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E K Markell

Publications and source records attributed to E K Markell.

At least 19 recordsLinked to original sources
PubMed1995

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. About 13% of the entire group had a single stool specimen examined, 19% had two examined, 65% had three examined, and 6% had more than three examined. Most infections were detected in the first specimen or specimens submitted, but many were not detected until later examination. Thirteen patients with E. histolytica (10.4%) required 4-9 examinations. The sensitivity of one examination was compared with that of three examinations; with the additional examinations, the yield increased 22.7% (95% confidence interval [CI] = 11.8-33.5%) for E. histolytica, 11.3% (95% CI = 6.9-81.8%) for G. lamblia, and 31.1% (95% CI = 17.7-54.4%) for D. fragilis. Our results suggest that a single stool specimen examination will miss many pathogenic protozoan infections in symptomatic persons.

Animals↗
PubMed1993

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. hominis and those not infected was similar, and no correlation was found between the presence of B. hominis and that of fecal leukocytes. High concentrations of B. hominis were more frequent and more nonpathogenic protozoa were found in symptomatic patients than in those who were asymptomatic.

Adolescent↗
PubMed1986

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. Of this number, 32 had at least 6 stool examinations performed. Twenty-seven of the 32 persons were later found to have greater than or equal to 1 recognized pathogens--Entamoeba histolytica, Giardia lamblia or Dientamoeba fragilis--and, after receiving appropriate therapy, became asymptomatic. The B hominis infection, however, was unaffected by therapy. Five persons with only B. hominis infection were treated with iodoquinol without effect; these persons fulfilled the medical criteria for irritable bowel syndrome. We believe that when an apparently symptomatic B. hominis infection responds to therapy, the improvement probably represents elimination of some other undetected organism causing the infection.

Diarrhea↗
PubMed1985

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.

Adolescent↗
PubMed1984

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. The spectrum of the disease in persons with acquired immune deficiency syndrome is not well established. I. belli did not stain well with the methods usually used for intestinal protozoa and was difficult to see unstained. However, it stained well with the acid-fast technique used for Cryptosporidium sp. and was easily identified by such stains. A case of combined infection with Cryptosporidium sp. and I. belli is reported.

Acquired Immunodeficiency Syndrome↗
PubMed1984

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. Infection with E. histolytica was correlated significantly with a prior history of syphilis or gonorrhea (P less than 0.0001), with the number of sexual partners in the preceding 12-month period (P less than 0.0001), and with the reported frequency of oral-anal sexual contact (P less than 0.001). Giardial infection was also significantly related to oral-anal sex (P less than 0.001). No relation was seen between the presence or absence of gastrointestinal symptoms and infection with pathogenic protozoa. Factors associated with parasitic infection differed little from those found in previous studies, although significance levels were considerably higher because of the larger size of our study group.

Adult↗
PubMed1983

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.

Adult↗
PubMed1981

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. Because KFPH membership included, at the time of the survey, approximately 27 percent of all residents of the San Francisco Bay Area, the membership may be considered approximately representative of the entire area. Fourteen percent of persons were found to be infected with one or more intestinal protozoan parasites, while 5.5 percent harbored potentially pathogenic sorts. Entamoeba histolytica was found in 0.7 percent of those surveyed, Giardia lamblia in 1.7 percent and Dientamoeba fragilis in 3.1 percent.

Adolescent↗
PubMed1977

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. The routine use of PVA fixation prior to transportation of the specimen to the laboratory is recommended.

Amebiasis↗