CHICKEN
POX&SMALL POX
Edited by:
Dr: HALA ALI ABED
Lecturer of public health
 Definition of the disease( bacterial ,viral,
zoonotic ……….etc).
 Magnitude of the problem.
 Epidemiology of the disease:
 Agent.
 Reservoir: man only, animal only
or man& animal.
 Mode of transmission.
 Incubation period.
 Susceptibility:
 Distribution of the disease according to
time , place person.
 * Immunity: natural( active& passive) and
acquired (active& passive).

* Herd Immunity.
 Diagnosis : - Clinical picture,
complication and investigation.
 Prevention
 Control
CHICKEN POX
Epidemiology
• Acute viral disease of children characterized by skin rash
(centripetal and pleomorphic). Chicken pox is also called
varicella.
• Causative agent: Varicella Zoster (V-Z) virus
• Reservoir:(man only)
•
Cases of varicella or herpes zoster: (V-Z) virus in the
respiratory secretions and fluid of skin rash.
• Mode of transmission:
Direct droplet infection (cough spray).
Droplet nuclei (air-borne).
Contact infection (fluid of vesicles).
Articles and fomites (by fluid of vesicles or respiratory
tract discharge).
Exposure to a case of herpes zoster
• Incubation period: 2-3 weeks.
• Communicability period:
•
Throughout the disease “1” day before and “7” days after
appearance of skin rash.
• Clinical picture
Prodroma:
Fever,
headache
and
malaise.
Skin rash:
Centripetal: more on the abdomen.
Pleomorphic:
all
stages
of
rash
present, macules, papules,
vesicles, pustule, crusts and scabs that
fall off within one week
• Complications
 Secondary infection of vesicles.
 Pneumonia.
 Encephalitis, rare.
 Fatality: rare
• Diagnosis:
• Clinical picture.
• Lab-isolation of virus
by tissue culture of
vesicles – fluid. “To
exclude
small
when suspected”.
pox
• Susceptibility :
• Infant born to immune mothers have passive immunity.
• Children (sporadic cases or outbreaks).
• Adults may be affected (severe disease).
• Vaicella zoster IgG modify or preventing disease if given
withen 4days after exposure.
• Durable immunity( virus remain latent, and disease may recure
years later as herpes zoster in 15% of older adult.
Prevention:
1- general prevention measures: for prevention of respiratory diseases.
• 2- specific:
A.Vaccine:
• Type: live attenuated vaccine.
• Adminsteration: 0.5 ml s.c
• Immunity: 85%-90% for prevention of disease .
100%for prevention of severity.
• Target group:
• -children aged 18 months and up to 12 y who have not
varicella before
• -contact of cases: if given within 3 days of exposure.
• Susceptible persons ˃ 13y e.g: health worker(2 doses
,4-8 weeks apart.
B. Seroprohylaxis: by specific immunoglobulin, to high
risk close contacts (prematures and debilitated children).
Control:
• a- Cases
• Notification, Isolation(isolate children from school for 1 week
after 1st appearance of the rash or until vesicles become dry).
• , & Disinfection ( concurrent an terminal).
• Symptomatic treatment: to relieve irritation of skin and
prevent infection
• Release: one week after appearance of rash (when rash
disappears).
• b- Contacts:
• -Enlistment, surveillance( for maximum i.p)
• - vaccine is given 3days after exposure if they are not
vaccinated.
• Seroprophylaxis for high- risk contacts.
• And for newborns of mothers who develop chicken pox
around delivery.
SMALL POX
VARIOLA
• Acute infectious disease characterized by generalized
skin rash, it has been eradicated from the world (1978).
• Causative agent:
• Variola virus.
• Resistant to glycerol.
• Destroyed by heat, potassium permanganate.
• Survives several months in crusts of eruption
• Reservoir
• Cases: Virus in respiratory discharges and skin rash.
• Incubation period:
• About 14 days (international)
• Mode of transmission:
 Direct droplet infection.
 Droplet nuclei and crusts (air-borne).
 Contact infection.
 Contaminated articles & fomites.
• Communicability
•
From onset of disease till disappearance of rash (2-3
weeks).
• Clinical picture:
• 1- Prodroma: Fever, headache and backache (sudden).
• 2- Skin rash:
• Appears at the end of 3rd day of disease.
• First on the face and then covers the body in 2-3 days.
• Characterized by being:
• - Centrifugal : more on face and extremities.
• - More on extensor than flexor surfaces (maxillae free).
• - More at areas of pressure.
• -
Monomorphic: only one stage present, the Stages of
rash are macules & papules. Vesicles, pustules, crusts,
Fall off at the end of 3rd w causing scar (permanent
scar)
• - Enanthema: Eruption of mucous membranes of
mouth, tongue, nose, pharynx, larynx and other parts
may be present.
Types
• 1- Variola major: with different forms of rash and severity
• - Discrete.
• - Confluent: extensive, severe rash fatal.
• - Hemorrhagic: very high fatality.
• 2- Variola minor (alastrim): Mild fever may simulate chickenpox
but it is centrifugal and monomorphic.
• 3- Varioloid: A mild form. In vaccinated cases, conjunctivitis and
corneal
ulcer,
bronchopneumonia.
mucosal
ulcers,
pneumonia
and
• Diagnosis:
• Clinical: Prodroma and typical skin rash.
• Laboratory: - Stained smears from vesicles and pustules.
•- Chick embryo culture (from blood and fluid of
eruption).
•- Paul’s test on rabbit cornea fluid of vesicles on
scarified rabbit cornea produces vesicles on rabbit
cornea.
• Prevention: By: (I) immunization.
•
(II) International measures.
• Control:
• a-Case: * Notification: even in suspected cases.
•
* Isolation in hospital.
•
* Disinfection.
•
* Treatment.
•
* Release: after all scabs disappear.
• b- Contacts:
•
- Vaccination.
•
- Surveillance for 2 weeks.
• c- Epidemic measures:
•
► Trace source and channels of infection.
•
► Mass vaccination of the area.