A.41 Herpes Virus Infections

Question 1

A.41 Herpes Virus Infections

Answer 1

Human herpes viruses (HHV) are a significant group of DNA viruses that can remain dormant in the body after initial infection. HHV includes a large family of viruses known as Herpesviridae, which infect humans.

Question 2

A.41 Herpes Virus Infections
These viruses are categorized into three main groups:

Answer 2

Alpha Herpes Viruses
- Examples: HSV-1, HSV-2, VZV (varicella-zoster virus)
- Have a fast replication cycle
- Establish a latent infection
- Persist in ganglion cells throughout the host’s lifespan

Beta Herpes Viruses
- Examples: CMV (cytomegalovirus), HSV-6, HSV-7
- Have a slow replication cycle
- Limited host range
- Persist in granulocytes and lymphocytes

Gamma Herpes Viruses
- Examples: EBV (Epstein-Barr virus) and Kaposi’s sarcoma-associated virus (KSV)
- Have an oncogenic potential
- Exhibit restricted host range
- Persist in B-lymphocytes

Question 3

A.41 Herpes Virus Infections
HHV-1 - Herpes Simplex Virus 1 (HSV-1)

Answer 3

Following primary infection, the virus typically remains dormant in the trigeminal ganglia.
Seroprevalence: ≥ 50% in adults
Mode of Transmission: Saliva, respiratory secretions
Management: Antivirals such as Acyclovir.
Diseases Associated with HSV-1:
Herpes labialis (cold sores)
Herpetic gingivostomatitis
Eczema herpeticum
Herpetic whitlow
Herpes simplex encephalitis
HSV keratiti etc.

Question 4

A.41 Herpes Virus Infections
HHV-2 - Herpes Simplex Virus 2 (HSV-2)

Answer 4

After primary infection, the virus typically remains dormant in the sacral ganglia.
Seroprevalence: 10-20% in adults
Mode of Transmission: Sexual intercourse, perinatal transmission
Management: Antivirals such as Acyclovir.
Diseases Associated with HSV-2:
Genital herpes
Eczema herpeticum etc.

Question 5

A.41 Herpes Virus Infections
HHV-3 - Varicella Zoster Virus (VZV)

Answer 5

Following primary infection, VZV can become latent in the dorsal root ganglia and trigeminal ganglia.
Seroprevalence: Up to 90%
Mode of Transmission: Respiratory secretions, vesicular fluid
Management: Vaccination is recommended to prevent VZV infection in adults over 60 years and in those at risk for shingles. Antivirals such as Acyclovir, Valacyclovir, and Famciclovir may be indicated.

Diseases Associated with VZV:
Primary infection: Chickenpox (varicella)
Reactivation: Shingles (herpes zoster)
Congenital varicella syndrome

Question 6

A.41 Herpes Virus Infections
HHV-4 - Epstein-Barr Virus (EBV)

Answer 6

Oncogenic potential; can immortalize and transform B cells, utilizing the CD21 receptor to cause infection.
Seroprevalence: 65% in children, teens, and young adults aged 6 to 19 years
Mode of Transmission: Saliva, respiratory secretions
Management: Symptomatic therapy; avoid physical activity that could trigger splenic rupture for at least three weeks.
Associated Diseases:
Infectious mononucleosis (typically diagnosed with the monospot test)
Oral hairy leukoplakia
Burkitt lymphoma
Nasopharyngeal carcinoma (particularly common in Southeast Asian populations)
Hodgkin’s lymphoma (mixed cellularity)
Primary CNS lymphoma (DLBCL)
Post-transplant lymphoproliferative disorder

Question 7

A.41 Herpes Virus Infections
HHV-5 - Cytomegalovirus (CMV)

Answer 7

Features large atypical lymphocytes with intranuclear inclusion bodies that resemble an owl’s eye; utilizes these mechanisms to cause infection.
Seroprevalence: Approximately 50% in the US
Mode of Transmission: Congenital, sexual contact, transfusions, organ transplants, saliva, and urine
Management: Antivirals may be recommended, including Ganciclovir, Foscarnet, and Fomivirsen.
Associated Conditions:
Cytomegalovirus infection
CMV mononucleosis (notably in immunocompromised individuals)
Congenital CMV infection

Question 8

A.41 Herpes Virus Infections
HHV-6 & HHV-7

Answer 8

Associated with Roseola infantum (more commonly linked to HHV-6 than HHV-7)
Seroprevalence: Approximately 90% in the US
Mode of Transmission: Spread through saliva; reactivation of latent virus or reinfection may occur in immunocompromised individuals
Management: Symptomatic treatment to reduce fever.

Question 9

A.41 Herpes Virus Infections
HHV-8 - Kaposi’s Sarcoma-Associated Virus (KSHV)

Answer 9

Has oncogenic potential; infects endothelial cells, causing multifocal, highly vascularized tumors.
Seroprevalence: Less than 10% in the US, higher in MSM and HIV-positive populations
Mode of Transmission: Primarily through sexual intercourse
Management: Focus on treating the underlying condition, such as ART in patients with HIV.
Associated Conditions:
Kaposi sarcoma
Diffuse large B-cell lymphoma