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Similar to Communicable diseases smallpox & chiken pox
Communicable diseases smallpox & chiken pox
- 1. Smallpox (Variola) DR.JEEVAN YADAV Professor, CommunityMedicine, D. Y. Patil Medical College, Kolhapur
- 2. Smallpox (Variola) 1stdisease been ERADICATED from India Milestones- – May 1975- last case in India (Bihar) – April 1977- India declared smallpox free – Oct 1977- World’s last case (Somalia) – 1978 – Laboratory accident – 8th May 1990- WHO declaration on smallpox eradication .
- 3. Smallpox Acute infectiousdisease caused by Veriola virus Fever of sudden onset with Centrifugal rash on 3rd day- characteristic, headache, backache, vomiting, sometime convulsion in child
- 4. Smallpox Smallpox eradication– Golden milestone in history of 20th century SmPx eradication –leads to prevention of – 2 million deaths, – few lakhs cases of blindness, – 10-15 million cases of smallpox disease
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- 7. Epidemiological factors whichled to eradication of smallpox: S- subclinical cases (total absent) - persons with subclinical cases don't transmit disease M- mutual (international) co-operation A- attack rate (Secondary A R) rare L- lifelong immunity after recovery from disease, lack of animal reservoir L- layman also can detect & report cases due to characteristic & simple rash P- person (human) not a carrier O- outbreaks –slow transmission X- vaccine- potent, stable, highly effective, confers long term protection
- 8. Current status 2017-40th anniversary of smallpox free status in India (1997-was 20th anniversary) smallpox eradication surveillance Laboratory stocks still maintained in Us (Atlanta) & Russia (Moscow) Because the pox viruses like – monkey pox, – cow pox, – camel pox, – tanapox etc whose natural histories are not known exists. In case of an outbreaks stocks will enable comparative studies on these animal pox viruses
- 9. Future 2 potentialsources of pox virus infection for humans exists This could be – I. Accidental infection from laboratory stocks or II. Infection with animal pox viruses 2 pox viruses- – monkey & tena pox have attracted attention as potentially capable of infecting humans 300 million vaccine stocks & bifurcated needles are maintained by WHO as protective measure
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- 11. Chickenpox (Vericella zosterinfection) Def: – Acute , highly infectious disease, – caused by vericella zoster (VZ) virus - characterized by vesicular rash with fever & malaise. Worldwide- epidemic & endemic form Chickenpox & herpes zoster – now regarded as different host responses to same etiological agent
- 12. Epidemiology Agent factors- a)Chickenpox, - v-z virus {human (alpha) herpes virus 3 } –Primary infection – causes Chickenpox
- 13. – Recovery fromprimary infection- followed by latent infection in sensory ganglia after decades without clinical manifestation, When cell mediated immunity wanes with age , immunosuppressive therapy- – virus reactivate – resulting in Zoster- a painful, vesicular, pustular eruption on one / more sensory nerve roots
- 14. b) Source ofinf- Case of chicken pox & rarely patients with herpes zoster Virus occurs in oropharyngeal secretions & lesions of skin & mucosa Scabs not infective Virus isolated from vesicular fluid- during first 3 days of illness
- 15. c) Infectivity- – 1-2days before rash & 4-5 days after rash d) Secondary attack rate- – Highly communicable disease , – SAR in household contact 90% e) Mode of spread- – Direct contact, – Droplet or air borne infection – Face to face (personal contact)
- 16. f) Incubation period- –14-16 days (15 days) g) Portal of entry- resp. tract h) Placental barrier- – crossed by virus- – infect fetus- congenital vericella
- 17. Host factors- 1. Age- children <10 yrs, may be until adulthood 2. Pregnancy- infection during pregnancy risk factor for fetus & neonate
- 18. 3. Immunity- oneattack give durable immunity, second attack rare Maternal antibody protect in first few months of life IgG antibodies protective against vericella Cell mediated immunity important in recovery from v-z infection
- 19. Environmental factors- Thisshows seasonal trend in India Common occurrence in first 6 months of yr (Jan-May) Overcrowding favors transmission
- 20. Clinical features- Mildto severe form Two stages 1. Pre-eruptive stage- Characterized by sudden onset of fever- mild to moderate, pain in back, shivering & malaise- last for 24 hrs
- 21. 2. Eruptive stage- In children- first sign is Rash Rash comes on day the fever starts Characteristics of Rash are- – ‘Centripetal distribution’-rash is symmetrical – First appears on trunk, then to face, arms, legs. – Also mucosal surfaces (buccal, pharyngeal) involved – Axilla may be affected, but palm & soles not
- 22. ii) Rapid evolution- –Rash advances quickly through stages of -Macule – papule – vesicle – scab – ‘Dew drop’ appearance – vesicles filled with clear fluid on skin, surrounded by area of inflammation & not umblicated – Scabbing begins 4-7 days after rash appears
- 23. iii) ‘Pleomorphism’ – –characteristic feature of rash in chickenpox – i.e. all stages of rash (macule, papule, vesicle, crust)- – seen simultaneously at one time, in same area, due to successive crops in 4-5 days. iv) fever- – usually exacerbations (increase temp) with each fresh crop of eruption
- 24. Complications- – Usually mild,self limiting – Mortality < 1% in uncomplicated cases – In immunosuppressive cases- pneumonia, hemorrhage, encephalitis, – Reye’s syndrome (acute encephalopathy with fatty degeneration of liver), congenital vericella – Maternal vericella- fetal wastage, birth defect, microcephally, oncogenecity
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- 27. Pleomorphic rash inchicken pox Papule , vesicle, crust
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- 29. Laboratory diagnosis- 1. Clinicalsigns 2. Examination of vesicle fluid- – immunofluroscent staining of vesicular scarping – Serological tests in epidemiological surveys
- 30. Control- No specifictreatment- (Antiviral-Azovir suspension in children just to reduce the severity?) Notification- Isolation - of cases for about 6 days after onset of rash Disinfection – of articles soiled nose & throat discharges
- 31. Prevention- 1. Passive immunization- Vericella-zoster immunoglobulin (VZIG)- ideally given within 3 days, if not at least within 7 days 125 – 600 IU (1.5 – 5ml IM) as per body wt. Reserved for immunocompromised contact / newborn contact / pregnant woman / pt. with leukemia Prevents or modifies disease
- 32. 2. Active immunization Vericella vaccine- Live attenuated OKA strain, Japan Available as lyophilized powder Dissolve in 0.5 ml diluent 12 mon – 12 yr – single Subcutaneous injection >13 yrs- 2 dose- 4-6 wks apart Efficacy- 95-99% No booster needed Prevents disease in >80% of exposed, if administered within 3 days of exposure
- 33. Chickenpox IP- 15days Prodormal - usually mild Distribution OF Rash- – CENTRPETAL – AXILLA AFFECTED – PALM & SOLE SELDOM AFFECTED – RASH MOSTLY ON FLEXOR SURFACE Smallpox IP- 12 days Prodormal sympt- severe Distribution OF Rash- – CENTRIFUGAL – AXILLA USUALLY FREE – PALM & SOLE FREQUENTLY INVOLVED – RASH MOSTLY ON EXTENSOR/BONY SURFACE
- 34. Chickenpox Characteristics of Rash- –Superficial – Unilocular, Dew drop like – Pleomorphic rash- one time – Inflamed area – around Smallpox Characteristics of Rash- – Deep seated – Multilocular, umblicated – Only one stage at one time – No inflamed area – around
- 35. Chickenpox Evolution ofRash- – Very rapid – Scab begin to form 4-7 day after rash appearance Fever- – Temp rises with each fresh crop of Rash Smallpox Evolution of Rash- – Slow, passes definite sages of M, P, V, Pustule – Scab begin to form 10-14 day after rash appearance Fever- – Fever subside with appearance of Rash, but rise again in Pustular stage (secondary rise of fever)
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- 40. Questions 1. Difference betweenChicken pox & small pox 2. Epidemiology of Chicken pox
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