Chicken pox

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Chicken pox

  1. 1. CHICKEN POX<br />Dr. sukhwantsingh<br />
  2. 2. * Chicken Pox is an acute, extremely contagious infection caused by -“Varicella Zoster Virus” ( VZV ) * It is a benign illness of childhood characterized by exanthematous vesicular rash.<br />
  3. 3. HOST FACTORS * Occurs Primarily among children under 10 years.* Both sexes & all races infected equally often.* More severe in adults.* One attack gives durable immunity.<br />
  4. 4. : ENVIRONMENT :(Shows seasonal trend)* First six months of the year in tropical regions.* Late winter and early spring in temperate regions.* Over crowding favours its transmission.<br />
  5. 5. AGENT * Varicella Zoster Virus. (Human alpha herpes virus-3). * Member of Herpesviridae. * Double stranded DNA. * Size 150 – 200 nm. * Molecular Weight -80Million. * Only one serotype is known. * Humans are the only hosts of the virus. * Virus can be grown in tissue culture. <br />
  6. 6. SOURCE OF INFECTION* A Case of Chicken Pox: Virus occurs in the oro- pharyngeal secretions and lesions of skin and mucosa.* Subclinical infections are rare ( Less than 5 % )<br />
  7. 7. TRANSMISSION* Person to person through droplet nuclei / direct contact ( in case of Herpes Zoster )* Portal of entry of virus is respiratory tract.<br />
  8. 8. INCUBATION PERIODRanges between 10-21 daysbut usually between14-17 days<br />
  9. 9. INFECTIVITY* Ranges from 1-2 days before the appearance of rash, and 4-5 days thereafter or until all vesicles are crusted.* Virus remains latent in the cranial nerves sensory ganglia& Spinal dorsal root ganglia until reactivated<br />
  10. 10. Clinical Features<br />
  11. 11. PRE-ERUPTIVE STAGE * Moderate Fever* Backache* Shivering* Malaise(Lasting about 24 hrs)In adults, the prodromal illness is more severe and lasts longer<br />
  12. 12.
  13. 13. ERUPTIVE STAGE “Rash”comes on the day the fever starts.* Symmetrical & Centrifugal.* Pleomorphic.* Looks like ‘dew drops’ * Surrounded by an area of inflammation.* Mucosa is generally involved but palms & soles not usually affected.* Vesicles involve corium & dermis<br />
  14. 14. SECONDARY ATTACK RATE70-90 percentin susceptible siblings within a household<br />
  15. 15. IMMUNITY* Maternal antibody protects the infant during first few months of life.* Presence of IgG antibodies correlates with protection against varicella* Cell mediated immunity is important in recovery from V-Z infections<br />
  16. 16. * Natural infection confers lifelong<br /> immunity. * However, the virus can remain latent in sensory rootGanglia. *Reduction in cell mediatedimmunity can resultin reactivation of the virus which causes Herpes zoster in 10-30 percent cases. * Thedisease occurs with greater severity among adults, newborn<br /> infants, immunocompromised children and pregnant women.<br />
  17. 17. COMPLICATIONS* Bacterial super infection of theskin ( Most Common )Strep. Pyogenes/Staph. Aureus* C.N.S. involvement in children.* Varicella pneumonia, Occurs in 20 % cases. ( Most serious complication )More common in adults than children<br />
  18. 18. : Other Complications :* Acute cerebellar ataxia* Encephalitis* Varicellahemorrhagical* Corneal lesions* Myocarditis* Reye’s syndrome* Arthritis* Ac. Glomerulo nephritis Mortality is less than 1% in uncomplicated cases.<br />
  19. 19. PREGNANCY* Associated with high peri natal mortality, when maternal disease develops within 5 days before delivery or 48 hours thereafter.( Neonatal varicella )* Mortality rate has been as high as 30 percent in this group. Limb hypoplasia, Cicatricial skin lesions,Microcephaly, low birth weight, cataract, chorioretinitis, deafness,cerebrocortical atrophy & fetal death.<br />
  20. 20. * Maternalinfection in first trimester can give rise to “congenital varicella<br /> syndrome”<br />
  21. 21. : LABORATORY DIAGNOSIS :1. Examination of vesicle fluid under electron microscope( shows round particles )2. Scrapings of the floor of the vesicles colored by Giemsa. ( Tzanck smear )( shows multinucleated giant cells )3. Four fold rise in antibody titre.4. Detection of viral DNA by PCR5. Fluorescent Antibody to Membrane Antigen.6. ELISA.<br />
  22. 22. :CONTROL:*Good hygiene – Daily bathing and soaks.* Avoid secondary bacterial infection of the skin by – Meticulous skin care Close cropping of fingernails* Relief of itching – Tepid water bath & wet compresses Topical dressingsAntipruritic drugs<br />
  23. 23. Contd…* Disinfection of articles soiled by nose and throat discharges. * Notification of the cases.* Isolation for 6 days after onset of rash.* Drugs – . Acyclovir (800 mg 5 times a day x 5-7 days) . Famicyclovir(250 mg tid x 5-7 days) . Valacyclovir ( 1 gm tid x 5-7 days)<br />
  24. 24. PREVENTION1. VZIGvaricella zoster immunoglobulin Given within 72 hrs of exposure. (12.5 U/Kg, repeated after 3 wks) to exposed susceptible individuals- . Persons with congenital cellular immunodeficiency . HIV/AIDS . Pregnant women . Newborns/Premature infants<br />
  25. 25. 2. VACCINE (Live attenuated varicella virus vaccine) * Recommended for 12-18 monthschildren who have not had Chickenpox. * Persons above 12 years need 2 doses 4-8 wks apart. * Duration of immunity is probably 10 years.<br />
  26. 26. * The vaccine is90%effective in preventing varicella in an outbreak, when given within 3-5 days after exposure.* Sero conversion occurs in 95% children after single dose.* In adolescents and adults, sero conversion occurs in 78 % after one dose and 99 % after two doses<br />
  27. 27. ADVERSE REACTIONS OF VACCINE* Tenderness & erythema at injection site (25 % )* Fever ( 10-15% )* Localized maculopapular rash ( 5% )<br />
  28. 28. CONTRAINDICATIONS TO VACCINE* Pregnancy* Immunodeficiency* Allergy to Neomycin* Salicylates should be avoided for 6 weeks following vaccination<br />

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