الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 132 |  |  |
| | | from | 132 | | |
Abstract
Cryptosporidium is a major cause of diarrheal disease that has a cosmopolitan distribution, approximately 30% of the adult population in developed economies and about 60% in developing countries have serologic evidence of prior infection with this organism. Cryptosporidiosis probably exerts most of its impact on pediatric health, where it accounts for up to 20% of all cases of childhood diarrhea and is predicted to be higher in children of developing countries, where 45% of the children are experiencing an infection before the age of two.
Despite the clinical and public health importance of Cryptosporidium, little is known about its transmission dynamics in Alexandria. Given the wide range of Cryptosporidium species, genotypes, and subgenotypes, each with different sources of infection, transmission routes, and pathogenicity, the diagnosis and genetic characterization of the different species is crucial for the prevention, surveillance and control of cryptosporidiosis.
Thus, the aim of the present study was to determine the molecular characterization and transmission dynamics of Cryptosporidium spp. among preschool children in Abbis 10 in Alexandria Governorate.A cross-sectional study was implemented, where 309 children below 6 years old were included in the study through a house to house survey.An interviewing questionnaire was designed to collect; socio-demographic, hygienic and medical data for each child.
A single stool sample was collected from each child and was examined macroscopically for color, odor and consistency. For each sample, formol-ether concentration techniquewasperformed for detection of intestinal parasites and MZN technique for detection of Cryptosporidium oocysts.Cryptosporidium species in microscopy positive samples were identified through nPCR targeting COWP gene then RFLP was performed on PCR- positive samples using Rsa I enzyme for genotyping.
from the present study, the following results were obtained:
• Cryptosporidium infection was detected in 7.4% of the children.
• Among Cryptosporidium infected cases, 78.3% had associated parasitic infection; Cryptosporidium was significantly associated with other coccidian infections, Cyclospora and Microsporidia with rates of 26.1% and 43.5% respectively.
• Regarding sex, the percentage of infection was higher among males (8.4%) compared to females (6.5%). However this association was not statistically significant.
• As regards age, the lowest infection rate of 4.5% was detected among children aged less than two years, it increased to 5.8% among those older than four years while the highest infection rate (10.7%) was detected in the (2-4 years old) age group. The association was not statistically significant.
• Cryptosporidium infection was higher among children attending DCCs (10.2%) compared to 5.2% among those who didn’t. However, the association was not statistically significant.
• Concerning type of drinking water, almost all the cases were using tap water except for one case that used filtered water.
• In relation to animal contact, Cryptosporidium infection was insignificantly higher among children who had no animal contact compared to those who had. (9.0% Vs 5.6% respectively).
• As regards the type of animals inside house, the highest infection rate was detected in children having cattle in their houses (9.4%) followed by those having birds (8.8%) without significant difference.
• Regarding GIT symptoms, the prevalence of cryptosporidiosis was significantly higher among the symptomatic children (14.4%) compared to 4.6% among the asymptomatic children.
• Among the symptomatic group;the highest percentage of Cryptosporidium infection was detected among children with diarrhea and colic (21.9%) followed by those with diarrhea and fever (15.0%), 11.1% in children with diarrhea alone while the lowest percentage was detected among those with diarrhea and vomiting (10.0%). However, the association was not statistically significant.
• Concerning the duration of diarrhea, almost all the cases had acute diarrhea (< 14 days)except for one case that had persistent diarrhea (≥ 14 days), however, Cryptosporidium infection was insignificantly higher among children with persistent diarrhea (20%) compared to14% among those with acute diarrhea.
• Cryptosporidium infection was also insignificantly higher among children who had another family member with diarrhea (16.7%) compared to 13.9% for those who hadn’t.
• Cryptosporidium infection was significantly associated with stool consistency, where the highest rate of infection was detected among children having liquid stool (33.3%) compared to 14.7% among those with soft stool while a much lower percentage of 2.5% was detected among those with formed stool.
• nPCR targeting COWP gene was able to detect Cryptosporidium copro-DNA in 12 out of the 23 positive cases (52.2%).
• Among the 12 cases detected by COWP nPCR, 9 (75.0%) wereC. hominis, 2 (16.7%) were C. parvum and one case could not be digested by Rsa I restriction enzyme.
• No statistical significant difference was detected among the different genotypes as regards gender, age, DCC attendance, type of drinking water and animal contact.
• No statistical significant difference regarding GIT symptoms was detected among the two genotypes.
• All C. parvum cases had soft stool, while C. hominis cases had soft and liquid stool (55.6% and 44.4% respectively). No statistical significant difference was detected.
from the results of the present study, it can be concluded that:
Molecular tools have been helpful to assess the potential source of infection. Most infected children had C. hominis with anthroponotic transmission, thus, direct person-to-person spread probably played an important role in Cryptosporidium transmission among the children in this study, which could also be supported by the low socioeconomic, overcrowded living conditions and poor hygienic practices of the study participants.
The lack of gold standard for Cryptosporidium diagnosis, due to the low sensitivity of copro-diagnosis using staining technique and the limitations of PCR thathinder its wide use,may limit early diagnosis and treatment of Cryptosporidium. Besides, the absence of effective, specific therapy against infection with this parasite, emphasize the importance of the preventivemeasures, especially, goodhygienic practices which seem to be the best solution for control of cryptosporidiosis in such areas.
Potential limitations of the study might be that the revealed results were based on a single stool sample for each participant andsmall number of cases was included. In addition, the effect of environmental conditions and seasonal variability on the study population is lacking.