Download Eradication Of Small pox

Small Pox
Sir Edward
Jenner
Definition
• Acute infectious disease caused by variola
virus and clinically characterised by
sudden onset of
fever,backache,headache,vomiting,and
sometimes convulsions,esp in children .on
third day of fever ,a typical rash appear
which is centrifugal in distribution and
passes through successive stage of
macule,papule,vesical pastule and scab
with subsequent scaring.
LANDMARKS IN THE HISTORY
OF SMALLPOX
Upto 1967
1975 17th
May
24th
May
5th
July
1977 April
26th
Octo
ber
1978
1980
8th
May
Endemic in more than 33 countries
Last indigenous case in India in Bihar
India’s last known case – An importation from
Bangladesh
India proclaimed to be a smallpox free country
A non-endemic area.
India was declared to be smallpox free by an
international commission for assessment of smallpox
eradication
World’s last case of smallpox in Somalia
Ali maow maalin – A cook from Somalia
Lab accident case – in Birmingham (UK)
WHO declared complete eradication of Smallpox from
the world
LANDMARKS IN THE HISTORY OF SMALLPOX
1981 May
The international Health regulations were
amended by the 34th World Health
Assembly to delete all reference to smallpox
and smallpox vaccination
1982
All the member states officially discontinued
compulsory vaccination of smallpox
1996 M A resolution from WHO’s Executive board to
ay the World Health Assembly recommended that
the stocks of the viruses be destroyed in 1999
(World health report – fighting disease,
fostering development)
Agent
SMALL - POX
• VARIOLA (ICD-10): B03
• Variola :- Orthopox Virus
»Large DNA virus
• Types- Major
Minor
•
5 subtypes Modified Sp (15%) Abortive attack
 Haemorrhagic Sp (2.7%)1. Early : Purpura Variolas
2. Late : Variola pustulosa H’gica
 Flat type (0.3%)
 Variola sine eruption (v. rare)
VARIOLA Major
–CFR 20% to 50%
–Classical Small pox (82%)
VARIOLA Minor
-Milder form
-Short duration
-Mistaken for chicken pox
-Mortality <1%
Host Factors
• Host: all age groups
• Occupation: Medical & Nursing
• Physiological:
Pregnancy & immuno-compromised
Immunity
Immunity: life long after infection
• Secondary sub-clinical cases were common
-They do not transmit infection,
– Only booster the immunity
• Source : Case of Sm. Pox,
»No carrier,
• Reservoir : NONE
• Infectivity: Untill the scab is formed
Max. during 1st week of of Rash
• S.A.R. = 35-40%
Environmental Factors
• Low temperature & High Humidity
Virus survival increased
• Season: Winter & Spring
• Ventilation: Overcrowding
Spread
Modes of Transmission
• Direct: Implantation on Nasal,
Oropharyngel, Mucous membrane
Secretion from the rash \scab
• Indirect: Air borne, Fomite borne,
Close contact with patients, or their
clothing or bedding, is thus required for
infection.
Incubation Period
• 10 days -17 days
– (average - 12days ) rarely 7-17 days
Signs &Symptoms
• Fever , Backache, Malaise, Headache,
Convulsions in children , Delirium
• Abdominal Colic in adults
• A rash appears after 2 to 4 days and progresses
through characteristic stages of papules,
vesicles, pustules and finally scabs.
• Scabes fall off at the end of 3rd or 4th week
Characteristics of lesions
Centrifugal distribution
Most dense
– On face & extremities than
on trunk
– Distal part of limbs than
proximal,
– Extensor surface
– Convexities,
The density of the rash is greater on the face than on
the body.
• Pocks are
usually present
on the palms
and on the
soles.
Day-1
• few raised spots called
papules appear.
• Usually seen first on the
face, and later on the
body and extremities.
Day-2
more papules
appear.
By day 3
• the rash has become
more distinct and raised
above the skin surface.
• Fluid is accumulating in
the papules to form
vesicles.
day 4,
•
the vesicles are more
distinct , they feel very
firm to the touch.
• When broken, they do
not collapse because
the fluid is contained in
many small
compartments.
By day 5,
• the fluid in the
vesicles has become
cloudy and looks like
pus.
• At this time, the fever
usually rises and the
patient feels more ill
than before.
On day 7
• The rash is definitely
pustular.
• Umbilication starts
• Although varying
somewhat in size, all
resemble each other in
appearance.
Day 8 and 9
• the pustules
increase
somewhat in size.
• They are firm to the
touch and deeply
embedded in the
skin.
Day 10-14
• The scabs begin to
appear
• The scabs contain live
smallpox virus.
• Until all scabs have
fallen off, the patient
may infect others.
By day 20,
• the scabs have
come off and lightcoloured or
depigmented areas
are observed.
• Non infectious stage
• Over a period of many weeks the skin
gradually returns to its normal
appearance.
• Scars which last for life may remain on the
face, an indication of previous infection
with smallpox.
Papules
3
4
5 Vesicles
Pustules
7
9
13
Scabs
FEVER
Days
–4 –3 –2 –1
2
Papules
RASH
Pre-eruption
1
Onset of rash
3
4
5
6
7
8
Pustules
9
10
11
12
13
Scabs
14
21
Complications
•
•
•
•
Pustules- secondary Infection
Ocular
Bones & joints
Resp.-Pneumonia
• Bronchitis, Pulm. Oedema
• G.I. syst- Diarrhoea, Ac. Dilatation of
Stomach, Infection of Intestine
• GU sys- Orchitis
• CNS- Encephalitis
Diagnosis
•
•
•
•
•
Clinical- & Lab :
Skin scab. Oro-pharyngeal,
Mucous membrane
Conjunctiva,
Urine
Eradication
• The eradication campaign was based on
two key strategies:
• (1) mass vaccination and
• (2) the detection and containment of all
cases of smallpox.
– Surveillance: Facial Pocks marks survey
Rumor register
Prevention & Control
• Isolation & Quarantine were used in early
days
• Vaccination:
• Early days: Variolation
• Edward Jenner (1796) - 1st Vaccination
using Cow Pox
• Surveillance: Facial Pocks marks survey
• Rumor register
Sir Edward Jenner
18th century
• People who survived from small pox (S.P)
did not get disease again--- Life long immunity.
• Variolation- To infect healthy individual with s.p.
material taken from the pustules of infected
individual
Some were developing the ds. Or developed
other infection
Small pox epidemic
Developed
disease
Did not developed
disease
Milkmaid women
had contact Cow pox
Hypothesis- Cow pox offers immunity to S.Pox.
Vaccination
Administration of Cow pox material to 8 yrs. Old healthy volunteer
After 6 weeks
Inoculated from small pox pustules
No disease
Large no. of people
Results
Immunization schedule
Evaluation of the effect & coverage
Eradication Of Small pox
Vaccination
• Dryvax was created in the late 1800s, by the
company that became Wyeth Laboratories
Multipuncture vaccination
by bifurcated needle
• Administrationby making 15 punctures in the
skin with a special needle.
• Revaccination
recommended at least every 10
years.
• Efficacy of vaccine- >95%
Vaccine Reaction
Virus- Vaccines
1976 76 countries officially hold the virus
1980 Worldwide only six laboratories hold the virus on stock
1983 Worldwide only two laboratories hold the virus on stock –
Both were the WHO collaborating centers
1. US laboratory in Atlanta, Georgia
2. Research Institute of Viral preparations, Moscow
Till As a protective measure against rare possibilities of
date smallpox or accidents vaccine stocks and bifurcated
needles for vaccination about 300 million people are
maintained indefinitely by WHO in Geneva, Toronto and
New Delhi.
Vaccination
• Wyeth stopped making the vaccine in the 1980s.
But government officials kept a stockpile of
about 15 million doses.
• The Dryvax came in handy in 2003, when it was
used to help contain an outbreak of monkeypox
in the United States.
Is
vaccination needed at
present?
Post Eradication Scenario
• Possibility of infection
A- Accidental infection with laboratory
associated stocks
B-Infection with animal virus--- monkey pox
& tenapox virus
Vaccination
• After 9/11 the
subsequent spread
of anthrax in
October 2001,
public health
officials regard the
use of biological
weapons by
terrorists as a real
possibility.
• It is believed that clandestine stocks of
smallpox exist in 10 or more other
countries.
Most recently, a CIA intelligence review
concluded that Iraq, France, North Korea, and
Russia have covert stocks of smallpox virus,
although the French government has denied
the allegation.
15 months after sept.11
• Bush ordered smallpox vaccine for military.
• Bush said he will also be getting the smallpox vaccine.
vaccine is now available under limited
circumstances:
•
Department of Defense military and civilian
personnel and State Department personnel who
work in high threat areas
• Healthcare providers and “first responders” who
volunteer for smallpox response teams
• For laboratory workers and others at risk for
exposure to the smallpox virus, or closely related
viruses
• Participants in smallpox vaccine clinical trials