VARICELLA ZOSTER

Intro Varicella-zoster virus is a herpesvirus

which causes varicella (chickenpox) and, after the virus has remained latent in the body (virus latency) and reactivates, herpes zoster (shingles)

Serious complications that can occur: central nervous system involvement, pneumonia, secondary bacterial infections, and death

Varicella is highly infectious, attack rates in susceptible contacts vary from 61%-100%

After primary infection, the virus persists in sensory nerve ganglia of the dorsal root and then establishes latent infection in neuronal cells.

Pathogenesis Varicella-zoster virus is 1 of the 8

herpesviruses of the Herpesviridae family The virus is a DNA a-herpesvirus with a

genome of approximately 125,000 bp that encode 70 genes

During the primary lytic infection, the genes are expressed sequentially

Sequential expression leads to the production of groups of immediate to early non-structural proteins, early non-structural proteins enzymes, and late structural proteins

Cont. The late structural proteins form a capsid

surrounding the DNA core, and a lipid-containing envelope

The envelope of the virion is composed of glycoproteins

After varicella-zoster has infected a cell, the virus replicates in the nucleus

The incubation period of varicella is in the range of 10-21 days

Cont. The virus spreads by droplets and

aerosols from the nasopharynx 1-2 days before onset of a rash, and from skin lesions during the first 5-7 days after appearance of a rash

The virus enters a susceptible host via the mucosal surfaces of the respiratory tract

Several viral glycoproteins act together to stick to mucosal cells which allows the virus to enter and spread from cell to cell

Heininger, Ulrich and Seward, Jane F. Varicella. Basel, Switzerland:

Division of Pediatric Infectious Diseases and Vaccinology, University Children’s Hospital, 2006.

The virus goes through 2 viraemic phases (the virus enters the bloodstream and can then affect the whole body)

Wikipedia, The Free Encyclopedia. Viremia. 19 January 2009. 1 April 2009. <http://en.wikipedia.org/wiki/Viremia >.

The virus multiplies in regional lymph nodes just before the first viraemic phase

 The virus then multiplies further in reticuloendothelial tissues

The second viraemic phase occurs between 10-21 days after the infection. This phase promotes viral spread to the nasopharyngeal surfaces and the skin, which causes the typical rash. The vesicles contain a great amount of the virus, and are believed to be the most important route of viral transmission.

The virus is no longer contagious when all the lesions have crusted.

Cont. Older age and a compromised immune

system can be risk factors that are linked with the severity of varicella disease and death

Video

Heininger, Ulrich and Seward, Jane F. Varicella. Basel, Switzerland:

Division of Pediatric Infectious Diseases and Vaccinology, University Children’s Hospital, 2006.

Spread of VZV It is believed that VZV can spread in two

ways 1: by release of enveloped virions into

the extracellular space, which occurs mainly in the vesicular skin lesions that develop in disease

2: by cell-to-cell spread of infection, which does not require enveloped virions.

Gershon, Anne A. and Hambleton, Sophie.Preventing Varicella-Zoster

Disease. New York: Department of Pediatrics, ColumbiaUniversity College of Physicians and Surgeons, 2005.

<http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=544176 >.

VZV virons are spherical and 150-200 nm in diameter.

Its DNA is a single, linear, double-stranded molecule, 125,000 nt long.

The capsid is surrounded by a number of loosely associated proteins called a tegument

Many of these proteins play critical roles in initiating the process of virus reproduction in the infected cell.

Wikipedia, The Free Enycylopedia. Varicella- Zoster Virus. 18 March 2009. 1 April 2009. <http://en.wikipedia.org/wiki/Varicella_zoster_virus >.

Epidemiology

The epidemiology differs in temperate and tropical climates

In most temperate climates, more than 90% of the population are affected by the virus before adolescence—in more tropical climates the disease affects people later in life

This could be because of differences in transmissibility of heat-labile varicella-zoster in hot, humid conditions

Heininger, Ulrich and Seward, Jane F. Varicella. Basel, Switzerland:

Division of Pediatric Infectious Diseases and Vaccinology, University Children’s Hospital, 2006.

Immune Evasion by the Virus

Although the immune system has many ways to destroy virus-infected cells, varicella-zoster virus has evolved several mechanisms to reduce presentation of viral proteins to the immune system and thereby evade detection.

Brunell, Philip A., Cohen, Jeffery I., Krause, Philip R., Straus, Stephen E. Recent Advances in Varicella-Zoster Virus Infection.1 June 1999. 3 April 2009. <http://www.annals.org/cgi/content/full/130/11/922>.

Quick Facts In the U.S., 9 out of 10 adults have had

chickenpox If you have had chickenpox, you can acquire

Shingles at any time with no warning, no way to predict if you even would get it, or how severe your case could be

Approximately 1 million cases of Shingles occur in the U.S. every year, and almost half of these cases occur in adults who are 60 years of age or older

1 out of every 2 people who live to age 85 will have Shingles

Risk Factors Increasing age A weakened immune system which could

be caused by various things such as certain drugs or cancer

Shinglesinfo.com. New Jersey: Merck & Co., Inc., 2009. 8 April 2009.

< http://www.shinglesinfo.com/index.html >.

Facts Chickenpox can strike at any age, but by

ages 9 or 10 about 80-90% of American children have already been infected.

Children living in rural areas and many foreign-born children are less likely to be immune

Because almost every case of chickenpox leads to lifelong protection against future attacks, adults account for less than 5% of all cases in the United States.

Causes and Symptoms A case of chickenpox usually starts

without warning or only with a slight fever.

Within a few days or even hours, small red spot begin to appear. After 12-24 hours these spot tend to become itchy, fluid-filled bumps called vesicles which begin to appear in crops lasting 2-6 days.

Some people may only develop only a few blisters, while in most cases the numbers tend to reach between 250-500.

Wells, Ken R. “Chickenpox”. The Gale Encyclopedia of Medicine. Ed. Jacqueline L. Longe. 3rd ed. Detriot: Gale, Online update, 2008. Vol 5.

Evolution For Chickenpox, the virus enters the

upper respiratory tract and conjunctiva and replicates at the site of entry.

New viruses are carried in blood and various tissues. Here they replicate several more times.

The release of these viruses causes fever and malaise. In 14-16 days after exposure, small, irregular, rose-colored skin lesions appear.

Cont. These lesions appear in cyclic crops over

2-4 days as the viruses go through cycles of replication.

These lesions are often important portals of entry for ordinary infections, especially with Staphylococcus aureus (Staph Infection).

Black, Jacuelyn. Microbiology: Principles and Explorations. Arlington: John Wiley & Sons Inc., 2008.

Chickenpox. Just a common childhood disease?

Although chickenpox are considered a common, childhood disease, it is also known to be fatal.

The virus can be known to invade and damage cells that line small blood vessels and lymphatics.

Circulating blood clots and hemorrhages from damaged blood vessels are common

Death from varicella pneumonia is due to extensive blood vessel damage in the lungs and the accumulation of erythrocytes and leukocytes in alveoli.

Cells in the liver, spleen, and other organs also die because of the extensive damage to the blood vessels within them.

Cont. Many children are hospitalized each year

with chickenpox or shingles. In the United States alone, about 100 people die each year from chickenpox.

Black, Jacuelyn. Microbiology: Principles and Explorations. Arlington: John Wiley & Sons Inc., 2008.

Uzzell, Jennifer. “Putting a Stop to Chickenpox”. Nursing 31.2 (Feb. 2001): 30-30. Academic Search Premier. EBSCO. 4 April 2009. http://ep.fmcc.edu:5001/login.aspx?direct=true&db=aph&AN=4114743&site=ehost-live.

Incidence and Transmission

Chickenpox is prevalent in industrialized societies in the temperate zone.

Its incidence is highest between March and April

The highest infection usually occurs between ages 5 and 9

Shingles is most common amongst individuals 45+ years old.

Infection can be spread by respiratory secretions and contact with moist lesions but not from crusted lesions

Cont. Study results reported by the Centers for

Disease Control and Prevention (CDC) indicate that more than 90% of American adults are immune to the chickenpox virus but, however, are much more likely to suffer more dangerous complications than children if infected.

More than half of all chickenpox deaths occur among adults.

Black, Jacuelyn. Microbiology: Principles and Explorations. Arlington: John Wiley & Sons Inc., 2008.

At Home Treatment Because chickenpox is a viral disease, antibiotics

are ineffective against it. Applying wet washcloths or bathing in cool or

lukewarm water can help the itch. 4-8oz. Of baking soda or 204 cups of oatmeal also

help to relieve symptoms. Calamine lotion also helps to reduce itchiness. Fever and discomfort can be reduced by medication

that does not contain aspirin (aspirin can increase the chances of developing Reye’s Syndrome)

* Reye's syndrome primarily targets the brain and liver. Brain swelling and chemical changes in the blood from liver damage affect the entire body. Drowsiness, confusion, seizures, coma, and in severe cases, death may result.

Wells, Ken R. “Chickenpox”. The Gale Encyclopedia of Medicine. Ed. Jacqueline L. Longe. 3rd ed. Detriot: Gale, Online update, 2008. Vol 5.

Chicken Pox Vaccine Chicken pox ( varicella) vaccine was first

licensed in Japan and Korea in 1988 The chicken pox vaccine was first

introduced in the US in 1995 Deaths went down 145-66 or has fallen

57% - 90% overall Has exceeded expectation

Szabo, Liz. "Chickenpox vaccine does a number on number of cases.(LIFE)."  USA Today. (Sept 2, 2008): 05D. Opposing Viewpoints Resource Center. Gale. Fulton Montgomery CC Evans Lib - SUNY. 15 Apr. 2009 <http://find.galegroup.com/ovrc/infomark.do?&contentSet=IAC-Documents&type=retrieve&tabID=T004&prodId=OVRC&docId=CJ184362210&source=gale&srcprod=OVRC&userGroupName=fmcc&version=1.0>.

Doctors' Orders.(Your Time/Health)."  Time. 165. 7 (Feb 14, 2005): 73. Opposing Viewpoints Resource Center. Gale. Fulton Montgomery CC Evans Lib - SUNY. 15 Apr. 2009 <http://find.galegroup.com/ovrc/infomark.do?&contentSet=IAC-Documents&type=retrieve&tabID=T003&prodId=OVRC&docId=A128148201&source=gale&srcprod=OVRC&userGroupName=fmcc&version=1.0>.

Vaccine Vaccination is recommended for adults and

children 1 year or older who do not have a history of chickenpox, healthcare professionals, and those who live and work in a crowded setting.

Because the vaccination contains a live virus, it is not recommended for pregnant women, children on steroids, and those with a generalized malignancy.

The vaccine is known to provide 70-90% protection against severe infection for an estimated 7-10 years.

What kind of vaccine is it Live attenuated vaccine Vaccine made from live chickenpox

germs that are weakened Administrated by a shot given in the fatty

tissue For children, adolescents and adults

Doses for kids and adults First dose 12-15 months of age Second dose between 4-6 years old Adults can get it at any time if they have

not already been vaccinated, get two doses

Side Effects About 20% of vaccine recipients

experience Discomfort of injection site Fever Mild rash Risk of Transmission Later Infection upper respiratory infection. Severe Side effects

“Chickenpox Vaccine.” Carenotes. 2008.McKesson Health Solutions.Web.9.Apr.2009.

Dugdale,David. “Vaccination.” 19 June 2008. Web. 9.April.2009. “Varicella virus (chickenpox) vaccine.” Cerner Multum. 1996. Web. 9.

Apr.2009. McNeil, Donald. “A Multitude of Vaccine Benefits, Yet Controversy

Persists.”19.June.2008. Web. 9. Apr.2008. “Vaccine Information.” 2009. Centers for Disease Control and Prevention.

Web. 9.Apr.2009 Pollack, Andrew. "Chickenpox Vaccine Cuts Deaths but Raises Questions on

Shingles, Experts Say.(National Desk)."  The New York Times. (Feb 3, 2005 pA18 col 01 (24 col): A18. Opposing Viewpoints Resource Center. Gale. Fulton Montgomery CC Evans Lib - SUNY. 16 Apr. 2009 <http://find.galegroup.com/ovrc/infomark.do?&contentSet=IAC-Documents&type=retrieve&tabID=T004&prodId=OVRC&docId=A128041884&source=gale&srcprod=OVRC&userGroupName=fmcc&version=1.0

Uzzell, Jennifer. “Putting a Stop to Chickenpox”. Nursing 31.2 (Feb. 2001): 30-30. Academic Search Premier. EBSCO. 4 April 2009. http://ep.fmcc.edu:5001/login.aspx?direct=true&db=aph&AN=4114743&site=ehost-live

Pregnant women Not immune and exposed should get shot

Varicella Zoster Immune Globulin ( VZIG) If mom develops chickenpox rash 5 days

before or 2 days after the birth of the baby, baby may be given VZIG

If serious symptoms occur may be given antiviral drug

Delay in Shot Being moderately to severely ill Pregnant women, potentially pregnant, or trying to

become pregnant Having a family history of weakened immune

system Having an untreated, active tuberculosis Receiving antibody containing blood products for

past 3-11 months Medicines that effect immune system like steriods Diseases that cause immune system to be

weakened –cancer, HIV/AIDS, Chemotherapy, ETC.

“Chickenpox (varicella) during pregnancy.”Clinical reference systems.2008.McKesson Health Solutions.Web.9.Apr.2009.

“Chickenpox Vaccine.” Carenotes. 2008.McKesson Health Solutions.Web.9.Apr.2009.

Facts In 1995, the American Academy of Pediatrics

began recommending that the varicella vaccine be given to all children between 12-18 months.

Prior to the vaccine’s availability, an average of 50 children died from chickenpox and related complications.

Today, 20 states require children to get vaccinated before they can enter childcare or preschool.

Research shows that the vaccine’s effectiveness is about 85% and offers excellent protection against the disease even 8 years after it was given.

“Preventing Chickenpox”. Scholastic Parent & Child. 12.1 (Sept. 2004): 65-65. Academic Search Premier. EBSCO. 4 April 2009. http://ep.fmcc.edu:5001/login.aspx?direct=true&db=aph&AN=14380524&site=ehost-live.

Shingles In shingles, much like chickenpox, lesions appear

(most often rather painful) and are usually confined to a small region of the body supplied by a particular nerve.

Such eruptions arise from latent viruses acquired during an earlier case of chickenpox.

During this period, the viruses can reside in ganglia in the cranium and/or near the spine.

When reactivated, the viruses spread from a ganglion along the pathway of its associated nerve(s).

Before the painful lesions appear, a pain and/or burning sensation of the skin may occur.

http://www.youtube.com/watch?v=7jeurTCz1CI

Symptoms The obvious factor that will allow you to

realize you have Shingles is a painful/blistering rash will appear usually on only 1 side of your body

Before the rash develops, there will be burning, itching, or tingling on your skin where the rash will form

The rash lasts approximately 30 days

Cont. These viruses damage nerve endings,

cause intense inflammation, and produce clusters of skin lesions indistinguishable from chickenpox lesions.

Symptoms range from mild itch to continuous, severe pain and can include headache, fever, and malaise.

Shingles is most severe in individuals with malignancies or immune disorders.

Cont. The latent virus is activated when cell-

meditated immunity drops below a critical, minimal level (ex: Spinal Cord trauma or immunosuppression).

Release of newly replicated viruses increases antibody production, but the antibodies may fail to stop viral replication.

Recovery from shingles is usually complete. Second and third cases can occur and depend on the degree of development of cell-meditated immunity and local interferon production.

Potential Complications of Shingles

Scarring Bacterial skin infections Decrease or loss of vision or hearing Paralysis on one side of your face Muscle weakness Long-term nerve pain, known as postherpetic

neuralgia, is the most common complication that occurs after Shingles. For many people this pain is very severe to the point where a clot touching their skin is very painful.

Statistics from the National Institute of Health at nihseniorhealth.gov show that 50% of Americans have had shingles by the time they reach 80.

http://www.youtube.com/watch?v=SUY-jb3Kwu8&NR=1

Black, Jacuelyn. Microbiology: Principles and Explorations. Arlington: John Wiley & Sons Inc., 2008.

Ponti, Karlene. “Shingles is a serious and common illness for those over 50: The illness, caused by the Chickenpox Virus, stay in the body and Reactivates Later”. McClatchy- Tribune Business News. 4 April 2009, ABI/INFORM Dateline Database.

Shingles Vaccine Shingles is also called Herpes Zoster Vaccine name is Zostavax Like chicken poxs shingles are caused by

herpes zoster virus Vaccine works by mimiking a shingles attack

but without pain Zostavax roughly equivalent to 14 doses of

chicken pox vaccine Strengthens body against virus

Reducing chances of outbreak and severity of the disease

Cont. For people 60 and older First vaccine in 30 years to be exclusively

for older people First vaccine that keeps an infection in

check

Harris, Gardiner. “ Vaccine to Cut Risk of Shingles in Older People Is Approved.”2006.Web.9.Apr.2009

Dugdale,David. “Vaccination.” 19 June 2008. Web. 9.April.2009.