Genetic Variability of Cryptosporidium Isolates from Humans in Greater Cairo, Egypt
Mai Abd El-Sameaa Shehata;
Abstract
Cryptosporidium parasite has been recognized worldwide as the most common cause of protozoal diarrhea leading to significant morbidity and mortality in industrialized and developing countries. Although person-to-person transmission has been considered the major route of transmission, zoonotic transmission of this protozoan may also occur. The majority of human cases of cryptosporidiosis are caused by two species: C. hominis and C. parvum. However, wide range of Cryptosporidium spp. and subtypes infect humans. Exposition of Cryptosporidium genotypes by molecular assays is required to recognize sources of infections and routes of transmission, facilitating the improvement of risk assessment and measures for prevention and control.
Hence, the present study aimed to determine Cryptosporidium genotypes in human stool samples with correlation with their respective demographic, environmental and clinical data among Egyptians from greater Cairo.
A cross sectional study was done during the period from June 2013 to March 2015. A total of 350 human cases with variable demographic, environmental and clinical presentations were subjected to mZN stain, then were examined by ICT kit. All positive Cryptosporidium cases diagnosed by mZN stain and/or ICT kit were processed for DNA extraction. The extracted DNA samples were genotyped using nPCR-RFLP targeting SSU rRNA and COWP genes.
Based on the obtained results, screening for Cryptosporidium infection was done using mZN stain, the prevalence of Cryptosporidium among the study population was 5.7% (20/350). 33/350 (9.4%) were immune reactive for Cryptosporidium using ICT kit.
All positive stool samples by microscopy and/or Crypto-Giardia ICT kit methods (40 samples) were subjected to DNA extraction. After DNA extraction, nPCR was done using SSU-rRNA and COWP genes. All samples couldnot be amplified by SSU rRNA gene.
Regarding nPCR targeting COWP gene, 15 (37.5%) of positive samples by mZN and 13 (32.5%) of positive samples by Crypto-Giardia ICT kit were successfully amplified. However, 5 (12.5%) of positive samples by mZN and 20 (50.0%) of positive samples by ICT were not amplified.
To validate the diagnosis of cryptosporidiosis, we considered detection of the organism by two of the three techniques as true positive cases. Among the diagnostic tests used, nPCR showed the highest sensitivity and specificity 100%, followed by mZN stain with 100% sensitivity as there were no false negative samples, 83.3% specificity as there were 5 false positive samples, with positive predictive value (PPV) 75% and negative predictive value (NPV) 100%. While, ICT showed 86.6% sensitivity as there were 2 false negative samples, 20% specificity as there were 20 false positive samples, with positive predictive value (PPV) 39.4% and negative predictive value (NPV) 71.4%.
Occurrence of Cryptosporidium was analyzed for associations with potential risk factors determined for the patient who is positive for Cryptosporidium. There was a significant association between Cryptosporidium infection and gender of the patients, with a higher prevalence among males when compared to females.
Hence, the present study aimed to determine Cryptosporidium genotypes in human stool samples with correlation with their respective demographic, environmental and clinical data among Egyptians from greater Cairo.
A cross sectional study was done during the period from June 2013 to March 2015. A total of 350 human cases with variable demographic, environmental and clinical presentations were subjected to mZN stain, then were examined by ICT kit. All positive Cryptosporidium cases diagnosed by mZN stain and/or ICT kit were processed for DNA extraction. The extracted DNA samples were genotyped using nPCR-RFLP targeting SSU rRNA and COWP genes.
Based on the obtained results, screening for Cryptosporidium infection was done using mZN stain, the prevalence of Cryptosporidium among the study population was 5.7% (20/350). 33/350 (9.4%) were immune reactive for Cryptosporidium using ICT kit.
All positive stool samples by microscopy and/or Crypto-Giardia ICT kit methods (40 samples) were subjected to DNA extraction. After DNA extraction, nPCR was done using SSU-rRNA and COWP genes. All samples couldnot be amplified by SSU rRNA gene.
Regarding nPCR targeting COWP gene, 15 (37.5%) of positive samples by mZN and 13 (32.5%) of positive samples by Crypto-Giardia ICT kit were successfully amplified. However, 5 (12.5%) of positive samples by mZN and 20 (50.0%) of positive samples by ICT were not amplified.
To validate the diagnosis of cryptosporidiosis, we considered detection of the organism by two of the three techniques as true positive cases. Among the diagnostic tests used, nPCR showed the highest sensitivity and specificity 100%, followed by mZN stain with 100% sensitivity as there were no false negative samples, 83.3% specificity as there were 5 false positive samples, with positive predictive value (PPV) 75% and negative predictive value (NPV) 100%. While, ICT showed 86.6% sensitivity as there were 2 false negative samples, 20% specificity as there were 20 false positive samples, with positive predictive value (PPV) 39.4% and negative predictive value (NPV) 71.4%.
Occurrence of Cryptosporidium was analyzed for associations with potential risk factors determined for the patient who is positive for Cryptosporidium. There was a significant association between Cryptosporidium infection and gender of the patients, with a higher prevalence among males when compared to females.
Other data
| Title | Genetic Variability of Cryptosporidium Isolates from Humans in Greater Cairo, Egypt | Other Titles | التنوع الجيني للكربتوسبوريديوم المعزولة من الإنسان في القاهرة الكبري، مصر | Authors | Mai Abd El-Sameaa Shehata | Issue Date | 2017 |
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