chickenpox (varicella)

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Chickenpox (Varicella). Dr. Harivansh Chopra DCH, MD PROFESSOR Department of Community Medicine, LLRM Medical College, Meerut. harichop@gmail.com. Objectives. To study the epidemiology of Chickenpox. - PowerPoint PPT Presentation

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  • Chickenpox(Varicella)Dr. Harivansh ChopraDCH, MDPROFESSORDepartment of Community Medicine,LLRM Medical College, Meerut. harichop@gmail.com

    Dr. Harivansh Chopra

    ObjectivesTo study the epidemiology of Chickenpox.To study the differential diagnosis and treatment of the disease.To study the prevention of Chickenpox.

    Dr. Harivansh Chopra

    Chickenpox (Varicella)It is characterised by vesicular rash that may be accompanied by fever and malaise. It is worldwide in distribution and occurs in both epidemic and endemic forms.

    Dr. Harivansh Chopra

    AgentThe causative agent of chickenpox, V-Z virus is also called Human (alpha) herpes virus 3.

    Dr. Harivansh Chopra

    AgentVaricella-zoster virus (VZV) causes primary, latent, and recurrent infections.The primary infection is manifested as Varicella (chickenpox) and results in establishment of a lifelong latent infection of sensory ganglion neurons.

    Microscopic view of sensoryganglion neurons: Common site of latent infection by Varicella

    Dr. Harivansh Chopra

    AgentReactivation of the latent infection causes Herpes Zoster (shingles).

    Dr. Harivansh Chopra

    Herpes ZosterReactivation of Varicella zoster virus.Associated with:Aging.Immunosuppression.Intrauterine exposure.Varicella at < 18 months of age.

    Dr. Harivansh Chopra

    Source of InfectionUsually a case of chickenpox. The virus occurs in the oropharyngeal secretions and lesions of skin and mucosa.Rarely the source of infection may be a patient with Herpes Zoster.

    Chickenpox transmission occurs mainly from the oropharyngealsecretions of a case.

    Dr. Harivansh Chopra

    InfectivityThe period of communicability of patients with Varicella is estimated to range from 1 to 2 days before the appearance of rash, and 4 to 5 days thereafter.

    Dr. Harivansh Chopra

    Incubation periodUsually 14 to 16 days, although extremes as wide as 7 to 21 days have been reported.

    Dr. Harivansh Chopra

    AgeChickenpox occurs primarily among children under 10 years of age.

    Dr. Harivansh Chopra

    ImmunityOne attack gives durable immunity. Second attacks are rare.The acquisition of maternal antibody protects the infant during the first few months of life. Hemorrhagic Varicella in infant :One attack of Varicellagives durable immunity.

    Dr. Harivansh Chopra

    ImmunityThe IgG antibodies persist for life and their presence is correlated with protection against Varicella.The cell- mediated immunity appears to be important in recovery from V -Z infections and in protection against the reactivation of latent V-Z virus.

    Structure of an IgG antibody:Antibody against Varicella isprotective

    Dr. Harivansh Chopra

    Pregnancy & VaricellaInfection during pregnancy presents a risk for the fetus and the neonate.

    Dr. Harivansh Chopra

    Environmental FactorsChickenpox shows a seasonal trend in India, the disease occurring mostly during the first six months of the year. Overcrowding favours its transmission.

    Dr. Harivansh Chopra

    Transmission

    Chickenpox is transmitted from person to person by droplet infection and by droplet nuclei.Most patients are infected by "face-to-face" (personal) contact.

    Dr. Harivansh Chopra

    TransmissionThe portal of entry of the virus is the respiratory tract.Since the virus is extremely labile, it is unlikely that fomites play a significant role in its transmission.

    Main portal of chickenpoxtransmission is respiratory

    Dr. Harivansh Chopra

    SECONDARY ATTACK RATE90%

    Dr. Harivansh Chopra

    TransmissionContact infection undoubtedly plays a role when an individual with Herpes Zoster is an index case. The virus can cross the placental barrier and infect the foetus, a condition known as Congenital Varicella.Mother-to-Child transmission of Varicella can cause Congenital Varicella

    Dr. Harivansh Chopra

    Congenital Varicella SyndromeResults from maternal infection during pregnancy.Period of risk may extend through first 20 weeks of pregnancy.Risk appears to be small (< 2%).MRI scan of foetus in-utero:Risk of transmission of Varicellaextends through first 20 weeks.

    Dr. Harivansh Chopra

    Congenital Varicella Syndrome FeaturesDamage to Sensory Nerves :Cicatricial skin lesions.Hypopigmentation.This neonate suffering fromCongenital Varicella died at 6th day: Typical skin lesions seen at autopsied body

    Dr. Harivansh Chopra

    Congenital Varicella Syndrome FeaturesDamage to Optic Stalk and Lens Vesicle :Microphthalmia. Cataracts.Chorioretinitis. Optic atrophy.Fetus with Congenital Varicella at autopsy (26 weeks). Note the collapsed cranium, disproportionate Necrosis of the ocular globes and flattened midface.

    Dr. Harivansh Chopra

    Congenital Varicella Syndrome FeaturesDamage to Brain/Encephalitis : Microcephaly. Hydrocephaly. Calcifications.Aplasia of brain. Brain sonograph of a fetus with Congenital Varicella at 18 weeks. Note the appearance of the falx cerebri, choroid plexus and cerebral hemispheres.

    Dr. Harivansh Chopra

    Congenital Varicella Syndrome FeaturesDamage to Cervical or Lumbosacral Cord : Hypoplasia of an extremity. Motor and sensory deficits.Absent deep tendon reflexes. Neonate with Congenital Varicella:Note hypoplasia of lower extremity.The extremity had sensory andmotor deficits.

    Dr. Harivansh Chopra

    Congenital Varicella Syndrome FeaturesDamage to Cervical or Lumbosacral Cord : Anisocoria.Horner syndrome. Anal/urinary sphincter dysfunction. Pictoral representation of anisocoria.(this case is not Congenital Varicella)

    Dr. Harivansh Chopra

    Anisocoria:Both pupils are usually of equal size. If they are not, that is termed anisocoria (from "a-", not + "iso", equal + "kore", pupil = not equal pupils)

    Dr. Harivansh Chopra

    The clinical features of Horner's syndrome can be remembered using themnemonic, "HornyPAMELa" forPtosis,Anhidrosis,Miosis,Enophthalmos andLoss of ciliospinal reflex.

    Dr. Harivansh Chopra

    Clinical features of Chickenpox The clinical course of chickenpox may be divided into two stages:Pre-eruptive Stage.

    (B) Eruptive Stage.

    Dr. Harivansh Chopra

    Pre-Eruptive StageOnset is sudden with mild or moderate fever, pain in the back, shivering and malaise.This stage is very brief, lasting about 24 hours.Pre-eruptive phase in Varicellais very brief characterised by Fever, pain in back, shivering,and malaise

    Dr. Harivansh Chopra

    Pre-Eruptive StageIn adults, the prodromal illness is usually more severe and may last for 2-3 days before the rash comes out.

    Dr. Harivansh Chopra

    Eruptive PhaseIn children the rash is often the first sign. It comes on the day the fever starts.

    Dr. Harivansh Chopra

    Eruptive Phase Fever The fever does not run high but shows exacerbations with each fresh crop of eruption.

    Dr. Harivansh Chopra

    The rash is symmetrical.It first appears on the trunk where it is abundant, and then comes on the face, arms and legs where it is less abundant.Eruptive Phase Rash

    Dr. Harivansh Chopra

    Mucosal surfaces (e.g. buccal, & pharyngeal mucosa) are generally involved.

    Eruptive Phase Rash

    Dr. Harivansh Chopra

    Eruptive Phase Rash Axilla may be affected, but palms and soles are usually not affected.The density of the eruption diminishes centrifugally.

    Dr. Harivansh Chopra

    Eruptive Phase Evolution of Rash The rash advances quickly through the stages of macule, papule, vesicle and scab.In fact, the first to attract attention are often the vesicles filled with clear fluid and looking like "dew-drops" on the skin.

    Dr. Harivansh Chopra

    Eruptive Phase Evolution of Rash They are superficial, with easily ruptured walls and surrounded by an area of inflammation.Usually they are not umbilicated.

    Dr. Harivansh Chopra

    Eruptive Phase Evolution of Rash The vesicles may form crusts without going through the pustular stage.Many of the lesions may abort. Scabbing begins 4 to 7 days after the appearance of rash.

    Dr. Harivansh Chopra

    A characteristic feature of the rash in chickenpox is its Pleomorphism, i.e. all stages of the rash (Papules, Vesicles and Crusts) may be seen simultaneously at one time, in the same area.

    Eruptive Phase Pleomorphic Rash

    Dr. Harivansh Chopra

    Varicella Differential DiagnosisHerpes simplex.

    2. Enterovirus.

    Staphylococcus aureus. (Bullous impetigo)

    Dr. Harivansh Chopra

    Varicella Differential DiagnosisDrug reactions.

    5. Contact dermatitis.

    Insect bites.

    Dr. Harivansh Chopra

    Varicella Differential DiagnosisSevere Varicella was the most common illness confused with smallpox before the eradication of this disease.

    Dr. Harivansh Chopra

    Differences between Smallpox and ChickenpoxDuring the first day or two of rash it may be impossible, from the rash alone, to differentiate smallpox from chickenpox.

    Dr. Harivansh Chopra

    On day 3, the rash associated with each of the diseases continues to look very similar.

    Differences between Smallpox and Chickenpox

    Dr. Harivansh Chopra

    By day 5, all of the smallpox lesions are at the same stage of development. However, the patient with chickenpox shows several different stages of rash There are papules, vesicles and pustules present.Differences between Smallpox and Chickenpox

    Dr. Harivansh Chopra

    The smallpox lesions are large : 5 10 mm in size; firm and deeply embedded in skin.Most of the chickenpox les

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