الفهرس 
Introduction and Aim of the present studyOnly 14 pages are availabe for public view
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Abstract
Blastocystis is a single celled protozoanparasite that comprises several species, living in the gastrointestinal tracts of species as diverse as humans, farm animals, birds, rodents, reptiles, amphibians, fish, and cockroaches; It exhibits low host specificity. A number of distinct genetic types of Blastocystis sp. can infect humans.
Blastocystis sp. has a worldwide distribution, appearing more frequently in tropical and subtropical countries. It is the most prevalent parasite infecting the large intestine of at least one billion people worldwide. The rate of infection is 5-10% in developed countries, and up to 50% in developing ones. In Egypt, different rates were recorded; it reached up to 65% and 52.5% among cases of inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) respectively. It was detected among 28.3% among diarrheic infants and preschool children, Also, in 6% of patients with diarrhea. Patients with immunocompromised status have an increased probability of acquiring a primary infection.
The aim of the present study was to study the validity of copro- antigen ELISA test versus coproscopic techniques for diagnosing Blastocystis hominis among patients on hemodialysis.
Stool samples were collected from 90 hemodialysis patients to diagnose infection with B. hominis. Each sample was examined for detectingB.hominis copro-antigen using ELISA technique. Subsample of each stool specimen was cultured on Jones’ medium, another subsample was examined as a direct wet mount (saline and iodine smears), then a thin film was prepared to be stained by trichrome technique.
An interviewing questionnaire was designed to collect data from hemodialysis patients (sociodemographic data, healthy practices, house environment data in addition to medical history).
from the present work, the following results were obtained:
1- Blastocystis hominis infection rate was computed to be 68.9% by the gold standard technique (Pooled data from the all samples examined by the three coproscopic techniques).
2- Percentage of B.hominis infection among studied sample according to their sociodemographic characteristics: Patients aged from 40 to less than 60 years had the highest rate of infection (72.5%). Male patients presented with a higher percentage of B.hominis infection than female patients. The highest percentage of infection was detected among patients of primary or preparatory education levels while illiterate individuals or those who can just read and write presented with the lowest infection rate. All farmers and manual workers patients suffered from B.hominis infection. The percentage of infection among those who lived in urban areas was higher than those who lived in rural areas. Single patients had higher percentage of infection than the married ones. There wasn’t any statistically significant difference between infection rates and all previous risk factors (p <0.05).
3- Percentage of B.hominis infection among studied sample according to their houses’ environment: The highest percentages of infection were detected among patients getting their water from private taps with filters, among those who were drinking it without any storage and among those who used tanks if the water was stored. The percentages of infected patients who used private latrines, who had municipal disposal of sewage and who did not have any animals were higher than the percentages detected among persons who used shared toilets, who did not have municipal disposal and who had animals .The differences were not statistically significant (p<0.05).
4- Percentage of B.hominis infection among studied sample according to their healthy practices: Eighty percent of individuals using a disinfectant in addition to water for cleaning their containers were infected while no infection was detected among those who used only water for cleaning. Patients declaring prolonged periods for containers cleaning presented with higher infection rate than those who confirmed the weekly regular wash. A slightly higher infection rate was also observed among individuals admitting covering of stored water than those denying it.A higher infection rate was detected among patients who were not eating green leafy vegetables outdoors than among those who were used to eat such vegetables outdoors. Females who admitted regular hand wash before food preparation presented with an insignificant higher percentage of B.hominis infection than those who denied washing hands. Equal rates of infection were observed among patients using gloves and those not using gloves in cleaning their animal excreta.
5- Percentage of B.hominis infection among studied sample according to their medical history: The highest infection rate was detected among patients who were on dialysis for less than 3 years. Patients with autoimmune diseases as main cause of their renal failure presented with the highestB.hominis infection rate followed by those suffering from urinary tract pathology, cardiovascular problems and those with inherited or congenital causes. An 80.0% of patients who did not complain from any symptoms suffered from Blastocystis hominis infection.
6- E.histolytica was the second prevalent intestinal parasite found among the studied sample, its infection rate amounted to13.3%, followed by E.coli (7.8%). Cryptosporidium sp infection rate was 3.3%. Only one case harbored Giardia lamblia cyst (1.1%). Almost all cases suffering from intestinal parasites were co infected with Blastocystishominis.
7- B.hominis infection rates were found to be 64.4% and 52.2% by using trichrome staining technique and the direct wet mount technique respectively. Culture technique on Jones’ medium revealed a rate of 46.7%.Variations in the infection rateswere observed between the three samples collected (on alternative days) from every patient for all coproscopic techniques but the differences were not statistically significant.
8- B.hominis infection rate was as low as28.9% when using ELISA technique for detection of copro-antigen. The difference between rates detected by ELISA and rates detected by either trichrome, iodine or culture techniques were statistically significant.
9- Diagnostic parameters of ELISA versus the gold standard technique for diagnosing B.hominis infection: ELISA test sensitivity was 32.26%, its specificitywas 78.57%, the PPV was 76.9%, the NPV was 34.38% with an overall diagnostic efficiency of 46.67%. The DA was11.28% and AUC was 0.568.
Diagnostic parameters of ELISA versus the three coproscopic techniques revealed an overall diagnostic efficiency of 51.11%, 54.4%and 57.78% compared to trichrome, wet mount and Jones’ culture techniques respectively. Its diagnostic accuracy was 17.5%, 13.1% and 15.5% when compared to the three techniques respectively.
In conclusion:
Blastocystis hominisis was the most prevalent intestinal parasite found among the studied sample followed by E. histolytica and E.coli.
Although no significant association was detected between the different sociodemographic factors, different house environmental factors and B.hominis infection, yet all farmers and manual workers were infected.
Patients with autoimmune diseases as main cause of their renal failure presented with a high B.hominis infection rate followed by those suffering from urinary tract pathology, cardiovascular problems and those with inherited or congenital causes.
Eighty percent of hemodialysis patients who didn’t complain of any symptoms were infected with B. hominis.
Coproscopic techniques used in the diagnosis of B.hominis infection either separately or collectively (gold standard technique) were more sensitive than copro-antigen detection by ELISA test. ELISA test sensitivity was 34.04%, 34.48%,35.71% and 32.26% when compared with direct wet mount (Iodine- Saline stain), trichome staining, Jones` culture and the gold standard techniques respectively. Its specificity was 76.74%, 81.25%, 77.08% and 78.57% respectively.