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Infectious diseases
Chickenpox is a highly contagious disease,
presenting with sudden onset of low grade
fever , a centripetal , pleomorphic rash
appearing on the first day of illness and
relatively short course of illness .
EPIDEMIOLOGY
Occurrence : Occurs worldwide in both
epidemic and endemic forms
B. Ecological triad:
• Agent: Varicella-Zoster (DNA virus, member
of herpes viruses )
• Host: Children under 10 yrs of age (peak
incidence between 5 – 9 years )
both sexes are susceptible
C. Environment: In temperate climate it is
common in winter but in subtropics common
in summer, over crowding favors spread
A.
NATURAL HISTORY
Reservoir: is a case of chickenpox
 Infective materials: oropharyngeal secretions,
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lesions of skin and mucosa
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Infectious period: for about 7days before the
appearance of rash and 6 days after first crop of
vesicles
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Mode of transmission: respiratory droplets,
direct contact
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Incubation period: 14 to 16 days .
Pathology : Macules ----- papules ------vesicles -----crust
 May cause interstitial pneumonia
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Nature of rashes : -
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Chickenpox causes a red, itchy rash on
the skin that usually appears first on the
abdomen or back and face, and then
spreads to almost everywhere else on
the body, including the scalp, mouth,
nose, ears, and genitals.
The rash begins as multiple small, red
bumps that look like pimples or insect
bites. They develop into thin-walled
blisters filled with clear fluid, which
becomes cloudy. The blister wall
breaks, leaving open sores, which
finally crust over to become dry, brown
scabs.
Chickenpox blisters are usually less
than a quarter of an inch wide, have a
reddish base, and appear in bouts over
2 to 4 days. The rash may be more
extensive or severe in kids who have
skin disorders such as eczema
CLINICAL FEATURES
Prodromal symptoms:
Mild Fever (38 to 39 c)
Malaise
Anorexia
• First sign:
Appearance of a characteristic rash on trunk
1st day of illness
The rashes spread to head and extremities
Macule-Papules-Vesicles-Pustules-Crusts
• Itching is marked
•
DIAGNOSIS
Clinical:
The disease is usually recognized by
characteristic clinical signs
• Laboratory examinations:
Cytology of vesicular fluid or scrapings ( during
first 3 days of onset )
ELISA for serological diagnosis
Detection of varicella specific antigen in
vesicular fluid with immunoflurescence
Serology : Culture of vesicular fluid
•
PREVENTION AND CONTROL
Preventive measures:
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Notification
Isolation in early first week
Disinfection of discharges from nose,throat,skin lesions
Immunization
Treatment:
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Symptomatic and supportive
Personel hygiene should be optimized
Symptomatic therapy: analgesics,antipyretics,antipruritics
Antiviral therapy for immunocompromised
Cont..
Acyclovir ( within 24 hours of onset of rash )
Dose : - 20 mg /kg four times a day for 5 days
Foscarnet ( acyclovir resistant cases )
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Local antiseptic: Dettol,Betadine,Savlon etc...
if secondary infectionsAntibiotic therapy:Flucloxacillin
Aspirin is contraindication for the risk of precipitating
Reye`s syndrome.
COMPLICATIONS
Viral effects:
• Pneumonia
• Facial nerve palsy
• Cerebellar ataxia
• optic neuritis
• Hepatitis
• ITP ( idiopathic thrombocytopenic purpura )
Secondary bacterial infections:
• Septicaemia
• Osteomyelitis/septic arthritis
• Glumerulonephritis
Intrauterine infections:
• Congenital limb defects( varicella embryopathy)
VACCINATION
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Varicella zoster immune gammaglobulin ( VZIG) : - 215 U / kg ( max. 625
U)
The antibodies against varicella have been detected in over 90% of
vaccines one year after immunization and immunity persists for beyond 20
years
Vaccine should be stored between +2 / +8 degree thus can be stored for 24
months
Indications:
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Immunocompromised children
Sero-negative women of child bearing age
All susceptible children (12mths- 12 yrs)
Health care workers
The vaccine is given subcutaneously,usually in the upper arm
Doses and schedule: 0.5ml of reconstituted vaccine contains one immunizing
dose,13 yrs and above with no h/o disease 2 doses with an interval of 6-10 weeks
Adverse effects:
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Redness at the site of injection (5%)
Varicella like rash (3-4%)
Contraindications:
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Pregnant women
Acute fever
Known hypersensitivity to neomycin
Total lymphocyte count < 1200/mm3
Reye's syndrome
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Reye's syndrome is a potentially fatal disease
that causes numerous detrimental effects to
many organs, especially the brain and liver. It is
associated with aspirin consumption by children
with viral diseases such as chickenpox.
The disease causes fatty liver with minimal
inflammation, and severe encephalopathy (with
swelling of the brain). The liver may become
slightly enlarged and firm, and there is a change
in the appearance of the kidneys. Early
diagnosis is vital, otherwise death or severe
brain damage may follow.
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.
Stage I
Persistent, heavy vomiting
 Generalized lethargy
 General mental symptoms, e.g. confusion
Stage II
 Stupor caused by minor brain inflammation
 Hyperventilation
 Fatty liver (found by biopsy)
 Hyperactive reflexes
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Stage III
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Stage IV
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Continuation of Stage I and II symptoms
Possible coma
Possible cerebral edema
Deepening coma
Large pupils with minimal response to light
Minimal but still present hepatic dysfunction
Stage V
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Very rapid onset following stage IV
Deep coma
Seizures
Multiple Organ failure [1]
Flaccidity
Extremely high blood ammonia (above 300mg/dL of blood)
Death