Epidemiology of chickenpox

Epidemiology of chickenpox

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  Chickenpox ( Varicella) Dr.Shubhangi Kshirsagar Assistant professor Department of Swasthavritta & Yoga
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  Chickenpox Chickenpox or varicellais an acute, highly infectious disease caused by varicella-zoster (V-Z) virus. It is characterized by vesicular rash that may be accompanied by fever and malaise
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  Agent factors a. Agent- V-Z virus (Human (alpha) herpes virus 3 b. Source of infection – case of Chickenpox c. Infectivity – 1 to 2 days before the appearance of rash 4 to 5 days after rash a. Secondary attack rate - in household contacts approaches 90 per cent
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  Host factors a. Age– under 10 years b. Immunity - one attack gives durable immunity, second attacks are rare. c. Pregnancy – Infection during pregnancy presents a risk for the foetus leading to congenital varicella syndrome. Infants, whose mothers had chickenpox during pregnancy, have a higher risk of developing herpes zoster in the first years of life.
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  Environmental factors Winter andspring
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  Mode of transmission Personto person by droplet infection and by droplet nuclei. Most patients are infected by "face-to-face" (personal) contact. The portal of entry - the upper respiratory tract or the conjunctiva. Incubation period – 14-16 days
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  Clinical features 1. Pre-eruptivestage Onset is sudden with mild or moderate fever, pain in the back, shivering and malaise. This stage is very brief, lasting about 24 hours. In adults, the prodromal illness is usually more severe and may last for 2-3 days before the rash comes out.
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  2. Eruptive stage Inchildren the rash is often the first sign. It comes on the day the fever starts. The distinctive features of the rash are : 1. Distribution 2. Rapid evolution 3. Pleomorphism 4. Fever
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  Chickenpox rash
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  A. Distribution - Therash is symmetrical. It first appears on the trunk then comes on the face, arms and legs. Mucosal surfaces (e.g., buccal, pharyngeal) are generally involved. Axilla may be affected, but palms and soles are not usually affected. The density of the eruption diminishes centrifugally
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  b. Rapid evolution Therash advances quickly through the stages of macule, papule, vesicle and scab. The vesicles filled with clear fluid and looking like "dew-drops" on the skin. They are superficial, with easily ruptured walls and surrounded by an area of inflammation. The vesicles may form crusts without going through the pustular stage. Scabbing begins 4 to 7 days after the rash appears.
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  c. Pleomorphism It ischaracteristic feature of the rash, in chickenpox. All stages of the rash (papules, vesicles and 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. d. Fever The fever does not run high but shows exacerbations with each fresh crop of eruption.
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  Laboratory diagnosis 1. Polymerasechain reaction (PCR) 2. Isolation of virus in cell culture from vesicular fluid, crusts, saliva, cerebrospinal fluid or other specimens. 3. Direct immunofluorescence assay
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  Control 1. Notification 2. Isolationof cases for about 6 days after onset of rash 3. Disinfection of articles soiled by nose and throat discharges 4. Antiviral compounds - acyclovir, valaciclovir, famiciclovir and foscarnet
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  Prevention 1. Varicella-Zoster Immunoglobulin(VZIG) Within 72 hours of exposure For exposed susceptible individuals particularly in immunosuppressed persons 2. Live attenuated varicella virus vaccine between 12-18 months Ex. Monovalent vaccine Combination vaccines (MMRV) - 9 months to 12 years.
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  Thank You