Zoster

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Zoster

• BIO 488L
• March14, 2006
• Samantha Eckman

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The History of Zoster

• Humans have been infected with Zoster since
  ancient times.
• At the end of the 19th century, the primary
  infection, varicella, was distinguished from
  smallpox.
• In 1875, Steiner inoculated volunteers with
  vesicular fluid from a patient with varicella,
  and determined that chickenpox was caused by an
  infectious agent.

The rash produced by varicella
The rash produced by smallpox
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The History of Zoster

• In 1888, Von Bokay observed a relationship
  between varicella and herpes zoster when children
  contracted varicella after coming in contact with
  herpes zoster.
• In 1958 the virus was isolated
• In 1970, the first live attenuated varicella
  vaccine was developed in Japan.
• In March 1995, the vaccine was licensed for use
  in the United States.

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Symptoms of Primary Infection

• Adults usually 1 to 2 days of fever and
  discomfort prior to the onset of rash.
• In children, rash is normally the first sign of
  illness.
• The rash is itchy and rapidly progresses from
  macules to papules to vesicular lesions before
  crusting.

Child with all stages of rash.
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Symptoms of Primary Infection

• The rash first appears on the scalp, followed by
  the trunk, and lastly the extremities.
• The rashes distribution is centripetal.
• Lesions may also be found on mucous membranes of
  the oropharynx, respiratory tract, vagina, and
  conjunctiva.
• Successive corps appear over several days, with
  lesions present in several stages.
• Recovery from primary infection usually results
  in lifetime immunity to zoster.

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Symptoms of Secondary Infection

• During primary infection, VZV enters sensory
  nerve endings and becomes latent.
• Secondary infection, Shingles, occurs when
  reactivation of the latent VZV occurs.
• The site of reactivation is a dermatome.

• Secondary infection is unilateral
• due to reactivation
• of a single dorsal root ganglion.

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Symptoms of Secondary Infection

• The rash occurs unilaterally.
• The area that is most times afflicted is the
  trunk or the area of the 5th cranial nerve.
• 2 to 4 days before the rash occurs, there may be
  pain associated with the portion of the body that
  is afflicted with the rash.
• After recurrence there may be pain, postherpetic
  neuralgia, which can last up to a year.

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Why are Some More Prone to Getting Shingles?

• Not very well understood
• Factors associated with recurrence are
• Older Individuals
• Immunocompromised Individuals
• Contracting varicella at 18 months or younger
• Tumors affecting the brain or spinal cord

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How Zoster Causes Disease

• VZV is a DNA virus
• (a) VZV nucleocapsid assemble in the nucleus.
• (b) VZV glycoproteins are synthesised in the
  rough ER and then move to the golgi where
  wrapping occurs, which gives rise to mature
  virons.

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How Zoster Causes Disease

• After primary infection, it infects monnuclear
  cells by crossing the surface epithelium in the
  respiratory tract.
• Then it is carried to the lymphoid tissues.
• It slowly replicates in the lymphoid tissue for
  about a week.
• Enters blood by the mononuclear cells.
• The virus exits from blood vessels thereby
  infecting the subepithelial and epithelial cells.
• The virus reaches the respiratory tract and sheds
  to infect others.
• 2 days later the skin lesions shed.

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The Immune Response

• Activation of IFN system and circulating T
  lymphocytes occurs during the incubation period.
• HLA-DR Antigen expression occurred on circulating
  T cells.
• T cell proliferation with in 3 days after
  exposure.

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Transmission of Zoster

• Enters through the respiratory tract or the
  conjuctiva.
• Person-to-person from infected respiratory tract
  secretions.
• Contact with airborne droplets, by contact or
  inhalation.

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Treatments of Varicella

• Baths
• Applications of creams to relieve itching and
  scratching. Which could lead to a secondary
  infection of varicella.
• Varicella vaccine

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Varicella Vaccine

• Before vaccination, 3 to 4 million cases of
  varicella occurred. Which is the entire birth
  cohort.
• Recommended for all healthy children between 12
  to 18 months of age and children who have not had
  chickenpox by their 13 birthday.

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VZIG

• Varicella zoster immune globulin
• Is a human blood product that contains large
  amounts of varicella zoster virus Ab.
• If administered with in 96 hours of exposure to
  zoster, it can prevent varicella, complications,
  and death.
• Given to immunocompromised individuals.
• Expensive

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Any Questions?