الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
HCV infection is a major public health problem because of its clinical consequences which are end stage liver failure and HCC. Parenteral routes, of which blood transfusion is the most frequent, are the main modes of transmission of HCV. In 1992, screening of blood donors for HCV was introduced, which represented a major step in prevention of transfusion of infected blood units. Anti-HCV ELISA are the licensed screening assays for blood donors, however, high false-positive results (30-60%) and delayed seroconversion may affect detection of HCV infection by these assays.
Need for a more sensitive and accurate confirmatory test is urgent. NAT assays provide an additional layer of blood safety. They were introduced in early 2000. They had been considered as the gold standard in HCV diagnosis. However, NAT techniques are expensive and require technical expertise and special laboratory which may restrict their wide scale usage in limited resource settings in screening of blood donors. LAMP was found to be simple, cost-effect and rapid test to replace NAT techniques in screening of blood donors.
The present study aimed to:
Evaluate the efficiency of LAMP technique in screening HCV among blood donors through detection of anti-HCV antibodies using third generation ELISA and comparing HCV RNA detection using NAT and LAMP techniques.
The present analytical cross-sectional study was carried out throughout the period from April to December 2019. It enrolled 200 volunteer blood donors visiting blood bank at the Medical Research Institute, Alexandria University.
Three ml of blood were collected from each blood unit recruited in the study, under strict aseptic conditions, in sterile tubes. The samples were left to clot and sera were separated by centrifugation at 3500 rpm for 10 minutes. Each serum sample was divided into 3 aliquots and stored at -80oC until tested. HCV infection was examined in each serum sample by third generation ELISA technique (Monolisa™), NAT technique and RT-LAMP technique.
The results of the present study revealed that:
1. Age range of the studied blood donors was from 19-65 years old.
2. More than half of blood donors (54.5 %) were in age group of 35<50 years, most of them were males (54.1%).
3. Male to female ratio among donors was almost 1:1, where 51.5% of studied blood donors were males.
4. None of studied blood donors reported alcohol intake or intravenous drug use.
5. Out of 200 studied blood donors, 95 (47.5%) and 73 (36.5%) were hypertensive and diabetics, respectively.
6. All donors were negative for syphilis, HBV and HIV.
7. Among 200 blood donors, 6 (3%) had a family history of hepatitis, 41 (20.5%) were living with HCV infected individuals, 69 (34.5%) had a history of schistosomiasis, 45 (22.5%) had undergone routine check-up and 39 (19.5%) had undergone previous blood or organ donor screening.
8. The percentages of HCV positivity among donors were 24% by ELISA, 9% by RT-LAMP and 8 % by NAT.
9. Out of 16 HCV positive donors by NAT, 9 (56.6%) were males and 7 (43.7%) were females, while out of 184 HCV negative donors by NAT, 94 (51.1%) were males and 90 (48.9%) were females.
10. Out of 16 HCV positive blood donors by NAT, 5 (31.3%) were in age group of 19<35 years, 8 (50%) were in age group of 35<50 years and 3 (18.7%) were in age group of 50≤ 65 years.
11. Out of 184 HCV negative blood donors by NAT, 69 (37.5%) were in age group of 19<35 years, 101 (54.9%) were in age group of 35<50 years and 14 (7.6%) were in age group of 50≤ 65 years.
12. Out of 200 blood donors, 145 (72.5%) were negative for HCV Abs, 7 (3.5%) had a weak positive reaction for the antibody and 48 (24%) were positive.
13. Among the 16 HCV NAT positive blood donors, 2 (12.5%) were negative for HCV Abs and 14 (87.5%) were positive.
14. Out of the 184 HCV NAT negative blood donors, 143(77.7%) were negative for HCV Abs and 7 (3.8%) had a weak positive reaction for the antibody and 34 (18.5%) were positive for HCV Ab.
15. One out of the two blood donors that were HCV NAT positive and HCV Ab negative was in age group of 35<50 years, and the other one was in age group of 50≤ 65 years.
16. Out of 14 HCV NAT and HCV Ab positive, 7 (50%) were in age group of 35<50 years, 5 (35.7%) were in age group of 19<35 years and 2 (14.3%) were in age group of 50≤ 65 years.
17. The two blood donors that were HCV NAT positive and HCV Ab negative were males.
18. Out of 14 HCV NAT and HCV Ab positive, half (50%) were males and half were females.
19. Out of 184 HCV NAT negative blood donors, 143 were negative for HCV Ab, 7 had a weak positive reaction for the antibody and 34 were positive for HCV Ab.
20. About 48.3% of the blood donors that were negative for the HCV antibody were in age group of 35< 50 years, 62 (43.3%) were in age group of 19< 35 years and 12 (8.4%) were in age group of 50≤ 65 years.
21. Out of 34 that were positive for HCV Ab, 5 (14.7%) were in age group of 19< 35 years, 27 (79.4%) were in age group of 35< 50 years and 2 (5.9%) were in age group of 50≤ 65 years.
22. The two HCV NAT positive donors that were negative for HCV Ab were positive by RT-LAMP assay. All donors that were positive for both HCV NAT and HCV Abs were positive by RE-LAMP assay.
23. Among 200 blood donors, 18 (9%) were positive for HCV by RT-LAMP assay and 182 (91%) were negative.
24. RT-LAMP assay correctly identified all 16 blood donors that were positive by HCV NAT.
25. Out of 184 blood donors that were negative by HCV NAT, 2 (1.1%) were positive by RT-LAMP assay and 182 (98.9%) were negative.
26. The sensitivity of RT-LAMP assay was 100%, and specificity was 98.9%. The PPV and NPV were 88.9% and 100%, respectively.
27.The measured agreement between RT-LAMP assay and NAT tests was almost perfect (kappa=0.936).
28.Five (31.3%) blood donors that were positive by NAT and RT-LAMP assays were in age group of 19< 35 years, 8 (50%) were in age group of 35< 50 years and 3 (18.7%) were in age group of 50≤ 65 years.
29.Nine (56.3%) blood donors that were positive by NAT and RT-LAMP assays were males and 7 (43.7%) were females.
It can be concluded from the present study that:
1.RT-LAMP is a highly sensitive technique in screening blood donors.
2.The sensitivity of HCV Abs detection was 87.5% and specificity was 81.5%. The positive predictive value and negative predictive value were 29.2% and 98.7% respectively.
3.The measured agreement between anti- HCV ELISA and NAT was fair (Kappa=0.315).
4.The measured agreement between RT-LAMP assay and NAT was almost perfect (Kappa=0.936).
from the results of the present study, the following recommendations are suggested:
1.The potential rapid utility of RT-LAMP may replace NAT in screening blood donors for HCV in endemic resource- limited regions.
2.Further studies using six primers, in RT-LAMP assay are recommended which may increase its sensitivity.
3.Further studies using quenched fluorescent primers, in RT-LAMP assay are recommended which may increase its specificity.