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PubMed2000

Immunohistochemical study of the cyst of Besnoitia besnoiti.

The present study has been undertaken in order to provide information on the molecular structure of the cysts of Besnoitia besnoiti. To that end, immunohistochemical techniques have been used to investigate the expression of several enzymes and proteins implicated in the cellular membrane permeability of bradyzoites. Paraffin and frozen sections, which were obtained from subcutaneous tissue samples taken from naturally infected cattle (coming from northeast Spain), were treated with a panel of antibodies. These were specific for Na(+), K(+)-ATPase, alkaline phosphatase, calmodulin, S100 protein, heat shock proteins, hsp60, and hsp70. Positive-cysts for the said antibodies were found in 23.3% of the cows studied. Bradyzoites showed a positive immunoreaction in every positive cyst with respect to all these antibodies. In addition to the low percentage of positive animals, it is worth noting that positive and unstained cysts were observed in the same tissue section. These results suggest that bradyzoites may pass through both active and dormant metabolic phases.

Adenosine Triphosphatases↗
PubMed2002

Neospora caninum and Hammondia heydorni are separate species/organisms.

Neospora caninum and Hammondia heydorni are two coccidian parasites with morphologically similar oocysts in canine feces. It was recently proposed that they are one species. In this paper, we review the biology and morphology of these parasites and present evidence that N. caninum and H. heydorni are separate species.

Animals↗
PubMed1994

Codon usage and bias among individual genes of the coccidia and piroplasms.

Codon usage has been analysed in individual gene sequences, derived from a variety of parasitic protozoa in the class Sporozoa of the phylum Apicomplexa using metric multidimensional scaling. The two groups of codon usage patterns detected reflect the two main subgroups of organisms studied (the coccidia and the piroplasms), and it is the pattern of usage of synonymous codons that has the largest influence on overall codon usage in the individual genes, rather than being the pattern of amino acid composition of the gene product. The magnitude of the codon usage bias in the sequences was determined using three commonly used indices-NC, GC3S and B. In general, although relatively low levels of codon usage bias were detected in these gene sequences, codon usage bias does explain at least some of the codon usage patterns observed. Codon usage bias was observed to be dependent on the overall base composition of the genes analysed, which in turn was reflected in the types of codons that were either over- or under-represented in the nucleotide sequences. In keeping with observations on prokaryotic organisms, it is speculated that the codon usage patterns detected in these parasitic protozoa are the result of directional mutation pressure on the base composition of the genomic DNA.

Animals↗
PubMed1999

The genus Hammondia is paraphyletic.

The phylogenetic relationships amongst Hammondia, Neospora and Toxoplasma were investigated by DNA sequence comparisons of the D2/D3 domain of the large subunit ribosomal DNA and the internal transcribed spacer 1. The results obtained allow us to reject the hypothesis that N. caninum and H. heydorni are the same species and show that Hammondia hammondi is probably the sister taxon to Toxoplasma gondii.

Animals↗
PubMed1999

The relationship of Hammondia hammondi and Sarcocystis mucosa to other heteroxenous cyst-forming coccidia as inferred by phylogenetic analysis of the 18S SSU ribosomal DNA sequence.

The complete sequence of the 18S small subunit (SSU) ribosomal DNA of Hammondia hammondi and Sarcocystis mucosa was obtained and compared to SSU rDNA sequences of Neospora caninum, Toxoplasma gondii, Besnoitia besnoiti, 2 species of Frenkelia, 3 species of Isospora, and 13 species of Sarcocystis. Analyses showed that H. hammondi and T. gondii are monophyletic and that these taxa shared a common ancestor with N. caninum and B. besnoiti. The weight of evidence shows that S. mucosa, S. neurona, and Frenkelia species form a clade thereby supporting the conclusion that Sarcocystis is paraphyletic.

Animals↗
PubMed1997

An epizootic of besnoitiosis in goats in Fars province of Iran.

Over 100,000 goats were grazing freely in isolated herds of 100 to 600 goats in a mountainous area of more than 2000 km2 to the north-east of Darab City in Fars Province in southern Iran. Twenty to fifty percent of the goats in this area were infected with besnoitiosis. Sheep, cattle and donkeys grazing in the same area showed no clinical manifestations of the infection. The diagnosis of the infection in the clinically suspected animals was confirmed by histological studies on skin biopsies from the ear tips and carpal and tarsal regions, and the distribution of this protozoon in the tissues and organs of this intermediate host was studied by post-mortem and histological examinations. Skin biopsies from the carpal and tarsal areas of 12% of clinically normal goats from the infected area were also lightly infected with besnoitia cysts.

Animals↗
PubMed1998

Schellackia calotesi n. sp. from agamid lizards of the genus Calotes in Thailand.

Schellackia calotesi n. sp. is described from the Thai agamids Calotes mystaceus and C. versicolor. Schellackia-type sporozoites were recovered from blood and liver of one C. versicolor from Kon Kaen North-East Thailand and two C. mystaceus from Chiang Mai, North Thailand. Specimens of both species were fed on sporozoite infected blood, of these only one C. mystaceus developed endogenous infection in the anterior intestine. Description, from histological material includes early and dividing meronts, micro and macrogamonts and non sporulated oocysts.

Animals↗
PubMed1995

Cross-reactivity of human Toxoplasma-specific T cells: implications for development of a potential immunotherapeutic or vaccine.

Previous reports from this laboratory have demonstrated that human CD4+ Toxoplasma-specific cytotoxic T cell (CTL) clones generated by stimulation of peripheral blood mononuclear cells with Toxoplasma RH strain antigens also recognized target cells expressing C strain antigens. To extend these observations, additional Toxoplasma isolates were studied. A simple system for assessment of cytotoxicity using T cell lines rather than cloned CTL was used. Stimulation of human peripheral blood mononuclear cells with Toxoplasma RH strain antigens elicited cytotoxic T cell lines specific for target cells expressing antigens derived from many other Toxoplasma strains. Cell lines produced by stimulation with antigens derived from the related, nonpathogenic coccidian Besnoitia jellesoni were also cytotoxic for target cells expressing Toxoplasma antigens. Proliferative responses to many Toxoplasma isolates and to the Toxoplasma p30 protein were also noted.

Animals↗
PubMed1999

Intestinal parasites in patients with diarrhea and human immunodeficiency virus infection in Zimbabwe.

OBJECTIVES: To determine the prevalence of intestinal parasites and risk factors for infection associated with diarrhea in HIV-infected patients in Harare, Zimbabwe. DESIGN: Prospective observational study. METHODS: Single stool samples were collected from 88 HIV-infected individuals presenting with diarrhea of greater than 1 week duration. Stools were examined for intestinal parasites using modified acid fast stain, fluorescence- labeled monoclonal antibody for Cryptosporidium parvum, as well as a modified trichrome stain and a PCR-based protocol for Enterocytozoon bieneusi. RESULTS: C. parvum was detected in 9% (seven out of 82) of samples evaluated, but no Cyclospora was detected. E. bieneusi was detected in 18% (10 out of 55) of stool by trichrome staining and in 51% (28 out of 55) of stool examined by PCR. Risk factors for E. bieneusi infection were: living in rural areas, consumption of nonpiped water, contact with cow dung and household contact with an individual with diarrhea. CONCLUSION: E. bieneusi infection was common in HIV-infected patients with diarrhea in Zimbabwe and may be acquired through person-to-person and fecal-oral transmission.

AIDS-Related Opportunistic Infections↗
PubMed2005

Ultrastructure of Goussia cruciata (Apicomplexa: Coccidia) infecting the liver of horse mackerel, Trachurus trachurus (L.), from Ibero-Atlantic waters.

The ultrastructure of developmental stages of Goussia cruciata and the pathology they cause in the liver of Trachurus trachurus (Teleostei: Carangidae) caught off the Galician (North-West Spain) and Portuguese North Atlantic coasts are described. Each oocyst contained four ellipsoidal sporocysts, with two sporozoites. The sporocyst wall consisted of a thick and dense inner layer with transverse striations and a multi-lamellated outer layer formed by parallel dense internal bands alternating with lighter areas. The lamellae formed filamentous extensions of the wall. The sporocyst wall striation period was smaller than that observed in G. clupearum, which has a similar habitat. The dehiscence suture, characteristic of the genus, was present in the sporocysts of G. cruciata. The sporocysts were arranged in a symmetrical and characteristic cross shape. A large number of sporocysts with sporozoites were observed in direct contact with host liver cells. No macroscopic lesions were observed. In heavily infected fish, aggregations of oocysts were often enveloped in a 'yellow body' composed of amylopectin granules derived from the parasite and necrotic or aggregated host cells. Degenerating parasites were frequently observed in liver tissue. Host inflammatory cells were accumulated near some oocysts. The ultrastructure of the parasite, together with its strict host specificity, confirmed G. cruciata as a separate and valid species.

Animals↗
PubMed1997

Waterborne protozoan pathogens.

Protozoan parasites were the most frequently identified etiologic agents in waterborne disease outbreak from 1991 to 1994. The waterborne parasites Giardia lamblia, Naegleria fowleri, Acanthamoeba spp., Entamoeba histolytica, Cryptosporidium parvum, Cyclospora cayetanesis, Isospora belli, and the microsporidia are reviewed. For each parasite, the review includes history, life cycle, incidence, symptoms, and therapy. Clinical detection methods are compared, and emerging technologies are discussed. Information on the association of these parasites with waterborne outbreaks is reviewed. Current information on protozoan parasites identified as etiological agents in waterborne outbreaks is discussed. Water industry issues related to recent disease outbreaks are examined in the context of water quality testing regulations for G. lamblia and those proposed for C. parvum. The review identifies the limitations of the American Society of Testing and Materials water-testing method for these parasites. An overview of federal regulations affecting the water industry and laboratories that test for water quality is also provided. The article highlights the importance of the clinical laboratory as a frontline defense for the detection of infectious organisms. The review points to the need for clinical laboratories, physicians, and public health personnel to cooperatively plan and assess the challenge of meeting this potential public health threat.

Acanthamoeba↗
PubMed2002

Studies on serological cross-reaction of Neospora caninum with Toxoplasma gondii and Hammondia heydorni.

The enzyme-linked immunosorbent assay (ELISA) was used to examine cross-reactivity of Neospora caninum with Toxoplasma gondii and Hammondia heydorni. Anti-T. gondii mouse and cat sera cross-reacted with N. caninum soluble antigen (NLA), but not with the recombinant surface antigen (NcSRS2). Anti-H. heydorni dog sera showed no cross-reactivity with either the NLA antigen or the NcSRS2. Lack of cross-reactivity between anti-H. heydorni sera and N. caninum antigens, and the cross-reactivity of anti-T. gondii sera with the NLA suggest that N. caninum has common antigens to T. gondii except for NcSRS2 based on serology. In light of several studies suggesting a closer relationship between N. caninum and H. heydorni than with T gondii, examination of serological cross-reactivity with N. caninum may be necessary to further classify the parasites in addition to molecular and morphological studies and clarification of the life cycle.

Animals↗
PubMed2000

Life cycle of Calyptospora funduli (Apicomplexa: Calyptosporidae).

The taxonomic status of the extraintestinal piscine coccidium Calyptospora funduli is based in part on its requirement of an intermediate host (the daggerblade grass shrimp Palaemonetes pugio). In the present study, grass shrimp fed livers of Gulf killifish (Fundulus grandis) infected with sporulated oocysts of C. funduli exhibited numerous sporozoites suspended in the intestinal contents when fresh squash preparations were examined by light microscopy. Using this method, sporozoites were not seen in intestinal epithelial cells of the grass shrimp or in any other cell types. Ultrastructural examination, however, revealed sporozoites in the cytoplasm of the gut basal cells. Cross-sections of 1-13 sporozoites were seen within a single cell, and those sporozoites each appeared to be situated in individual membrane-bound vesicles, rather than in a single parasitophorous vacuole. These ultrastructural observations indicate that in the grass shrimp intermediate host, sporozoites that develop into an infective stage probably undergo that development in gut mucosal basal cells. Prior studies revealed that these sporozoites modified their structure over 4-5 days and that before that time, they were not infective to the fish host. Following ingestion of an infected shrimp by a killifish, the infective sporozoites apparently reach the liver of their killifish definitive hosts through the bloodstream. Sporozoites were seen in blood smears from the longnose killifish, Fundulus similis, 4 hr after fish were fed experimentally infected grass shrimp. Additionally, coccidian trophozoites and early meronts were seen in hepatocytes from several longnose killifish at 48, 72, and 96 hr postinfection. This study, in conjunction with previous findings, clearly confirms that a true intermediate host is required in the life cycle of C. funduli, that a developmental period of about 5 days in grass shrimp is necessary for sporozoites to become infective to killifishes, and that sporozoites do occur intracellularly in gut basal cells of the grass shrimp.

Animals↗
PubMed2005

Molecular characterization of isosporoid coccidia (Isospora and Atoxoplasma spp.) in passerine birds.

Prevalence and disease caused by isosporoid coccidia in passerine birds are well recognized, but confusion about the life cycles of the parasites has led to taxonomic inconsistencies. In this study, we characterized segments of the chromosomal small and large-subunit ribosomal RNA (rRNA) genes of coccidial parasites from 23 species of passerine birds, as well as heat shock protein 70, apicoplast rRNA, and chromosomal 5.8s rRNA genes from a subgroup of these animals, and we correlated genetic data with morphologic findings for different parasite developmental stages, host phylogeny, and overall taxonomic relations within the phylum Apicomplexa. Our findings indicate that isosporoid coccidia of passerine birds are monophyletic but exhibit substantial diversity, with most avian species having one or several unique parasite lineages that underwent synchronous speciation with their hosts, interrupted by sporadic episodes of lateral transmission across species and families. Molecular analyses support a homoxenous life cycle, with sexual forms occurring chiefly in the intestines and asexual merozoites present systemically. Rarely, extraintestinal sexual stages can occur. The passerine coccidia are genetically most closely related to species of Eimeria rather than Isospora. We suggest that these parasites, whether identified from blood merozoite stages or fecal oocysts, be provisionally grouped as a homogeneous clade of individual species in a single taxon and formally named when reliable criteria allowing reclassification of related genera in the suborder Eimeriina are clarified.

Animals↗
PubMed2000

Two simultaneous cases of Cyclospora cayatensis enteritis returning from the Dominican Republic.

According to the "International Passenger Survey," published in 1996 by the Office of Trading Standards, 534,000 British people traveled to the Caribbean area (personal communication, ABTA, 1998). The Dominican Republic, the eastern end of a large Caribbean island, has become in recent years one of the most popular destinations for UK holidaymakers as well as for travelers from many other countries. Cyclospora cayatensis has been firmly identified as a cause of gastroenteritis among international travelers,1 including human immunodeficiency virus (HIV)-positive individuals,2 but it has not been previously reported in the literature in British individuals returning from this increasingly popular vacation destination.

Aged↗