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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↗
PubMed1992

Concurrent Hepatozoon canis and Toxoplasma gondii infections in a dog.

A female 1-year-old dog died suddenly and was submitted for necropsy. Numerous grey-tan-colored nodules were seen in the lungs, brain and lymph nodes. Microscopically, the predominant lesion was necrosis associated with numerous Toxoplasma gondii tachyzoites. The parasites reacted positively with anti-T. gondii serum in an immunohistochemical test. Schizonts of Hepatozoon canis were seen in sections of lymph nodes and the spleen.

Animals↗
PubMed1993

Ultrastructure of Hepatozoon canis in the dog.

The ultrastructure of several stages of Hepatozoon canis found in dogs with clinically diagnosed infections was determined using transmission electron microscopy. Stages were found in skeletal muscle tissue that corresponded to the 'onion skin' cyst stage, as described at the light microscopic level, and were composed of an electron-transparent material that appeared to radiate from a central core. Larger cysts, walled off by fibroblasts, contained a transformed host cell located centrally within them. The parasitic stage within these transformed cells contained numerous organelles including mitochondria and Golgi apparatus, and was singularly nucleated. In cardiac muscle, a meront was observed which produced merozoites by ectomerogony. Adjacent to this meront was a granuloma containing merozoites within mononuclear phagocytes which may either serve as a reservoir of parasites for reinfection of the host or differentiate into the circulating gamont stage of the parasite. Gamonts were found within parasitophorous vacuoles inside circulating neutrophils. They had a condensed cytoplasmic appearance and were extremely electron dense with respect to other observed parasite stages. In vitro cultivation of parasitized neutrophils resulted in the appearance of a stage of the parasite with altered ultrastructure compared with gamonts found in circulating neutrophils. This stage was judged to be a possible gamete stage of the parasite.

Animals↗
PubMed1994

Diarrhea associated with Cyclospora Sp. in Bangladesh.

A spherical acid-fast organism measuring approximately 10 microns in diameter (Cyclospora sp.) has recently been implicated in diarrheal diseases in many parts of the world. We detected this organism in the stools of six Bangladeshi patients with diarrhea. Four patients had chronic diarrhea and two had acute diarrhea at the time of presentation. This is the first report of infection with this organism in the indigenous population from this region.

Adult↗
PubMed2006

Chromatin supraorganization, DNA fragmentation, and cell death in erythrocytes of the rattlesnake, Crotalus durissus terrificus (Serpentes, Viperidae), infected with the protozoan, Hepatozoon spp. (Apicomplexa, Hepatozoidae).

Forms of the protozoan of the Hepatozoon genus are detected free in the circulation and also within some of the erythrocytes of infected snakes. In healthy snakes, DNA fragmentation and cell death usually affect a few circulating erythrocytes in agreement with the long life span expected for these cells. In the present study we investigated whether infection by Hepatozoon spp. affected the incidence of DNA fragmentation and cell death in erythrocytes from the rattlesnake, Crotalus durissus terrificus. Methods such as the kinetics of Feulgen-DNA hydrolysis, and the TUNEL and comet assays, previously used for the study of chromatin organization and DNA fragmentation in erythrocytes of healthy snakes, were used. The results indicated that Hepatozoon spp. increased the DNA fragmentation and chromatin condensation typical of cell death in circulating erythrocytes of C. d. terrificus, including cells that do not harbour the parasite. The Hepatozoon infection is thus suggested to accelerate destruction of erythrocytes in the rattlesnake, not only affecting cells harbouring the parasite, but also in those without it.

Animals↗
PubMed2004

Epizootiology of blood parasites in an Australian lizard: a mark-recapture study of a natural population.

The dynamics of a naturally endemic blood parasite (Hepatozoon hinuliae) were studied in a lizard (Eulamprus quoyii) host population, using 2 years of longitudinal data. We investigated how parasite abundance in the population varied over time, examined whether certain host sub-populations were more prone to infection, and compared parasite loads in relation to host reproductive behaviour. We recorded blood parasite infections of 331 individuals, obtained in 593 captures. Prevalence (the proportion of the host population infected) of blood parasites was high; approximately 66% of the lizard population was infected. Probability of infection increased with host age and size, but did not differ between the sexes. Within individuals, parasite load (the intensity of infection within individuals) did not vary over time, and was independent of host reproductive behaviour. Parasite load was significantly higher in males compared to females.

Age Factors↗
PubMed2004

Reproductive and feeding ecology of parasitic gnathiid isopods of epaulette sharks (Hemiscyllium ocellatum) with consideration of their role in the transmission of a haemogregarine.

Epaulette sharks Hemiscyllium ocellatum were surveyed on Heron Island, Great Barrier Reef, Australia for gnathiid isopods and protozoan (haemogregarine) parasites to determine the prevalence and intensity of infection and to investigate the potential role of gnathiids as vectors of these haemogregarines, the first such study carried out on elasmobranchs. Juvenile gnathiids were collected and quantified using a novel non-invasive and chemical-free technique and gnathiid squashes were examined for haemogregarine developmental stages. The feeding and reproductive ecology of the Gnathia spp. was investigated to better understand the relationship between gnathiids and haemogregarines. Gnathiids were found on all sharks and intensities ranged between two and 66. Only third-stage gnathiid juveniles were found, which fell into two size groups (A and B). These juveniles remained attached to H. ocellatum for up to 17 days, the longest period of attachment yet recorded for gnathiids. Group A female gnathiids produced broods of 45-187 (median =120) first stage juveniles from between 54 and 82 days (median=63 days) after detachment. First stage juveniles survived for an average of 15.8+/-0.1 (SEM) days without feeding. The prevalence (6.7%) and parasitaemia (usually <0.1% infected erythrocytes) of infections of the haemogregarine Haemogregarina hemiscyllii were relatively low and most stages were immature gamonts. Two undescribed Gnathia spp. were identified by examining adult male gnathiids that metamorphosed from juveniles from each of the two size groups. Our hypothesis that Gnathia spp. transmit H. hemiscyllii is neither supported or refuted, as although intact H. hemiscyllii gamonts were detected in squashes of gnathiids that had engorged on haemogregarine-positive H. ocellatum 24-57 days previously, no further developmental stages were detected.

Animals↗
PubMed2005

Dogs with Hepatozoon canis respond to the oxidative stress by increased production of glutathione and nitric oxide.

Canine hepatozoonosis is a disease caused by the tick-borne protozoan Hepatozoon spp. It has been reported in the United States, southern Europe, the Middle East, Africa and the Far East. In Turkey, canine hepatozoonosis was reported for the first time in 1933. In the present study, serum glutathione (GSH), malondialdehyde (MDA), nitric oxide (NO) and ceruloplasmin levels were analysed in 14 dogs infected with Hepatozoon canis as well as in 10 healthy dogs. Blood smears were prepared from peripheral blood and ticks were collected for identification in the laboratory. Rhipicephalus sanguineus was found only on diseased dogs. No ticks were observed on healthy dogs. The diagnosis of H. canis is made mainly by the detection of gametocytes within neutrophils and monocytes. The haematological diagnosis was confirmed using PCR analyses by amplifying a partial 18S rRNA gene sequence of Hepatozoon spp. Infection was detected in 14 animals. Compared to controls, the serum GSH, MDA and NO levels in infected animals increased significantly (p<0.05, <0.01 for MDA), whereas the concentrations of ceruloplasmin in diseased animals remained unaltered. The results of the present study suggest that in dogs infected with H. canis increased levels of GSH, MDA and NO may be related to host's defences against parasitic infection.

Animals↗
PubMed2005

A parasitological, molecular and serological survey of Hepatozoon canis infection in dogs around the Aegean coast of Turkey.

Canine hepatozoonosis is caused by the tick-borne protozoon Hepatozoon spp. The prevalence of the infection in the Aegean coast of Turkey was investigated by examination of blood smear parasitology and polymerase chain reaction (PCR) using blood samples from 349 dogs collected from Central Aydin, Kusadasi, Selcuk, Central Manisa, Bodrum and Marmaris within the Aegean coast of Turkey. The indirect fluorescent antibody test (IFAT) for the detection of Hepatozoon canis antibodies was also used to detect the exposure rate to H. canis. PCR amplifying a 666bp fragment of 18S rRNA gene of Hepatozoon spp. was used in the epidemiological survey. The prevalence of Hepatozoon spp. infection was 10.6% by blood smear parasitology and 25.8% by PCR. IFAT revealed that 36.8% of serum samples were positive for antibodies reactive with Hepatozoon spp. The PCR products of 18S rRNA gene of Hepatozoon spp. isolated from six infected dogs, one isolate originating from each of the six different locations, were sequenced. The results of sequence analysis indicate that they are closely related to Indian and Japanese isolates of H. canis. This is the first epidemiological study on the prevalence of H. canis infection in the dog, in Turkey.

Animals↗
PubMed1992

Ultrastructural studies on oocysts, sporulation and sporozoites of Schellackia cf. agamae from the intestine of the starred lizard Agama stellio.

Young intracellular oocysts of Schellackia cf. agamae in the gut epithelium of agama stellio were bound by several fine membranes. Later-stage oocysts and sporoblasts in the lamina propria were intercellular and were bound by a thin but firm tri-layered wall. Oocysts had a large central refractile body which, during sporulation, sent extensions into the developing sporozoites. Sporozoites escaped into the gut tissue, leaving a large oocyst residuum with the remains of a refractile body. These sporozoites invaded a variety of connective tissue cells, endothelial cells and circulatory leucocytes in the lamina propria. Sporozoites caused lysis of the host cell cytoplasm at their perimeter and multiple sporozoite infections led to complete degradation of the host cell.

Animals↗
PubMed1999

Phylogenetic relationships among Hepatozoon species from snakes, frogs and mosquitoes of Ontario, Canada, determined by ITS-1 nucleotide sequences and life-cycle, morphological and developmental characteristics.

The molecular biological characteristics of Hepatozoon species infecting various species of snakes, frogs and mosquitoes were investigated by determining the nucleotide sequences of the first internal transcribed spacer region. A phylogenetic analysis was performed on seven isolates of Hepatozoon infecting snakes, including Hepatozoon sipedon and four morphologically similar but not identical forms, and two isolates of Hepatozoon catesbianae infecting Green frogs (Rana clamitans melanota). This analysis, which utilised data from first internal transcribed spacer nucleotide sequences, morphological and morphometric features of gamonts, oocysts and sporocysts, and previously determined life-cycle and host-specificity characteristics, revealed that H. sipedon is a polymorphic species with a wide host and geographic range. Four synapomorphies. including two nucleotide substitutions and two morphological character state changes, supported a monophyletic group of six isolates of H. sipedon from the central region of Ontario which was the sister group for an isolate (HW1) from the southern part of the province. Based on the results of this study, an evaluation of which criteria are useful for describing species of Hepatozoon is presented, with the intent of curtailing the practice of naming species based on morphological features of gamonts or on incomplete life-cycle data.

Animals↗