For under graduate and post graduate medical students

1. SMALL POX &
CHICKEN POX
Dr.Benny PV
Professor & HOD
Department of Community Medicine
Sree Gokulam Medical College

2. SMALL POX
Obituary

3. History
• Was one of the major killer
throughout the world
• An International campaign
between 1967 and 1979 led to
the eradication of Small Pox

4. History..
• Last indigenous case in India in
17th May 1975 in Bihar
• Last known case was imported
from Bangladesh on 24th May
1975
• India was declared smallpox free
by an international Commission
for Assessment of Small pox
eradication on April 1977

5. History
• World’s last case was in
Somalia on 26thOctober
1977
• 8th May 1980 , WHO
declared that Small Pox had
been eradicated

6. Etiological agent (Variola
Virus)
• 4 orthopoxviruses are known to
infect humans: variola, vaccinia,
cowpox, and monkeypox
• Variola major is severe and the
most common form with more
extensive rash and higher fever
with a death rate of 30%
• Variola minor has less common
presentation and much less
severe with death rate of 1%

7. Transmission (Variola Virus)
• Humans are the only natural
host of smallpox (no animal
reservoir)
• Transmission generally occurs
from direct and fairly
prolonged face-to-face contact
• Infected aerosols and air
droplets spread in face-to-face
contact

8. Pathogenesis
• Portal of entry is respiratory tract or
inoculation on skin
• Source of infection is excretions from
the mouth and nose, rather than scabs
• The virus proceeds through infection,
replication, and liberation (usually
accompanied by cell necrosis) first at
the site of inoculation and then to the
regional lymph nodes, then deeper
lymph nodes and bloodstream

9. Small pox eradication
• One of the most brilliant
accomplishments in medical
history in recent times, and
indeed a historic milestone

10. Clinical features
• Sudden onset of fever,
headache, back ache, vomiting
and sometimes convulsions,
especially in children.
• Rash centrifugal passes through
successive stages of maculae,
papule, vesicle, pustule, and
scab with subsequent scarring.

11. Diffence
distribution of
rashes

12. Vaccination
• Live vaccinia virus
• Administered using a bifurcated
needle, not an injection
• Bifurcated needle is dipped into
the vaccine and then used to
prick the skin 15 times in about 3
seconds in a 5mm radius area
• Administered into the superficial
layer of the skin

13. Edward Jenner
• He found that, the cowpox would
protect the patient from smallpox
• He proposed it in 1798
• In England vaccination with cowpox
became compulsory in 1853
• Jenner was honoured for his
technique, and ‘Vaccine’ became
the universally used term to
indicate introducing material under
the skin to produce a protection
against disease

14. Edward Jenner:
smallpox
vaccination
Edward Jenner vaccinating his child
against smallpox; coloured
engraving

15. What we gained?
• Prevention of
• 2 million deaths
• A few hundred
thousand cases of
blindness
• 10-15 million cases
of disease

16. Epidemiological Basis Of
Eradication
• No known animal reservoir
• No long-term carrier of the virus
• Life-long immunity, after
recovery from the disease
• Easy detection; coz
Characteristic rashes in the
visible parts

17. Epidemiological Basis Of
Eradication
• Persons with sub clinical
infection did not transmit the
disease.
• Vaccine highly effective; easily
administered, heat stable and
confers long-term protection.
• International cooperation

18. Course of vaccination
• If vaccination is successful- a red,
itchy bump develops at the vaccine
site in 3-4 days
• a papule surrounded by erythema
• In the first week the bump becomes
a blister, fills with pus, and begins to
drain
• During the second week the blister
begins to dry and a scab forms; the
scab then falls off leaving a scar
• It is given on the right side
universally

19. CHICKEN POX
Varicella

20. Chicken pox
• Acute, highly infectious disease
caused by Varicella- Zoster (V–Z)
virus
• Chicken pecked skin appearance,
chickpea appearance
• World-wide in distribution and
occurs in endemic and epidemic
forms
• Chickenpox and Herpes zoster as
different host responses to the
same etiological agent
• In India, approx. 28,000 cases per
year

21. Varicella zoster
virus

22. Agent
• Human (alpha) herpes virus
• Primary infection causes chicken pox
• Recovery followed by latent infection
• Reactivation results in zoster- a
painful, vesicular, pustular eruption in
distribution of one or more sensory
nerve roots
• Can be grown in tissue culture
• Incubation period: 14-16 days (7-21
days)

23. Source of
infection
• Usually a case of chicken pox
• Virus present in oropharyngeal
secretions and lesions of skin and
mucosa
• Rarely may be a patient with
herpes zoster
• It can be isolated from the
vesicular fluid during the first 3
days of illness

24. Mode of
transmission
• It is transmitted from person to person by
direct contact (touching the rash)
• Droplet or air born spread (coughing and
sneezing)
• Vesicle fluid or secretions of the respiratory
tract of cases or of vesicle fluid of patients with
herpes Zoster
• It could also transmit indirectly through articles
freshly soiled by discharges from vesicles and
mucous membranes of infected people

25. Infectivity
• Period of communicability: 1-2
days before the appearance of
rash, and 4-5 days thereafter
• It tends to die out before the
pustular stage
• Patient ceases to be infectious
once the lesion have crusted
• Secondary attack rate: About
90% in household contacts

26. Host factors
• Age
• Children under 10 years of age
• Few escape until adulthood but can be severe in
adults
• Immunity
• One attack give durable immunity
• Maternal antibody protects the infant for few
months
• No age is exempt in the absence of immunity
• IgG antibodies persist for life and correlate with
protection
• Cell mediated immunity is important in recovery
• Pregnancy
• Risk for fetus and neonate

27. Environmental
factors
• It shows a seasonal trend, occurring
mostly during the first six months of
the year
• Overcrowding
• In temperate climates, there is little
evidence of seasonal trend

28. Clinical features
• Clinical spectrum
• Mild illness with few scattered lesions
• Severe febrile illness with widespread rash
• Pre-eruptive stage
• Sudden onset with mild to moderate fever
• Pain in the back, shivering and malaise
• Duration about 24 hours – In adults
• Prodromal illness is usually more severe and
may last for 2-3 days before the rash

29. Clinical features..
(Eruptive stage)
• In children the rash comes on day the fever starts and
first sign
• The distinctive features of rash are
• Rash is symmetrical
• Appears on the trunk and then comes to face, arms
,legs
• Mucosal surfaces (buccal, pharyngeal) are involved
• Axilla affected
• Palms and soles usually not involved
• The density of eruption diminishes centrifugally
• Pleomorphism
• All stages of rash (papules, vesicles and crusts) may
be seen simultaneously in the same area

30. Clinical features..
Evolution of rashes
• The rash advances quickly through the stages of
• Macule, papule, vesicle and scab
• Vesicles filled with clear fluid resembling ‘dew-drops’
• Superficial in site, with easily ruptured walls and
surrounded by an area of inflammation
• Vesicles may form crusts directly
• Many lesions may abort
• Scabbing begins 4-7 days after the rash appears
• Fever not high but exacerbations with fresh crop

31. Complications
• It’s a mild, self-limiting disease
• Patients at risk of complications are
• Immunosuppressive patients
• Cancer patients
• Recipients of organ transplants
• Chemo, radio, steroid therapy recipients
• HIV infected
• Children with leukemia

32. Complications..
• Haemorrhages (varicella haemorrhagica)
• Pneumonia
• Encephalitis, Acute cerebellar ataxia
• Reye’s syndrome
• Maternal varicella may cause foetal wastage & birth
defects
• Acute retinal necrosis
• Secondary bacterial infections (Cellulitis, erysipelas,
epiglottitis, osteomyelitis, scarlet fever and
meningitis)
• Pitted scars

33. Congenital defects in
babies
• Damage to brain: encephalitis, microcephaly,
hydrocephaly, aplasia of brain
• Damage to the eye: microphthalmia, cataracts,
chorioretinitis, optic atrophy
• Other neurological disorder: damage to cervical and
lumbosacral spinal cord, motor/sensory deficits,
absent deep tendon reflexes, anisocoria/Horner's
syndrome
• Damage to body: hypoplasia of upper/lower
extremities, anal and bladder sphincter dysfunction
• Skin disorders: (cicatricial) skin lesions, hypo
pigmentation

34. Laboratory
diagnosis
• Most rapid and sensitive
• Examination of vesicle fluid under electron
microscope
• Round particles which may be used for
cultivation
• Scrapings of floor of vesicles show
multinucleated giant cells coloured by Giemsa
stain (Tzank test)
• Serology for epidemiological surveys

35. Control
• Notification
• Isolation of cases for about 6 days after
onset of rash
• Disinfection of articles soiled by nose
and throat discharges
• Antiviral drugs provide effective therapy
for varicella (acyclovir, valaciclovir,
famiciclovir and foscarnet)

36. Prevention
• Varicella zoster immunoglobulin (VZIG) &
• Postexposure prophylaxis of varicella in high risk
individuals
• Include immunocompromised children and
adults
• Newborns of mothers with varicella shortly
before or after delivery
• Premature infants, neonates and infants <1 year
old
• Adults without evidence of immunity, pregnant
women
• To reduce severity of varicella
• Varicella vaccine

37. Varicella zoster
immunoglobulin (VZIG)
• One single-dose by IM inj ideally within 96 hours of
exposure
• Divide dose and give in ≥2 inj sites; max 3mL per inj site
• Inject into deltoid muscle or anterolateral aspects of the
upper thigh
• Avoid gluteal region; if needed, only use upper, outer
quadrant
• ≤2kg: 62.5 IU; 2.1–10kg: 125 IU; 10.1–20kg: 250 IU;
20.1–30kg: 375 IU; 30.1–40kg: 500 IU; ≥40.1kg: 625 IU
• Consider 2nd full dose for high risk patients with
additional exposure >3 weeks after initial dose

38. Vaccine
• A live modified Varicella virus
lyophilised vaccine which can be
stored at low temp is available for
protection

39. Vaccination
• IAP recommends
• 2-dose childhood varicella vaccination
• 1st dose at age 12-15 months
• 2nd dose at age 4-6 years
• Catch-up vaccination of children and
adolescents who had previously received one
dose – 2 doses for all adolescents and adults
without evidence of immunity

40. Vaccine
• Monovalent vaccine
• 0.5 ml subcutaneous injection
• Two dose schedule for persons aged >13 years
• Minimum interval between doses 6 weeks
• Duration of immunity probably 10 years

41. Difference between small pox and chicken pox
Charecteristics Small pox Chicken pox
Incubation 12 days (7-17) 15 days (7-21)
Prodromal Severe Mild
Distribution of rash rash Centrifugal Centripetal Palms
Palm and Soles involved Not involved
Axilla Axilla free Axilla affected

42. Thank you