Podcast
Questions and Answers
How does the virus reach the ganglion from the periphery?
What percentage of the adult population is infected with VZV during childhood?
What portion of varicella infections occurs in childhood?
During which stage does VZV spread through the blood?
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What percentage of the population does not become infected by VZV during childhood?
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What is the primary function of the sensory dorsal root ganglion?
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What is meant by latency in relation to sensory dorsal root ganglion?
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What age group is primarily affected by chickenpox?
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Which part of a nerve does latency affect according to the content?
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Which statement accurately describes shingles?
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What is the composition of the sensory dorsal root ganglion?
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How is chickenpox primarily transmitted?
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How does latency influence the function of sensory nerves?
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Which of the following best differentiates chickenpox from shingles?
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At what point in life does shingles typically occur?
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What is the significance of a CD4 count of less than 200 cells/mm3?
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Which test is NOT typically used to confirm HIV infection?
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What does the CD4/CD8 ratio indicate in the context of HIV?
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What is the main purpose of measuring HIV viral load?
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Which method is utilized for the measurement of HIV viral load?
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What is a common cause of accidental needle prick injuries among medical personnel?
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Which of the following describes vertical transmission?
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Which group is particularly at risk of needle prick injuries?
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What can be a consequence of a needle prick injury in medical personnel?
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During which process can vertical transmission primarily occur?
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What is the primary benefit of understanding dermatomes in medicine?
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Which statement best reflects the importance of dermatomes?
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How do dermatomes contribute to patient care?
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Which of the following best describes a common misconception about dermatomes?
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In the context of dermatomes, what is the significance of nerve roots?
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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.
