20180108 chicken pox
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1. Chickenpox (Varicella) is caused by the varicella-zoster virus and results in a characteristic rash with superficial vesicles in crops over the body. 2. It is highly contagious from 1-2 days before the rash appears until the lesions crust over, about 4-5 days after rash onset. 3. The rash progresses quickly through stages from macule to papule to vesicle to scab over 4-7 days, with new crops appearing as older ones resolve, resulting in a pleomorphic rash.
20180108 chicken pox
- 2. EPIDEMIOLOGY
- 3. AGENT FACTORS • Agent: HHV-3 • Source of infection: a case of chicken pox – Oropharyngeal secretions and lesions of skin and mucosa. – Rarely - a patient with Herpes Zoster. • Infectivity: – Period of Communicability: • 1-2 days before rash & • 4-5 days thereafter • Secondary attack rate: 90%
- 4. • Varicella-zoster virus (VZV) causes primary, latent, and recurrent infections. • The primary infection - manifested - Varicella (chickenpox) and results in establishment of a lifelong latent infection of sensory ganglion neurons. • Reactivation of latent infection - Herpes Zoster (shingles).
- 5. HOST FACTOS • Age: Children <10 yrs. • Immunity: – Durable – Second attacks – rare – Maternal antibody - first few months of life. – CMI- Zoster • Pregnancy: risk for foetus and neonate Hemorrhagic Varicella in infant: One attack -durable immunity.
- 6. ENVIRONMENTAL FACTORS • Seasonal trend • First six months of the year • Overcrowding
- 7. TRANSMISSION • Person to person – Droplet nuclei – Face to face • Portal of entry: – Respiratory tract – Placental: • Congenital varicella
- 8. INCUBATION PERIOD • 14 to 16 days • 10 to 21 days
- 9. CLINICAL FEATURES • The clinical course may be divided into two stages: (A)Pre-eruptive Stage. (B) Eruptive Stage.
- 10. Pre-Eruptive Stage 1. Onset - sudden - mild or moderate fever, pain in the back, shivering and malaise. 2. Very brief- about 24 hours. 3. Adults- usually more severe and may last for 2-3 days before the rash comes out.
- 11. Eruptive Phase 1. In children - rash is often the first sign. 2. It comes on the day the fever starts.
- 12. ERUPTIVE PHASE – FEVER • The fever does not run high but shows exacerbations with each fresh crop of eruption.
- 13. ERUPTIVE PHASE – RASH 1. Symmetrical. 2. It first appears - on the trunk where it is abundant, and then comes on the face, arms and legs where it is less abundant. 3. Mucosal surfaces (buccal, & pharyngeal)- generally involved.
- 14. ERUPTIVE PHASE – RASH 4. Axillae - may be affected, but palms and soles- usually not affected. 4. The density of the eruption diminishes centrifugally.
- 15. ERUPTIVE PHASE – EVOLUTION OF RASH 1. The rash advances quickly through the stages of macule, papule, vesicle and scab. 2. First to attract attention - vesicles filled with clear fluid and looking like "dew- drops" on the skin. 3. They are superficial, with easily ruptured walls & surrounded by an area of inflammation. Superficial vesicles Unilocular Vesicles; Dew-drop like. Inflammation around vesicles
- 16. ERUPTIVE PHASE – EVOLUTION OF RASH 4. Usually they are not umbilicated. 5. The vesicles may form crusts without going through the pustular stage. 6. Many of the lesions may abort. 7. Scabbing begins 4 to 7 days after the appearance of rash. Pleomorphic Rash
- 17. COMPLICATIONS 1. Secondary bacterial infection of lesions. 2. Cellulitis, Lymphadenitis, and Subcutaneous abscess. 3. Varicella gangrenosa from S.pyogenes – a life- threatening infection. 4. Bacteremia causing pneumonia, arthritis, and osteomyelitis. 5. CNS manifestations – Encephalitis & Cerebellar ataxia. 6. Varicella hepatitis.
- 18. GROUPS AT INCREASED RISK OF COMPLICATIONS 1. Healthy adolescents & adults 2. Immunocompromised persons 3. Pregnant women 4. Newborns of mothers with rash onset within 5 days before delivery to 48 hours after delivery. 5. Children with malignancy if chemotherapy was given during the I.P.
- 19. LABORATORY DIAGNOSIS • Examination of vesicle fluid under the electron microscope, which shows round particles (brick-shaped in smallpox) and may be used for cultivation of the virus.
- 20. 2. Scrapings of floor of vesicles show multinucleated giant cells coloured by Giemsa stain (not in smallpox). 3. Serology is used mainly for epidemiological surveys.
- 21. TREATMENT OF UNCOMPLICATED VARICELLA • Oral therapy with Acyclovir – 20 mg/kg/dose maximum: 800 mg/dose 4 doses per day X 5 days should be used to treat uncomplicated Varicella
- 22. TREATMENT IN HIGH-RISK PATIENTS • Acyclovir guanine – 500 mg/m2 8 hourly I.V. X 7 days. • Given within 72 hrs. prevents progressive Varicella and visceral dissemination in high- risk patients. • Drug therapy does not interfere with induction of immunity.
- 23. TREATMENT OF HERPES ZOSTER • Acyclovir also useful for treatment of Herpes zoster in dose of 500 mg/m2 or 10 mg/kg 8 hourly.
- 24. PREVENTION 1. VZV transmission is difficult to prevent because the infection is contagious for 24-48 hr before the rash appears. 2. Infection control practices, including caring for infected patients in isolation rooms with filtered air systems, are essential.
- 25. PREVENTION – VARICELLA VACCINE • Composition : Live virus (min. 2000 PFU) (Oka/Merck strain) • Efficacy: 95% (65%-100%). • Duration of: > 7 years. • Vaccination Schedule: 1 Dose subcutaneous (<13 years of age). • May be administered simultaneously with measles, mumps, and rubella (MMR) vaccine.
- 26. VARICELLA VACCINE FOR CHILDREN 1. Routine vaccination at 15-18 months of age. 2. Recommended for all children without evidence of Varicella immunity by the 13th birthday.
- 27. VARICELLA VACCINE FOR ADOLESCENTS AND ADULTS 1. Recommended to all persons >13 years of age without evidence of Varicella immunity. 2. Two doses separated by 4-8 weeks.
- 28. VARICELLA VACCINE– ADVERSE REACTIONS • Injection site complaints – 19% (children) 24% (adolescents and adults). • Rash- 3 – 4% of vaccinees. – Rash may be maculopapular rather than vesicular. – Average 5 lesions. • Systemic reactions not common.
- 29. ZOSTER FOLLOWING VACCINATION 1. Most cases in children. 2. Risk from vaccine virus less than from wild virus. 3. Usually a mild illness without complications.
- 30. VARICELLA VACCINE– CONTRAINDICATIONS AND PRECAUTIONS 1. Severe allergic reaction to vaccine component or following a prior dose. 2. Immunosuppression. 3. Pregnancy. 4. Moderate or severe acute illness. 5. Recent blood product transfusion.
- 31. Conclusions 1. Varicella or Chickenpox is a vaccine preventable disease occuring commonly in children. 2. It is characterized by fever & pleomorphic rash in centripetal distribution. 3. It causes many complications if it occurs in adults.
- 32. MCQs 1. “Pleomorphism” is the characterstic of rash of : 1. Measles. 2. HHV – 3. 3. Smallpox. 4. Fifth disease. Ans. – 2.
- 33. MCQs 2. A child presenting with fever and Varicella rash on day 1 : 1. Has already transmitted the virus to other children. 2. Is infectious to his siblings. 3. Will continue to infect others for 4 – 5 days. 4. All of the above. 5. Only 1 & 2 are correct. Ans. – 4.
- 34. MCQs 3. Following are not false about “Congenital Varicella Syndrome” except: (multiple choice) 1. Risk of transmission is maximum in the 2nd trimester of pregnancy. 2. Extensive involvement of neurological system of foetus. 3. Hyper-pigmentation of skin is pathognomic sign. 4. If fetus is born alive, may have problem in defecation and micturition. Ans. – 1,3.
- 35. MCQs 4. Complications of Varicella : (multiple choice) 1. Occur more commonly in children infected within first 5 years of life. 2. Pnuemonia is more common in adults. 3. Can be prevented by early administration of Acyclovir. 4. Varicella gangrenosa is a life-threatening infection caused by superadded Clostridium infection. Ans. – 2,3.
- 36. MCQs 5. All are false about Varicella vaccine except : (multiple choice) 1. It may be given along with MMR vaccine (live vaccine). 2. AIDS patients, not having previous history of Varicella, should receive this vaccine. 3. The child is 100% protected for his entire life. 4. A susceptible female should be immunized in the first trimester of pregnancy itself Ans. – 1.
- 37. Differences Smallpox Chickenpox • IP – About 12 days (range 7-17 days) • Prodromal symptoms - Usually mild • Distribution of rash – • - palms and soles frequently involved • Axilla usually free • Rash predominant on extensor surfaces and bony prominences • About 15 days (range 7-21 days) • Usually mild • - seldom affected • Axilla affected • Rash mostly on flexor surfaces
- 38. Characteristics of the rash • deep-seated • Vesicles multilocular and umbilicated • Only one stage of rash may be seen at one time • No area of inflammation is seen around the vesicles • superficial • unilocular; dew-drop like appearance • pleomorphic-different stages of the rash evident at one given time, because rash appears in successive crops • an area of inflammation is seen around the vesicles
- 39. Evolution of rash • evolution of rash is slow, deliberate and majestic, passing through definite stages of macule, papule, vesicle and pustule • - scabs begin to form 10-14 days after the rash ap • evolution of rash very rapid • - scabs begin to form 4- 7 days after the rash appears
- 40. Fever • Fever subsides with the appearance of rash, but may rise again in the pustular stage (secondary rise of fever) • Temperature rises with each fresh crop of rash