The intestinal protozoa of man /

Dobell, Clifford; O'connor, F. W.

doi:10.5962/bhl.title.59616

Cited by 64 publications

(53 citation statements)

References 75 publications

(119 reference statements)

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“…Giardia was initially described by van Leeuwenhoek in 1681 as he was examining his own diarrheal stools under the microscope (66). The organism was described in greater detail by Lambl in 1859, who thought the organism belonged to the genus Cercomonas and named it Cercomonas intestinalis (172).…”

Section: History Of the Discovery And Species Designation Of Giardiamentioning

confidence: 99%

Biology ofGiardia lamblia

2001

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Giardia lamblia is a common cause of diarrhea in humans and other mammals throughout the world. It can be distinguished from other Giardia species by light or electron microscopy. The two major genotypes of G. lamblia that infect humans are so different genetically and biologically that they may warrant separate species or subspecies designations. Trophozoites have nuclei and a well-developed cytoskeleton but lack mitochondria, peroxisomes, and the components of oxidative phosphorylation. They have an endomembrane system with at least some characteristics of the Golgi complex and encoplasmic reticulum, which becomes more extensive in encysting organisms. The primitive nature of the organelles and metabolism, as well as small-subunit rRNA phylogeny, has led to the proposal that Giardia spp. are among the most primitive eukaryotes. G. lamblia probably has a ploidy of 4 and a genome size of approximately 10 to 12 Mb divided among five chromosomes. Most genes have short 5′ and 3′ untranslated regions and promoter regions that are near the initiation codon. Trophozoites exhibit antigenic variation of an extensive repertoire of cysteine-rich variant-specific surface proteins. Expression is allele specific, and changes in expression from one vsp gene to another have not been associated with sequence alterations or gene rearrangements. The Giardia genome project promises to greatly increase our understanding of this interesting and enigmatic organism

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Section: History Of the Discovery And Species Designation Of Giardiamentioning

confidence: 99%

Biology ofGiardia lamblia

2001

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“…The seeds of doubt concerning the pathogenicity of D. fragilis were unfortunately planted by Jepps and Dobell (65) and nourished by Dobell and O'Conner (38) and account at least partially for the lingering resistance in many clinical circles to accept the disease-causing potential of this organism. However, the evidence supporting the pathogenicity of D. fragilis is too convincing to justify the continued neglect of this parasite as a cause of diarrhea, abdominal pain, flatulence, fatigue, and anorexia, the symptoms most commonly observed in patients infected with this organism (68).…”

Section: Introductionmentioning

confidence: 99%

Emerging from Obscurity: Biological, Clinical, and Diagnostic Aspects of Dientamoeba fragilis

2004

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Ever since its first description in 1918, Dientamoeba fragilis has struggled to gain recognition as a significant pathogen. There is little justification for this neglect, however, since there exists a growing body of case reports from numerous countries around the world that have linked this protozoal parasite to clinical manifestations such as diarrhea, abdominal pain, flatulence, and anorexia. A number of studies have even incriminated D. fragilis as a cause of irritable bowel syndrome, allergic colitis, and diarrhea in human immunodeficiency virus patients. Although D. fragilis is most commonly identified using permanently stained fecal smears, recent advances in culturing techniques are simplifying as well as improving the ability of investigators to detect this organism. However, there are limitations in the use of cultures since they cannot be performed on fecal samples that have been fixed. Significant progress has been made in the biological classification of this organism, which originally was described as an ameba. Analyses of small-subunit rRNA gene sequences have clearly demonstrated its close relationship to Histomonas, and it is now known to be a trichomonad. How the organism is transmitted remains a mystery, although there is some evidence that D. fragilis might be transmitted via the ova of the pinworm, Enterobius vermicularis. Also, it remains to be answered whether the two distinct genotypes of D. fragilis recently identified represent organisms with differing virulence

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“…It was first described in the late 17th century by the Dutch microscopist Antonie van Leeuwenhoek (62), and research into its epidemiology, pathogenesis, and treatment has intensified since G. lamblia waterborne outbreaks were reported in Europe and the United States during the 1960s and 1970s (53,81,123,128,174). Giardia infects approximately 2% of the adults and 6 to 8% of the children in developed countries worldwide and is currently responsible for the largest number of waterborne outbreaks of diarrhea in the United States (54,139).…”

Section: Introductionmentioning

confidence: 99%

Treatment of Giardiasis

2001

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Giardia lamblia is both the most common intestinal parasite in the United States and a frequent cause of diarrheal illness throughout the world. In spite of its recognition as an important human pathogen, there have been relatively few agents used in therapy. This paper discusses each class of drugs used in treatment, along with their mechanism of action, in vitro and clinical efficacy, and side effects and contraindications. Recommendations are made for the preferred treatment in different clinical situations. The greatest clinical experience is with the nitroimidazole drugs, i.e., metronidazole, tinidazole, and ornidazole, which are highly effective. A 5- to 7-day course of metronidazole can be expected to cure over 90% of individuals, and a single dose of tinidazole or ornidazole will cure a similar number. Quinacrine, which is no longer produced in the United States, has excellent efficacy but may be poorly tolerated, especially in children. Furazolidone is an effective alternative but must be administered four times a day for 7 to 10 days. Paromomycin may be used during early pregnancy, because it is not systematically absorbed, but it is not always effective. Patients who have resistant infection can usually be cured by a prolonged course of treatment with a combination of a nitroimidazole with quinacrine

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The intestinal protozoa of man /

Cited by 64 publications

References 75 publications

Biology ofGiardia lamblia

Biology ofGiardia lamblia

Emerging from Obscurity: Biological, Clinical, and Diagnostic Aspects of Dientamoeba fragilis

Treatment of Giardiasis

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