Epidemiology Of Varicella Research Articles

Epidemiology of varicella in Slovenia over a 20-year period (1979-98).

Varicella is one of the most common childhood diseases. The course of the disease is usually mild and uncomplicated. In Slovenia, varicella is a notifiable communicable disease which must be reported. Data collected from 1979-98 were analysed. Over the 20-year period the number of varicella cases reported ranged from a low of 11,086 (in 1994) to a maximum of 21,141 (in 1987). During the last 10 years, the highest incidence of varicella was reported in children aged from 12 months to 2 years. In adults over 20, incidence has slightly but steadily increased over the 20 year period. Overall, the number of males with varicella exceeded that of females. The proportion of females was higher only in the 20-30-year age group, probably as a consequence of more frequent and closer contact with infected children by mothers. The highest number of reported cases was during winter and early spring.

Partial uptake of varicella vaccine and the epidemiological effect on varicella disease in 11 day-care centers in North Carolina.

The increasing use of varicella vaccine in children attending day care has rapidly decreased the incidence of wild-type varicella disease. The herd immunity noted is significant and will have an effect on the epidemiology of natural varicella. To monitor the change in varicella incidence in day-care attendees after the licensure of varicella vaccine. A prospective observational cohort study design. Eleven private day-care centers and preschools in North Carolina participated in the study from January 1, 1995, through December 31, 1999. All children in the 11 centers were eligible for participation. Some participated more actively, supplying information on a regular basis. Others participated passively. Day-care personnel provided information about all cases of varicella. None. The change in the incidence of varicella disease was documented as the use of varicella vaccine increased. Varicella vaccine coverage increased substantially from 4.4% in 1995 to 63.1% in December 1999. The vaccination rate accelerated dramatically in 1996 and 1997, leveled off in 1998, and rose again in 1999. Cumulative varicella incidence decreased from 16.74 cases per 1000 person-months in July 1996 to 1.53 cases per 1000 person-months in December 1999 in unvaccinated children. The varicella vaccination rate continued to increase slowly in the day-care population after an initial rapid uptake. The decrease in varicella disease is greater than the increase in varicella vaccination. This herd effect is welcome and even apparent in the unvaccinated children younger than 1 year.

Live-Attenuated Varicella Vaccine

This article reviews the history and development of live attenuated varicella vaccine from its early days in Japan to its widespread use throughout the world. The vaccine has proven extremely safe after immunization of as many as 10 million healthy children and adults in the United States alone. The vaccine is also highly immunogenic and offers close to 100% protection from severe chickenpox and 90% protection from illness. It is expected to have a major impact on the epidemiology of varicella and zoster in countries with high vaccine uptake.

Epidemiology of primary varicella and herpes zoster hospitalizations: the pre-varicella vaccine era.

To determine the epidemiology and costs of hospitalization with primary varicella and herpes zoster in the prevaccine era and the usefulness of hospital discharge data to determine the population impact of vaccination on these conditions, statewide hospital discharge data in Connecticut from 1986 to 1995 were analyzed. Annual hospitalizations for herpes zoster were 4-fold higher than for primary varicella (16.1 vs. 4.1/100,000). Overall, 69% and 83%, respectively, had no underlying immunosuppressive conditions. Regarding primary varicella, 53% of patients were aged <15 years, there was a marked winter-spring seasonality, and Hispanics and blacks were 4.1 and 2.6 times more likely than whites to be hospitalized. Regarding herpes zoster, 66.9% of patients were aged >64 years, and there was no seasonality. The mean patient charges in 1995 were $12,819 for primary varicella and $15,583 for herpes zoster. Analysis of population-based hospital discharge data is a feasible means of monitoring the impact of varicella immunization on severe morbidity due to primary varicella and herpes zoster.

Epidemiology and cost analysis of varicella in Italy: results of a sentinel study in the pediatric practice. Italian Sentinel Group on Pediatric Infectious Diseases.

Describing the epidemiology of varicella is relevant to the development of specific prevention strategies and to building up of economic models evaluating the cost:efficiency ratios of these strategies. Our study was designed to describe the epidemiology of chickenpox among Italian children and to assess the resulting economic and health burden on the country. Thirty-nine Italian pediatricians participated in a sentinel network on pediatric infectious diseases representing a total pediatric population of 30 168 children. Each case of varicella observed from January through December, 1997, was recorded. Economic analysis was conducted from the societal point of view. All costs were broken down into two groups: direct and indirect costs. A total of 1599 cases of varicella were reported among children 0 to 14 years old. There were 1266 primary cases (mean age, 4.5 +/- 2 years) and 333 secondary cases (mean age, 3.6 +/- 3.2 years). The global incidence of chickenpox was 51.01/1000/year. Complications were seen in 56 cases (3.5%). Drugs were prescribed in 672 cases. A group of adults (364 susceptible and 193 with uncertain status) were exposed to primary cases. Seventy (12.5%) were eventually infected among whom there were 4 pregnant women. For pediatric patients an average cost of $146.90 (250 400 lire) was estimated; this is largely accounted for by indirect costs. The epidemiology of varicella in Italy is consistent with that found in previous studies in industrialized countries. Severe complications did not occur in our population. We believe that the health arguments in favor of universal vaccination of children > 18 months of age do not differ in our own country from those of other industrialized nations. Our data could now be incorporated into pharmacoeconomic models to establish cost-efficient strategies for Italy.

A cost benefit analysis of routine varicella vaccination in Spain

The objective of the study was to assess varicella epidemiology and the cost of disease in Spain, in order to perform a cost–benefit analysis of universal vaccination at 15 months of age. Epidemiological data were obtained from a survey of 150 children with varicella, from hospitalizations and from the Spanish literature. A Markov decision tree was designed with two alternatives, vaccination or nonvaccination. Direct costs derived from the disease were lower than the cost of vaccination (ratio 0.54:1), however when indirect costs, such as working time loss were taken into account, vaccination was the best alternative, with a saving of ₧2627 per vaccinated subject (₧1.6 recovered per peseta invested in the program). Sensitivity analysis shows that decreasing vaccine coverage and efficacy to 0.7, increasing the annual discount rate to 20% and with a vaccine price less than ₧6000, vaccination is always the best alternative. In conclusion, from the economic point of view, a universal varicella vaccination program in children at 15 months of age would be justified in Spain.

Varicella infections in pregnancy and the newborn: A review prepared for the UK Advisory Group on Chickenpox on behalf of the British Society for the Study ofn Infection

In 1869 Trousseau wrote 'no physician has ever seen a patient die of chickenpox, though of course, there may be a fatal issue from some complication independent of the exanthematous fever'. These words are no longer true, reflecting a change in the epidemiology of chickenpox. Chickenpox is becoming more frequent in adult populations and with this the number of patients who suffer the sequelae of infection, including death, is increasing.

High incidence of breakthrough varicella observed in healthy Japanese children immunized with live attenuated varicella vaccine (Oka strain).

In order to know the rate of occurrence of varicella among vaccinees (breakthrough varicella: BV), questionnaire postcards were sent to 593 healthy children who had received varicella vaccine (Oka strain) from March 1987 to December 1989. The questionnaire survey was repeated once a year until January 1996. The annual attack rate from the 1st to 3rd questionnaire was approximately 12%: however, from the 5th to 8th one it was 1-4%. To February 1996, the cumulative attack rate was 157/459 (34.2%). This rate was comparable to that among vaccinees who had confirmed seroconversion; namely, 51/132 (38.6%). These rates are much higher than those reported by other authors. All BV cases were clinically mild; even subjects who had received the vaccine 7 years prior to the disease showed mild symptoms. The high incidence may be partly explained by the regional epidemiology of varicella. The decrease in annual incidence with time after vaccination may be due to the following reasons: some vaccinees remained free from BV owing to reinforcement of their immunity from subclinical infection of varicella-zoster virus (VZV) and others from diminution of opportunity for exposure to VZV with increasing age. Varicella vaccine seems to be effective in modifying the symptoms of varicella, but not potent enough in protecting from VZV infection.

Varicella-zoster virus epidemiology--a changing scene?

Chickenpox is a relatively mild disease in healthy children but may be life threatening in immuno-suppressed patents, neonates, and normal adults, especially smokers-for whom the risk of varicella pneumonia is high. The epidemiology of chickenpox appears to be changing: There has been an unexplained upward shift in the age distribution of cases over the last 20 years. This is reflected by increased consultations for chickenpox in general practices and more deaths in England and Wales. On the basis of hospital admissions for chickenpox in young adults, there is evidence of a similar trend in the United States. This epidemiologic change has important consequences for future mortality rates and for risk of infection in health care workers and pregnant women. The potential use of the varicella vaccine should be considered as a measure to reduce the risk of nosocomial transmission in view of the possible changing epidemiology of varicella.

THE EPIDEMIOLOGY OF VARICELLA-ZOSTER VIRUS INFECTIONS

Historically, varicella has been a disease predominantly affecting preschool and school-aged children in the United States. The live attenuated varicella vaccine was licensed in this country in 1995 and has been recommended for routine use in immunization of children 12 to 18 months of age. As an increasing proportion of the children in the United States are protected from varicella by vaccination, changes in the current epidemiology of the disease are anticipated. This article reviews the current epidemiology of VZV infection and outlines issues related to possible changes in varicella epidemiology that may follow widespread use of the live varicella (Oka) vaccine.

Mass vaccination to control chickenpox: the influence of zoster.

The impact of transmission events from patients with shingles (zoster) on the epidemiology of varicella is examined before and after the introduction of mass immunization by using a stochastic mathematical model of transmission dynamics. Reactivation of the virus is shown to damp stochastic fluctuations and move the dynamics toward simple annual oscillations. The force of infection due to zoster cases is estimated by comparison of simulated and observed incidence time series. The presence of infectious zoster cases reduces the tendency for mass immunization to increase varicella incidence at older ages when disease severity is typically greater.

Varicella-Zoster virus: Recent therapeutic advances

<h2>Summary</h2> Chickenpox is a common childhood problem. In otherwise healthy children, the disease is usually benign, although secondary complications can occur. Symptomatic therapy has long been the mainstay of treatment. Acyclovir use in such cases remains controversial secondary to the marginal benefit in relation to the additional cost incurred by an already costly disease. Advancements in the form of prevention have been made in an attempt to decrease the current hardship of VZV infection. The Oka strain of varicella vaccine should soon be available in the United States. Varicella vaccine has been shown to be immunogenic and well tolerated in healthy children. Lifetime follow-up is needed to determine the true duration of immunity and any effect on the epidemiology of adult varicella or recurrent zoster compared to natural infection. With the development of immunization, it is hoped that the varicella vaccine will become the next addition to the childhood vaccination schedule, possibly as a "quadrivalent" product with measles, mumps, and rubella. Widescale use of the varicella vaccine may render this once common childhood disease obsolete.

Epidemiology, outcome and control of varicella-zoster infection

Summary Chickenpox is a mild disease in children, but may be life threatening in immunosuppressed patients, neonates and normal adults, particularly smokers in whom the risk of varicella pneumonia is high. Infection during the first 5 months of pregnancy carries a small risk (probably <1%) of congenital varicella syndrome characterised by unilateral limb hypoplasia, dermatomal skin scarring and neurological damage. However, the greatest burden of morbidity attributed to varicella-zoster infection arises from herpes zoster, which affects 1 in 4 adults by the eighth decade of life. The epidemiology of chickenpox appears to be changing with an unexplained upward shift in the age distribution of cases over the last 20 years. This has important consequences for future mortality rates, and the risk of infection in pregnancy and health care workers. The effectiveness of existing prophylactic and therapeutic measures for varicella zoster infection are reviewed and the potential uses of varicella vaccine are discussed in the light of current evidence of its safety and efficacy in normal and high risk groups.

Varicella in pediatric patients.

To summarize the literature describing the epidemiology, transmission, clinical manifestations, diagnosis, treatment, and prevention of varicella in the pediatric population. A literature search of English-language articles from 1982 to 1992 using MEDLINE and bibliographies of relevant articles. The search term used was varicella. All review articles and original studies addressing the epidemiology, transmission, clinical manifestations, complications, diagnosis, treatment, and prevention of varicella in pediatric patients were reviewed. Emphasis was placed on controlled studies done in the US. Data from human studies were extracted by the authors and evaluated according to patient population, sample size, dosing regimen, efficacy, and safety. Varicella-zoster virus is a highly contagious virus that produces a common and costly disease in the pediatric population. The primary manifestation of varicella is the eruption of vesicular lesions. In most cases varicella is benign, but it can be associated with serious complications. Diagnosis is based primarily on clinical findings. Otherwise healthy children have traditionally received only symptomatic treatment for varicella, but recent literature suggests that antiviral therapy may be useful in these patients. Immunocompromised patients benefit from both symptomatic and antiviral therapy. Isolation and varicella-zoster immune globulin are used to prevent varicella. In the future, varicella vaccine will play an important role in preventing the disease. Varicella vaccine has been shown to be immunogenic and clinically effective in both healthy and immunocompromised children. Adverse reactions associated with the vaccine include fever, injection-site reactions, and rash. Although zoster can follow vaccination, the incidence appears to be lower in vaccinated individuals. Preliminary studies have shown that the vaccine provides protection from varicella-zoster virus for an extended period of time. Varicella is a common, usually benign disease of childhood. All patients may benefit from symptomatic therapy. Current literature does not support the use of antiviral therapy in all pediatric patients with varicella. When commercially available, varicella vaccine will play an important role in prevention. Long-term studies are needed to fully assess the risk of developing varicella and zoster following vaccination.

Epidemiology of chickenpox in England and Wales, 1967-85.

Routine sources of data on chickenpox morbidity and mortality in England and Wales were reviewed for 1967-85. Only two epidemics occurred, one in 1967 and one in 1980, both of which were immediately followed by two to three years of low incidence. The age distribution of the disease appears to be changing, with more cases now being reported in children aged 0-4 years. The number of deaths in adults have, however, increased, particularly those deaths that are associated with pneumonia and immunosuppression. At present in England and Wales more deaths are attributed to chickenpox than to whooping cough and mumps. Widespread use of selective immunisation against chickenpox might be justified in England and Wales, but before routine immunisation of the child population can be considered special surveys to determine the incidence and severity of chickenpox and the effect of the vaccine on the subsequent development of herpes zoster are needed as well as cost-benefit studies of immunisation.

Live attenuated varicella vaccine

This article reviews the history and development of live attenuated varicella vaccine from its early days in Japan to its widespread use throughout the world. The vaccine has proven extremely safe after immunization of as many as 10 million healthy children and adults in the United States alone. The vaccine is also highly immunogenic and offers close to 100% protection from severe chickenpox and 90% protection from illness. It is expected to have a major impact on the epidemiology of varicella and zoster in countries with high vaccine uptake.

Live attenuated varicella vaccine

This article reviews the history and development of live attenuated varicella vaccine from its early days in Japan to its widespread use throughout the world. The vaccine has proven extremely safe after immunization of as many as 10 million healthy children and adults in the United States alone. The vaccine is also highly immunogenic and offers close to 100% protection from severe chickenpox and 90% protection from illness. It is expected to have a major impact on the epidemiology of varicella and zoster in countries with high vaccine uptake.

The Epidemiology of Varicella in Staff and Students of a Hospital in the Tropics

A five-year retrospective survey of the epidemiology of varicella in staff and students at our hospital revealed a high incidence of 0.72 cases per 100 per year. The incidence was highest among 17-24 year-olds, especially among student nurses (3.22 cases per 100 per year). Most cases of varicella occurred in the cooler and more humid months of the year. Among 102 candidate student nurses aged 17-20 years, only 29.7% had complement-fixing antibodies to varicella-zoster virus. Thus our hospital personnel are at high risk of contracting and transmitting nosocomial varicella. These results corroborate existing evidence that the epidemiology of varicella in the tropics is different from that in temperate regions.

HERPES ZOSTER HOUSE EPIDEMIC IN STEROID-TREATED PATIENTS. A CLINICAL AND VIRAL STUDY.

Bokay1was the first, three quarters of a century ago, to claim purely on clinical grounds that varicella and herpes zoster were caused apparently by the same agent. Since then, this view has been corroborated by many clinical observations,2-5epidemiological data,6and viral research results.7-14There are, however, still many aspects of the correlation between the two conditions that are unclarified.6More recently significant changes have been noted in the clinical symptoms and in the epidemiology of varicella, and especially of herpes zoster, in patients treated with corticosteroids.2,15-17We have been unable, however, to find in the literature available to us, data for virus isolation and identification, as well as antibody studies in local and generalized herpes zoster developing during corticosteroid treatment. The aims of this paper are: (1) to describe a house epidemic of herpes zoster starting from one case of shingles; (2) to present the results of

THE ASSOCIATION OF HERPES ZOSTER AND VARICELLA

The possibilities of this subject are obviously extensive, but space limitations will not permit more than an occasional reference to the etiology, epidemiology and immunology of zoster and varicella. I shall attempt to do two things: first, to report a case of associated herpes zoster and varicella which in some of its relations is almost unique in medical literature; and second, to present certain recommendations deduced from an examination of the literature on this particular association which, if followed, would contribute to the clarification of a subject upon which there is now great confusion. The report presented covers a case which falls into Group 3 in the classification given below: A man with zoster developed varicella which he passed on to a daughter not otherwise exposed. REPORT OF A CASE History.— The patient, a physician on the house-staff of a sanatorium, in early middle life, of regular habits, in good