By Roopa Rani Halder Under the guidance of Dr. Venkatesh Contents Introduction Definition Etiology Clinical Manifestations Pathogenesis And Pathology Primary Infection Recurrent Infection • Differential Diagnosis • Laboratory Findings Continued… Complications Epidemiology Transmission Prevention Facts Conclusion Reference Definition Varicella Zoster is a virus which is responsible for two distinct clinical entities: Varicella(chicken pox) and Herpes zoster (Shingles) This virus is one among the Human Herpes Viruses and is considered as HHV type-3. Etiology A clinical association between varicella and Herpes zoster has been recognized for nearly 100 years. Viral isolates from patients with chicken pox and herpes zoster produced similar alterations in tissue culture. These results suggested that the viruses were biologically similar. continued VZV is a member of the family Herpes viridae. It has a lipid envelope surrounding a nucleocapsid with icosahedral symmetry. Diameter: 180-2oonm Centrally located double stranded DNA Chicken pox It is a Primary infection which usually occurs in childhood with the virus entering the mucosa of the upper respiratory tract. This virus remains latent in the dorsal root and cranial nerve ganglia. Years later it may be reactivated. Clinical features Symptoms are usually mild in children but can be severe in adults. Lesions are present on the palate before the rash appears. Characteristic rash appears on the trunk on the second day of the illness. Continued…. Then on the face and finally the limbs are involved. Macules appear first and within a few hours the lesions become papular then vesicular and within 24 hours, pustular. Whether or not the pustules rupture, they dry up in a few days to form scabs. Herpes zoster It is a Sporadic disease that results from reactivation of latent VZV from dorsal root ganglia. It occurs at all ages but its incidence is highest among individuals in the 6th decade. Continued… Herpes zoster is characterized by a unilateral vesicular eruption within a dermatome. Dermatomes involved are T3 to L3. Pathogenesis and pathology Primary infection Recurrent infection Transmission occurs readily by respiratory route Localized replication of the virus at an undefined site (Nasopahrynx) Seeding of the reticulo endothelial system Development of Viremia Viremia is reflected in the diffuse and scattered nature of the skin lesions Vesicle formation and the vesicular fluid becomes cloudy. The vesicle either rupture and release their fluid or are gradually reabsorbed. Differential diagnosis The diagnosis of chickenpox is not difficult. Varicella can be confused with HIV infection with atopic Dermatitis. Coxsackievirus infection. Echovirus infection. Atypical measles. Smallpox sometimes. More commonly with Rickettsialpox. Continued… Rickettsialpox can be distinguished easily by detection of the “Herald spot” at the site of the mite bite and there will be development of Head ache. Serologic testing is also useful in differentiating Rickettsialpox from Varicella and can confirm it. The lesions of Small pox are larger than those of chickenpox. Smallpox Chickenpox Rickettsialpox chickenpox Laboratory findings Laboratory diagnosis is rarely required as clinical signs are clear-cut. The most rapid and sensitive means of diagnosis is examination of vesicle fluid under electronic microscope which shows round particles. Scrapings of floor of vesicles show multinucleated giant cells. Serology is used mainly for epidemiological surveys. Epidemiology Humans are the only known reservoir for VZV. Chicken pox is highly contagious. Persons of both sexes and all races are infected equally often. The virus is endemic in the population at large. Children 5-9 yrs old are most commonly affected. transmission Chicken pox is transmitted from person to person by droplet infection and by droplet nuclei. Most patients are infected by Face to face contact. The Portal of entry of the virus is the respiratory tract. Fomites play a significant role in transmission The virus can cross the placental barrier and infect the foetus. Complications Complications include Pneumonia. More common in adults and can result in adult respiratory distress syndrome. Cerebellar syndrome. Encephalitis occurs 1 in 100 cases. Death may occur. prevention VARICELLA ZOSTER IMMUNOGLOBULIN (VZIG) given within 72 hours of exposure has been recommended in Immunosuppressed persons. VZIG is given by IM injection in a dose of 12.5 units/kg weight with a repeat dose in 3 weeks. Continued… A live attenuated varicella virus vaccine is safe and currently recommended for children between 12- 18 months of age. All susceptible adolescents and adults should be immunized, with special emphasis on high risk groups. faCts…. The lesions of Herpes resembles the hood of the snake and is always the same. There is a superstitious belief that Herpes is due to the Curse of NAGADEVATA due to the resemblance of the pustular lesion with that of snake. conclusion References API text book of medicine. Textbook of Pathology by HARSHMOHAN HARRISON’s Preventive and Social Medicine by K.PARK DAVIDSON’s VAIDYALOKA magazine WIKIPEDIA through Internet..
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