Elongate and Round Gametocytes of Leucocytozoon simondi (Mathis & Léger) in Ducks Inoculated with Megaloschizonts

SYNOPSIS. Single megaloschizonts give rise to elongate and round gametocytes, the former outnumbering the latter. Male and female elongate gametocytes develop from merozoites of a single megaloschizont. Elongate gametocytes were seen 2–7 days and round gametocytes 6–11 days after megaloschizonts had been inoculated into ducklings. Experimental evidence indicates that merozoites of megaloschizonts invade blood cells and develop into elongate gametocytes. Other merozoites infect tissue cells and develop into secondary exoerythrocytic schizonts which give rise to round gametocytes. Relapse in Leucocytozoon simondi infections is discussed in relation to megaloschizont-induced exoerythrocytic schizogony.     

Plasmodium (Sauramoeba) pelaezi n. sp., a malaria parasite of the mexican iguanid lizardUrosaurus bicarinatus bicarinatus (Dumeril, 1856) (Sauria: Iguanidae)

A new Mexican species of saurian malaria parasite,Plasmodium (Sauramoeba) pelaezi, is described from the iguanid lizardUrosaurus bicarinatus bicarinatus. Two out of 12 specimens collected at Chila de la Sal (Puebla, México) were found infected. The species is characterized by round and oval gametocytes. Schizonts are mostly round with a single mass of pigment and with 16 merozoites in mature forms. Gametocytes cause shrinkage of infected cells and schizonts render the host cell nuclei spherical.     

Saurian Malarial Parasites in Eastern Panama

SYNOPSIS Plasmodium gonatodi sp. nov. is described from Gonatodes albogularis fuscus of eastern Panama. It is characterized by elongate gametocytes and polymorphic schizonts containing 12-46 nuclei when apparently mature. Both proerythrocytes and erythrocytes are commonly parasitized, host cells are hypertrophied and distorted, and their nuclei are displaced. Prematuration sexual stages may be irregularly shaped and larger than mature gametocytes.
Plasmodium diploglossi Aragão and Neiva , 1909 is reported from Mabuya mabouya in eastern Panama, and Plasmodium morulum sp. nov. is described from this host. P. morulum usually parasitizes immature erythrocytes, and is characterized by lenticular or oval to round gametocytes, and schizonts with 14-40 nuclei usually arranged in a globular mass. Host cells are slightly hypertrophied and distorted, and their nuclei are usually displaced. Inoculation of infected blood into clean hosts produces numerous schizonts in white cells as well as in the erythrocyte series.
Pigment in both P. gonatodi and P. morulum , if present, consists of a few minute dark dots which do not meet the polarized light test for hemozoin.     

The saurian malarias of Venezuela: Haemosporidian parasites of gekkonid lizards

Telford S. P., Jr. 1978. The saurian malarias of Venezuela: haemosporidian parasites of gekkonid lizards. International Journal for Parasitology8: 341–353. Five haemosporidian species were found among 185 gekkonid lizards from Estados Portuguesa, Cojedes and Aragua, Venezuela, four of which were new to science. A pigmented Plasmodium species is described from Gonatodes taniae of Estado Aragua. It produces 8–20 merozoites in variably shaped schizonts, and elongate, irregularly margined prematuration gametocytes which contract to form round to broadly elongate mature gametocytes. Phyllodactylus ventralis of Estado Portuguesa is parasitized by two new unpigmented malarial species. One produces 11–35 merozoites in schizonts which are often rounded or elongated, occasionally fan-shaped. Gametocytes are always elongated and usually lie diagonally across one end of the host cell or laterally to the nucleus. The second species forms rounded mature schizonts nearly filled with 14–32 merozoites. The sexual stages are usually round or oval, rarely elongate. Plasmodium aurulentum Telford, 1971 was found in Thecadactylus raplcaudus of Estados Portuguesa and Cojedes. A single Thecadactylus from Cojedes was infected by a haemosporidian species of uncertain generic identity which resembles a parasite found earlier in a Panamanian gecko.     

A malarial parasite of Australian skinks, Plasmodium mackerrasae sp. n.

Plasmodium mackerrasae sp. n. parasitizes the Australian lizards Egernia cunninghami and E. striolata (Sauria: Scincidae). Described from an experimental host, E. whitei, it produces mature schizonts containing 6--12 nuclei arranged peripherally as a rosette, and round to oval gametocytes which are equal to or slightly smaller than host cell nuclei. Both schizonts and gametocytes parasitize all cells in the erythrocyte series. Presence of pigment in both asexual and sexual stages is correlated with maturity of the host cell. Asexual forms contain a single large vacuole, whereas mature gametocytes may show 1--4 vacuoles. Plasmodium mackerrasae resembles most closely P. sasai of Japan and P. tropiduri of tropical America. It differs from P. sasai by lacking fan-shaped schizonts and by having less heavily pigmented gametocytes, and from P. tropiduri by less variability in shape and greater vacuolation of the gametocytes. Host and geographic differences further support its distinction.     

Malaria Parasites of the “Borriguerro'’Lizard,Ameiva ameiva (Sauria: Teiidae) in Panama*

SYNOPSIS. The teiid lizard Ameiva ameiva praesignis in Panama is parasitized by 2 species of Plasmodium: P. cnemidophori Carini and P. diminutivum sp. n. The Panamanian strain of P. cnemidophori has thick macrogametocytes which are larger than the oval microgametocytes, and schizonts which contain 42–119 nuclei. P. diminutivum is characterized by round to oval gametocytes which are usually smaller than the host cell nucleus; fan-shaped schizonts with 4–6 nuclei; and prominently vacuolated young stages, with a thick band of chromatin along the periphery of the vacuole.     

Gametocyte formation by the progeny of single Plasmodium falciparum schizonts

Gametocytogenesis of the malaria parasite Plasmodium falciparum was studied in monolayers of erythrocytes attached to tissue culture dishes. Merozoites produced by single schizonts in erythrocytes overlaying the monolayer infected the attached erythrocytes and produced clusters of progeny. Parasites in these readily indentifiable clusters then underwent either asexual growth or sexual differentiation. The progeny of most schizonts yielded no gametocytes. However, the progeny of those schizonts that did yield gametocytes showed a marked tendency to produce multiple gametocytes. Gametocytogenesis, therefore, was not random. Instead, the progeny of certain schizonts were committed to produce gametes. However, even those clusters containing several gametocytes also contained asexual forms. Therefore, not all merozoites of a single schizont were committed to gametocytogenesis. In those cells infected with two or more merozoites the formation of a gametocyte was usually associated with a block in the further development of other parasites.     

A Malaria Parasite, Plasmodium aurulentum sp. nov. from the Neotropical Forest Gecko Thecadactylus rapicaudus

SYNOPSIS. Plasmodium aurulentum sp. nov. from the neotropical forest gecko Thecadactylus rapicaudus in Panama is characterized by oval or round to lenticular gametocytes, 6–22 nuclei in crudely fan-shaped schizonts, and light golden pigment masses. A prominent, pinkish red-staining mass, present in older schizonts, disappears by the time schizonts reach maturation.     

Two malaria parasites (Apicomplexa: Plasmodiidae) of the Australian skink Egernia stokesii

The Australian skink Egernia stokesii is parasitized uncommonly by Plasmodium circularis n. sp. and by Plasmodium mackerrasae. Plasmodium circularis is distinguished from all other plasmodiids by immature schizonts that encircle host cell nuclei, forming an unbroken ring from apparent fusion of the attenuated ends. Mature schizonts contract into halteridial or dumbbell-shaped forms 15.6 x 4.3 microm, LW 66.2 microm2, with 19-52 nuclei. Rounded or oval gametocytes are 9.0 x 7.3 microm, LW 66.9 microm2, and L/W 1.24. Gametocyte LW is 2.63 x host erythrocyte nucleus size and 1.79X uninfected erythrocyte nuclei. Plasmodium mackerrasae occurs in high prevalence and often massive parasitemia in E. stokesii. Schizonts, often oblong, elongate, or oval, are 5.1 x 3.7 microm, LW 19.8 microm2, with 7.2 merozoites. Immature gametocytes, elongate with terminal nucleus, may produce multiple infections of 6 or more parasites. Mature gametocytes, usually rounded, are 5.8 x 4.6 microm, LW 26.7 microm2, and L/W 1.29. Gametocyte size is 0.98 x host erythrocyte nucleus size and 1.03 x uninfected erythrocyte nuclei. Phanerozoites, in endothelium or connective tissue of most organs, may appear in large numbers in circulating blood as seemingly intact bodies of regular form, similar to or larger than phanerozoites seen in sections. Previously unreported phenomena for hemosporidian parasites include extremely large, highly irregular exoerythrocytic schizonts, in circulating blood, perhaps torn from endothelial lining of blood vessels and sinuses, and a visible flooding of free merozoites into the blood stream.     

Schizogony and Gametogony of Leucocytozoon simondi and Associated Reactions in the Avian Host*

SYNOPSIS. Stages of development of Leucocytozoon simondi in White Pekin ducklings and their reactions to the parasite were studied on successive days after infecting them artificially with sporozoites from Simulium rugglesi. The minimum prepatent period was 5 days. The first asexual cycle occurred exclusively in the parenchymal cells of the liver. Progeny of these hepatic schizonts followed one of 3 courses: (a) invaded parenchymal liver cells to give rise to another hepatic cycle, (b) penetrated blood cells to form round gametocytes, and (c) were phagocytized by macrophages and grew into megaloschizonts thruout the body. The appearance of elongating gametocytes coincided with the period of maturation and release of merozoites from the megaloschizonts. Experimental evidence supports the hypothesis that the round gametocytes arise from the hepatic schizonts and the elongate forms from the megaloschizonts. Mature megaloschizonts released millions of merozoites, but a high 2nd peak in parasitemia did not develop because of retention of developing gametocytes in the deep circulation, particularly the liver and spleen, and a pronounced host reaction.     

贝氏隐孢子虫在北京鸭体内发育的超微结构研究

贝氏隐孢子虫各期虫体均位于宿主粘膜上皮细胞的带虫空泡中。在虫体与上皮细胞接触处,虫体表膜反复折迭形成营养器。子孢子或裂殖子与粘膜上皮细胞接触后,逐步过渡为球形的滋养体;滋养体经2—3次核分裂、产生含4或8个裂殖子的两代裂殖体,裂殖体以外出芽方式产生裂殖子;裂殖子无微孔,顶端表皮形成3—4个环嵴,裂殖子进一步发育成为配子体;大配子体含有两种类型的成囊体。小配子呈楔形,无鞭毛和顶体,有一个致密的长椭圆形细胞核,小配子表膜内侧有9根膜下微管;孢子化卵囊内含四个裸露的子孢子和一个大残体。本文是有关鸭体内隐孢子虫超微结构的首次报导。     

Plasmodium spp. (Apicomplexa: Plasmodiidae) of the flying lizardDraco volans (Agamidae)

The agamid lizardDraco volans from Palawan, Republic of the Philippines, was found to be parasitised by threePlasmodium species:P. draconis n. sp.,P. volans n. sp. andP. vastator, Laird 1960. BothP. draconis andP. volans, but notP. vastator, were also present inD. volans from Sarawak. The species are readily distinguished by schizont size, merozoite number, and gametocyte size and shape.P. volans has schizonts approximately one-half the size of those ofP. draconis and produces 4–6 merozoites in comparison to 4–16 in the larger species. Gametocytes of both new species are predominantly oval in the Palawan sample and elongate in that from Sarawak.P. draconis gametocytes are approximately twice the size ofP. volans gametocytes, but on average no more than one-half the size of gametocytes ofP. vastator.     

A new species of Plasmodium from Malagasy vangas

During a recent examination of blood smears from Malagasy birds, a species of avian Plasmodium unlike those currently known was observed. All infected birds were members of the Vangidae, which is endemic to Madagascar and the Comoro Islands. Plasmodium parvulum n. sp. is described, and classified as a member of the subgenus Haemamoeba because of gametocyte and schizont shape, displacement of the host cell nucleus, as well as distortion of the host cell. Round, rosettelike schizonts with 6-8 merozoites, clumped refractile granules, and little cytoplasm were observed. Both schizonts and mature, round gametocytes rotated and displaced the erythrocyte nucleus. A brief comparison to P. relictum is included.     

Observations on First-Generation Schizogony of Leucocytozoon caulleryi in Chickens

ABSTRACT. First and second generation schizogony of Leucocytozoon caulleryi occurred in chickens infected with sporozoites. First generation schizogony was studied by light and electron microscopy. First-generation schizonts were first detected in capillary endothelial cells in the spleen, lung, liver, and bursa of Fabricius between 3 and 6 d post-sporozoite inoculation (DPI). The schizonts ranged from 15 to 65 μm in diameter and were surrounded by a thin pellicle. Early schizonts contained numerous round or oval nuclei, endoplasmic reticulum, and mitochondria. The schizonts reached maturity 5 DPI and produced first-generation merozoites which were released into the peripheral bloodstream. The merozoites. which were infective to chickens, measured 7.1 μm in length. They were slender and had a large nucleus, a mitochondrion, and an apical complex consisting of three polar rings, rhoptries, numerous micronemes. The morphology of first-generation merozoites was different from that of second-generation merozoites.     

Haemoproteus palumbis sp. nov. (Sporozoa, Haemosporina) of the English Wood-Pigeon Columba p. palumbus

SYNOPSIS. Haemoproteus palumbis sp. nov. is described from the English wood-pigeon, Columba p. palumbus. Its pigmented gametocytes inhabit erythrocytes and resemble those of H. columbae (in C. livia ) but may be slightly longer and narrower. It is characterized by having oval or slightly lobed, not elongate, schizonts in endothelial cells of lung and heart, a prepatent period of 14 days, and a sporogonic cycle in the hippoboscid fly Ornithomya avicularia lasting 6 1/2–7 days. H. palumbis sp. nov. cannot infect C. livia but can infect a small proportion of individuals of Pseudolynchia canariensis , the vector of H. columbae.     

The Fine Structure of Differentiating Merozoites of Haemoproteus columbae Kruse*

SYNOPSIS. The first sign of merozoite formation in schizonts of Haemoproteus columbae is the accumulation of dense material at intervals beneath the plasma membrane of the schizont. The schizont's membrane then invaginates in deep furrows cleaving the parasite into pseudo-cytomeres. thereby increasing the area of membrane available for differentiation. Signs of differentiation appear under this membrane as soon as it is formed. Rhoptries and polar rings develop in the region of the dense accumulations, the cytoplasm containing these structures begins to elevate, and each evagination differentiates into a merozoite. When the merozoite is half-formed, the cytostome appears, then dense bodies at the apex of the organism, and finally a spherical body intimately associated with a mitochondrion. These merozoites of Haemoproteus are assumed to be the forms that penetrate erythrocytes and become gametocytes. They contain the same organelles as merozoites of Plasmodium. However, the merozoites of Haemoproteus are oval like the erythrocytic merozoites of Plasmodium rather than elongate like the exoerythrocytic merozoites. This body shape may be a generic characteristic or it may indicate a structural difference between exoerythrocytic merozoites and merozoites that infect erythrocytes. When the merozoites of Plasmodium, Haemoproteus and Leucocytozoon are compared, the first 2 genera appear closely related, but Leucocytozoon seems very different. Perhaps it should not be included within the Haemoproteidae.     

Fallisia parasites (Haemosporidia: Plasmodiidae) from the flying lizard, Draco maculatus (Agamidae) in Thailand

Plasmodium (Fallisia) siamense n. sp. was described from the flying lizard Draco maculatus (Agamidae) collected near Bangkok, Thailand. Parasitic in thrombocytes, it produces 18-64 merozoites in schizonts that are larger than the usually oval gametocytes. Both gametocyte sexes showed a prominent nucleus, elongate in macrogametocytes and triangular in microgametocytes. This is the first Fallisia parasite described from a host outside the Neotropical Region, although presence of the genus in Australasia was reported 40 years ago, without formal taxonomic designation.     

Development of Haemogregarina pestanae in the toad Bufo regularis*

SYNOPSIS. Haemogregarina pestanae França, 1910, is apparently rare in Egypt, having been found in 1 toad Bufo regularis Reuss out of 689 examined. Capsulated capped, young thin, and young and advanced broad forms were present in the peripheral blood. Schizogony occurred in the liver. Two types of schizonts were present—macroschizonts producing 150 or more elongate oval merozoites surrounding a large residual body, and microschizonts producing 60 or less banana-shaped merozoites often radiating from a small, eccentric residual body. Merozoites of the first type developed into a large broad form representing early schizonts of the second type. The latter developed into thin young intraerythrocytic forms and apparently later into encapsulated capped gametocytes. H. pestanae, H. aegyptia and H. tunisiensis all occur in toads (Bufo regularis for the first two, and B. mauritanicus for the third), and produce characteristic encapsulated looped gametocytes in peripheral blood. The capsules contain dark-staining material condensed into a single well-developed cap in H. aegyptia and 1 or 2 much smaller caps in H. pestanae; this material is scattered regularly around the parasite in H. tunisiensis. The capsule of H. pestanae is more or less cylindrical along most of its length, more slender and slightly shorter than the regularly oval capsule of H. tunisiensis or the spindle- or egg-shaped capsule of H. aegyptia.     

Observations on Haemogregarina balli sp. n. from the Common Snapping Turtle,Chelydra serpentina*

SYNOPSIS. Haemogregarina balli sp. n. is described from the blood and organs of the common snapping turtle Chelydra serpentina serpentina and from the gastric and intestinal ceca of the presumed invertebrate hosts, the leeches Placobdella parasitica and Placobdella ornata. In the peripheral blood of the turtle, male and female gametocytes and immature erythrocytic schizonts are found within erythrocytes. The maturation of erythrocytic schizonts containing 6–8 merozoites is recorded from liver imprints. Schizonts with 13–25 merozoites are found in various cells of the liver, lung and spleen. In the gastric ceca of the leeches the host erythrocytes are digested, releasing the gametocytes and immature erythrocytic schizonts. Immature erythrocytic schizonts degenerate. Association of the gametocytes occurs in the intestinal ceca. The microgametocyte apparently gives rise to 4 nonmotile microgametes, one of which fertilizes the macrogamete while the other remain as condensed, residual nuclei on the periphery of the developing oocyst. The oocyst increases in size with maturity. A mature oocyst produces 8 sporozoites from a single germinal center. Sporozoites liberated from the oocyst are found in the tissues of the leech. Transovarial transmission of the parasite does not occur in the turtle. Attempts at experimental transmission failed. Previously unfed (control) leeches were negative for the parasite. Haemogregarina balli is compared with other haemogregarines described from C. serpentina. Features of species of Haemogregarina and Hepatozoon as well as the taxonomy of these genera are discussed.