The document provides an overview of smallpox, including its history, morphology, transmission, clinical presentation, diagnosis, treatment and prevention. It discusses that smallpox was the first disease to be eradicated through vaccination efforts. Key points include that smallpox is caused by variola virus, has an incubation period of 7-17 days and rash onset marks the most contagious period. Vaccination was critical to its global eradication, declared by WHO in 1980.

1. Presented by….
SAMIR MOIRANGTHEM
Msc Medical Microbiology
RIPANS

2. Overview
 Introduction of Organism
 History
 Morphology and Classification
 Epidemiology
 Clinical features
 Transmission
 Disease in Humans and animal
 Diagnosis
 Prevention and Control

6. INTRODUCTION
 The first infectious disease to be eradicated from the world. It was
characterized by highly contagious severe exanthema (rashes).
 The agents of smallpox were
• variola major
• variola minor
 The disease provides at least three ‘firsts’:
1. the first vaccine,
2. the first disease to be totally eradicated by immunization,
3. and the first virus infection against which chemotherapy was clinically
effective.

8. The Organism
 Double stranded DNA
 Orthopoxvirus
 Variola, cowpox, vaccinia, monkeypox,
 Variola major or minor
 Stable outside host

9.  large, brick-shaped or ovoid double-stranded DNA viruses
 200–300 nm in diameter with a complex structure.
 neither icosahedral nor helical: referred to as complex.
 The outer membrane consists of a network of tubules and is sometimes surrounded
by an envelope.
 Inside there is a dumbbell-shaped core structure and two accompanying lateral
bodies, so named after their location in the virion.
 It has a protein-rich multilayered coat that makes it resistant to disinfectants
to disinfectants and antiseptics

11. Four major elements:
1. core ( 9 nm thick membrane, biconcave disk, a tightly compressed
2. lateral bodies
3. outer membrane ( a protein shell 12nm thick, the surface consists of irregularly
4. envelope ( an inconstant element, proteins are glycosylated and acylated)
Virons are present in two infectious forms:
1. EEV (Extracellular Enveloped Virus)- released from cells spontaneously by
exocytoses, are enclosed within a lipoprotein envelope
2. IMV (Intracellular Mature Virus) – released by cellular disruption, lacks envelope,

12. History of Smallpox
 First appeared in Northeastern
Africa around 10,000 BC
 Skin lesions on mummies
 1570-1085 BC
 Ramses V
 1763, Sir Jeffrey Amherst
 Smallpox in blankets for Indians
 18th century Europe
 400,000 deaths
 Case fatality, 20-60%
 Scars, blindness
 Infants, 80-98% CF

13. Edward Jenner
 1796, May
 Inoculated James Phipps
with fluid from milkmaid’s
pustule
Subsequent variolation of
boy produced no reaction
 Development of vaccine
using cowpox
 Protective for smallpox
Edward Jenner
1749-1823

14. Smallpox Clinical Disease
 Incubation period 7-17 days
 Range 12-14 d
 Initial signs
 Small red spots in mouth and on tongue
 Rash on face
 Spreads to arms, legs, hands, feet
(centrifugal)
 Entire body within 24 hours

15. FEVER
RASH Pre-eruption Papules-Vesicles Pustules Scabs
Onset of rash
Days – 4 – 3 – 2 – 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 21

16. Clinical Forms of Smallpox
 Variola major
 Most common and severe form
 Extensive rash, higher fever
 Ordinary (discrete, confluent, semi-confluent)
 Modified
 Flat
 Hemorrhagic (early and late)
 Variola minor
 Less common, less severe disease

17. Variola Major
 Discrete
 Pustules separate and not merging with one another
 Most common form of smallpox

18.  Semi-Confluent
 Pustules begin to merge
• Confluent
Pustules joining
and becoming
confluent

19.  Flat
 No raised vesicles
 Very uncommon
 Grave prognosis
 Hemorrhagic
 Less than 3% of all cases
 2 types, early and late
 Death occurs before pox lesions appear

20. Variola Minor

21. Smallpox Transmission
1.Person-to-person
 Inhalation of droplets
2. Direct contact
 With infected body fluids
3. Scabs
4. Contaminated objects
 Bedding, clothing, bandages
5. Aerosol
 Rarely
6. Spread more easily in cool, dry winter months
 Can be transmitted in any climate
7. No transmission by insects or animals

22. 8. Transmission from a smallpox case
Prodrome phase, less common
 Fever, no rash yet
Most contagious with rash onset
 First 7-10 days
9. Contagious until last scab falls off

25. Prognosis
 Variola major
 Ordinary cases, 20-40% case fatality rate
 Flat and hemorrhagic cases, usually fatal
 Blindness, limb deformities
 Variola minor
 Less than 1% case-fatality rate
 Recovered cases, lifelong immunity

26. Laboratory Diagnosis
 Direct detection in scrapings from rashes:
 Intracytoplasmic inclusion bodies (Paschen bodies)
 Electron microscopy: Brick-shaped appearance with biconcave
DNA core.
 Egg inoculation:
 Characteristic pock formation is seen on the chorioallantoic
membrane (CAM) of a chick embryo.

29. TREATMENT
 Cases used to be treated in the past with:
 Vaccinia immunoglobulins
 Antiviral drugs such as methisazone, cidofovir or tecovirimat.
 If exposed but not showing signs, vaccinate
 Within 3 days, lessens severity
 Within 4-7 days, some protection
 Quarantine
 If showing clinical signs
 Isolate patient
 Supportive therapy
 Cidofovir

30. Smallpox and Animals
 Animals do not show signs of disease
 No animal reservoir for smallpox
 Not zoonotic
 Some animals naturally susceptible to pox viruses
 Cats and cowpox

31. The Smallpox Vaccine
 Vaccinia virus
 Protects against variola virus
 Origins unknown
 Live vaccine
 Used in US until 1972
 Immunity high for 3-5 years
 Potentially protective much longer
 Cowpox vaccine discovered by Edward Jenner (the
father of vaccination)

33. FEVER
RASH
Appearance
Development
Distribution
On palms & soles
DEATH
SMALLPOX CHICKENPOX
At time of rash
2–4 days before the rash
Pocks in several stages
Pocks at same stage
Rapid
Slow
More pocks on body
More pocks on arms & legs
Usually absent
Usually present
Very uncommon
More than 10%
Differentiating Diseases

34. Chickenpox vs. Smallpox
 Chickenpox
 Lesions on trunk
 Very few lesions on
arms or hands
• Smallpox
− Lesions are dense
on arms and legs

35. Chickenpox vs. Smallpox

36. Who Should Not Get the Vaccine?
 Eczema or atopic dermatitis
 Skin conditions
 Chickenpox, herpes, psoriasis, shingles
 Weakened immune system
 Transplant, chemotherapy, HIV, others
 Pregnant women
 Less than 18yr.
 Breastfeeding mothers
 If exposed, get vaccine no matter what

37. Adverse Vaccine Reactions
 Prior to 2003 vaccination campaign
 For every 1 million people vaccinated
 1,000 serious reactions
 14-52 life-threatening reactions
 1-2 deaths
 Vaccinia immune globulin (VIG)
 Effective treatment for serious or life-threatening reactions to the
vaccine
 IV form, Investigational new drug

38. Smallpox Stores
 CDC in Atlanta, Georgia, U.S.
 Vector Laboratories in Koltsovo, Russia

39. Eradication was declared by WHO nearly after three
years of the last case, i.e. on 8th May 1980.

40. Eradication Success
 Vaccine available
 No animal reservoir
 Vaccinees easily identifiable
 Vaccinees could “vaccinate” close contacts
 Diseased easily identifiable

41. The End of Smallpox
 Oct. 26, 1977, last case of smallpox
 May 8, 1980, official declaration by WHO - Smallpox Eradicated!
Last case
of Variola
minor,
Somalia
1977
Last case
of Variola
major,
Banglades
h 1975