Viral Infectious Agents: Herpes Simplex Virus
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Questions and Answers

How does the virus reach the ganglion from the periphery?

  • Along nerve axons (correct)
  • By following synaptic pathways
  • By moving freely in the bloodstream
  • By penetrating surrounding tissue

What percentage of the adult population is infected with VZV during childhood?

  • 25%
  • 90% (correct)
  • 70%
  • 50%

What portion of varicella infections occurs in childhood?

  • 10%
  • 90% (correct)
  • 50%
  • 70%

During which stage does VZV spread through the blood?

<p>Viraemic stage (D)</p> Signup and view all the answers

What percentage of the population does not become infected by VZV during childhood?

<p>10% (C)</p> Signup and view all the answers

What is the primary function of the sensory dorsal root ganglion?

<p>To process sensory information (D)</p> Signup and view all the answers

What is meant by latency in relation to sensory dorsal root ganglion?

<p>A period of inactivity before signals are transmitted (B)</p> Signup and view all the answers

What age group is primarily affected by chickenpox?

<p>Children aged 4-10 (C)</p> Signup and view all the answers

Which part of a nerve does latency affect according to the content?

<p>Axons reaching the ganglion (C)</p> Signup and view all the answers

Which statement accurately describes shingles?

<p>It is caused by reactivation of the chickenpox virus. (C)</p> Signup and view all the answers

What is the composition of the sensory dorsal root ganglion?

<p>A cluster of nerve cell bodies (A)</p> Signup and view all the answers

How is chickenpox primarily transmitted?

<p>Droplet infection (A)</p> Signup and view all the answers

How does latency influence the function of sensory nerves?

<p>It delays sensory signal processing (B)</p> Signup and view all the answers

Which of the following best differentiates chickenpox from shingles?

<p>Shingles results from reactivation of the chickenpox virus. (A)</p> Signup and view all the answers

At what point in life does shingles typically occur?

<p>In adults (B)</p> Signup and view all the answers

What is the significance of a CD4 count of less than 200 cells/mm3?

<p>It indicates a high risk of opportunistic infections. (B)</p> Signup and view all the answers

Which test is NOT typically used to confirm HIV infection?

<p>CD4 count measurement (C)</p> Signup and view all the answers

What does the CD4/CD8 ratio indicate in the context of HIV?

<p>It provides insight into immune system function. (C)</p> Signup and view all the answers

What is the main purpose of measuring HIV viral load?

<p>To monitor the effectiveness of treatment. (C)</p> Signup and view all the answers

Which method is utilized for the measurement of HIV viral load?

<p>Nucleic acid tests (C)</p> Signup and view all the answers

What is a common cause of accidental needle prick injuries among medical personnel?

<p>Infection from emergency patients (C)</p> Signup and view all the answers

Which of the following describes vertical transmission?

<p>Infection passed from mother to child during pregnancy or lactation (A)</p> Signup and view all the answers

Which group is particularly at risk of needle prick injuries?

<p>Medical personnel working in emergency settings (C)</p> Signup and view all the answers

What can be a consequence of a needle prick injury in medical personnel?

<p>Potential infection from pathogens present in the patient’s blood (A)</p> Signup and view all the answers

During which process can vertical transmission primarily occur?

<p>During labor and breastfeeding (A)</p> Signup and view all the answers

What is the primary benefit of understanding dermatomes in medicine?

<p>It aids in recognizing and treating issues related to specific nerve roots. (D)</p> Signup and view all the answers

Which statement best reflects the importance of dermatomes?

<p>Dermatomes help in mapping areas of sensation and potential nerve damage. (C)</p> Signup and view all the answers

How do dermatomes contribute to patient care?

<p>By improving the accuracy of identifying nerve-related issues. (B)</p> Signup and view all the answers

Which of the following best describes a common misconception about dermatomes?

<p>Dermatomes play no role in understanding neuropathic pain. (C)</p> Signup and view all the answers

In the context of dermatomes, what is the significance of nerve roots?

<p>Nerve roots connect to specific dermatomes that help in diagnosis. (B)</p> Signup and view all the answers

Flashcards

Accidental needle prick

A common injury in medical staff when exposed to contaminated needles from patients.

Vertical transmission

Transmission of infection from a pregnant person to their baby during pregnancy or through breastfeeding.

Medical personnel

Healthcare workers such as doctors, nurses, and paramedics.

Emergency patients

Patients requiring immediate medical attention.

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Pregnancy

The time when a woman carries a baby in her womb.

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HIV Infection Confirmation

Presence of HIV detected through observed band formation.

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Nucleic Acid Tests

PCR and gene probes detect HIV DNA or RNA.

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HIV Viral Load

Measurement of the amount of HIV in the body.

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CD4 Count

Measurement of CD4 cells per cubic millimeter of blood.

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AIDS Diagnosis (CD4)

AIDS diagnosed with CD4 count below 200 cells/mm3.

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Sensory dorsal root ganglion

A cluster of nerve cells where sensory axons reach.

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Latency period

Time the infection stays inactive in host.

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Axons

Nerve fibers that carry signals.

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Nerve fibers

Long projections that transmit signals throughout the body.

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Host Lifetime

Length of time infection remains dormant in host.

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Chickenpox

Primary infection caused by a virus (varicella).

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Shingles

Reactivation of a previous chickenpox infection (zoster).

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Shingles vs. Chickenpox

Shingles is the reactivation of the chickenpox virus in adulthood; chickenpox is the initial infection, typically experienced in childhood. Understanding the difference is important.

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Transmission (Chickenpox)

Chickenpox spreads through droplets in the air.

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Age Range (Chickenpox)

Chickenpox typically affects children between 4-10 years old.

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VZV Transmission Path

VZV, the virus causing chickenpox, reaches the ganglia along nerve axons or through blood during viremia.

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Viral Ganglia Reach

The virus travels from the body's periphery (outer parts) to the ganglia along nerve fibers or through the bloodstream.

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VZV Infection Prevalence

About 90% of adults get chickenpox in childhood; 10% get it during varicella infection as a child.

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Peripheral Route

The path the virus takes to enter the ganglia, usually via nerves.

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Blood-borne Route

Virus transmission via the bloodstream.

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Dermatomes and Nerve Roots

Specific areas of skin are linked to particular nerve roots. Understanding this connection helps diagnose and treat nerve-related issues.

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Nerve Root Conditions

Problems with nerve roots can impact specific areas of skin sensation or movement.

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Diagnosis of Nerve Issues

By analyzing skin sensations, issues with nerves are identified using dermatome maps.

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Effective Treatment

Understanding dermatomes allows for more precise and targeted therapies related to nerve issues.

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Dermatome Treatment

Targeting nerve root issues through knowledge of associated skin areas improves treatment efficacy.

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Study Notes

Viral Infectious Agents

  • Viral infections are caused by viruses, which are microscopic entities composed of genetic material (DNA or RNA) surrounded by a protein coat.
  • Herpesviridae family: viruses exhibit latent phases in viral pathogenesis.
  • Herpes Simplex Virus (HSV) type 1: causes primary HSV infection, typically in children.
    • Transmission: primarily through direct contact (e.g., saliva, tears).
    • Clinical presentation: vesicles on an erythematous base, vesicles rupture, and form crusts that heal within 7-10 days without scarring.
  • Primary HSV infection: Acute Gingivostomatitis (most common).
    • Characterized by vesicles on the gingiva.
  • Secondary HSV infection: Latent Infection
    • Virus particles travel along the axons to the sensory root ganglion.
    • Latency: in the trigeminal ganglion, lasting a lifetime.
    • Reactivation: can recur every 2-3 years, influenced by stress or immune status.
    • Recurrent infections: Herpes labialis (fever blisters or cold sores) - reactivation of the primary gingivostomatitis.
  • Varicella-Zoster Virus (VZV): presents in two forms
    • Primary infection: Varicella (chickenpox) - generalized eruption.
    • Reactivation infection: Zoster (shingles) - localized form.
      • Chickenpox: typically in children (4-10 years). Droplet infection.
      • Shingles: reactivation of latent VZV in adults. Traveling along nerve axons or via blood during the viremic stage of varicella infection. Symptoms confined to one dermatome. Characteristic rash.
  • Varicella Rash: Initially macular, then papules, vesicles and finally pustules that heal without scar formation. The rash often appears first on the trunk, then spreads to the limbs.
  • Zoster Rash: Unilateral & confined to one dermatome. Painful vesicular eruption.
  • Laboratory diagnosis:
    • Specimen: Smears of vesicular lesions.
    • Direct Virus detection.
    • Serology: Detect specific VZV antibodies (IgM or rising titer of IgG) by ELISA.
  • Poxviridae Family:
    • Largest viruses (300nm) – seen by light microscopy.
    • Brick-shaped (complex symmetry).
    • Enveloped.
    • Double-stranded DNA.
    • Smallpox virus is an example, but no longer exists.
  • Hepatitis B Virus (HBV):
    • DNA virus of Hepadnaviridae family.
    • Causes serum hepatitis.
    • Complete virus (virion): Dane particle.
    • Diagnosed with HBV surface antigen (HBsAg), and anti-HBs in the blood.
    • Viral DNA detected by probe or PCR.
    • Liver function tests (e.g. ALT and bilirubin) support diagnosis.
  • Human Immunodeficiency Virus (HIV):
    • Enveloped virus, requiring direct contact with blood to infect.
    • Envelope: glycoprotein complex (gp120 and gp41): gp120 attaches to CD4+ T cells, and gp41 facilitates fusion and entry.
    • Genome: two identical copies of positive-sense ssRNA, associated with reverse transcriptase.
    • Transmission: sexual contact, blood/blood products (e.g., needles), and vertical transmission (mother to child).
  • HIV Diagnosis:
    • Antibody screening with ELISA (less specific).
    • Confirmatory test (Western Blot).
  • HIV progression is further characterized by nucleic acid tests (PCR, gene probes) and CD4 counts. A CD4 count below 200 cells/mm3 and CD4/CD8 ratio <1 are indicators of AIDS.

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Description

This quiz focuses on viral infections caused by herpesviruses, particularly Herpes Simplex Virus type 1. It covers modes of transmission, clinical presentations, and the differences between primary and secondary infections. Test your knowledge on the pathogenesis and latency of this common viral agent.

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