An economic analysis of varicella vaccination for health care workers

A simulation model was constructed to assess the relative costs and cost-effectiveness of different screening and vaccination strategies for dealing with hospital incidents of varicella exposure, compared with current policies, using data from published sources and a hospital survey. The mean number of incidents per hospital year was 3.9, and the mean annual cost of managing these incidents was pounds 5170. Vaccination of all staff would reduce annual incidents to 2.2 at a net cost of pounds 48,900 per incident averted. Screening all staff for previous varicella, testing those who are uncertain or report no previous varicella, and vaccinating those who test negative for VZV antibodies, reduces annual incidents to 2.3 and gives net savings of pounds 440 per incident averted. Sensitivity analyses do not greatly alter the ranking of the options. Some form of VZV vaccination strategy for health care workers may well prove a cost-effective use of health care resources.

The epitopes for some antiphospholipid antibodies are adducts of oxidized phospholipid and beta2 glycoprotein 1 (and other proteins)

Circulating autoantibodies to phospholipids (aPLs), such as cardiolipin (CL), are found in patients with antiphospholipid antibody syndrome (APS). We recently demonstrated that many aPLs bound to CL only after it had been oxidized (OxCL), but not to a reduced CL analogue that could not undergo oxidation. We now show that the neoepitopes recognized by some aPLs consist of adducts formed between breakdown products of oxidized phospholipid and associated proteins, such as beta2 glycoprotein 1 (beta2GP1). Addition of human beta2GP1, polylysine, native low-density lipoprotein, or apolipoprotein AI to OxCL-coated wells increased the anticardiolipin antibody (aCL) binding from APS sera that first had been diluted so that no aCL binding to OxCL could be detected. No increase in aCL binding was observed when these proteins were added to wells coated with reduced CL. The ability of beta2GP1, polylysine, or low-density lipoprotein to be a "cofactor" for aCL binding to OxCL was greatly reduced when the proteins were methylated. Incubation of beta2GP1 with oxidized 1-palmitoyl-2-linoleyl-[1-14C]-phosphatidylcholine (PC), but not with dipalmitoyl-[1-14C]-PC, led to formation of covalent adducts with beta2GP1 recognized by APS sera. These data suggest that the reactive groups of OxCL, such as aldehydes generated during the decomposition of oxidized polyunsaturated fatty acids, form covalent adducts with beta2GP1 (and other proteins) and that these are epitopes for aCLs. Knowledge that the epitopes recognized by many aPLs are adducts of oxidized phospholipid and associated proteins, including beta2GP1, may give new insights into the pathogenic events underlying the clinical manifestations of APS.

The use of danazol in the therapy of immune-mediated disease of dogs

Currently available therapeutic protocols for immune-mediated diseases in dogs and cats can be associated with poor response rates and a high incidence of side effects. The development of multidrug protocols often results in a synergistic effect that more efficiently suppresses the immune response. One drug that may be added to other therapies is danazol, an androgen with immunomodulating properties. Androgens are known to suppress aberrant immune responses, and the fact that immune-mediated diseases are more common in females supports this. Danazol has been used in humans with immune-mediated hemolytic anemia and thrombocytopenia with some success. Danazol appears to reduce the binding of immuno-globulin and complement to the red blood cell or platelet surface and also may alter cytokine concentrations. The use of danazol in dogs with immunemediated hemolytic anemia and thrombocytopenia has been reported; however, the small number of animals evaluated make it difficult to assess its usefulness in veterinary medicine.

The use of cytotoxic agents in the treatment of immune-mediated diseases of dogs and cats

Cytotoxic drugs are often combined with glucocorticoids in the therapy of immune-mediated diseases. Cyclophosphamide, azathioprine, chlorambucil, and methotrexate are cytotoxic drugs used most commonly for the purpose of immunosuppression. Cyclophosphamide and chlorambucil are alkylating agents, which cause cross-linking of DNA resulting in altered protein production, decreased cell division, and cell death. Azathioprine and methotrexate are anti-metabolites, which cause inhibition of DNA synthesis and a cascade of other effects. These drugs, in general, are more effective if administered during the initial phases of disease when immunocompetent lymphocytes are in a phase of rapid proliferation. This is often impractical in the clinical situation and may explain therapeutic failures. This article focuses on the use of these drugs in the treatment of immune-mediated diseases in dogs and cats and covers mechanisms of action, dosages, and side effects of individual cytotoxic agents.

Immunosuppression--an overview

The therapy of immune-mediated diseases in dogs and cats requires effective immunosuppressive therapy. The ideal therapy would suppress the abnormal (anti-self) immune responses while leaving the normal (anti-pathogen) immune responses intact. Unfortunately, such a therapy is not readily available. Current therapeutic strategies designed to suppress aberrant immune responses include combinations of glucocorticoids, cytotoxic drugs, and other immunomodulating agents such as cyclosporine and androgens. Glucocorticoids have a multitude of effects on the immune response at several levels and are both antiinflammatory and immunosuppressive. Cytotoxic drugs such as cyclophosphamide and azathioprine suppress the immune response by inhibiting protein (ie, antibody) synthesis, DNA replication, and cell division. Some cytotoxic drugs cause lysis of immunocompetent cells. Cyclosporine A suppresses production of interleukin-2, a cytokine necessary for the amplification stages of the immune response and critical for the activation of both T and B lymphocytes. Androgens modulate the immune system by as yet poorly defined mechanisms involving alterations in lymphocyte numbers and function as well as mononuclear-phagocytic cell function. Newer immunosuppressive agents are being studied in laboratory animals and human transplant patients that either inhibit do novo synthesis of nucleotides or signal transduction in lymphocytes, thereby reducing the number or function of immunocompetent cells. These newer agents can be combined with more traditional therapies for enhanced immunosuppressive effects.

An evaluation of nine commercial EIA kits for the detection of measles specific IgG

Nine commercial EIAs for measles-specific IgG were compared with haemagglutination inhibition (HI) and plaque reduction neutralization (PRN). A total of 174 sera selected, to give approximately half of the sera without measles antibody by HI, were tested by all EIAs and HI. However, there was sufficient volume of only 101 samples for testing by PRN. A dilution curve of the British Standard measles antibody serum was also tested by each EIA. Assays were evaluated qualitatively against a consensus EIA result, HI and PRN: Gull, Melotest and Behring EIAs performed best. Quantitative evaluation was by assessment of the characteristics of the standard dilution curve, and by plotting differences with PRN against mean: Gull and Melotest EIAs were best.

Childhood infection with hepatitis A and B viruses in England and Wales

Infection with hepatitis B and A viruses during childhood was studied using serum specimens collected from children aged 13 and 14 years by 12 public health laboratories in England and Wales from 1986 to 1995. Six of the 2025 specimens tested for markers of hepatitis B infection showed evidence of earlier resolved infection, one specimen showed evidence of recent infection, and hepatitis B surface antigen (HBsAg) was detected in three specimens. The HBsAg carriage rate of 0.15% (3/2025) was consistent with that expected from vertical transmission before the introduction of antenatal screening and neonatal hepatitis B vaccination, for which the children in our study would not have been eligible. Five of the six children with earlier resolved hepatitis B infection also showed evidence of hepatitis A infection, whose coexistence raises the possibility that both infections were acquired abroad in areas of high endemicity. At present, by adolescence, about one in 200 children has at some time been infected with hepatitis B virus. The current practice of screening pregnant women for HBsAg and selectively vaccinating neonates at high risk of acquiring hepatitis B infection may reduce this rate in the future. Immunisation of all infants against hepatitis B would prevent very few more childhood infections than the current policy. The incidence of hepatitis A infection has fallen in the past decade, suggesting the potential for an epidemic resurgence in the future as more of the population becomes susceptible. The average annual incidence of hepatitis A infection in children aged 0 to 14 years from 1986 to 1995 was 800 per 100 000, fifty times higher than the reported incidence of laboratory confirmed disease in this age group. Most hepatitis A infections in this age group are therefore likely to be subclinical or very mild.

The European Sero-Epidemiology Network

The purpose of serological surveillance is to monitor levels of immunity to particular diseases within a population in order to enhance the quality of information on which public health measures, such as vaccination programmes, are based. Serological surv

Coronary angiography and angioplasty after acute myocardial infarction

PURPOSE

To assess the data that support the use of coronary angiography and angioplasty after acute myocardial infarction, that identify the risks of these procedures, and that analyze their use and costs.

DATA SOURCES

English-language articles published between 1970 and June 1995 identified through a search of the MEDLINE database.

STUDY SELECTION

Studies that contained information about benefits, risks, use, and costs of coronary angiography and angioplasty after acute myocardial infarction.

DATA EXTRACTION

Descriptive and analytic data from each study were collected.

DATA SYNTHESIS

The outcome for patients who have complications of myocardial infarction (such as shock) is poor. Such patients usually undergo angiography, although the evidence that supports this practice is weak. Preliminary data suggest that patients who immediately have angiography and angioplasty after acute myocardial infarction have better outcomes than do patients who receive thrombolytic therapy with angioplasty only for specific indications in experienced centers. After the acute phase of myocardial infarction, patients who have noninvasive evidence of persistent or recurrent ischemia are believed to benefit from angiography. In the remaining patients, however, angiography after myocardial infarction has not been shown to be beneficial. Coronary angiography is done in 30% to 81% of patients after acute myocardial infarction in different settings and regions; for many of these patients, the benefit is questionable. Better outcomes are not always associated with more frequent use of the procedure. In the United States, catheterizations after myocardial infarction cost approximately $1 billion per year.

CONCLUSIONS

Although many patients benefit from angiography and angioplasty after myocardial infarction, others probably do not. Substantial resources are at stake.

The epidemiology of rubella in England and Wales before and after the 1994 measles and rubella vaccination campaign: fourth joint report from the PHLS and the National Congenital Rubella Surveillance Programme

The national immunisation campaign carried out in the United Kingdom in November 1994 was designed to give children aged 5 to 16 years of age a single dose of a combined measles and rubella vaccine. Its main objective was to prevent an epidemic of measles predicted in school age children. The rubella component of the vaccine was included in order to reduce the high level of susceptibility to rubella in young adult males and thus reduce the risk of transmission from this group to pregnant women. Susceptibility to rubella in children aged 5 to 16 years has fallen from 15.7% to 3.4% since the measles and rubella campaign. Despite this the incidence of laboratory confirmed rubella rose substantially in 1996, largely on account of cases among males aged 17 to 24 years, who were not vaccinated in the 1994 campaign and about 16% of whom are susceptible. The impact of the resurgence on the incidence of infection in pregnancy has been relatively limited, due to the low level of susceptibility in the antenatal population (2% in nulliparous and 1.2% in parous women for 1994/5). No cases of congenital rubella arising from administration of measles and rubella vaccine during the campaign have been identified. The numbers of babies born with congenital rubella and terminations of pregnancy for rubella arising from the 1996 resurgence are expected to be similar to those that followed the 1993 resurgence. The reduction in susceptibility in future cohorts of young men who received measles and rubella vaccine in the 1994 campaign should prevent future resurgences after the year 2000. If a second dose of measles, mumps, and rubella (MMR) vaccine had not been introduced, susceptibility levels in the school age population would have risen to about 12% in the future. The effect of the second dose of MMR vaccine introduced for children aged 4 to 5 years in October 1996 will be assessed through serological surveillance.

The epidemiology of measles in England and Wales since the 1994 vaccination campaign

The incidence of measles in England and Wales has fallen since the national vaccination campaign in November 1994, in which 92% of children aged 5 to 16 years were vaccinated. A total of 148 confirmed cases with onsets in the 18 months from January 1995 to June 1996 have been ascertained. Notified cases did not provide a reliable measure of incidence: 11,343 suspected cases were notified in the same period, 6426 (57%) of whom were tested for salivary antibody. Only 90 (1.4%) of cases tested were confirmed. Many confirmed cases occurred in small clusters; 12 imported cases were identified. The pattern of small, local clusters is what would be expected from the introduction of imported cases into a population with herd immunity. Serological surveillance showed that the campaign produced a significant fall in the proportion of 5 to 16 year old children with low levels of measles antibody: the proportion with levels < 50 mIU/ml fell from 8.4% to 2.1%; the proportion with levels < 100 mIU/ml fell from 15.7% to 6.6%. About 15% of 2 to 4 year old children had antibody levels < 100 mIU/ml before and after the campaign. The addition of a routine second dose of measles vaccine (as measles, mumps, and rubella vaccine) to the vaccination schedule will provide another opportunity to immunise these children before they start school. The two dose vaccination programme should maintain the herd immunity of the population and the elimination of endemic measles transmission.

Mumps surveillance in England and Wales supports introduction of two dose vaccination schedule

Sentinel surveillance in general practice and laboratory reports to the PHLS Communicable Disease Surveillance Centre show that the incidence of mumps has fallen to very low levels since vaccination against measles, mumps, and rubella was introduced in 1988. Hospital admissions for mumps show a 92% decline compared with the prevaccination era, to a rate of 0.2 per 100,000 population per year. Serological surveillance has shown an increase in the proportion of school age children who have no detectable antibody to mumps, which is consistent with the reduction in mumps virus transmission. The proportion of children aged 11 to 15 years with no detectable antibody is expected to peak at 19% in 1997. Mathematical models suggest that this increase in susceptibility is unlikely to allow a large resurgence of mumps in the short term but that school outbreaks may become more common. Outbreaks in universities and military establishments are possible in the medium term. Analysis of efficacy data for mumps vaccine indicates that mumps is unlikely to be eliminated with a single dose of vaccine at current coverage rates. A second dose of vaccine, which is now being offered to preschool children, will reduce morbidity and should eventually eliminate mumps if coverage is high enough.

National surveillance of dialysis associated diseases in the United States--1994

Dialysis centers in the United States were surveyed in 1994 regarding a number of hemodialysis associated diseases and practices. A total of 2,449 centers, representing 206,884 patients and 50,314 staff members, responded. In 1994, 99% of centers used bicarbonate dialysate as the primary method of dialysis, 45% used high flux dialysis, and 75% reused dialyzers. Hepatitis B vaccine had been administered to 31% of patients and to 80% of staff members. Acute infection with hepatitis B virus occurred in 0.1% of patients and was more likely to be reported by centers with lower proportions of patients vaccinated against hepatitis B virus and those not using a separate room and dialysis machine to treat hepatitis B surface antigen positive patients. The prevalence of antibody to hepatitis C virus was 10.5% among patients and 1.9% among staff members and varied according to geographic region. Pyrogenic reactions in the absence of septicemia were reported by 22% of centers and were most highly associated with dialyzer reuse. Human immunodeficiency virus infection was reported to be present in 1.5% of patients; 37% of centers provided hemodialysis to one or more patients infected with human immunodeficiency virus.

Effect of schedule on reactogenicity and antibody persistence of acellular and whole-cell pertussis vaccines: value of laboratory tests as predictors of clinical performance

The performance of four acellular pertussis vaccines containing between two and five pertussis antigens combined with diphtheria and tetanus toxoids was compared with that of British whole-cell diphtheria/tetanus/pertussis (DTP) vaccine both in laboratory assays for potency, toxicity and immunogenicity, and for reactogenicity and immunogenicity in infants. Clinical responses were evaluated in double blind randomized Phase II trials using 3/5/9 month and 2/3/4 month schedules. The acellular DTPs had much lower toxicity than whole-cell DTP in laboratory tests and were significantly less pyrogenic than whole-cell DTP under both schedules. Local reactions were not consistently lower in acellular than whole-cell vaccinees and varied with the source of the diphtheria and tetanus antigens used. Differences in endotoxin level and content of active pertussis toxin (PT) between acellular DTP vaccines were not clinically significant. The reactogenicity advantage of the acellular vaccines was substantially reduced under the 2/3/4 month schedule due to the reduced reactogenicity of the whole-cell DTP vaccine when given at a younger age. There was no relationship between antigen content measured in micrograms per dose and ELISA antibody responses to filamentous haemagglutinin (FHA) and PT in infants, nor was murine immunogenicity predictive of immunogenicity in humans. Antibody response to PT was attenuated in the whole-cell group under the 2/3/4 month schedule but was unaffected in the group receiving acellular vaccines with individually purified components; antibody response to pertactin (69 kDa antigen) was similar in recipients of the whole-cell and component acellular vaccines under the 2/3/4 month schedule. PT antibody persistence until 4-5 years of age was significantly better in recipients of the component acellular than either the whole-cell vaccine or the co-purified acellular vaccine under the 3/5/9 month schedule. However, diphtheria antitoxin levels were reduced in acellular vaccine recipients under both schedules. Despite significantly lower tetanus potencies of the acellular vaccines in laboratory tests, no differences were found in tetanus anti-toxin responses in children.

Expression of an antigen homologous to the human CO17-1A/GA733 colon cancer antigen in animal tissues

The CO17-1A/GA733 antigen is associated with human carcinomas and some normal epithelial tissues. This antigen has shown promise as a target in approaches to passive and active immunotherapy of colorectal cancer. The relevance of animal models for studies of immunotherapy targeting this antigen in patients is dependent on the expression of the antigen on normal animal tissues. Immunohistoperoxidase staining with polyclonal rabbit antibodies to the human antigen revealed the human homologue on normal small intestine, colon and liver of mice, rats and non-human primates, whereas mouse monoclonal antibodies to the CO17-1A or GA733 epitopes on the human antigen did not detect the antigen. Polyclonal rabbit antibodies, elicited by the murine antigen homologue derived from recombinant baculovirus-infected insect cells, immunoprecipitated the antigen from mouse small intestine, colon, stomach, kidney and lung. The isolated recombinant murine protein bound polyclonal, but not monoclonal, antibodies to the human CO17-1A/GA733 antigen, and recombinant human antigen bound polyclonal antibodies elicited by the murine antigen homologue. Thus, the antigen homologue expressed by animal tissues is similar, but not identical, to the human antigen. These results have important implications for experimental active and passive immunotherapy targeting the CO17-1A/GA733 antigen.

Epidemiological determinants of pertussis

In countries with pertussis immunisation programmes, the main epidemiological determinant of the disease is the quality of protection induced by the vaccine and the coverage level achieved. Epidemiological data from England and Wales provide strong evidence that whole-cell pertussis vaccines can give good protection against both clinical disease and transmission of infection, and can generate herd immunity at high coverage levels. Models of pertussis transmission indicate that, even in the absence of waning immunity, the incidence of the disease is likely to increase in older age groups in countries with sustained high coverage. Active surveillance to detect the occurrence of pertussis in adults is required as the ascertainment of such cases through passive clinical reporting systems is low. Comprehensive post-licensing surveillance of the effectiveness of acellular pertussis vaccines will be essential to assess their long-term protection against both clinical disease and transmission of infection, and to determine the optimum boosting strategy.

New interface metaphors for complex information space visualization: an ECG monitor object prototype

Wearable augmented reality medical (WARM) interfaces could provide ubiquitous point-of-care decision support and enhance the quality and efficiency of clinicians' efforts. Creation of such systems involves the design and evaluation of new information displays that leverage the representational and presentational capabilities of three-dimensional AR environments. We describe our first efforts in this process: the implementation of interface objects for display of real-time electrocardiographic monitoring information and an evaluation methodology using a simulated clinical environment. Our pilot data confirm the utility of presentation modes that place simultaneous information tasks in close proximity, and highlight issues encountered in designing new representations of medical information.

Studies on tetrachloroethene respiration in Dehalospirillum multivorans

Tetrachloroethene (PCE) respiration was studied in the tetrachloroethene-utilizing anaerobe, Dehalospirillum multivorans, with respect to localization of the catabolic enzymes, the electron carriers potentially involved in electron transport, and the response to ionophores and specific inhibitors. Hydrogenase and formate dehydrogenase were recovered in the periplasmic cell fraction and were membrane-associated. Electron-accepting tetrachloroethene dehalogenase was found in the cytoplasmic fraction. In the PCE dehalogenase assay, only artificial electron donors with a standard redox potential of D. multivorans (Eo' = -445 mV) could serve as electron donor for PCE reduction. However, the reaction rate with ferredoxin was only 1% of that with methyl viologen, whereas the pyruvate-ferredoxin oxidoreductase exhibited almost the same reaction rates with methyl viologen and ferredoxin as electron acceptors for pyruvate oxidation. Reduced menadione (2-methyl-1, 4-naphthoquinone) did not serve as electron donor in the PCE dehalogenase reaction. 2-Heptyl-4-hydroxyquinoline-N-oxide (HOQNO) had no significant effect on PCE dechlorination in cell suspensions and in crude extracts. Whole cells catalyzed the reductive dechlorination of PCE with H2 or formate as electron donors. The dechlorination in cell suspensions rather than in cell extracts was inhibited by the ionophores carbonylcyanide-p-(trifluoromethoxy)phenylhydrazone (FCCP) and tetrachlorosalicylanilide (TCS), indicating that a membrane potential and/or a pH gradient may be required for the reaction in vivo.

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.