VARicella - zoster virus (chickenpox)

1. VARicella-zoster virus (chickenpox) presented by Julie Minton

2. History Chickenpox disease first described in 1767 by an English doctor, William Heberden. Dr. Heberden realized two important points. Chickenpox is different than the more deadly disease smallpox. Once a person has chickenpox they usually never get it again.

3. DEVELOPMENT OF VACCINE • Varicella-zoster virus vaccine developed by Merck, Sharp, Dohme in the 1980s from the Oka strain. • Submitted to the USFDA for approval in 1990. • Live attenuated vaccine was licensed in 1995. • Vaccine has been added to recommended vaccine schedules for children in United States and many other countries. • United States vaccine coverage for varicella-zoster virus is almost 90%. • Data has shown vaccine is effective for over 10 years at preventing varicella.

4. FATAL CASE OF CHICKENPOX • 42-year-old man presented with 1 week history of colicky abdominal pain, vomiting and jaundice. • History included 2 days prior to admission developed vesicular skin rash over face and chest. • 4 days prior to his illness 2 of his children had a febrile illness with vesicular skin rash diagnosed with chickenpox. • Remarkable findings on physical examination included he was jaundiced with pedal edema and vesicular eruption all over his body. Conjunctival hemorrhage of both eyes. Bilateral inspiratory crackles at both lung bases. • Tzank Smear of vesicular lesion from chest revealed inclusion bodies. • Upon admission treatment started with high dose intravenous acyclovir and meropenem • Patient required intubation and clinical condition continued to deteriorate with development of acute renal failure and disseminated intravascular coagulation. • Despite aggressive management patient died on the fourth day following admission.

5. SUMMARY OF THE DISEASE Causative agent. Chickenpox is a very contagious disease caused by the human herpesvirus 3 (HHV-3), also called varicella-zoster virus. Varicella-zoster virus is an enveloped DNA virus. Pathogenesis and virulence factors. Varicella-zoster virus enters via the respiratory tract. Once in the respiratory tract it attaches to the respiratory mucosa, invades and enters the bloodstream. On the skin the virus causes adjacent cells to fuse and then lyse resulting in characteristic skin lesions of the disease. Virus enters sensory nerves and travels to the dorsal root ganglia. An important virulence factor of varicella-zoster is it can remain latent in the ganglia. The ganglia provides a resting site that protects the virus from attack from the immune system. The virus can reactivate years later and cause shingles.

6. TRANSMISSION • Humans are the only natural host for the varicella-zoster virus. The chickenpox virus is spread from person to person through the air or by contact with fluid from chickenpox blisters. • Through the air by coughing or sneezing. • By touching or breathing in virus particles from chickenpox blisters. • How long is a person contagious? • Chickenpox can be spread by a person 1-2 days before they get the rash until all their blisters have formed scabs. • What is the incubation time? • It takes 10-21 days after a person has been exposed to chickenpox or shingles to develop the illness. • Interesting points. • A vaccinated person that gets the disease can still spread it to others. • A person who has had chickenpox can get a painful rash called shingles years later. • For most, getting chickenpox provides immunity for life. • Some people do get chickenpox more than once, although this is not common. Photo source: AAP Red Book Online Visual Library

7. Symptoms • Chickenpox most commonly causes illness that lasts 5-10 days. • Classic symptom. • Rash that turns into itchy, fluid-filled blisters that eventually turn into scabs. • Rash may first show up on face, chest, back, and then spread to rest of body including inside of mouth, eyelids, genital area. • Usually takes about 1 week for all the blisters to turn in to scabs. • Other symptoms. • High fever. • Tiredness. • Loss of appetite. • Headache. • Vaccinated people can still get the disease. • Symptoms are milder. • Fewer blisters. • Mild or no fever. • 25-30% of people vaccinated for chickenpox who get chickenpox will develop illness as serious as an unvaccinated person. DIAGNOSIS Chickenpox diagnosis is usually made based on the characteristic pox rash. Source: American Academy of Pediatrics

8. COMPLICATIONS • Some people with serious complications from chickenpox will need to be hospitalized. Serious complications include: • Dehydration. • Pneumonia. • Bleeding problems. • Infection or inflammation of the brain. • Bacterial infections of the skin and soft tissues. • Blood stream infections. • Toxic shock syndrome. • Bone infections. • Joint infections. • People at risk for complications include: • Infants • Adults. • Elderly. • Pregnant women. • People with weakened immune systems due to illness or medications.

9. TREATMENT • Varicella usually is self-limiting and only requires symptomatic treatment. • Calamine lotion and colloidal oatmeal baths to relieve itching. • Over-the-counter non-aspiration medications, such as acetaminophen, to relieve fever. • Secondary bacterial infections can be treated with topical or systemic antibiotics. • People considered high risk for serious complications can be given oral acyclovir or other antivirals within 24 hours of onset of rash.

10. Pregnant women should not get vaccinated until after they have given birth. • Women should wait 1 month after receiving the vaccine before getting pregnant. • People who are moderately to severely ill should wait until they recover before receiving the vaccine. • A person with any illness that compromises the immune system or that is receiving treatment that affects the immune system should consult their doctor before receiving the vaccine. Prevention Best prevention is the vaccine. CDC recommends 2 doses of the vaccine for children, adolescents, adults. The vaccine is very safe and 98% effective at preventing the disease. VACCINE STATS Before the vaccine, 4 million people each year would get the disease in the United States. Before the vaccine, 11,000 people were hospitalized each year in the United States due to the disease. Before the vaccine, 100-150 people died from the disease.

11. REFERENCES • American Academy of Pediatrics. (n.d.). AAP Press Room Photos. Retrieved July 13, 2013, from http://www.aap.org/en-us/about-the-aap/aap-press-room/aap-press-room-media-center/pages/AAP-Pressroom-Photos.aspx. • Photos of vaccine-preventable diseases. • Bhatti, M. A., Manglani, C. B., Khan, M.A., (n.d.) Journal of Pakistan Medical Association. Fatal Case of Chickenpox in an Adult: A Case Report. Retrieved July 17, 2013, from http://www.jpma.org.pk/full_article_text.php?article_id=349 • Case report on adult chickenpox patient. • Centers for Disease Control. (April 25, 2013). Chickenpox (Varicella). Retrieved July 11, 2013, from http://www.cdc.gov/chickenpox. • Facts, history, photos of varicella-zoster virus. • Centers for Disease Control. (March 18, 2008). Chickenpox VIS. Retrieved July 13, 2013, from http://www.cdc.gov/vaccines/hcp/vis/vis-statements/varicella.html#wait. • Vaccine information • Isaiah, A. (March 17, 2012). PRLOG. Chicken Pox Pictures Early Stage of Chicken Pox. Retrieved July 11, 2013, from http://www.prlog.org/11827099-chicken-pox-pictures-early-stage-of-chicken-pox.html. • Early stage varicella-zoster description and photo. • Cowan, M. K. (2013). Microbiology Fundamentals A Clinical Approach. New York: McGraw-Hill. • Pgs 442-443 description of chickenpox virus. • Wikipedia. (July 12, 2013). Chickenpox. Retrieved July 13, 2013, from http://en.wikipedia.org/wiki/Chickenpox. • Summary of chickenpox. • Wikipedia. (June 11, 2013). Varicella Zoster Virus. Retrieved July 13, 2013, from http://en.wikipedia.org/wiki/Varicella_zoster_virus. • Description of varicella-zoster virus. • Wikipedia. (July 6, 2013). William Heberden. Retrieved July 11, 2013, from http://en.wikipedia.org/wiki/William_Heberden. • Life and works of William Heberden.