How many stool examinations are necessary to detect pathogenic intestinal protozoa?

Recent reports have suggested that examination of one stool specimen is sufficient to detect protozoa in symptomatic patients. To verify this hypothesis, we examined specimens submitted to the regional laboratory of a large, prepaid health plan that provides primary care to a membership representative of the general population in northern California. We examined the number and results of stool specimen examinations in the two-month period before detection of Entamoeba histolytica in 125 infected persons, of Giardia lamblia in 154 infected persons, and of Dientamoeba fragilis in 60 persons infected with this parasite.

Blastocystis hominis: prevalence in asymptomatic versus symptomatic hosts.

Blastocystis hominis, other protozoans, and fecal leukocytes were tabulated on trichrome-stained fecal smears from 182 asymptomatic and 125 symptomatic control patients. No statistically significant difference in prevalence of B. hominis was found between the asymptomatic study group and the symptomatic control group; the clinical profile of subjects with B.

Blastocystis hominis: pathogen or fellow traveler?

Blastocystis hominis, an intestinal organism of uncertain taxonomic position, has long been considered nonpathogenic. Some recent studies suggest, however, that it may be associated with diarrhea and may respond to treatment with iodoquinol or metronidazole. To investigate this possibility, we identified 148 persons whose stools contained this organism.

Intestinal nematode infections.

This article discusses strongyloidiasis, hookworm infection, trichostrongyliasis, ascariasis, trichuriasis (whipworm infection), and enterobiasis (pinworm infection). For each infection, the author describes the organism, the epidemiology and geographic distribution, symptomatology and pathogenesis, and diagnosis and treatment.

Demonstration of Isospora belli by acid-fast stain in a patient with acquired immune deficiency syndrome.

Isospora belli, like Cryptosporidium sp., a sporozoan parasite of the small intestine, has been isolated from both immunodeficient and immunologically normal persons. In immunocompetent persons the infection may be asymptomatic; it frequently causes mild and self-limited diarrhea.

Intestinal protozoa in homosexual men of the San Francisco Bay area: prevalence and correlates of infection.

To compare the prevalence of intestinal parasitic infection in male homosexuals selected from other sources with the levels previously reported from clinic-derived populations, various homosexual groups of the San Francisco Bay Area were checked by means of stool examination and questionnaires for prevalence of intestinal parasites and for related sexual behavioral patterns during a 3-year period. The prevalence of Entamoeba histolytica (28.6%) was similar to that reported in other studies, whereas that of Giardia lamblia was lower.

Intestinal parasitic infections in homosexual men at a San Francisco health fair.

In a sample of homosexual men attending a San Francisco Bay Area health fair, there were strikingly higher prevalence rates of intestinal parasitic infections compared with rates in a control group of health plan members who had a routine multiphasic health examination. Physicians treating homosexual men must be aware of the likelihood of such infections, whether or not the patients are symptomatic.

Intestinal protozoan infections: prevalence in the San Francisco Bay Area.

A sample of 415 members of the Kaiser Foundation Health Plan (KFHP) were tested for intestinal protozoa. This parasite survey group was found to be comparable in age distribution, sex and ethnic background with the membership at large. Gastrointestinal complaints were no more numerous in this group than in a large series of KFHP members taking multiphasic examinations.

Egg counts utilizing trichrome-stained smears from polyvinyl alcohol (PVA)-preserved fecal specimens.

A simple method of making egg counts on fecal specimens is described. It utilizes PVA-preserved stool, yields a permanent stained slide, and is as accurate and reproducible as other methods in common use.

Comparison of immediate polyvinyl alcohol (PVA) fixation with delayed Schaudinn's fixation for the demonstration of protozoa in stool specimens.

Immediate fixation of stool specimens in polyvinyl alcohol fixative (PVA) was compared with Schaudinn's fixation delayed until the specimens were received in the laboratory, in a series of 100 consecutive positive stool specimens. More specimens were found positive following PVA fixation, and the numbers of organisms present on the slides were greater in specimens processed by this technique than after Schaudinn's fixation. It is concluded that immediate fixation results in the preservation of larger numbers of organisms in a recognizable state.