Varicella

1. Varicella-Zoster Virus
(VZV)

2. Properties
 ds DNA enveloped virus
 One antigenic serotype only
 Causes two major diseases:
• Chickenpox (Varicella), usually in
childhood. Is a primary infection
• Shingles (Zoster), later in life. Is a
reactivation of an earlier varicella
infection

3. Entry of virus via
respiratory tract
Lymphoid system
Viremia
Epithelium at
different sites
After 14 days
reaches the main
Target: the skin
Becomes latent in
the cerebral or
posterior root ganglia
Reactivation
Pathogenesis

4. Replication of VZV

5. Varicella (Chickenpox)
• Is a primary infection
• Incubation period: 14-21 days
• Highest prevalence in the 4 - 10 years
old age group
• Presents with fever, lymphadenopathy,
a widespread vesicular rash.
• Is highly communicable, with an attack
rate of 90% in close contacts.

6. Rashes of Chickenpox

7. • Is a reactivation of an earlier
varicella infection
• Mainly affects a single
dermatome of the skin
• Any age but majority >50 years
of age
• Characteristic vesicles often
accompanied by intense pain
which may last for months
(postherpetic neuralgia)
Herpes Zoster (Shingles)

8. Herpes Zoster (Shingles)
• Herpes zoster affecting the eye
and face may pose great
problems
• Complications include
encephalitis and disseminated
herpes zoster.

9. Management
Varicella
• Uncomplicated varicella is a self
limiting disease
• Acyclovir
Herpes Zoster
• Acyclovir
• The main problem is post herpetic
neuralgia

10. Prevention
• For urgent protection
passive immunization with
Zoster immunoglobulin
(ZIG)

11. Cytomegalovirus (CMV)

12. Properties
• ds DNA enveloped virus
• Named so as it can form
multinucleated cells (syncytia)
with characteristically staining
inclusions

13. Epidemiology: Transmission
• Can be vertical or horizontal
• May occur in utero, perinatally
or postnatally.
• Sexual contact
• Blood and blood products
• Transplanted organ
• Life long carrier state
• Reactivation

14. Clinical Manifestations
• Congenital infection
– cytomegalic inclusion disease
• Perinatal & Postnatal infection -
usually asymptomatic

15. Congenital Infection
• Defined as the isolation of CMV from the
saliva or urine within 3 weeks of birth.
• Commonest congenital viral infection;
affects 0.3 - 1% of all live births.
• The second most common cause of mental
handicap after Down's syndrome
• Responsible for more cases of congenital
damage than rubella

16. Characterized by:
• Involvement of CNS: Significant
defects within 2 years of life
Severe hearing loss
Ocular abnormalities
Mental retardation
Congenital Infection

17. Management
Congenital infections
• Not usually possible to detect
Perinatal and postnatal infection
• Usually not necessary to treat

18. Epstein-Barr Virus
(EBV)

19. Epidemiology
• In developing countries, by the age of
two, 90% of children are seropositive.
• The virus is transmitted by contact with
saliva, in particular through kissing.

20. Disease Association
1. Infectious Mononucleosis
3. Burkitt's lymphoma
4. Nasopharyngeal carcinoma
5. Oral leukoplakia in AIDS patients
6. Chronic interstitial pneumonitis in
AIDS patients

21. Infectious Mononuclosis (IM)
• Features include:
Fever
Lymphadenopathy
Splenomegaly
Usually a self-limiting disease
• Jaundice (in some patients)

22. • Diagnosis of IM
Detection of EBV IgM
Atypical lymphocytes are present in
the blood
• There is no specific treatment
Infectious Mononuclosis (IM)

23. Burkitt’s Lymphoma (BL)
• Endemic in parts of Africa (where it is the
commonest childhood tumor)
• Usually in age 3-14 years
• Responds well to chemotherapy
• It is restricted to areas with malaria: may be
a cofactor.
• In theory BL can be controlled by the eradication
of malaria (as has happened in Papua New
Guinea) or vaccination against EBV

24. Nasopharyngeal Carcinoma (NPC)
• It is very prevalent in S. China, where it
is the commonest tumor in men and the
second commonest in women.
• Prognosis is poor.

25. Diagnosis
• Acute EBV infection
The heterophile antibody test
Detection of anti-EBV IgM
• Burkitt’s lymphoma: Histology
• NPC
Histology
The determination of the titre of anti-EBV
IgA in screening for early lesions of NPC

26. Immunocompromised Patients
• Transplant recipients e.g. renal
– Associated with lymphoproliferative disease and
lymphoma
• AIDS patients
– Associated with oral leukoplakia and with various
Non-Hodgekin’s lymphoma
• Ducan X-linked lymphoproliferative syndrome
– This condition occurs exclusively in males who had
inherited a defective gene in the X-chromosome

27. Vaccination
• A vaccine against EBV which prevents
primary EBV infection should be able
to control both BL and NPC
• Must be given early in life to:
– Seronegative organ transplant recipients
– Those developing severe IM
• This vaccine is being tried in Africa.