Chickenpox/ varicella-zoster virus Muhammad Saadullah Virology Presentation 3-22-06 Chickenpox=Herpes? Chickenpox is caused by Varicella-Zoster Virus Varicella-Zoster virus is a member of the Herpes family VZV is also known as Human Herpes Virus 3 (HHV-3) VZV is one of 8 Herpes viruses to affect humans Varicella-zoster (VSV) Chickenpox is usually mild, but it may be severe in infants, adults, and people with impaired immune systems. The virus is highly contagious and is spread through respiratory droplets or by direct contact. Almost everyone gets chickenpox by adulthood (more than 95% of Americans). Approximately 4 million cases occur in the United States each year. Approximately 90% of persons in a household who have not had chickenpox will get it if exposed to an infected family member. Symptoms Symptoms begin with a low fever Loss of apetite Decreased activity Symptoms last 2-4 days after breaking out The average child develops 250 to 500 small, itchy, fluid-filled blisters over red spots on the skin Most pox will not leave scars unless they become contaminated with bacteria from scratching. Contagiousness The contagious period for chickenpox begins about 2 days before the rash appears and lasts until all the blisters are crusted over. A child with chickenpox should be kept out of contact with others until all of the blisters have dried completely. Pregnant women, as well as people with diseases or problems with their immune system, should not be near a person with chickenpox as there is a risk to transfer the virus to the baby. Physiology Chickenpox consists of an itchy, red rash that breaks out on the face, scalp, chest, back and, to a lesser extent, arms and legs. The spots quickly fill with a clear fluid in the form of a blister, rupture and then turn into hard crust Structure of the varicella?zoster virus particle. -The core region of varicella?zoster virus (VZV) consists of a linear double-stranded DNA genome. The genome is surrounded by a complex nucleocapsid composed of 162 capsomeres. -The capsomeres form the icosahedron. -VZV also possesses an amorphous proteinaceous tegument, which bridges the lipid envelope and the nucleocapsid. VZV Pathway The enveloped virus creates the chickenpox rash and can travel from the skin to sensory nerves. Once in the sensory nerves, the virus moves to the sensory ganglia where it becomes latent. If reactivated, the virus travels from the sensory ganglia back to the skin where it creates the shingles rash. Every year there are approximately 5,000-9,000 hospitalizations and 100 deaths from chickenpox in the United States. The greatest number of cases of chickenpox occurs in the late winter and spring. Complications Secondary bacterial infection is by far the most common complication of varicella. Rash becomes secondarily infected (Cellulitis) . Other serious complications are due directly to the virus infection and include viral pneumonia, bleeding problems and infection of the brain (encephalitis). Serious complications from chickenpox include bacterial infections which can involve many sites of the body including the skin, tissues under the skin, bone, lungs, joints, and the blood. Other complications: Erysipelas- This is a red, swollen rash of the face caused by an infection of streptococcal bacteria Symptoms: Face -- red, usually glossy appearance; swollen, hot, may or may not have blisters Pain Fever Chills Some more complications! Epiglotitis-When the epiglottis becomes inflamed or infected Meningitis-A serious condition that affects the membranes (meninges) that enclose and protect the brain and spinal cord from outside invasion. Osteomyelitis- Bone infection Treatment Uncomplicated cases (majority) require symptomatic relief only: Keep skin clean Calamine lotion for itching Oatmeal baths for itching Antihistamines -- over the counter Benadryl or prescription Zyrtec are good choices. Tylenol for fevers Treatment in Complicated cases: Anti-viral therapy such as Acyclovir or Famvir by mouth Immune compromised (such as HIV Infection) may need intravenous Acyclovir. Prevention Varicella vaccine has been given to children since 1995 Varicella vaccine is given to children who are over 12 months as well as adults The vaccine is about 70% to 85% effective at preventing mild infection, and more than 95% effective in preventing moderate or severe disease. Prevention Continued? People who do develop chickenpox after vaccination have much milder symptoms with fewer skin blisters and a fast recovery. Varicella-zoster immune globulin (VZIG) is given to newborns whose mothers had chickenpox at the time of delivery Points to take away Get Vaccinated! If chickenpox occurs let it take its course Once you catch chickenpox it stays in your body for your lifetime Take preventative measures to reduce the spread
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