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.     

Freeze-Preservation of Leucocytozoon simondi Sporozoites in Liquid Nitrogen

SYNOPSIS. Sporozoites of L. simondi were maintained in a viable state for 7 months in liquid nitrogen. Comparison of parasite development initiated with fresh and frozen sporozoites showed a delay in development of each stage studied. Comparisons of prepatency, first elongate gametocytes, peak density of round and elongate forms, anemia and disappearance of megaloschizonts were made. In each phase there was a delay of 2–3 days in ducks infected with frozen sporozoites.     

The fine structure of elongate gametocytes of Leucocytozoon ziemanni (Laveran).

In an effort to establish comparative data within the genus Leucocytozoon, elongate gametocytes of L. ziemanni from naturally infected great horned owls (Bubo virginianus) were examined by electron microscopy. Micro- and macrogametocytes proved to be easily distinguishable at the electron microscopic level due to dramatic dimorphism at maturity and cytoplasmic and nuclear morphology. The parasite membrane architecture, number and type of cytoplasmic ribosomes of both micro- and macrogametocytes, presence and arrangement of osmiophilic bodies and electron dense spheres, mitochondrial morphology, endoplasmic reticulum cisternae morphology, mitochondria containing pocket infoldings of the nuclear membrane of the microgametocytes, and cytostome and food vacuole formation compare favorably with available information on L. simondi and L. smithi. Comparative variations exist only in that L. ziemanni gametocytes apparently lack compartmentalization of the cytoplasm by aligned unit membranes and parasite induced separations of the host cell nucleus as reported for L. simondi.     

Redescription of the life cycle of Haemogregarina simondi (Laveran and Mesnil, 1901) in its vertebrate host the marine fish Solea solea (Linnaeus).

The life cycle of Haemogregarina simondi is described in its vertebrate host the marine flatfish Solea solea. An intraleucocytic schizogony is followed by an intraerythrocytic schizogony giving rise to eight gametocytes. A differentiation into micro- and macro-gametocytes was also observed and thus confirms the results of other authors for H. aeglefini, H. bigemina, and H. sachai. It is postulated that most if not all of the haemogregarines of marine fish undergo similar life cycles as the one described here.     

Ultrastructural Study of Gametocytes and Gametogenesis of Haemoproteus metchnikovi

SYNOPSIS. The ultrastructure of gametocytes and microgametogenesis of Haemoproteus metchnikovi , an intracellular malaria parasite of chelonians, was compared with other malarial parasites. Gametocytes resemble those described for other avian, reptilian and mammalian malarial parasites. The process of microgametogenesis is similar in many respects to that reported for Leucocytozoon simondi (Aikawa et al., 1970) and Haemoproteus columbae (Bradbury and Trager, 1968). Atypical centrioles are described from both microgametocytes and macrogametocytes. Axoneme development begins before the microgametocyte leaves the host red blood cell. Fully developed microgametes which bud off from the parent gametocyte contain a single axoneme with the typical 9 + 2 pattern of microtubules.     

Observations on the ultrastructure of Haemogregarina simondi in the marine flatfish Solea solea (L.).

Developing stages of Haemogregarina simondi from the marine fish Solea solea (L.) were examined by electron microscopy. Merozoites lay in a parasitophorous vacuole and were bound by a pellicle of three unit membranes beneath which lay a ring of 45--61 microtubules. The cytoplasm contained 4--6 rhoptries, more than 169 micronemes, several mitochondria, and amylopectin granules. A conoid and one polar ring were observed at the anterior end. Intraleucocytic and intraerythrocytic schizonts with up to eight merozoites were described also. Intraerythrocytic and free gametocytes were characterized by distinct refractile bodies and a pellicle consisting of only two unit membranes. The number of micronemes was in excess of 194. The results were discussed in comparison with other members of the Haemogregarinidae.     

Studies of growth and development of gametocytes in Haemoproteus columbae Kruse.

As determined by their ability to exflagellate and round up, it took the macrogametocyte and the microgametocyte of Haemoproteus columbae in pigeons 68 and 116 h, respectively, after patency to reach maturity. Pigment granules appeared in the undifferentiated gametocytes 8 h after invasion of blood. Vacuoles were observed in young gametocytes and persisted in the older forms. The growth curve of H. columbae is close to the sigmoidal curve for growth in protozoa. Multiple infection was noticed in pigeons with high levels of parasitemia, but no more than 2 gametocytes reached maturity; such multiple infections were rare in relapses. The sex ratio of the gametocytes was 1:1. Strong lateral displacement of the nuclei of infected erythrocytes was the rule; hypertrophy was negligible.     

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.     

Hematozoa of waterfowl from Michigan

Two hundred eighteen and 127 wild waterfowl (Anatidae) of five species were sampled from the Kellogg Biological Station area (Michigan, USA) during the summer (1 June to 24 August 1995) and fall (9 September to 8 October 1995), respectively. Twelve (6%) of those sampled in summer and 13 (11%) sampled in the fall were infected with hemosporids. Haemoproteus nettionis, Haemoproteus greineri, and Leucocytozoon simondi infected both summer and fall birds, with H. nettionis the most common (4% summer; 7% fall). Mean intensities were low; the highest mean intensity was 4.6+/-1.1 gametocytes per 5,000 uninfected erythrocytes for H. nettionis in summer. Of 123 local waterfowl, none were infected with any blood parasite. Thirty-five captive year-round resident waterfowl also were sampled and no blood parasites were found.     

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.     

Malarial Parasites of the "Jesu Cristo" Lizard Basiliscus basiliscus (Iguanidae) in Panama

SYNOPSIS. The iguanid lizard Basiliscus basiliscus in Panama is parasitized by Plasmodium basilisci and P. achiotense sp. nov. P. basilisci in this host is characterized by schizonts containing 4–14 merozoites, with schizonts parasitizing proerythrocytes containing more merozoites than those in erythrocytes. Asexual parasites lack cytoplasmic projections, while mature gametocytes are round or oval with regular margins.
P. achiotense is characterized by the combination of prominently pigmented, large schizonts containing 36–56 merozoites and oval or round gametocytes which are about 1/3 larger than those of P. basilisci.
EE-schizonts of P. basilisci were observed commonly in thrombocytes and occasionally in lymphocytes, and appeared early in experimental infections induced by blood inoculation.     

Studies of Growth and Development of Gametocytes in Haemoproteus columbae Kruse*

SYNOPSIS As determined by their ability to exflagellate and round up, it took the macrogametocyte and the microgametocyte of Haemoproteus columbae in pigeons 68 and 116 h, respectively, after patency to reach maturity. Pigment granules appeared in the undifferentiated gametocytes 8 h after invasion of blood. Vacuoles were observed in young gametocytes and persisted in the older forms. The growth curve of H. columbae is close to the sigmoidal curve for growth in protozoa. Multiple infection was noticed in pigeons with high levels of parasitemia, but no more than 2 gametocytes reached maturity; such multiple infections were rare in relapses. The sex ratio of the gametocytes was 1:1. Strong lateral displacement of the nuclei of infected erythrocytes was the rule; hypertrophy was negligible.     

Anemia in Ducks Infected with Leucocytozoon simondi*†

SYNOPSIS. Thirty-four white Pekin ducklings were used to study the anemia associated with infection by Leucocytozoon simondi. The first appearance of gametocytes in the peripheral blood, as detected by thin smears, marked the onset of anemia. This anemia lasted for the duration of the initial parasitemia, usually reaching a low point early in the infection (1 to 5 days post patency) and returning slowly to normal as the parasitemia decreased. Greatest gametocyte density occurred 5 to 8 days post patency. In a number of cases recovery from anemia began simultaneously or even prior to the highest level in the gametocyte density. In low level parasitemias a fluctuation occurred in erythrocyte numbers which corresponded with the peaks of gametocyte density. In none of the infections was a sufficient number of parasite observed to account for the existing anemia. Haemopoietic activity was observed for a brief period at the time of maximum erythrocyte loss in only a few birds. The overcompensation for erythrocyte loss at the end of the primary parasitermia favors the view that increased erythrocyte production may account for the short duration of haemopoiesis.     

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.     

Populations of Leucocytozoon gametocytes in blue grouse (Dendragapus obscurus) from Hardwicke Island, British Columbia

Population dynamics of round and elongate gametocytes of Leucocytozoon in wild and captive blue grouse (Dendragapus obscurus (Say)) from Hardwicke Island, British Columbia, were studied from 1980 to 1982. Blue grouse chicks were sampled weekly throughout each transmission season. Three patterns in the type of gametocyte produced during primary infection were observed in naturally infected captive and wild blue grouse chicks. Such variation in the expression of the gametocyte stage within a single host population suggests a different interpretation than has been previously reported for species of Leucocytozoon. The data from the primary patterns and profiles coupled with reexposure data and the asynchronous appearance of round and elongate gametocytes can be best interpreted as infection with two concurrent species of Leucocytozoon in blue grouse. More detailed research on the life cycle is necessary to confirm if two species of Leucocytozoon exist in blue grouse.     

Garnia karyolytica n. sp. (Apicomplexa: Haemosporina: Garniidae), a blood parasite of the Brazilian lizard Thecodactylus rapicaudus (Squamata: Gekkonidae).

Development of meronts and gametocytes of Garnia karyolytica nov. sp., is described in erythrocytes of the neotropical forest gecko Thecodactylus rapicaudus from Pará State, north Brazil. Meronts are round to subspherical and predominantly polar in position: forms reaching 12.0 x 10.0 microns contain from 20-28 nuclei. Macrogametocytes and microgametocytes are predominantly elongate, lateral in the erythrocyte and average 16.6 x 6.3 microns and 15.25 x 6.24 microns respectively. Occasional spherical forms of both sexes occur in a polar or lateropolar position. All stages of development are devoid of malarial pigment. They have a progressively lytic effect on the host-cell nucleus, particularly the mature gametocytes, which enlarge and deform the erythrocyte. Possible vector(s) of garniid parasites are considered, and phlebotomine sandflies are high on the list of suspects.     

Populations of Leucocytozoon Gametocytes in Blue Grouse (Dendragapus obscurus) from Hardwicke Island,British Columbia1

Population dynamics of round and elongate gametocytes of Leucocytozoon in wild and captive blue grouse (Dendragapus obscurus (Say)) from Hardwicke Island, British Columbia, were studied from 1980 to 1982. Blue grouse chicks were sampled weekly throughout each transmission season. Three patterns in the type of gametocyte produced during primary infection were observed in naturally-infected captive and wild blue grouse chicks. Such variation in the expression of the gametocyte stage within a single host population suggests a different interpretation than has been previously reported for species of Leucocytozoon. The data from the primary patterns and profiles coupled with reexposure data and the asynchronous appearance of round and elongate gametocytes can be best interpreted as infection with two concurrent species of Leucocytozoon in blue grouse. More detailed research on the life cycle is necessary to confirm if two species of Leucocytozoon exist in blue grouse.     

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.     

Gametocytogenesis of Leucocytozoon Smithi

ABSTRACT. Development of young gamelocytes of Leucocytozoon smithi into morphologically mature forms was studied using electron microscopy. Gametocytogenesis began on day seven post inoculation when merozoites, released from ruptured hepatic schizonts, developed into gametocytes within mononuclear phagocytes or leukocytes (monocytes or lymphocytes). No gametocytes were observed in any erythrocytes or polymorphonuclear leukocytes. Two gametocyte forms, round and elongate, were observed. Immature round gametocytes occurred on days 7-10 post inoculation in the deep vasculature of liver, lung and spleen. Mature elongate gametocytes were observed beginning on day 12 post inoculation in both the deep tissue vasculature and peripheral circulation of the turkey host. Growth and elongation of the gametocyte resulted in distortion of the host cell and its nucleus. the host cell nucleus initially was elongated and displaced to one side or indented by the growing parasite. Eventually, the nucleus was laterally compressed or split into two or three fragments. the compressed host cell cytoplasm was displaced longitudinally and stretched over the parasite to form hornlike cytoplasmic extensions from each end. the potential role of microtubules in the elongation of the gametocyte and its host cell, and possibly in the indentation and splitting of the host cell nucleus, is discussed.     

Hematozoa of hatch-year common mergansers from Michigan

Fifty-five hatch-year common mergansers (Mergus merganser) were sampled for hematozoa from Douglas Lake (Michigan, USA) on 17 July 1995. Forty-one (75%) were infected with hematozoa. Haemoproteus greineri and Leucocytozoon simondi were common, infecting 28 (51%) and 26 (47%) common mergansers, respectively. Plasmodium circumflexum infected two (4%) birds. The common merganser is a new host record for H. greineri and P. circumflexum. Intensity data indicate possible negative interspecific interaction between H. greineri and L. simondi.