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At least 19 recordsLinked to original sources
PubMed1998

Light and electron microscope studies of Hepatozoon mehlhorni, Bashtar et al., 1991 (Adeleina, Eucoccidiida) naturally infecting the viper Echis carinatus.

Light and electron microscopy have been used to study blood stages of H. mehlhorni as well as different developmental stages of the parasite within lung tissues of the naturally infected vipers Echis carinats captured from Siwah Oases, Egypt. A natural infection rate of 60% was recorded among vipers. Two types of meronts were observed within the endothelial cells of the viper's lung. The first type is the small one, produced 6-15 merozoites. The second type is the large one, produced 20-40 merozoites. In both types of meronts, merozoites were developed through an ectomerogenous manner. The erythrocytic parasites and the merozoites within the endothelial cells of the viper's lung sharing all general architecture of the apicomplexa. Moreover, evident peculiarities of haemogregarines were recorded, such as the presence of micronemes and rhoptries on both sides of the parasite nucleus, and the presence of large number (up to 100) of subpellicular microtubules and micronemes (up to 150).

Animals↗
PubMed1983

Transmission electron microscopy of intracellular sporozoites of Eimeria vermiformis (Apicomplexa, Eucoccidiida) in the mouse.

Sporozoites of Eimeria vermiformis from the mouse were first seen in the epithelial cells of villus tips and the crypts of Lieberkühn four hours after inoculation (HAI). They were always within a parasitophorous vacuole. By 12 HAI, most were in crypt epithelial cells between the basement membrane and host cell nucleus. The sporozoites in the villus tips had 26 subpellicular microtubules, two polar rings, two preconoidal rings, two refractile bodies surrounded by amylopectin-like granules, a lamellar Golgi apparatus, numerous micronemes, and rhoptries. The sporozoites in the crypt cells had fewer amylopectin-like granules, micronemes, and rhoptries. A nucleolus was visible, as were pieces broken off from the posterior refractile body. Later, the sporozoites folded over to become U-shaped; the infolded membranes fused; and then the inner membranes disappeared so that spherical meronts were formed. Folding sporozoites were first seen 16 HAI and persisted until 52 HAI.

Animals↗
PubMed1998

A foodborne outbreak of Cyclospora cayetanensis at a wedding: clinical features and risk factors for illness.

BACKGROUND: Cyclospora cayetanensis, a coccidian parasite, has increasingly been recognized as a cause of gastrointestinal tract illness. We describe an outbreak of Cyclospora infection following a wedding reception. OBJECTIVES: To investigate and characterize risk factors associated with the outbreak of Cyclospora and to describe the observed clinical course and spectrum of illness. METHODS: Retrospective cohort study involving 94 of the 101 guests who attended a wedding reception at a restaurant in Boston, Mass. RESULTS: Fifty-seven respondents met the case definition of infection; 12 of these had laboratory-confirmed Cyclospora. The epidemic curve was consistent with a point source outbreak with a median incubation period of 7 days. Commonly reported symptoms included diarrhea (100%), weight loss (93%), fatigue (91%), and anorexia (90%). The illness had a characteristic waxing and waning course, with 51 persons (89%) reporting recurring symptoms and 35 (61%) reporting illness lasting more than 3 weeks. By univariate analysis, infection was significantly associated (P<.05) with consumption of wine and a dessert containing raspberries, strawberries, blackberries, and blueberries. Only the dessert remained significant by stratified analysis with an adjusted relative risk of 2.1 (95% confidence interval, 1.4-3.2). CONCLUSIONS: Findings from this study support a point source outbreak of the newly identified pathogen C cayetanensis, with berries as the vehicle of transmission. It suggests that Cyclospora may cause severe diarrhea associated with profound anorexia and weight loss, and should be considered in the evaluation of prolonged gastrointestinal tract illness.

Animals↗
PubMed1998

Guillain-Barré syndrome after Cyclospora infection.

We present a patient who developed Guillain-Barré syndrome (GBS) after a Cyclospora-induced diarrheal illness. We raise the possibility that Cyclospora is an infectious trigger for GBS in this patient. An active search for this agent in patients with GBS preceded by diarrheal illness is recommended.

Animals↗
PubMed1996

Hepatozoon canis: the prevalence of antibodies and gametocytes in dogs in Israel.

A survey for the prevalence of antibodies to Hepatozoon canis and for intraneutrophilic H. canis gametocytes in the peripheral blood neutrophils of dogs in Israel showed that 33.1% were seropositive, while only 1% of the dogs sampled had detectable parasites in their blood smears. Exposure to H. canis is widespread but it appears that most infected dogs undergo a subclinical infection and only a small proportion develop clinical disease.

Animals↗
PubMed1994

The development of Hepatozoon sipedon sp. nov. (Apicomplexa: Adeleina: Hepatozoidae) in its natural host, the Northern water snake (Nerodia sipedon sipedon), in the culicine vectors Culex pipiens and C. territans, and in an intermediate host, the Northern leopard frog (Rana pipiens).

The life cycle of Hepatozoon sipedon sp. nov. was studied in two snake species, the Northern water snake and the Eastern garter snake, in its mosquito hosts Culex pipiens and C. territans, and in the Northern leopard frog. Gametogenesis, fertilization and sporogony occurred within fat body cells in the haemocoel of mosquitoes that had fed on infected water snakes. Mature oocysts averaging 263 microns in diameter and containing more than 500 sporocysts were observed in mosquitoes 28 days post-feeding. Each sporocyst enclosed eight sporozoites. Dizoic cysts were found in the liver of frogs that had been fed infected mosquitoes seven days previously. Two rounds of merogony in various internal organs and intraerythrocytic gamonts were observed in snakes that had been fed frogs which had been orally inoculated with infected mosquitoes. Developmental stages were not seen in snakes that were fed infected mosquitoes directly. A comparison of this life cycle with those described for other Hepatozoon species infecting snakes is presented with reference to the different modes of transmission featured by these parasites.

Animals↗
PubMedDate not supplied

Cyclospora cayetanensis: first imported infections in Germany.

Over the last decade increasing numbers of enteritis cases have been attributed to infection with a new coccidian species that was named Cyclospora cayetanensis in 1993. Diarrhea caused by this agent is clinically indistinguishable from cryptosporidiosis, isosporiasis and microsporidiosis, but Cyclospora infections are often very prolonged (up to 15 weeks) and may cause severe weight loss. Diagnosis of infection is important because, in contrast to diarrhea caused by Cryptosporidium and microsporidia, treatment with co-trimoxazole is effective. Here we report the cases of two female patients, aged 70 and 58 years old, respectively, who suffered from severe, prolonged diarrhea after a vacation in Singapore, Java and Bali. Routine microbiological laboratory diagnostics were unable to demonstrate the presence of known enteropathogenic bacteria. Modified Ziehl-Neelsen staining of fecal smears revealed oocysts of Cyclospora cayetanensis, and treatment of the patients with co-trimoxazole was promptly effective. We would like to increase awareness of the possibility of Cyclospora infections in patients with prolonged diarrhea who have travelled to endemic areas.

Aged↗
PubMed2000

Prevalence and intensity of the blood parasite Hemolivia mariae in a field population of the skink Tiliqua rugosa.

The impacts of virulent parasites on humans or domestic animals are well documented. Less is known of the impact of parasites in natural host-parasite associations. A population of the Australian sleepy lizard Tiliqua rugosa is infected with the blood microparasite Hemolivia mariae, which is transmitted by the ectoparasitic tick Amblyomma limbatum. In most infected lizards a very small proportion, usually < 1%, of red blood cells are infected. A study of the prevalence of the microparasite in the field population found no difference either over 5 years of study or among times within a lizard activity season. Juvenile and sub-adult lizards and larger adults were less frequently infected with H. mariae than were other adults. In sub-adults this was related to a lower level of tick infestation. In adults, male and female lizards were equally frequently infected with H. mariae, but the presence or absence of ticks was not predictive of infection. The lizards' body condition was measured as the residual of the regression of log snout-vent length against log body mass. In female lizards the body condition was not affected by infection. In males the body condition declined over the sampling period each year, probably as a result of mate attendance. The body condition was poorer in male lizards with H. mariae infection than in uninfected males. Possible explanations for the associations of microparasites and host lizards are discussed.

Animals↗
PubMed1999

Transmission of the blood parasite Hemolivia mariae between its lizard and tick hosts.

The haemogregarine Hemolivia mariae is found in the erythrocytes of a natural population of the lizard Tiliqua rugosa. It infects two tick species, Amblyomma limbatum and Aponomma hydrosauri, which parasitise lizards. In laboratory experiments, engorged Amb. limbatum nymphs from infected lizards transmitted the haemogregarine to uninfected lizards significantly more often than engorged Ap. hydrosauri nymphs. Dissections of larvae and nymphs of both species fed on the same infected hosts showed that Amb. limbatum ticks were significantly more likely to become infected than Ap. hydrosauri ticks. In Amb. limbatum, oval cysts containing parasite stages thought to be infective to the lizard host had developed within 15 days of engorged nymphs detaching from an infected host. The chance of Ap. hydrosauri becoming infected and the intensity of infection in Amb. limbatum increased when ticks were fed on infected hosts as larvae and as nymphs compared with those fed on an infected host only as a nymph. This suggests that infections can accumulate over the tick life stages. Since the two tick species have broadly parapatric distributions, the boundary between the tick species may have implications for the distribution of H. mariae.

Animals↗
PubMed2000

Ultrastructure studies on post-oocyst development of the lizard hemogregarine Hemolivia mariae in the tick Amblyomma limbatum.

The ultrastructural features of the development of Hemolivia mariae, a blood parasite of the Australian lizard, Tiliqua rugosa, from sporokinetes to sporozoites in their vector tick Amblyomma limbatum are described. Sporokinetes, released from oocysts, re-establish themselves in tick-gut epithelial cells within a parasitophorous vacuole, the wall of which becomes evaginating and anastomosing and is underlined extensively by endoplasmic reticulum. The sporozoites forming within the encysting sporokinete body become bordered by a prominent thick wall, which eventually forms the resistant sporocyst wall. The main differences between the ultrastructural features of Hemolivia and those of other hemogregarine taxa are discussed.

Animals↗
PubMed2000

Ultrastructure of Hemolivia mariae gamonts in the blood of the lizard Tiliqua rugosa and their development to oocyst stage in the tick Amblyomma limbatum.

The ultrastructural features of the development of Hemolivia mariae from intra-erythrocytic gamonts in their host, the Australian lizard Tiliqua rugosa, to oocysts containing sporokinetes in their vector, the tick Amblyomma limbatum, are described. Mature intra-erythrocytic gamonts, as well as gamonts ingested by the tick were encased in a thick (30 nm) capsule with distinct suture sites at each of the two apices. In the only image of a presumed syzygy, both partners were still encased. Further stages, the young and ongrowing oocysts, were bound by a membranous wall. Sporokinetes developed within the oocyst around a primordial crystalloid body. The fully differentiated sporokinetes, still resting within the oocyst wall, exhibited a very short conoid in the apical complex and were heavily loaded with crystalloid material.

Animals↗
PubMed1991

The fate of Hepatozoon species naturally infecting Florida black racers and watersnakes in potential mosquito and soft tick vectors, and histological evidence of pathogenicity in unnatural host species.

Haemogregarine parasites, derived from the Florida snakes Coluber constrictor and Nerodia fasciata and ingested by Aedes aegypti, completed sporogony within the hemocoeles of nearly all fed mosquitoes in 14-18 days, and produced oocysts typical of Hepatozoon. However, mortalities and morbidity were high in the Culex which had fed on the Coluber. Oocysts were not found in any Ornithodoros turicata (Argasidae) which fed upon either snake host, but many sections of fed ticks had gametocyte-like cells within the gut lumen. Most lizards, Anolis carolinensis and Anolis sagrei, infected per os with oocysts derived from both snake species developed infections. Infections in the lizards were largely confined to hepatic schizonts with few parasites found in erythrocytes. Unlike naturally infected snake hosts, Hepatozoon schizonts in livers of lizards were often either surrounded by an unidentified dark pigment or heavily infiltrated with mononuclear inflammatory cells.

Animals↗
PubMed1996

Demonstration of common and stage-specific anti-Hepatozoon mocassini antibodies in experimentally infected unnatural lizard hosts.

This study examines the immunological response to Hepatozoon mocassini in lizards. Three lizard species were infected experimentally with H. mocassini. Baseline and post-infection (PI) sera were assayed for anti-H. mocassini meront and gametocyte antibody by immunohistochemistry and IFA. Seroconversion occurred at 38 d PI with endpoint IFA titers of 1:64. Antisera from non-parasitaemic and parisitaemic lizards exhibited similar affinities for merozite and gametocyte antigens. Antibody specific for the membranes of gametocyte-infected erythrocytes was demonstrated exclusively in parasitaemic lizards. The results demonstrate that lizards infected with snake haemogregarines mount an antibody response with common and stage-specific components.

Aedes↗
PubMed1996

Characterization of the clinical and anatomical pathological changes associated with Hepatozoon mocassini infections in unnatural reptilian hosts.

Laboratory-reared Aedes aegypti mosquitoes were employed in the successful transmission of Hepatozoon mocassini from a cotton-mouth moccasin (Agkistrodon piscivorus leucostoma) to 3 lizard species (Sceloporus undulatus, Eumeces obsoletus and Sceloporus poinsetti). Marked to severe lethargy and anorexia developed in the S. undulatus, E. obsoletus and S. poinsetti at 15, 38, and 96 days postinfection (PI), respectively. All 3 lizards developed a leukocytosis and had increased plasma aspartate aminotransferase activity (AST) by 14 days PI. Multifocal random hepatocellular necrosis and intrahepatic aggregates of heterophils centered on mature H. mocassini meronts were demonstrated in all 3 lizards. The pulmonary interstitium was multifocally thickened by aggregates of heterophils centered on meronts. No comparable clinical or anatomical pathological changes were demonstrated in naturally infected snakes. The results of this study suggest that H. mocassini is capable of inducing necrotizing inflammatory by lesions in unnatural reptilian hosts.

Aedes↗