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January 2003 Variola Virus Photo Courtesy of CDC/Public Health Image Library 1.

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Presentation on theme: "January 2003 Variola Virus Photo Courtesy of CDC/Public Health Image Library 1."— Presentation transcript:

1 January 2003 Variola Virus Photo Courtesy of CDC/Public Health Image Library 1

2 January 2003 History Ancient scourge – many millions killed Global eradication in 1977

3 January 2003 Photo Courtesy of National Archives

4 January 2003 Photo Courtesy of World Health Organization 2

5 January 2003 Bioweapon Potential Precedence –Prior use in French-Indian War –Produced by USSR

6 January 2003 Bioweapon Potential Reality of the risk –Viral stocks exist –Non-immune population

7 January 2003 Photo Courtesy of CDC 3

8 January 2003 Epidemiology No animal reservoir/vector Mortality 25-30% Person-to-person transmission –Via respiratory droplets –Household and face-to-face contacts –High risk of nosocomial spread –Secondary attack rate 25-40% –Up to 20 contacts infected per case

9 January 2003 Photo Courtesy of World Health Organization 4

10 January 2003 Epidemiology Aerosol route of transmission –Likely in bioterrorism setting

11 January 2003 Virology Orthopoxviridae DNA Viruses –Variola variants Variola major – high mortality Variola minor – low mortality, 20 th Century –Vaccinia Current smallpox vaccine

12 January 2003 Virology Orthopoxviridae DNA Viruses –Other pox viruses Cowpox Monkeypox

13 January 2003 Pathogenesis Virus contacts respiratory mucosa Carried to lymph nodes Primary viremia Organ seeding WBCs infected Dermal invasion Vesicle Sepsis

14 January 2003 Clinical Features Incubation Stage –Asymptomatic –10-12 days (range 7-17)

15 January 2003 Clinical Features Prodromal Stage –Sudden nonspecific flu-like illness High fevers Headache Backache Prostration –2-5 days duration

16 January 2003 Clinical Features Eruptive Stage –Characteristic rash Centrifugal location Grouping Depth of lesions

17 January 2003 Photo Courtesy of World Health Organization 5

18 January 2003 Clinical Features Distribution of the rash

19 January 2003 Photo Courtesy of World Health Organization 6

20 January 2003 Photo Courtesy of World Health Organization 7

21 January 2003 Photo Courtesy of National Archives

22 January 2003 Photo Courtesy of National Archives

23 January 2003 Photo Courtesy of World Health Organization 8

24 January 2003 Photo Courtesy of World Health Organization 9

25 January 2003 Photo Courtesy of World Health Organization 10

26 January 2003 Photo Courtesy of World Health Organization 11

27 January 2003 Photo Courtesy of World Health Organization 12

28 January 2003 Photo Courtesy of World Health Organization 13

29 January 2003 Photo Courtesy of World Health Organization 14

30 January 2003 Photo Courtesy of World Health Organization 15

31 January 2003 Photo Courtesy of World Health Organization 16

32 January 2003 Photo Courtesy of World Health Organization 17

33 January 2003 Photo Courtesy of CDC/James Hicks 18

34 January 2003 Photo Courtesy of CDC 19

35 January 2003 Clinical Features Severity of the classical rash –Discrete (<10% mortality) –Semi-confluent (25-50%) –Confluent (50-75%)

36 January 2003 Discrete Smallpox Photo Courtesy of National Archives

37 January 2003 Semi-Confluent Smallpox Photo Courtesy of World Health Organization 20

38 January 2003 Confluent Smallpox Photo Courtesy of National Archives

39 January 2003 Smallpox Complications Eye infection or blindness Arthritis Encephalitis Secondary bacterial infections

40 January 2003 Differential Diagnosis Varicella (chickenpox) Monkeypox Drug eruptions Generalized vaccinia Multiple insect bites Molluscum contagiosum Secondary syphilis Viral exanthems (e.g. HHV-6, Cocksackie, etc)

41 January 2003 Chickenpox Photo Courtesy of World Health Organization 21

42 January 2003 Monkey Pox Photo Courtesy of CDC 22

43 January 2003 Erythema Multiforme Photo Courtesy of New England Journal of Medicine 23

44 January 2003 Generalized Vaccinia Photo Courtesy of CDC 24

45 January 2003 Generalized Vaccinia Photo Courtesy of CDC 25

46 January 2003 Molluscum Contagiosum Photo Courtesy of American Academy of Pediatrics 26

47 January 2003 Secondary Syphilis Photo Courtesy of American Academy of Pediatrics 27

48 January 2003 Hand-Foot-Mouth Disease (Enterovirus Infection) Photo Courtesy of American Academy of Pediatrics 28

49 January 2003 Differential Diagnosis Chickenpox (varicella virus) –Distribution of rash –Grouping of lesions Asynchronous development –Vesicle appearance Shallow –Short Prodrome

50 January 2003 Chickenpox Photo Courtesy of World Health Organization 29

51 January 2003 Photo Courtesy of World Health Organization 30

52 January 2003 Photo Courtesy of World Health Organization 31 smallpox chickenpox

53 January 2003 Chickenpox Photo Courtesy of American Academy of Pediatrics 32

54 January 2003 Chickenpox Photo Courtesy of American Academy of Pediatrics 33

55 January 2003 Non-Classical Rash Presentations Modified variant of smallpox –Seen in ~25% of cases who were previously vaccinated –Much lower mortality, milder disease –Harder to distinguish from chickenpox –May be predominant form seen if cases appear in a vaccinated population

56 January 2003 Modified Smallpox Photo Courtesy of National Archives

57 January 2003 Flat (Malignant) Smallpox Photo Courtesy of World Health Organization 34

58 January 2003 Non-Classical Rash Presentations Flat (Malignant) variant of smallpox –5-10% of smallpox cases in outbreak setting –Severe systemic disease –Flat, leathery lesions –Lesions coalesce, no discrete pustules –Mortality 97% –May be associated with compromised hosts

59 January 2003 Flat (Malignant) Smallpox Photo Courtesy of World Health Organization 35

60 January 2003 Hemorrhagic Smallpox Photo Courtesy of World Health Organization 36

61 January 2003 Non-Classical Rash Presentations Hemorrhagic variant of smallpox –<5% of all cases –Rapidly progressive fulminant illness –Lesions become hemorrhagic before pustules form –Predilection for pregnant women –May be difficult to diagnose –Differential diagnosis: Menigococcemia DIC Hemorrhagic Chickenpox

62 January 2003 Meningococcemia Photo Courtesy of American Academy of Pediatrics 37

63 January 2003 Hemorrhagic Chickenpox Photo Courtesy of American Academy of Pediatrics 38

64 January 2003 Diagnosis Clinical –Classic rash is sufficient in outbreak setting –Must have high index of suspicion

65 January 2003 Photo Courtesy of World Health Organization 39

66 January 2003 Diagnosis Smallpox should be ruled out if: –Classic rash is present –Suspicious rash with severe systemic illness

67 January 2003 Diagnosis From vesicle/pustule fluid Traditional confirmation –Electron microscopy –Culture Newer rapid tests –PCR –Immunohistochemistry –Reference labs (e.g. CDC)

68 January 2003 Diagnosis Photo Courtesy of CDC/Dr. Fred Murphy, Sylvia Whitfield 40

69 January 2003 Management Isolation of suspected cases No effective antivirals Supportive care –Fluid, electrolyte balance –Hemodynamic, ventilatory support Antibiotics for secondary infections +/- vaccination with smallpox vaccine

70 January 2003 Post-Exposure Prophylaxis For exposure to aerosol or suspected case –Household or face-to-face contacts

71 January 2003 Post-Exposure Prophylaxis Vaccine –Protective within 3-4 days of exposure –Reduces incidence 2-3 fold –Decreases mortality >50% Cidofovir –Effective vs other poxviruses –Nephrotoxic antiviral agent

72 January 2003 Vaccination Vaccinia live virus vaccine U.S. stock –>20 years old, still viable –10 fold dilution still >95% effective –Jennerian pustule = protection Photo Courtesy of CDC 41

73 January 2003 Vaccination Efficacy –10 fold reduction 2 o attack rate –Full protection for 3-10 years –Modest protection from mortality up to 20 yr –Multiple vaccinations boost duration

74 January 2003 Vaccination Adverse Effects –3/100,000 vaccinees Death –1/million vaccinees historically Highest risk –Infants –Primary vaccinees Absolute contraindications –None in outbreak setting

75 January 2003 Vaccination Relative contraindications –Age <1 year old –Pregnancy –Immunocompromised –Skin Disorders Eczema Atopic Dermatitis –Contact with high-risk persons

76 January 2003 Vaccination Serious complications –Encephalitis 1:300,000 primary vaccinees 25% mortality No treatment Often permanent neurological defects –Progressive Vaccinia (a.k.a. vaccinia gangrenosum/necrosum) Untreated mortality near 100% –Eczema vaccinatum History of eczema or chronic skin disorder 40% mortality in young children

77 January 2003 Vaccination Mild complications –Generalized vaccinia –Autoinoculation –VIG can treat or prevent

78 January 2003 Infection Control Isolation of Cases –Contact precautions Gloves, gowns –Airborne precautions Negative pressure HEPA filtered room, N95 masks –Home isolation an option –Immunized persons should provide care

79 January 2003 Infection Control Management of Case Contacts –Period of infectiousness Oral lesions all scabs –Fever precedes rash Fever Isolation –Contact identification Exposure to case after fever onset –Face-to-face contact –< 3 meters –Immediate vaccination –17 day observation Isolate if > 38 o

80 January 2003 Infection Control Nosocomial transmission –All patients and staff in hospital with a case should be vaccinated Quarantine may be necessary


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