Disease
Varicella (Chickenpox)

Author
Rosemary Brunet, BIOL 230, Spring 2009

Causative Agent
The infectious agent of the disease chickenpox is the varicella-zoster virus. 

Varicella Virus
The varicella virus is an enveloped, double-stranded DNA virus, which is a member of the Herpesvirus family. The herpesvirus family are approximately 200 nanometers (def) in size.  Characteristic of this family of viruses is the ability to insert their DNA into the hosts DNA after primary infection.  They can remain in a latent form within the host DNA for an indefinite period. Individuals who were infected with chickenpox as a child, have the potential to develop shingles as an adult. This is in response to possible environmental stresses which may cause the virus DNA to remove itself from the infected-host DNA and then begin to replicate itself.

Epidemiology
Varicella (Chickenpox) is an extremely contagious illness following exposure. Chickenpox is considered a childhood disease as it is extremely prevalent in the ages 14 and younger.  It occurs most frequently during the months of March, April, and May.

Prior to the development of a vaccine in 1995 there were approximately 4 million cases per year in the United States. The total number of cases per year was estimated at 60 million.

Most of those who are infected by Chickenpox make a full recovery or have some residual scarring but some may encounter more serious complications to their health. Each year in the United States, 4,000 to 9,000 persons require hospital care due to chickenpox.

Transmission
The Varicella virus is passed through the air by inhalation of particles from the coughing and sneezing or by direct contact with fluid from broken chicken pox blisters of an infected individual.

In its initial stages, chickenpox is highly contagious. If an individual who has not had this disease is exposed to the virus they have a 70-80% chance of contracting chicken pox.

Signs and Symptoms
The normal incubation period is 7 to 23 days from the initial exposure to the virus.  Normally, the very first symptoms are headache, fever and malaise (def). Extremely young children may not experience these initial symptoms which normally appear in older children and adults.

Chickenpox typically produces a mild fever and a pruritic (def) outbreak of blisters on the infected persons body. The blisters become scabs and dry within 5 days  A person who is infected will be contagious for a period of  one or two days before showing signs (rash or blistering & scabbing) of the disease. Normally Chickenpox can be diagnosed by symptoms. If confirmation is required a blood test may be administered.

Most people recover from chickenpox without problem or with only minor scars. However, a small percentage of infected individuals experience more serious complications. Complications that may result from chickenpox are infections to the skin, pneumonia (def), encephalitis (def), Reye’s syndrome (def)) and hepatitis (def). Chickenpox can also cause severe problems in during pregnancy, causing stillbirth, birth defects, or infection of the newborn during birth.
Prevention and Treatment

Since 1995, Children in the United States have been vaccinated against the varicella virus to prevent the onset of the chickenpox. This vaccine was licensed in 1995 and is comprised of actual live but weakened varicella virus.  It is believed that this vaccine will provided life time immunity.

It is recommended that children receive two standard dosages of this vaccine at suggested intervals. The initial dosage at 12-14 months of ages and the second is recommended at 4-6 years of age. Normally this is prior to the entrance of kindergarten or first grade.

When an individual has chickenpox there are several home remedies that can help in decreasing the severity of the symptoms. Oatmeal baths aid in soothing itchy skin. Calamine lotion can also be applied to the skin to help with itching. An antihistamine like Benadryl can also be taken to assist with itching. Nails can also be cut short to avoid possible bacterial infection due to scratching. It is extremely important to not give aspirin or aspirin products to an individual who is believed to have or does have chickenpox. Aspirin given during chickenpox infection can lead to Reye’s Syndrome (def.)

Bibliography

David Peristein, MD,FAAP. Chickenpox. MedicineNet.com Retrieved April 19, 2009 from www.medicinenet.com/chickenpox_varicella.htm

 Heather Brannon, MD. Chickenpox-varicella virus infection updated July 22, 2007 About.com. Retrieved April 19, 2009 from http://dermatology.about.com/cs/chickenpox/a/chickenpox.htm

http://www.brown.edu/Courses/Bio_160/Projects2000/CommunityHealth/html/varicella_epidem_.html. Retrieved April 19, 2009

http://www.dhpe.org/infect/Chicken.html. Retrieved April 19, 2009

http://bioinfo.bact.wisc.edu/themicrobialworld/AnimalViruses.html. Retrieved April 19, 2009