Today is our topic of discussion Definition of Chickenpox
Definition of Chickenpox
Definition:
Chickenpox or is an acute, highly infectious disease caused by varicella-zoster virus.
Epidemiological determinants:
Agent factors:
Agent:
Varicella-zoster virus
Source of infection:
Oropharyngeal secretions & lesions of skin and mucosa.
Infectivity:
1-2 days before appearance of rash and 4-5 days thereafter.
Secondary attack rate:
The disease is highly contagious, so secondary attack rate in contacts ~90%.
Host factors:
Age:
Primarily among children under 10 years. Few may escape until adulthood.
Immunity:
One attack gives life-long immunity
Pregnancy:
Presents a risk for the foetus and the neonate.
Environmental factors:
Overcrowding favours its transmission.
Transmission:
Droplet infection. Vertical transmission is possible & can infect
Incubation period:
Usually 14 to 16 days. The range may vary from 7 to 21 days.
Clinical features:
a) Pre-eruptive stage: Onset is sudden with mild to moderate fever, pain in the back, malaise. This stage is very brief in children. In adults these prodromal illnesses may be prominent lasting 2-3 days.
b) Eruptive stage: In children the rash is often the first sign –
- Distribution is symmetrical. First appears on the trunk where it is abundant and then gradually spreads in the centripetal manner.
- Rapid evolution: The rash advances quickly through the stages of macule, papule, vesicle and scab.
- Pleomorphism: All stages of the rash appear simultaneously.
- Fever: In children, low grade fever may be observed.
Laboratory diagnosis:
Examination of the scrapping of the floor of vesicles.
reatment & control measure:
1. There is no specific treatment for chickenpox.
2. Aspirin should be avoided, especially in children. Paracetamol is usually sufficient.
3. Notification and isolation of cases for about 6 days after onset of rash.
4. Disinfection of articles soiled by nose and throat discharges
Fig: Varicella zoster (complication of chicken pox)
Complication:
1. Varicella zoster (shingles): The dormant virus flares up with vesicular rash along one or more sensory nerve distribution.
2 . Secondary infection and scarring
3. Pneumonia
4. Arthritis
Prevention:
1. Vaccination: Children vaccinated may still develop a mild case of chickenpox. They recover much more quickly and have only a few poxes (<30). These cases are often harder to diagnose. However, they can still spread to others. 2. Varicell-Zoster immunoglobulin: Within 72 hours of exposure is effective.
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