Diagnostic Virology

Learning Outcomes

  • 1a-POM-MILO-5 Explain the principles underlying common laboratory techniques, demonstrating appropriate means of presenting and interpreting data

  • 1-POM-3-1 Microbial infection: Recall the main types of infectious agents that cause disease in humans, examples of each type and the disease it causes, and describe how they replicate.

  • 1-POM-3-3 Antimicrobial therapies: Summarise the mechanisms of action of important antimicrobials, and recognise that antimicrobial therapy provides a selection pressure for the spread of antimicrobial resistance

Case Study

Scenario

  • 27 year old female, recently arrived from the Gambia

  • Attends a sexual health clinic with vaginal discharge and Chlamydia trachomatis is diagnosed and treated

  • She last had unprotected sexual intercourse 7 days ago with a new partner

  • She agrees to be tested for other Sexually Transmitted Infections/Blood Borne Virus

What viral infections would you request tests for?

HIV (Human Immunodeficiency Virus):

  • Reason: High global prevalence, including in Sub-Saharan Africa. Transmission through unprotected sexual intercourse is a significant risk.

  • Tests:

    • HIV antigen/antibody (4th generation test): Detects both p24 antigen (early marker of infection) and HIV antibodies.

    • Consider a follow-up test 6 weeks and 3 months after exposure if in the window period.


Point of Care HIV Test

A point-of-care (POC) HIV test is a diagnostic test for HIV that is performed and provides results immediately or within a short time (typically 15–20 minutes) at the site where the patient is receiving care, such as a clinic, community center, or mobile testing unit. These tests are designed to be simple, rapid, and do not require complex laboratory equipment, making them suitable for resource-limited settings or situations where quick results are needed.

The test comes back as non-reactive. What would you do?

  • Consider pREP