Chickenpox or Varicella

Chickenpox / Varicella 

Definition : It is an acute viral highly infectious disease caused by varicella-zoster (V-Z) virus. It is characterised by sudden onset of fever followed by appearance of rashes (macule, papule, vesicle and scab), starting from trunk and spread to face and limbs.

AGENTS FACTORS 
Agents : Varicella-Zoster / Human (alpha) herpes virus 3
Source of infection : Person to person contact or direct contact.
Infective material : Nasopharyngeal secretions, Oropharyngeal secretions, Lesions of skin & mucosa and Vesicular fluid.
Period of communicability : 1-2 days before and 4-5 days after appearance of rashes. 
Secondary Attack Rate : Chickenpox is highly communicable. SAR is 90%

HOST FACTORS 
Age : Below than 10 years is common.
Sex : Equal effects on both sexes.
Immunity : One attack gives durable immunity and second attack is rare.
Pregnancy : Risk present for fetus.

ENVIRONMENTAL FACTORS 
Season : First half of year (Jan - June).
Area : Overcrowding area and unventilated houses.

Mode Of Transmission : Direct droplet transmission.
Incubation Period : Usually 14-16 days ( extremes as wide as 21 days ).

CLINICAL FEATURES 
i. Pre-eruptive stage : 
  • Fever (mild to moderate ).
  • Running nose (rhinorrhea).
  • Sneezing.
  • Coughing.
ii. Eruptive stage : Firstly rashes appear 
  1. Distribution of rashes : Firstly rashes appear on trunk than face than arms than legs, mucosal surface (buccal, pharyngeal), axilla. (* Soles and palm are not affected ).
  2. Rapid evolution : Firstly appear macule which convert into papule than vesicle than scab.
  3. Pleomorphism : All stages of the rash (macule, papule, vesicle and scab) may be seen simultaneously at one time, in the same area.
  4. Fever : Mild to moderate.
COMPLICATIONS 
  • Hemorrhage.
  • Pneumonia.
  • Encephalitis.
  • Acute cerebeller ataxia.
  • Reye's syndrome - acute encephalopathy associated with fatty degeneration of the viscera specially liver.
PREVENTION & CONTROL 
  1. Early diagnosed.
  2. Isolation.
  3. Symptomatic treatment.
  4. Immunization - Passive immunization (VZ-Ig ), vaccine.

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