Blastocystis hominis may be a potential cause of intestinal disease

Prevalence of non-pathogenic types of gastrointestinal protozoa in population in Slovakia and their potential importance in the aspect of public health

The aim of the research was to determine the prevalence of non-pathogenic protozoa circulating in the human population of Slovakia. We particularly focused on the socially deprived areas with poor sanitation conditions, as they are one of the factors affecting the transmission of these infections. Within this study, 2760 people were coprologically screened for the presence of protozoan cysts. The analyzed group comprised 1173 men and 1587 women from different regions of Slovakia. The total prevalence (2.03%) of non-pathogenic protozoa species was determined. The prevalence of Entamoeba coli was 0.80%, the prevalence of Endolimax nana 0.58%, and the prevalence of Blastocystis hominis was 0.65%. The presence of non-pathogenic protozoa was more frequent in women than that in men, in all age groups. The highest incidence of Entamoeba coli was found in children aged one month - seven years (0.79%), the lowest in the age group of 19-88 years (0.66%). Endolimax nana was most frequent in 8-18 year-olds (0.95%), where the statistical significance was found (p<0.05). The prevalence of Blastocystis hominis by the age group ranged from 0.39 to 0.95%. We did not find any statistical significance (p>0.05) for Entamoeba coli, and similarly for Blastocystis hominis associated with the sex and age. Although the circulation of non-pathogenic protozoa in the human population is far from being limited to the developing countries, their occurrence is also frequent in the population of developed countries. Despite their controversial pathogenicity, they should not be neglected, particularly in the patients with gastrointestinal symptoms.

Blastocystis hominis and the evaluation of efficacy of metronidazole and trimethoprim/sulfamethoxazole

Blastocystis hominis is commonly found in the intestinal tract of humans. Although the pathogenicity of this unicellular parasite is controversial, anti-protozoan agents are usually administered to infected individuals. At present, the first choice of chemotherapeutic agent is Metronidazole as described in the literature. In this study, we evaluated the effects of metronidazole and Trimethoprim/Sulfamethoxazole (TMP/SMX) on persons infected with B.hominis. A total of 104 subjects infected with B. hominis were admitted to the laboratory from 2002 to 2003. All individuals were non-immunocompromised and subjects were monitored for 1 year after treatment. All stool samples were microscopically examined after staining with iodine and by culturing in an egg slant medium. Of the 104 infected individuals (52+/-16 years of age, M:F=60:44) with B. hominis infection, 28 were discharging large numbers of parasites before treatment. Of 28 severely infected individuals, 12 were treated with metronidazole/250-750 mg at a regimen of 3 x/day/10 days and 4 of the 12 were eradicated. Nine individuals were treated with TMP/SMX/1 tab at a regimen of 3 x/day/10 days and 2 of the 9 were eradicated. For severe B. hominis infections, it appears that metronidazole and TMP/SMX are effective in some individuals, but not all.

Triple Faeces Test: an effective tool for detection of intestinal parasites in routine clinical practice

Microscopic examination of stool specimens is the cornerstone of detection of intestinal parasites in parasitology laboratories. In Europe, fresh, nonpreserved stool specimens are generally used for examination. Because intestinal parasites are shed intermittently, patients are asked to deliver multiple stool samples for examination. The limitation of this diagnostic approach is that detection of the vegetative stages of protozoa may be missed because of delays in processing and/or low compliance with the request to submit multiple stool samples. To overcome this limitation, a diagnostic test that combines multiple sampling (on 3 consecutive days), a fixative (SAF; sodium acetate acetic acid formalin), a concentration method and an easy-to-use permanent stain (chlorazol black dye) was developed for use in routine clinical practice. The results of the test, called the "Triple Faeces Test" (TFT), were compared with those of the conventional diagnostic method, i.e. ether sedimentation of a single fresh stool specimen. Stool samples from 544 patients were examined. Vials from the TFT-sets were filled by patients precisely according to instructions in 462 of 544 (85%) of the cases. Using the conventional method and the TFT, 106 and 209 patients, respectively, were diagnosed with infection by one or more parasitic species ( P<0.005). Pathogenic species were detected by the conventional method and by the TFT in 39 and 94 cases, respectively, and nonpathogenic species were detected in 124 and 288 cases, respectively ( P<0.05). Additional costs for the sampling device, laboratory reagents and handling of the TFT were acceptable. The results of this study suggest that the TFT is an effective method for detection of intestinal parasites in stool samples in routine clinical practice.

Blastocystis hominis revisited

Blastocystis hominis is a unicellular organism found commonly in the intestinal tract of humans and many other animals. Very little is known of the basic biology of the organism, and controversy surrounds its taxonomy and pathogenicity. There morphological forms (vacuolar, granular, and ameboid) have been recognized, but recent studies have revealed several additional forms (cyst, avacuolar, and multivacuolar). The biochemistry of the organism has not been studied to any extent, and organelles and structures of unknown function and composition are present in the cells. Several life cycles have been proposed but not experimentally validated. The form used for transmission has not been defined. Infections with the organism are worldwide and appear in both immunocompetent and immunodeficient individuals. Symptoms generally attributed to B. hominis infection are nonspecific, and the need for treatment is debated. If treatment appears warranted, metronidazole is suggested as the drug of choice, although failures of this drug in eradicating the organism have been reported. Infection is diagnosed by light microscopic examination of stained smears or wet mounts of fecal material. Most laboratories identify B. hominis by observing the vacuolar form, although morphological studies indicate that other forms, such as the cyst form and multivacuolar form, also should be sought for diagnosis.

Bacteria, viruses, yeasts and protozoans associated with diarrheal disease in Singapore

Labile toxin producing enterotoxic E. coli (ETEC) were the commonest pathogen isolated from diarrheal stools of hospitalized children (21%) and adults (26%) in Singapore. Salmonellas ranked a close second in children (19%). Other bacterial pathogens were isolated from less than 5% of subjects. Blastocystis hominis was detected in 4.3% of diarrheal stools when a simple sedimentation technique was used. Cryptosporidium was not detected at all. An analysis of yeast counts in smears of diarrheal and non-diarrheal stools suggested they were etiologically associated with at least 6% of diarrhea in children and 19% in adults. Testing for rotaviruses by Latex agglutination and for adenovirus by electronmicroscopy showed an association with 6 per cent and 3 per cent diarrhea respectively. The study highlighted a need for: case control studies on ETEC and B. hominis; studies on the epidemiology of diarrhea by yeasts; establishing the true incidence of adenovirus diarrhea; studies on the prevalence and seasonality of rotavirus infection in Singapore.

Incidence of Blastocystis hominis in patients with diarrhoea

We studied the occurrence of the parasite Blastocystis hominis in 1066 stool specimens from patients with diarrhoea, and investigated the relationship between the presence of B. hominis in the faeces and the age of patients. The parasite was recovered from 3.7% samples, but as the sole species of micro-organism in the stool it was recovered from 1% samples. There was no statistically significant difference in the number of B. hominis-positive stools between the younger and the older patients (P < 0.25), yet in the latter, B. hominis was more frequently identified as the only species of micro-organism as compared with the younger group (P < 0.005). The presence of B. hominis in faecal samples of patients with diarrhoea harbouring no other intestinal pathogens suggests an aetiology that should receive more attention in Slovenia.