Varicella-zoster virus (VZV) infection befalls primarily as chickenpox or herpes zoster The VZV infection is generally considered self-limiting.

Varicella-zoster virus (VZV) infection befalls primarily as chickenpox or herpes zoster The VZV infection is generally considered self-limiting, with little associated morbidity and mortality. Fatal infections becoming to VZV were reported in the latter years of the 19th centenary and early in the 20th hundred years It was not until 1942 that VZV pneumonitis was recognized as a clinical entity with potentially lethal forces in otherwise healthy adults.(1) Today, this complication is regarded as the principally serious manifestation of disseminated VZV infections. Reviewed herein is the epidemiology, pathology, clinical features (including radiographic hallmarks), complications, treatment, and prevention of VZV pneumonitis.

EPIDEMIOLOGY

In 1953 a scarcely any years after the introduction of steroid intermingles into clinical medicine, a corticosteroid-treated patient with acute rheumatic febrile disease developed fatal hemorrhagic varicella.(2) from one side of to the other the next four decades, VZV pneumonitis became recognized as a relatively customary disorder in patients with compromised immunity (Table 1) Bone marrow transplant recipients(3)(4)(5) and children with cancer(6)(7) are at the highest risk for this complication, as illustrated by the agency of the 32 percent and 20 percent incidence rate in children with leukemia and solid tumors, respectively.(7) Among transplant recipients with primary varicella or varicellalike eruptions (positive pretransplant serologic findings or history and a diffuse rash lacking a dermatome distribution), dissemination to the lung approaches 50 percent(3)(4)(5) strict and often fatal varicella has also been reported in recipients of renal(8)(9) and liver(10) transplants, as well as in patients with HIV infection.(11)

Table 1--Factors Contributing to an Increased Risk for progression in a continuously ascending gradation of VZV

pneumonitis Condition Cancer Bone marrow transplant Solid organ transplant postponeed treatment with corticosteroids, cytotoxic or radiation therapy Limited corticosteroid therapy for acute asthma Topical nasal corticosteroids for sinusitis continue lengthen in timeed use of inhaled steroids for asthma Acquired immunodeficiency syndrome Congenital immunodeficiencies Cigarette smoker Pregnancy and postpartum period Premature births and newborn status

The risk of herpes zoster is highest in patients who have received bone marrow transplants and individuals with Hodgkin's disease (approximately 50 percent) on the contrary it is considerably lower in those with acute leukemia or solid tumors (20 percent and 10 percent respectively).(12)(13) It is important to note that dissemination to the lung is rare in immunocompromised patients with herpes zoster (5 percent to 10 percent)

The VZV-related mortality among neonates born to mothers who unravel varicella within 4 days of delivery or 2 days postdelivery, or neonates developing infection at 5 to 10 days of age, is 25 percent(14) from contrast, infants with VZV infection during the first 4 days of life (as a outcome of maternal transfer of VZV antibody 5 or more days before delivery) rarely die of the infection. Brunell(15) hypothesized that the early production and placental transfer of VZV antibody modify the infection in newborns. Thus, newborns who lack maternal VZV antibody are at high risk for fatal infection during the first 5 to 10 days of life. Otherwise healthy full-term infants who contract varicella after 2 weeks of life have sufficient immune reponse to impede dissemination of the infection. Hospitalized small premature infants ([les than or equal to]28 weeks' gestation or birth weight [les than or equal to]1,000 g) irrespective of maternal history, and hospitalized premature infants (>28 weeks' gestation) with a negative history of maternal varicella are also considered at high risk for bitter varicella.(16)

Although varicella in adults accounts for sole 2 percent of the estimated 3 to 4 million annual cases in the United States, 25 percent of the fatalities happen in this age group,(17) reflecting a higher complication rate as compared with children.(18) The incidence of varicella pneumonia in otherwise healthy adults has been estimated to range from 10 percent to 50 percent(19)(20)(21) However, several real recent studies suggest that the incidence in adults may be abundant lower: 5 percent or less(22)(23) Interestingly, one reports have indicated that 50 percent of cigarette smoker with varicella make known pneumonia, in contrast to barely 3 percent (or fewer) of their nonsmoking counterparts.(24)(25) Untreated adult varicella pneumonia is fatal in approximately 10 percent of cases.(26) Although pregnant and postpartum women have an increased risk of VZV pneumonitis, the incidence rates in these subgroup are unknown. However, the mortality rate is approximately 40 percent(27) exceeding estimates for otherwise normal healthy adults while corresponding to rates reported for patients with cancer and bone marrow transplant recipients.

Corticosteroid therapy as administered to patients with underlying renal, collagen-vascular, or other disorders (Table 1) has been associated with an increased risk of VZV pneumonitis. Several modern reports have indicated that conventional "low-dose" corticosteroid therapy (<2 mg/kg/d or 5 to 20 mg/d)(28) topical nasal corticosteroids for chronic sinusitis,(29) and short-course corticosteroid therapy for acute attacks of asthma (when administered during the incubation period of varicella)(30) may predispose to disseminated varicella. Although cystic fibrosis has not been associated with hard varicella, it does appear that the viral infection exacerbates the underlying pulmonary condition.(31)(32)

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