Screening For Blood Transfusion

SCREENING FOR BLOOD TRANSFUSION

PRINCIPLES OF SCREENING To detect high risk donors Deffer those who are positive Prevent transmission of infection to the recipients To promote Voluntary Blood Donation

INFECTIOUS AGENTS Virus: HIV, HBV, HCV Bacteria: Tryponema, Cholera Protozoa: Malaria, Tryponosoma Fungus

DONOR SCREENING AND DEFERRAL Education History Examination Donation Screening Deferral

VOLUNTARY BLOOD DONATION Safe donor : Regular, voluntary,non remunerated donors from low risk population High risk donors : Family/ replacement and paid donors Activities to promote voluntary blood donation : 1. National blood donor programme 2. Training of staff 3. Records 4. Donor education 5. pre & post donation counselling 6. Monitoring of infection in donor 7. Evaluation of blood donor programme

SCREENING ASSAY Test samples Types of screening: Elisa Particle agglutination assay Simple rapid assay Test results

APPROPRIATE ASSAY Principle of the assay Incubation period Sensitivity Specificity Availability Cost

HIV

SCREENING

Window period :following infection and before the appearance of antibody. Antibody detection is commonly done by Elisa. Confirmed by western blot. Viral RNA is first to be detected- not done

Western blot

HBV

Acute

Chronic

Recovered

Vaccinated

HBsAg +ve HBeAg +ve IgM anti HBC+ve DNA +ve HBsAg +ve HBeAg +ve IgManti HBC+ve DNA +ve Anti HBe + HBsAg - ve HBeAg - ve IgManti HBC+ve DNA - ve Anti HBe + Anti HBs + ve

HCV Viral RNA : First marker Anti HCV : Main serological marker HCVAg : Now used for screening HTLV 1 & 2 Viral RNA in lymphocytes Anti HTLV : Detected after 30 - 90 days Persists for life

TRYPONEMA PALLIDUM Non specific : VDRL, RPR Specific : TPHA, Elisa PLASMODIUM SPECIES : Detection of parasites Detection of antibody TRYPONOSOMA : Protozoa in blood film Blood culture Antibody

PERIPHERAL SMEAR

FACTORS INFLUENZING SCREENING PROGRAMMES Staff training Equipment & reagent required Supply of assay kits Storage of assay kits Condition of the sample to be tested Supply of external quality control samples Cost of screening

PREVENTION Careful selection of donors Direct screening of donated blood Promoting self exclusion

REFERENCE 1. WHO 2. Transfusion medicine - Lawrence.D.Petz