preface to the First Edition 18
CHAPTER I. Trypanosoma rangeli 20
I. Introduction 20
II . Morphology in Blood and Culture, Life Cycles in Vertebrate and Invertebrate Hosts Transmission
III. Definition, Taxonomy, and Nomenclature 35
IV. Host–Parasite Relationships in Vertebrate and Invertebrate Hosts 37
V. Biochemistry and Molecular Biology 41
VI. Cultivation 50
VII. Antigenicity, Immunity in the Vertebrate Host, and Serological Diagnosis 51
VIII. Epidemiology: Distribution, Prevalence in Man, Animals, and Triatomines 55
IX. Diagnosis and Treatment 60
X. Summary 62
Acknowledgments 64
References 64
CHAPTER 2. Trypanosomatids of Plants 74
I. Introduction 74
II. Taxonomy and Nomenclature 75
III. The Morphology of Phytomonas 83
IV. Transmission and Life Cycle of Phytomonas 84
V. Host-Parasite Relationships 90
VI. Culture 92
VII· Biochemistry and Molecular Biology 95
VIII. Evolution and Ecology 97
IX. Summary and Concluding Statement 99
Acknowledgments 99
References 100
CHAPTER 3. Trypanosomes Causing Diseases in Man in Africa 104
I. Introduction 104
II. Morphology and Life Cycle 109
III. Taxonomy 116
IV· Host–Parasite Relationships 119
V. Biochemistry and Physiology 133
VI. Cultivation 142
VII. Antigenicity 144
VIII. Immunity 150
IX. Epidemiology and Control 153
X. Conclusion 156
References 157
CHAPTER 4. Animal Trypanosomiasis in Sub-Saharan Africa 176
I. Introduction 176
II. Etiology 180
III. Biochemistry 200
IV. Antigenic Variation 206
V. Epidemiology 213
VI. Clinical Disease 221
VII. Pathology 227
VIII. Immunology 239
IX. Diagnosis 247
X. Control 254
XI. Conclusions 264
Acknowledgments 264
References 264
CHAPTER 5. Salivarian Trypanosomes Causing Diseases in Livestock Outside Sub-Saharan Africa 296
I. Introduction 296
II. Mechanical Transmission 297
III. Trypanosoma (Trypanozoon) evansi (Steel, 1885) Balbiani, 1888 299
IV. Trypanosoma (Trypanozoon) equiperdum Doflein, 1901 314
V. Trypanosoma (Duttonella) vivax viennei Lavier, 1921 321
VI. Summary and Conclusions 325
Acknowledgments 326
References 326
Index 334
Contents of Future Volumes 344

Textauszug

Chapter 2

Trypanosomatids of Plants

F.G. Wallace; I. Roitman; E.P. Camargo

I Introduction

In view of the widespread distribution of protozoa, both free living and parasitic, their scarcity as internal parasites of the land spermatophytes is noteworthy. Only certain amoebae (see Nieschultz, 1931) and some of the lower trypanosomatids are known to occur in these plants. In only 12 families in 9 of the 52 orders of Spermatophyta are parasitic protozoa known. These are almost all trypanosomatids and most of the known ones are in latex-containing plants.

From the time of their first discovery (Lafont, 1909), flagellates of laticiferous plants were recognized as being related to Trypanosoma and Leishmania. Lafont was a medical officer in the French army whose interest in latex was prompted by the reputed medicinal qualities of the juice of Euphorbia pilulifera. The abundant starch granules in the latex suggested that it might be a good culture medium, so he asked his assistant, David, to examine the latex of many plants in search of motile organisms. The flagellates he found were named Leptomo nas davidi. Migone (1916), who discovered flagellates in latex of Araujia angustifolia of the milkweed family (Asclepiadaceae) in Paraguay, was a veterinarian. During a field expedition in search of reservoir hosts of Trypanosoma vivax, he looked at the milky juice of Araujia, keeping Lafont’s discovery in mind. After finding flagellates, he injected some of the juice into laboratory animals with negative results.

Much of the early research was stimulated by the vain expectation that plants might be reservoir hosts for human or animal hemoflagellates. The microscopic techniques were those of hematology and the culture media were often those used for trypanosomes. The editor of a botanical journal asked a leading protozoologist of the time to write a review of plant flagellates with the hope of gaining interest from his readers in the subject. There is little evidence that the excellent review that resulted (Mesnil, 1921) had the desired effect.

In the first two decades after their discovery there were numerous records of trypanosomatids from laticiferous plants from many countries, mostly in the tropics, but then there was a long period with little interest in them. In the 1930s Phytomonas was discovered in the sieve tubes of coffee trees in Suriname, causing a disease, but with the decline of coffee culture in that country research on the subject languished.

The modern revival of interest in plant flagellates was due in large part to the late R. B. McGhee who, with his associates, studied the distribution of the milkweed flagellate, traced its life cycle, pointed out the differences between the Phytomonas in its insect host and other trypanosomatids in the same host, and participated in the discovery of pathogenic Phytomonas in palm trees. With the discovery of the palm tree diseases in South and Central America (Parthasarathy et al., 1976; Dollet et al., 1977), an expansion of research on all aspects of trypanosomatids of plants has occurred. Other infections of possible economic significance have been found in manioc, tomatoes, and beans. Wenyon (1926), Nieschulz (1931), and Dollet (1984) have reviewed the subject.

II Taxonomy and Nomenclature

A THE GENERA OF LOWER TRYPANOSOMATIDS

The organisms called “lower trypanosomatids,” to which the plant flagellate parasites belong, do not constitute a formal taxonomic group but include those members of the family that are monoxenous parasites of invertebrate hosts or parasites of plants and insects and comprise the genera Leptomonas, Herpetomonas, Crithidia, Blastocrithidia, Rhynchoidomonas, and Phytomonas. The trypanosomatid parasites of plants are almost all in the genus Phytomonas but, because of the possible confusion of insect stages of that genus with those of other genera and the occasional occurrence of insect parasites as incidental parasites of plants, all of the genera of lower trypanosomatids are defined here. Further information on them may be found in articles by Wallace (1979) and McGhee and Cosgrove (1980). The genera may be defined by using the terms for morphological stages within the family Trypanosomatidae that are characterized as follows (Figure 2.1).

Figure 2.1 Morphological stages of trypanosomatids. 1, promastigote; 2, opisthomastigote; 3, amastigote; 4, epimastigote; 5, trypomastigote; 6, choanomastigote; 7, sphaeromastigote (From Vickerman, 1976.)

1. Promastigote: Elongated forms with kinetoplast, anterior to the nucleus, flagellum arising near it and emerging from the anterior end.

2. Opisthomastigote: Elongated forms with kinetoplast, posterior to the nucleus, flagellum arising near it, then passing through the body and emerging from its anterior end.

3. Amastigote: Rounded or elongated forms devoid of an external flagellum.

4. Epimastigote: Elongated forms with kinetoplast near the nucleus, flagellum arising near kinetoplast and emerging from the side of the body to run along its surface or along a short undulating membrane to the anterior tip from which it extends as a free flagellum.

5. Trypomastigote: Elongated forms with kinetoplast, posterior to the nucleus, flagellum arising near it and emerging from the side of the body to ran along its surface or along an undulating membrane to the anterior tip from which it may or may not extend as a free flagellum.

6. Choanomastigote: Relatively short, stout, “barleycorn” forms with kinetoplast near and usually anterior to the nucleus. Flagellum emerges from a funnel-shaped reservoir that opens in the wide anterior end.

7. Sphaeromastigote: Rounded forms possessing a free flagellum.

The genera of lower trypanosomatids are characterized as follows: Leptomonas are promastigote parasites of invertebrate animals. Herpetomonas are promastigote parasites of insects that have opisthomastigote stages as well. Blastocrithidia are epimastigote parasites of invertebrate animals. Crithidia are choanomastigote parasites of invertebrate animals. Rhynchoidomonas are trypomastigotes that are tapered to a point at each end; they are parasites of insects. Phytomonas are promastigote parasites of plants and insects. Cysts (spores) are produced by some species of Leptomonas and Blastocrithidia.

The pattern of occurrence of ornithine-arginine cycle enzymes is characteristic of each genus of trypanosomatids (Camargo et al., 1987). Figure 2.2 shows the relationship of the enzymes in the cycle.

Figure 2.2 Arginine cycle. A, arginase; AD, arginine deaminase; ASL, arginino-succinate lyase; ASS, arginino-succinate synthetase; CH, citrulline hydrolase; OCT, ornithine carbamoyl transferase.

Arginine is converted to ornithine and urea by arginase (A). Citrulline hydrolase (CH) converts citrulline to ornithine. The conversion of arginine to citrulline requires arginine deaminase (AD). Ornithine carbamoyl transferase (OCT) converts ornithine to citrulline. The conversion of citrulline to arginine is mediated by arginino-succinate synthetase (ASS) and arginino-succinate lyase (ASL).

In mammals ornithine is derived from glutamate. The conversion ornithine → citrulline → arginine → ornithine is repeated and at each cycle ammonia is taken up by ornithine and by citrulline and converted to urea at the arginine-ornithine step.

In trypanosomatids the arginine cycle amino acids are not derived from glutamate but must come from an exogenous source. The cycle is not repeated, as one or more of the enzymes is always missing. These one-celled organisms can excrete ammonia and have no need to convert it to urea. However, there are usually enzymes to convert arginine or citrulline into ornithine. The polyamines, which are essential for many important reactions related to nucleic acid metabolism, are derived from ornithine.

None of the trypanosomatids has all of the enzymes of the arginine cycle. Trypanosoma has none and Leishmania has arginase. We know the enzyme patterns for three genera of insect trypanosomatids (Figure 2.3). We do not know the enzyme patterns for Blastocrithidia because the only species readily cultured is B. culicis, which has a symbiote that supplies all of the enzymes.

Figure 2.3 Arginine-cycle enzyme patterns for trypanosomatids. 1, Crithidia-, 2, Leptomonas; 3, Herpetomonas and Phytomonas; 4, Leishmania.

The genera may be separated first by the presence or absence of arginase. Crithidia and Leptomonas have arginase and Herpetomonas and Phytomonas do not. Crithidia and Leptomonas can be distinguished from each other by the absence of the arginino-succinate part of the...

Produkt-Details

• Erscheint lt. Verlag: 2.12.2012
• Mitarbeit: Herausgeber (Serie): John R. Baker, Julius P. Kreier
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete ► Mikrobiologie / Infektologie / Reisemedizin
• Themenwelt: Studium ► Querschnittsbereiche ► Epidemiologie / Med. Biometrie
• Themenwelt: Naturwissenschaften ► Biologie ► Mikrobiologie / Immunologie
• Themenwelt: Naturwissenschaften ► Biologie ► Zoologie
• Themenwelt: Technik
• Themenwelt: Veterinärmedizin ► Klinische Fächer ► Parasitologie
• ISBN-10: 0-08-092413-1 / 0080924131
• ISBN-13: 978-0-08-092413-7 / 9780080924137