It is an acute, highly infectious disease caused by varicella-zoster(v-z) virus. It is worldwide in distribution and occurs in both epidemic and endemic forms.

1. AB RAJAR
ASSOCIATE PROFESSOR
COMMUNITY HEALTH SCIENCES.

2. CONTENTS
Introduction.
Definition.
Epidemiological Determinants.
Clinical Features.
Diagnosis.
Treatment.
Prevention and control measures.

3. INTRODUCTION
Also known as “Varicella.”
It is an acute, highly infectious disease caused by varicella-
zoster(v-z) virus.
It is worldwide in distribution and occurs in both epidemic
and endemic forms.
Chickenpox and Herpes zoster are now regarded as
different host responses to the same etiological agent.

4. INTRODUCTION
•> 90% of population infected by 15 years.
•Attack rates 90% for household contacts
•Morbidity
–Bacterial skin infections
–Pneumonia
–Encephalitis, post varicella cerebritis
–Days from school/work
–Hospitalizations (<1%)

5. INTRODUCTION
•Risk of death:
–Lower for children than infants
–Increases with age for adolescents/adults
•30% for perinatally exposed infants
•2/100,000 aged 1-14
•2.7/100,000 aged 15-19
•25.2/100,000 aged 30-49

6. EPIDEMIOLOGICALDETERMINANTS

7. AGENT FACTORS
AGENT:
◦ V-Z virus also known as “Human(alpha) herpes virus 3”.
◦ Recovery from primary infection is commonly followed by latent
infection in the cranial nerves sensory ganglia & spinal dorsal root
ganglia, often for decades.
◦ When the cell mediated immunity wanes /decreases with age or
following immunosuppressive therapy, the virus may reactivate,
resulting in herpes zoster in 10-30% of persons.

8. AGENT FACTORS
SOURCE OF INFECTION:
◦ Usually a case of chickenpox.
INFECTIVITY:
◦ The period of communicability ranges from 1 to 2 days before the
appearance of rash & 4 to 5 days thereafter.
SECONDARY ATTACK TRATE:
◦ It is a highly communicable disease.
◦ The secondary attack rate in household contacts approaches 90%.

9. HOST FACTORS.
AGE:
◦ Primarily among children under 10 years of age.
◦ Few persons escape infection until adulthood.
◦ No age, however is exempt in the absence of immunity.
IMMUNITY:
◦ One attack gives durable immunity, second attacks are rare.
◦ The acquisition of maternal antibody protects the infant during the first few
months of life.
PREGNANCY:
◦ Infection during pregnancy presents a risk for the fetus and the neonate.

10. INCUBATION PERIOD:
Usually 14 to 16 days { as wide as 10 to 21 days}
PERIOD OF COMMUNICABILITY:
2 days from appearance of rashes till 5 days thereafter.
RESERVOIR OF INFECTION:
Infected persons.

11. TRANSMISSION
A. DIRECT TRANSMISSION:
◦ Chickenpox transmitted from person to person by droplet infection
and by droplet nuclei.
◦ Most patients are infected by “face to face”,(personal) contact.
◦ The portal of entry of the virus is the respiratory tract.
B.TRANSPLACENTAL TRANSMISSION:
◦ From pregnant mother to child leading to congenital Varicella.
◦ The virus can cross the placental barrier and infect the fetus, a
condition known as “congenital varicella”.

12. ENVIRONMENTALFACTORS.
Chicken pox shows a seasonal trend in India and Pakistan, the
disease occurring mostly during the first six months of the year.
Over-crowding favors the its transmission.
In temperate climates, there is little evidence of any seasonal trend.

13. CLINICALFEATURES
The clinical spectrum of chickenpox may vary from a mild
illness with a few scattered lesions to a severe febrile illness
with widespread rash.
The clinical course of chickenpox may be divided into two
stages:

14. CLINICALFEATURES
A.PRE-ERRUPTIVE SATGE:
Onset is sudden with mild or
moderate fever, pain in the back,
shivering and malase,lasting
about 24 hrs.
In the adults, the prodromal
illness is usually more severe and
may last for 2-3 days before the
rash comes out.

15. CLINICALFEATURES
B.ERUPTIVE STAGE:
a) Distribution:
The rash is symmetrical. It first appears
on the trunk where it is abundant, and
than comes on the face,arms,and legs
where it is less abundant.
Mucosal surfaces (e.g., buccal,
pharyngeal) are generally involved.
Axilla may be affected but palms and
soles are not usually affected.

16. CLINICALFEATURES
b) RAPID EVOLUTION:
The rash advances quickly through
the stages of
macule,papule,vesicale and scab.
The vesicles filled with clear fluid
and looking like “dew-drops” on
the skin.
They are not umbilicated.
Scabbing begins 4 to 7 days after
the rash appears.

17. CLINICALFEATURES
C) PLEOMORPHISIM:
A characteristic feature of the rash in
chickenpox is its pleomorphism,that is,
all stages of the rash (papule, vesicles
& crusts) may be seen simultaneously
at one time, in the same area.
This is due to the rash appearing in
successive crops for 4 to 5 days in the
same area.

18. CLINICALFEATURES
d) FEVER:
The fever does not run high but
shows exacerbations with each
fresh crop of eruption.

19. COMPLICATIONS
 Hemorrhages.
 Pneumonia.
 Encephalitis.
 Acute cerebeller ataxia.
 Reye’s syndrome (acute encephalopathy associated with fatty degeneration of
viscera especially liver).
 Secondary bacterial infections.
 Immunocompromised patients are at increased risk of complications.

20. COMPLICATIONS
Maternal varicella may results in:
birth defects
◦ LBW,
◦ Cataract,
◦ Microphthalmia,
◦ Chorioretinitis,
◦ Deafness.

21. CONTROL
The usual control measures are notification.
Isolation of cases for about 6 days after onset of rash.
Disinfection of articles soiled by nose and throat discharges.
Antiviral compounds:
◦ Acyclovir,
◦ Valacylovir,
◦ Famiciclovir.
◦ Foscarnet.

22. PREVENTION
1.VARICELLA ZOSTER IMMUNOGLOBULIN (VZIG).
◦Given within 72 hrs of exposure has been recommended for
prevention of chickenpox in exposed susceptible individuals
particularly in immunosuppressed persons,viz,
a. Susceptible person.
b. Persons with congenital cellular immunodeficiency.
c. HIV/AIDS.
d. Susceptible & exposed persons, in particular pregnant women.
e. Newborns.
f. Pre-mature infants of low birth weight.

23. PREVENTION
2.VACCINE.
A live attenuated varicella virus vaccine is safe and currently recommended for
children between 12-18 months of age who have not had chickenpox.
All susceptible adolescents and adults should be immunized.
Post-exposure prophylaxis has not been widely studied but it has been
suggested that it is 90% effective in preventing varicella in an outbreak,
particularly when given within 3-5 days after exposure.
The vaccine is immunogenic,sero-conversion occurs in 95% of children after a
single dose.
In adolescents ( older than 12 yrs) and adults the sero-conversion is seen in 78%
after one dose and 99% after two doses.

24. DIFFB/WSMALLPOX&CHICKENPOX
SMALL POX CHICKEN POX
Cause: Variola Virus Cause: Varicella Virus
I.P: About 12 days (range 7-17 days) I.P: range 15 days (range 7-21 days)
Prodromal Symptoms: Severe Prodromal Symptoms: Mild
Rash Distribution: Centrifugal Rash Distribution: Centripetal
Palm & Soles: Frequently Involved Palm & Soles: Seldom affected
Axilla: usually not affected Axilla: Frequently affected.
Limbs: rash on extensor surfaces Limbs: Rash on flexor surfaces
Nature of rash: Deep seated
vesicles,multilocular,
Nature of rash: Superficial,unilocular,
Rash Evolution: Slow Rash Evolution: Rapid
Fever: Fever subsides with appearance of
rash but may rise again in pustular stage.
Fever: Fever rises with each fresh crop of the
rash.