Transfusion transmissible infections are an important limiting factor in transfusion services1,2. It is the responsibility of Blood Transfusion Services to provide a safe and sufficient supply of blood and blood products to all patients who require a transfusion. Viruses such as HIV, Hepatitis B, Hepatitis C, CMV, EBV, WNV have a significant effect on blood transfusion services. In Sri Lanka, hundred percentage of the donated blood received from voluntary non-remunerated donors. Before the blood donation, each blood donor will be counseled and examined by a medical officer and pre-check will be done by a Public Health Inspector. All donated blood samples will be screened for HIV, Hepatitis B and Hepatitis C, Syphilis and Malaria. National Blood Center has a strict quality control system which works in association with international laboratories to ensure high standards. Sri Lankan blood donors have lower transfusion-transmissible infection rates when compared to the other countries in the region. Hepatitis B virus (HBV) remains a major risk in transfusion practice due to long window period, infection with mutant viruses and occult transmission of HBV infection. Reduction of residual risk on HBV depends on the development of more sensitive HBV surface antigen (HBsAg) tests, and HBV nucleic acid tests (NAT). The residual risk of transfusion-transmitted infection is the highest for HBV compared to hepatitis C or HIV, mainly because HBV screening is based solely on hepatitis B surface antigen. The detection of HBs antigen in the serum indicates an infection caused by the hepatitis B virus. It is a marker that appears and can be observed two or three weeks before the clinical and biological symptoms of the disease. Surface antigen can be present in the blood for a period of 6 weeks to 6 months. If HBs antigen persists for more than 6 months in the serum it indicates chronic hepatitis. Due to the existence of numerous asymptomatic chronic carriers, hepatitis B represents an important risk of transfusion and the prevention of transmission is based on the detection of the HBs antigen at the time of each blood donation. Hepatitis B surface antigen is detected by 4th generation qualitative one-step “sandwich” enzyme immunoassay. Monolisa HBs Ag ULTRA assay test method is currently used by both MRI and NBTS.
hepatitis C virus (HCV) is an enveloped RNA virus that belongs to the family of
flavivirids, of which six major genotypes were identified. HCV is recognized as
the main cause of non-A and non-B viral hepatitis. HCV infection is
characterized by an acute and chronic infection that can lead to cirrhosis and
evidence of HCV infection can be found through blood tests to detect HCV
antigens and / or antibodies and / or RNA. Compared to a test for anti-HCV
antibodies alone, the use of a combined screening test for both anti-HCV
antibodies and for HCV antigen can reduce the serological window period and
improve the detection of the infection.
Monolisa HCV Ag-Ab ULTRA is a qualitative enzyme
immunoassay for the detection of infection by the hepatitis C virus (HCV) based
on the detection of anti-HCV antibodies and antigen in human serum or plasma.
This hepatitis C screening test is used by both MRI and NBTS microbiology/
virology laboratories. At NBTS there are significant number of donors who are permanently
deferred from the system due to repeat reactive of Hepatitis B and Hepatitis C
screening tests every month, because NBTS does not have a confirmation testing facility.
Therefore, an arrangement was made recently as the second samples of these repeat
reactive donors are sent to the MRI for further investigation and confirmation
by ELISA and PCR methods. NBTS faces difficulties to trace all repeat reactive
donors specially donors with significantly high OD values
for hepatitis B & C screening tests
due to several reasons. There is a lack of proper system to trace Hepatitis B
and Hepatitis C donors similar to the one existing for HIV. NBTS needs to
postulate new strategies to improve the traceability and follow up of the blood
donors who become positive for hepatitis B & C screening tests as well as
the donors who become confirmed positive.
Significant difference is noticed between the tests results obtained from MRI and NBTS even though both institutions use the same Monolisa (ELISA) test kits for Hep B and Hep C.