Sowmiya _Chicken pox_varicella_zoster_virus.pptx

Chickenpox, also known as varicella, is a highly contagious viral infection caused by the varicella-zoster virus (VZV). It primarily affects children but can also occur in adults. The disease is characterized by a distinctive itchy rash that starts as red spots and progresses to fluid-filled blisters.

Symptoms:
Fever
Fatigue
Loss of appetite
Headache
Itchy rash that spreads over the body
The rash usually starts on the chest, back, and face, and can spread to other parts of the body. Over a few days, the blisters burst and form scabs.

Transmission:
Chickenpox spreads through direct contact with the rash or via respiratory droplets from an infected person. It is contagious from 1-2 days before the rash appears until all the blisters have crusted over.

Complications:
While chickenpox is usually mild in children, it can lead to complications, especially in adults, pregnant women, and individuals with weakened immune systems. These may include:

Bacterial skin infections
Pneumonia
Encephalitis (brain inflammation)

Prevention:
Vaccination is the most effective way to prevent chickenpox. The varicella vaccine is part of routine childhood immunizations in many countries, reducing the spread and severity of the disease.

Most people who contract chickenpox recover fully without long-term effects, but in rare cases, the virus can reactivate later in life, causing shingles (herpes zoster).

1. Varicella-Zoster Virus Chicken Pox Sowmiya A M . Sc., Biotechnology Vivekandha college of arts and sciences for women Autonomous

2. Contents: Introduction The virus Epidemiology Pathogenesis Immunity Response Signs & symptoms

3. Clinical Features: Complications of Varicella Laboratory diagnosis Antiviral therapy Prevention Conclusion Reference

4. Introduction: Varicella-Zoster Virus (VZV) is ubiquitous human alpha-herpesvirus, which causes Varicella ( chicken pox) and herpes zoster (Shingles).

5. Varicella results from primary VZV infection; it is a common childhood illness associated with fever and a generalized pruritic vesicular rash. As a characteristic of the alpha-herpesviruses, VZV establishes latency in the cells of the dorsal root ganglia after primary infection.

6. The Virus The VZV virion consists of a nucleocapsid surrounding a core that contains the linear , double stranded DNA genome; a protein tegument separates the capsid from the lipid envelope, which incorporates the major viral glycoproteins.

7. Epidemiology: VZV is found in worldwide geographic distribution, but annual epidemics are more prevalent in temperate climates, occuring most often during late winter and spring. In temperate countries, chickenpox is primarily a disease of children, with most cases occurring during the winter and spring, most likely due to school contact.

8. Pathogenesis: Varicella zoster virus (VZV) is transmitted through Inhalation of Infected secretions or contact with infectious skin lesions. Typically, the virus is spread via coughing and sneezing, as this allows viral- containing droplets to be come airborne.

9. Long Incubation period Usually around 15 days ( upto 21 days) Primary Viremia: During this incubation period, the virus spreads to the lymph nodes, the liver, and the lungs.

10. Secondary viremia: As the incubation period progresses, the virus makes its way to the skin via both CD4+ and CD8+ T cells, initiating secondary viremia. As the infection progresses, small skin vesicles filled with pus and infected cell particles form on the skin surface. These lesions are the ‘ pox’ of chickenpox.

11. Infective period: Between 1-2 days pre- eruption and 5-days post eruption.

12. Causes of chickenpox in picturised form🖼️

13. Varicella zoster virus causes the chickenpox infection

14. Most cases occur through contact with an infected person

15. The virus is contagious to those around you for one to two days before Our blisters appear.

16. VZV remains contagious until blisters have crusted over

17. Contact with fluid from the blisters

18. Immunity response: Adaptive immunity in action These memory cells direct the more vigorous secondary adaptive immune response, which produces many new T cells & B cells programmed specifically to attack chickenpox viruses.

19. Signs and symptoms: The hallmark symptoms of chickenpox is rash

20. A general feeling of being unwell ( Malaise) Fever, which is usually worse in adults than children

21. Aching muscles Loss of appetite

22. Eruption occurs 1-3 days after beginning of symptoms. Vesicles on erythematous base. “ Different stages of healing” Groups of polymorphic skin lesions Severely pruritic Eruption generally ceases after 4 days

23. Clinical Features: COMPLICATIONS OF VARICELLA: Secondary bacterial infections Congenital Varicella syndrome ( Due to infection during pregnancy) Encephalopathies Pneumonia Shingles

24. LABORATORY DIAGNOSIS: Clinical diagnosis PCR for viral DNA Direct flurocence antibody Serology to assess for immunity ( IgG against VZV)

25. Antiviral therapy: Treatment For Varicella is supportive .

26. Valacyclovir Acyclovir Famciclovir Are antiviral agents that are licensed for the treatment of VZV infection.

27. PREVENTION: MMRV vaccine 1/5 children will still develop chickenpox if exposed to VZV Have a milder form of chickenpox

28. Conclusion: Sorivudine, a nucleoside analog, has been reported to be effective in the treatment of primary Varicella in healthy adults (case reports only), but large- scale clinical trials are still needed to demonstrate its efficacy. There has also been speculation that continuous dosing of ACICLOVIR by mouth for a period of time can eradicate VZV from the host, although further trials remain to discern whether eradication is actually viable.

29. Reference: Clinical Microbiology Reviews, July 1996,p. 361-381 0893-8512/96/$04,00+0 Copyright ©1996, American society of Microbiology VARICELLA-ZOSTER VIRUS Ann M. Arvin Department of pediatrics and microbiology/Immunology, Stanford university school of medicine, Stanford, California 94305-5119