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.     

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.     

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.     

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.     

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.     

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.     

A New Malaria Parasite Plasmodium (Sauramoeba) heischi in Skinks (Mabuya striata) from Nairobi, with a Brief Discussion of the Distribution of Malaria Parasites in the Family Scincidae

ABSTRACT. A new species of malaria parasite, Plasmodium (Sauramoeba) heischi , is described from African skinks (Mabuya striata). Eleven individuals of 90 specimens collected in Nairobi were found to be infected. The new parasite is a large species, characterized by spindle-shaped gametocytes, the female often with a subterminal nucleus. The schizonts produce up to 65 nuclei and cause great hypertrophy and distortion of the host cell. Although similar to P. (Sauramoeba) giganteum in dimensions and merozoite numbers, P. heischi is easily distinguished by gametocyte and schizont shapes.     

The malarial parasites of Anolis species (Sauria: Iguanidae) in Panama

Lizards of the iguanid genus Anolis in Panama are parasitized by four species of Plasmodium. P.floridense occurs in A. limifrons, A. biporcatus, A. pentaprion and A. frenatus. The number of nuclei in mature schizonts is influenced by host species as is gametocyte shape but not gametocyte size. P. tropiduri parasitizes A. limifrons, A. pentaprion, A. biporcatus, A. frenatus, A. lionotus and A. poecilopus. The number of nuclei in schizonts varies according to host and type of blood cell parasitized. Gametocyte size varies slightly by host but shape remains relatively constant. Position of the parasite in the host cell may be affected by host species. Both schizonts and gametocytes are produced in white cells of all host species studied. P. balli occurs in A. limifrons, A. lionotus and A. poecilopus. Schizont and gametocyte size and shape are affected by host and blood cell type, with the parasite exhibiting different preferences for various blood cells in each host. P. minasense parasitizes A. limifrons, A. frenatus and A. capito, but its diagnosis in the last species may not be correct as gametocyte size and distribution of pigment differ considerably from other hosts. The mean number of nuclei in schizonts is not greatly affected by the host species. P. floridense is postulated to be of middle American origin in the genus Anolis, and to have reached Florida through the Caribbean.     

Plasmodium (Huffia) hermani sp. n. from wild turkeys (Meleagris gallopavo) in Florida*

SYNOPSIS. Plasmodium (Huffia) hermani sp. n. is described from wild turkeys (Meleagris gallopavo Linnaeus) in Florida. It produces rounded schizonts with 6–14 nuclei arranged peripherally as a rosette and elongate, slender gametocytes with irregular margins. Asexual stages parasitize all cells in the erythrocyte series and, in heavy infections, predominantly occur in erythroblasts and their precursors. Presence and degree of pigmentation vary with maturity of the host cell. Gametocytes occupy erythrocytes only, with pigment dispersed in black granules throughout the cytoplasm. Cells containing schizonts are often rounded and enlarged and those parasitized by gametocytes may be somewhat distorted in shape by lateral hypertrophy. Host cell nuclei may be displaced, but are not distorted, except slightly by pressure from the parasite. Plasmodium hermani differs from P. (Giovannolaia) durae by producing low level (> 6%), nonlethal parasitemias in turkey poults, an absence of phanerozoites in capillary endothelium of the brain and viscera, and inability to infect chicks. Plasmodium hermani is more like P. (Huffia) elongatum in gametocyte morphology, schizogony in all types of erythrocyte precursors, with gametocytes occurring in erythrocytes only, and concentration of schizonts in heavy infections in bone marrow and spleen. It differs from P. elongatum by its lack of infectivity to passeriform and anseriform hosts and by a strong immune response which develops in infected birds.     

Discovery of the pre-erythrocytic stages of a saurian malaria parasite, hypnozoites, and a possible mechanism for the maintenance of chronic infections throughout the life of the host

Re-examination of tissue sections from four Takydromus tachydromoides (Sauria: Lacertidae) naturally infected with Plasmodium sasai found liver parenchymal cells, containing uninucleate parasites which may correspond to the hypnozoite stage of primate malaria parasites, schizonts and segmenters in parenchymal cells, and hepatic macrophages which contained numerous schizonts. Following destaining of the original H&E and prolonged restaining with warm Giemsa stain, encysted schizonts, protected by a hyaline wall, were discovered in the connective tissue or capillary endothelium of lung, liver, brain, heart, pancreas, kidney, intestine wall, testis, and both intra- and intermuscularly in the femoral muscles. Unencysted schizonts in the pulmonary endothelium apparently represent the phanerozoic stages, which, following encystment in the various tissues, are recognized as a new stage in the life cycle of reptilian malarial parasites, the chronozoic schizonts. A hypothesis is presented to describe the life cycle of P. sasai, which may be characteristic of other saurian malaria parasites. It interprets the sequence of pre-erythrocytic stages found as follows: sporozoites enter hepatic parenchymal cells where some may become dormant as hypnozoites, and others form cryptozoic schizonts. The cryptozoites parasitize hepatic macrophages and form metacryptozoic schizonts. Metacryptozoites produce phanerozoic schizonts in the capillary endothelium and connective tissue of the lung and other organs. Phanerozoites and possibly metacryptozoites then invade the erythrocytes to begin the erythrocytic cycle. Some of the phanerozoites in endothelium, connective tissue and skeletal muscle become encysted as chronozoic schizonts, and their progeny, chronozoites, renew the erythrocytic cycle throughout the life of the host and produce seasonal relapses of gametocytemia, in spring, at the end of hibernation by the lizard.     

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.     

Studies on African saurian malarias: Plasmodium holaspi n. sp. from the flying lacertid Holaspis guentheri

The African flying lizard Holaspis guentheri (Lacertidae) from the Uluguru Mountains, Tanzania was found infected by an undescribed malarial parasite, Plasmodium holaspi n. sp. Gametocytes were elongate, approximately twice the size of host cell nuclei, and showed prominent, irregular pigment granules. Schizonts were oblong or formed as rosettes, approximated the host cell nucleus in size, and produced 8-18 merozoites. Maturing gametocytes contained large masses or blocks of chromatin which can obscure sexual differentiation by staining reaction, while young gametocytes and asexual stages almost always occupy marginal positions in host cells. These characteristics distinguish P. holaspi from all other saurian Plasmodium species. This is the first malarial parasite described from African lacertid species.     

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 New Saurian Malarial Parasite Plasmodium balli from Panama

SYNOPSIS. Plasmodium balli sp. nov. is described from Anolis lionotus and A. poecilopus of central Panama.
Large, elongate gametocytes and segmenters containing up to 100 merozoites are produced by P. balli. Proerythrocytes and normoblasts are more commonly parasitized than erythrocytes. Pigment is uncommon, but when present consists of a minute dot. Hypertrophy, distortion and lysis of host cell nuclei may result from parasitization of immature blood cells by gametocytes, while enucleated host cells are common.     

Intralymphocytic schizonts associated with an initial infection of Saurocytozoon tupinambi in Tupinambis teguixin

An initial natural infection of Saurocytozoon tupinambi in a juvenile Tupinambis teguixin from Venezuela was studied for 131 days following capture of the host. Intralymphocytic parasites appeared in this sequence: small uninucleate and binucleate stages (days 1–31 and again on day 41); schizonts with 3–102 nuclei (days 8–14 and 29–35); immature gametocytes (days 29–35) and apparently mature gametocytes of Saurocytozoon tupinambi from day 41. Maximum parasitemia of trophozoites and binucleate schizonts occurred on day 4 when 11% of lymphocytes were infected. Maximum parasitemia by larger schizonts occurred on day 8 at 0.13% of lymphocytes, while maximum gametocytemia was found on day 49 with 16.4% of lymphocytes parasitized. Two types of schizonts were observed: intralymphocytic and the same type free of host cells, and fragments of varying size which may have been torn from capillary endothelium.Due to presence of concurrent infection by a small Plasmodium species, identity of intralymphocytic asexual stages with S. tupinambi cannot be established. Presence of asexual and sexual stages in the same type of host cells (lymphocytes and close derivatives), sequential appearance of trophozoites, schizonts and gametocytes over a period of 40 days, and correlated fluctuations in lymphocyte density suggest they are conspecific, and that Saurocytozoon, which has a plasmodiid type of sporogony may prove to further differ from leucocytozoids by presence of an asexual cycle in circulating blood cells.     

Plasmodium chiricahuae sp. nov. from Arizona Lizards

SYNOPSIS Plasmodium chiricahuae sp. nov. from the Arizona lizards Sceloporus jarrovi and S. clarki is similar to P. mexicanum Thompson and Huff, but differs by having larger gametocytes and smaller erythrocytic schizonts (4-8 merozoites). It produces low-level parasitemia with early appearance of gametocytes. Gametocytes may persist over one year following cessation of erythrocytic schizogonic activity. P. chiricahuae varies in prevalence at different altitudes, being most common between 6000 and 8000 feet. Infected hosts were collected at a maximum of 9200 feet.     

Development of Eimeria auburnensis in Cell Cultures

SYNOPSIS. Monolayer established cell line cultures of bovine kidney (Madin-Darby) and human intestine (Intestine 407), as well as embryonic bovine tracheal and embryonic spleen cell line cultures were inoculated with E. auburnensis sporozoites and observed for a maximum of 22 days. Mature 1st generation schizonts developed in the kidney, tracheal and spleen cells. In the intestine cells, trophozoites were seen in 3 of 4 experiments, but schizonts were not found. Sporozoites penetrated cells, beginning within a few minutes after inoculation. Penetration was usually accomplished within 10 seconds, and the body of the sporozoite underwent a slight constriction as it passed thru the host cell membrane. Some sporozoites left cells. Numerous intracellular sporozoites were observed in kidney, tracheal and spleen cultures. Crescent bodies were seen in the parasitophorous vacuole as early as 1 day after inoculation. At this time, the nuclei of most intracellular sporozoites had changed from vesicular to compact. Beginning 4 days after inoculation, enlarged sporozoites and parasites having a sporozoite shape, but with 2-5 nuclei, were frequently seen. These enlarged sporozoites and sporozoite-shaped schizonts evidently transformed into trophozoites and spheroidal schizonts by means of lateral outpocketings. Few trophozoites were seen. More immature schizonts developed in kidney cells than in the other cell types. The numbers of mature schizonts observed in kidney and tracheal cells were similar, but development occurred less consistently in the latter. Few immature and mature schizonts developed in spleen cells. Mature schizonts, first seen 9 days after inoculation, were considerably smaller than those reported from calves. Some motile merozoites were seen; evidently no development beyond these occurred. The nucleus and nucleolus of host cells were enlarged; this enlargement was not as pronounced as in infections in calves. Multiple host cell nuclei were frequently observed. Degenerative changes in the cultured cells and in the parasites usually occurred, beginning 9-17 days after inoculation; these were more pronounced in the spleen cells than in the others.