Transfusion Transmitted Infections Overview

Transfusion Transmitted Infections (TTIs)

• Transfusion-transmitted infections (TTIs) are infections caused by introducing a pathogen into a person via blood transfusion.
• Objectives for the lecture include outlining blood bank measures to reduce TTI risk, blood donation criteria, and the factors involved in TTI establishment. The lecture also aims to name common pathogens, describe their characteristics, modes of transmission, pathogenesis, and diagnostic approaches.
• Blood transfusion is the process of receiving blood or blood products intravenously. It is used to replace lost blood components or as a therapy.

Common Infectious Diseases Transmitted Through Blood Transfusion

• RNA Viruses:
  • HIV (Human Immunodeficiency Virus): The causative agent of AIDS. Enveloped, single-stranded RNA virus. Transmitted sexually, parenterally (blood transfusion, needle-sharing), tissue transplantation, and vertically (during pregnancy, childbirth, and breastfeeding)
  • HTLV (Human T-cell Lymphotropic Virus): An oncogenic virus causing adult T-cell leukemia and lymphomas. Transmitted sexually, through blood transfusion, breast-feeding, and vertically.
  • HCV (Hepatitis C Virus): An enveloped, single-stranded RNA virus causing hepatocellular carcinoma. Transmitted parenterally through needle sharing, blood transfusions, dialysis, and organ transplantation (less commonly, sexually and vertically).
• DNA Viruses:
  • HBV (Hepatitis B Virus): Double-stranded DNA virus, commonly causing hepatocellular carcinoma. Transmitted via sexual contact, contaminated needles, blood transfusions, organ transplants, and vertically.
  • EBV (Epstein-Barr Virus): Enveloped DNA virus, known for causing infectious mononucleosis. Transmitted primarily through saliva. Blood transfusion and organ transplant may also be involved.
  • CMV (Cytomegalovirus): Enveloped DNA virus commonly latent and asymptomatic. Transmitted by body fluids (especially saliva), sexually, vertically, and through blood transfusions and organ transplants.
• Other agents:
  • HHV-8 (Human Herpesvirus-8): Causes Kaposi's sarcoma (a tumor of endothelial cells). Transmitted through saliva, blood transfusion, and vertical transmission.
  • Parvovirus B19: Non-enveloped DNA virus, causing anemia, abortion, polyarthritis, and aplastic crises. Transmitted via respiratory droplets, blood transfusion, and vertically.
  • Bacteria (e.g., Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Klebsiella, Proteus, Yersinia enterocolitica): Often a result of improper donor procedures.
  • Treponema pallidum (Syphilis): A bacterium; transmitted sexually and vertically, through blood transfusions.
• Protozoa:
  • Plasmodium species (Malaria): Transmitted through the bite of infected mosquitoes, transplacentally, and through blood transfusion. A parasite invading red blood cells and hepatocytes.
  • Toxoplasma gondii: Causes toxoplasmosis. Transmitted through ingestion of contaminated foods or water, vertical transmission, and blood transfusions

Reducing the Risk of TTIs

• Standard donor screening questionnaires
• Screening of blood:
  • PCR
  • Bacterial cultures
  • Antigen/antibody detection (e.g., HBV, HCV, HIV, HTLV, syphilis)
• Pathogen inactivation techniques (chemicals and/or UV light)

Criteria for Blood Donation and Rejection

• Age: 17-65 years old.
• Weight: 50 kg or above
• Normal pulse rate
• Normal body temperature
• Normal blood pressure
• Hemoglobin concentration: >12 g/dL (women), >13 g/dL (men)
• Medical history: Epilepsy, psychotic disorders, severe bleeding tendencies, thalassemia, sickle cell anemia, or malignancy
• Infection: HIV, hepatitis, malaria, and syphilis

Factors in TTI Establishment

• Viral window period (time between infection and detection)
• False-negative lab results
• Bacterial contamination
• Asymptomatic, immunocompetent donors
• Laboratory errors
• Personal errors

HIV Replication Cycle

• Adsorption: HIV attaches to CD4+ T-helper cells
• Uncoating: Viral RNA released
• Reverse transcription: Viral RNA converted to DNA
• Integration: Viral DNA incorporated into host DNA
• Transcription and protein synthesis
• Assembly
• Release: Budding from cell

Other Important Details

• Pathogenesis describes how an infection develops.
• Diagnosis methods include specific tests targeting the organism, antibodies, or viral nucleic acids.
• Complications from TTIs can include splenic rupture, malignancies (like lymphoma), and other organ damage.

This quiz focuses on transfusion-transmitted infections (TTIs), highlighting their causes, the pathogens involved, and blood bank measures for reducing TTI risks. It covers important aspects like blood donation criteria, modes of transmission, and diagnostic approaches for common infections associated with blood transfusions.