Transfusion-Transmitted Infections Overview

Transfusion-Transmitted Infections (TTIs)

• TTIs are infections that result from pathogens entering a person through a blood transfusion.
• Objectives of the lecture include outlining measures to reduce TTI risk in blood banks, recognizing blood donation criteria and rejection causes, identifying factors for TTI establishment, and naming common pathogens, describing their characteristics (morphology, classifications, transmission, pathogenesis, diagnostic methods), and outlining the viral window period.
• Blood transfusion involves receiving blood or blood products intravenously to replace lost components or as therapy.

Types of Transfusion-Transmitted Pathogens

• RNA Viruses: HIV, HTLV, HCV
• DNA Viruses: HBV, Epstein-Barr virus, Cytomegalovirus, Human Herpesvirus 8, Parvovirus B19
• Protozoa: Plasmodium, Toxoplasma
• Bacteria: Various types, including contamination by Staphylococcus epidermidis, Staphylococcus aureus, Cutibacterium acnes, Escherichia coli, Klebsiella, Proteus, and Yersinia enterocolitica.
• Spirochete: Treponema pallidum (causes syphilis)
• Prions: 72 agents currently

Reducing TTI Risk

• Donor Screening: Use of a standard donor questionnaire and screening of donated blood samples.
  • Methods used include PCR, bacterial culture, antigen and antibody detection of specific pathogens (HBV, HCV, HIV, HTLV, and syphilis)
• Pathogen Inactivation: Treating blood components with chemicals and/or UV light to inactivate pathogens.

Factors Contributing to TTI Establishment

• Viral Window Period: Time between acquiring a viral infection and its detection by lab tests. This period can vary and can cause false-negative results; eg., HIV has a window period of 11-180 days depending on the test.
• Bacterial Contamination: Contamination from donor skin disinfection, equipment or donor bacteremia.
• Asymptomatic Immunocompetent Donors: Some donors may harbor infections without presenting symptoms.
• Laboratory Errors:
• Personal Errors:

Criteria for Blood Donation and Rejection

• Age: 17-65 years old
• Weight: 50 kg or above
• Pulse Rate: Normal
• Body Temperature: Normal
• Blood Pressure: Normal
• Hemoglobin Concentration: > 12 grams/dL (women) and 13 grams/dL (men)
• Medical History: (e.g., epilepsy, psychosis, abnormal bleeding, thalassemia, sickle cell anemia, malignancy are permanently unfit)
• Infection: HIV, hepatitis, malaria, syphilis

Pathogens and Details

• HIV:*
• Virology: Enveloped single-stranded RNA virus.
• Classification: Retroviridae, HIV-1 and HIV-2.
• Transmission: Sexual, parenteral (transfusion, needle-stick, sharing needles), tissue transplantation, vertical (pregnancy, childbirth, breastfeeding).
• Replication Cycle: Adsorption, uncoating, reverse transcription, integration, transcription, protein synthesis, and assembly and release by budding.
• Disease: Acquired Immunodeficiency Syndrome (AIDS).
• HTLV:*
• Virology: Single-stranded RNA virus.
• Classification: Retroviridae.
• Target Cells: T helper cells.
• Transmission: Sexual, blood transfusion, vertical (breastfeeding).
• Disease: Adult T-cell leukemia and lymphomas.
• HCV:*
• Virology: Enveloped single-stranded RNA virus, oncogenic.
• Transmission: Parenteral (needle-sharing, blood transfusion, dialysis, organ transplantation). Rare sexual and vertical transmission.
• Disease: Hepatocellular carcinoma (HCC).
• HBV:*
• Virology: Double-stranded DNA virus.
• Transmission: Sexual, parenteral (contaminated needles/instruments), organ transplants, and vertical transmission.
• Prevention: Vaccine available.
• Disease: Hepatocellular carcinoma (HCC).
• EBV:*
• Virology: Enveloped DNA virus.
• Transmission: Body fluids (especially saliva). Blood transfusion/organ transplantation, sexual contact.
• Disease: Infectious mononucleosis, lymphoma.
• CMV:*
• Virology: Enveloped DNA virus.
• Transmission: Body fluids(saliva), vertical, blood/tissue transplants.
• Disease: Mononucleosis syndrome, interstitial pneumonitis, retinitis, encephalitis, congenital infections
• HHV-8:*
• Transmission: Sexual, saliva, transplacental.
• Disease: Kaposi's Sarcoma.
• Parvovirus B19:*
• Transmission: Inhalation, vertical, blood transfusion.
• Disease: Severe anemia (fetuses, children, adults with chronic anemia)
• Treponema pallidum (Syphilis):*
• Bacteriology: Gram-negative spirochete with axial filaments.
• Transmission: Sexual, vertical (transplacental), blood transfusion.
• Disease: Syphilis.
• Plasmodium:*
• Etiology: Various Plasmodium species.
• Classification: Sporozoa, obligate intracellular protozoa.
• Transmission: Bite of infected female Anopheles mosquito, transplacental, blood transfusion.
• Disease: Malaria
• Toxoplasma gondii:*
• Classification: Sporozoa, obligate intracellular protozoa.
• Transmission: Ingestion of oocysts (cat feces), tissue cysts (undercooked meat), transplacental, blood transfusion.
• Disease: Asymptomatic in immunocompetent hosts, serious in immunocompromised hosts and fetuses, affecting the brain, eyes, lungs, and other organs.

Diagnostic Methods

• Rapid antigen detection tests
• Microscopy (stained blood films) for various stages of pathogens
• PCR (detecting viral DNA)
• Serology (detecting antibodies)
• Mono-spot detects heterophile antibodies for EBV.
• Peripheral blood smears can detect atypical lymphocyctes

This quiz covers the essential aspects of Transfusion-Transmitted Infections (TTIs), focusing on the pathogens involved, their characteristics, and the measures to mitigate TTI risks in blood transfusion practices. It also discusses blood donation criteria and common pathogens associated with TTIs, including their transmission and diagnostic methods.