The mercury concentration in saliva: correlation to number and extension of dental amalgam restorations

Neuraminidase as an enzymatic marker for detecting airborne Influenza virus and other viruses

Little information is available regarding the effectiveness of air samplers to collect viruses and regarding the effects of sampling processes on viral integrity. The neuraminidase enzyme is present on the surface of viruses that are of agricultural and medical importance. It has been demonstrated that viruses carrying this enzyme can be detected using commercial substrates without having to process the sample by methods such as RNA extraction. This project aims at evaluating the effects of 3 aerosol-sampling devices on the neuraminidase enzyme activity of airborne viruses. The purified neuraminidase enzymes from Clostridium perfringens, a strain of Influenza A (H1N1) virus, the FluMist influenza vaccine, and the Newcastle disease virus were used as models. The neuraminidase models were aerosolized in aerosol chambers and sampled with 3 different air samplers (SKC BioSampler, 3-piece cassettes with polycarbonate filters, and Coriolis μ) to assess the effect on neuraminidase enzyme activity. Our results demonstrated that Influenza virus and Newcastle disease virus neuraminidase enzymes are resistant to aerosolization and sampling with all air samplers tested. Moreover, we demonstrated that the enzymatic neuraminidase assay is as sensitive as RT-qPCR for detecting low concentrations of Influenza virus and Newcastle disease virus. Therefore, given the sensitivity of the assay and its compatibility with air sampling methods, viruses carrying the neuraminidase enzyme can be rapidly detected from air samples using neuraminidase activity assay without having to preprocess the samples.

Evaluation of the Becton Dickinson Rapid Influenza Diagnostic Tests in Outpatients in Germany during Seven Influenza Seasons

BACKGROUND

An extensive retrospective study spanning several seasons was undertaken to evaluate the diagnostic performance of the BD rapid influenza diagnostic test (RIDT) in comparison with the RT-PCR assay.

METHODS

A total of 2,179 respiratory samples were tested in parallel by in-house RT-PCR and the RIDT. During the 2003-2004, 2006-2007, 2007-2008, and 2008-2009 (n=1671) seasons, the BD Directigen Flu A+B test was used, and during the 2010-2011, 2011-2012 and 2012-2013 (n=508) seasons, the BD Directigen EZ Flu A+B test b was used.

RESULTS

The sensitivity, specificity, PPV and NPV for the BD Directigen Flu A+B test calculated for types A and B together were 39%, 99%, 98%, and 56%, respectively. For the BD Directigen EZ Flu A+B test, these values were 47%, 100%, 100%, 55%, respectively. The sensitivity of the BD Directigen Flu A+B test did not differ significantly from season to season or between types A (44%) and B (37%). The sensitivity of the BD Directigen EZ Flu A+B test calculated for type A only was 59%, which was considerably higher than the sensitivity of this test for type B (23%). The sensitivity of the RIDT was approximately 40-50% in children and teenagers, but it was only 18.% in adults aged 20 years and older. The specificity of both RIDTs was very high (>99%) during all seasons.

CONCLUSIONS

Due to their rapid turnaround time, RIDTs can help guide decisions about the clinical management of influenza. Because of the high specificity, a positive result can be interpreted as a true positive, and antiviral therapy as well as appropriate measures to prevent the transmission of influenza can be initiated. The best sensitivity of the RIDT is achieved in children. However, even in this group, the RIDT will only recognize influenza infection in approximately half of the cases, and influenza should still be considered in patients with negative results; negative RIDT results must be confirmed by PCR.

Clinical Predictors of Influenza in Young Children: The Limitations of "Influenza-Like Illness"

BACKGROUND

Influenza-like illness (ILI) definitions have been infrequently studied in young children. Despite this, clinical definitions of ILI play an important role in influenza surveillance. This study aims to identify clinical predictors of influenza infection in children ≤5 years old from which age-specific ILI definitions are then constructed.

METHODS

Children aged 6-59 months with a history of fever and acute respiratory symptoms were recruited in the Western Australia Influenza Vaccine Effectiveness (WAIVE) Study. Clinical data and per-nasal specimens were obtained from all children. Logistic regression identified significant predictors of influenza infection. Different ILI definitions were compared for diagnostic accuracy.

RESULTS

Children were recruited from 2 winter influenza seasons (2008-2009; n = 944). Of 919 eligible children, 179 (19.5%) had laboratory-confirmed influenza infection. Predictors of infection included increasing age, lack of influenza vaccination, lower birth weight, fever, cough, and absence of wheeze. An ILI definition comprising fever ≥38°C, cough, and no wheeze had 58% sensitivity (95% confidence interval [CI], 50-66), 60% specificity (95% CI, 56-64), 26% positive predictive value (95% CI, 21-31), and 86% negative predictive value (95% CI, 82-89). The addition of other symptoms or higher fever thresholds to ILI definition had little impact. The Centers for Disease Control and Prevention definition of ILI (presence of fever [≥37.8°C] and cough and/or sore throat) was sensitive (92%; 95% CI, 86-95), yet lacked specificity (10%; 95% CI, 8-13) in this population.

CONCLUSIONS

Influenza-like illness is a poor predictor of laboratory-confirmed influenza infection in young children but can be improved using age-specific data. Incorporating age-specific ILI definitions and/or diagnostic testing into influenza surveillance systems will improve the accuracy of epidemiological data.

Viral agents causing lower respiratory tract infections in hospitalized children: evaluation of the Speed-Oligo® RSV assay for the detection of respiratory syncytial virus

Respiratory syncytial virus (RSV) is the viral agent which is more frequently involved in lower respiratory tract infections (LRTIs) in infants under 1 year of age in developed countries. A new oligochromatographic assay, Speed-Oligo® RSV, was designed and optimized for the specific detection and identification of RSV subtypes A and B. The test was evaluated in 289 clinical samples from 169 hospitalized children using an immunochromatography (IC) test, virus isolation by culture, and an in-house real-time polymerase chain reaction (RT-PCR). Other viruses causing LRTIs were investigated by cell culture or PCR-based tests. Sixty-two patients were infected by RSV (36.7%). In addition, adenovirus, influenza B, parainfluenza 2, and human metapneumovirus were detected in rates ranging from 5 to 8%. A proportion of 10.1% of the patients had mixed infections. The sensitivity, specificity, and positive and negative predictive values were, respectively, 94.9, 99.4, 98.9, and 97.4% for Speed-Oligo® RSV, 92.9, 96.3, 92.9, and 96.3% for RT-PCR/RSV, and 58.4, 98.1, 93.3, and 82.6% for IC. Our rates of viral detection and co-infection were similar to those of previously reported series. Finally, we find that Speed-Oligo® RSV is a rapid and easy-to-perform technique for the detection of RSV and the identification of subtypes A and B.

Diagnosis of Novel Pandemic Influenza Virus 2009 H1N1 in Hospitalized Patients

A real-time RT-PCR assay was standardized and evaluated for the detection of the recent pandemic 2009 H1N1 strain that circulated around the world causing colossal loss of human life. We amplified the conserved regions of the hemagglutinin (HA) gene of 438 clinical specimens using real-time RT-PCR assay for rapid identification of pandemic influenza virus. The real-time RT-PCR was optimized and the primers and probes were tested against a panel of known negative and positive controls. RNA isolated from the HeLa cell line served as quality control. The conventional RT-PCR which is an established method of influenza virus diagnosis was compared to real-time RT-PCR. Of 438 clinical specimens tested, 212 specimens were found positive for influenza A virus (SD 46.669) in which 139 specimens were diagnosed positive for the pandemic 2009 H1N1 while 73 were the seasonal influenza viruses. We report that the real-time RT-PCR assay offers both, a high sensitivity and specificity when compared with the traditional identification method. The real-time RT-PCR assay allows rapid identification of the pandemic swine 2009-H1N1 at very low viral loads that are negative by the traditional RT-PCR. This optimized assay can be a very useful tool to assist both epidemiologists and the clinicians.

Pneumonia and influenza hospitalizations in elderly people with dementia

OBJECTIVES

To compare the demographic and geographic patterns of pneumonia and influenza (P&I) hospitalizations in older adults with dementia with those of the U.S. population and to examine the relationship between healthcare accessibility and P&I.

DESIGN

Observational study using historical medical claims from the Centers for Medicare and Medicaid Services (CMS) and CMS records supplemented with information derived from other large national sources.

SETTING

Retrospective analysis of medical records uniformly collected over a 5-year period with comprehensive national coverage.

PARTICIPANTS

A study population representative of more than 95% of all people aged 65 and older residing in the continental United States.

MEASUREMENTS

Six million two hundred seventy-seven thousand six hundred eighty-four records of P&I between 1998 and 2002 were abstracted, and county-specific outcomes for hospitalization rates of P&I, mean length of hospital stay, and percentage of deaths occurring in a hospital setting were estimated. Associations with county-specific elderly population density, percentage of nursing home residents, median household income per capita, and rurality index were assessed.

RESULTS

Rural and poor counties had the highest rate of P&I and percentage of influenza. Patients with dementia had a lower frequency of influenza diagnosis, a shorter length of hospital stay, and 1.5 times as high a rate of death as the national average.

CONCLUSION

The results suggest strong disparities in healthcare practices in rural locations and vulnerable populations; infrastructure, proximity, and access to healthcare are significant predictors of influenza morbidity and mortality. These findings have important implications for influenza vaccination, testing, and treatment policies and practices targeting the growing fraction of patients with cognitive impairment.

Enhancement of influenza surveillance with aggregate rapid influenza test results: New Mexico, 2003-2007

OBJECTIVES

We sought to determine whether monitoring rapid influenza laboratory tests improved the influenza-like illness surveillance already in place in New Mexico.

METHODS

For the past 3 influenza seasons, the New Mexico Department of Health examined influenza-like illness visits and positive rapid influenza test results.

RESULTS

The proportion of positive rapid influenza test results started to rise earlier than did the percentage of clinical visits because of influenza-like illness in each of the past 3 influenza seasons: 5 weeks earlier during the 2004-2005 season; 3 weeks earlier in 2005-2006; and 2 weeks earlier in 2006-2007. In addition, rapid influenza tests showed a spike in influenza B activity late in the 2005-2006 season that influenza-like illness syndrome surveillance did not.

CONCLUSIONS

Laboratory-based rapid influenza test surveillance required relatively few resources to implement and offered a sensitive mechanism to detect the onset of influenza activity while allowing for the distinction of influenza types.

Comparison of the performance of the rapid antigen detection actim Influenza A&B test and RT-PCR in different respiratory specimens

Nowadays, influenza antigen detection test kits are used most frequently to detect influenza A or B virus to establish the diagnosis of influenza rapidly and initiate appropriate therapy. This study was conducted to evaluate the performance of the actim Influenza A&B test (Medix Biochemica). Overall, 473 respiratory specimens were analysed in the actim Influenza A&B test and the results were compared with those from an RT-PCR assay; 461 of these samples originated from paediatric patients aged 7 weeks to 6.5 years either with influenza-related symptoms or from the intensive care unit, and 12 samples originated from adults with underlying lung or haematological diseases. Diagnosis of influenza A or B virus could be established using the actim Influenza A&B test (9/473 samples for influenza A virus and 6/473 for influenza B virus). RT-PCR revealed 23 patients with influenza virus (13/473 for influenza A virus and 10/473 for influenza B virus). The sensitivity and specificity of the actim Influenza A&B test were 65 and 100 % compared with the RT-PCR assay. However, 32 external quality assessment samples containing seven different strains of influenza A subtypes H1N1 and H3N2 and the avian H5N1 were detected correctly by the actim Influenza A&B test. No cross-reactivity to a range of bacterial, fungal and other viral pathogens was observed. In conclusion, the actim Influenza A&B test is reliable for positive results due to its high specificity. Nevertheless, negative results from this test need to be confirmed by a more sensitive assay because of the low sensitivity observed with diagnostic samples.

Strategies to improve global influenza surveillance: a decision tool for policymakers

BACKGROUND

Global pandemic influenza preparedness relies heavily on public health surveillance, but it is unclear that current surveillance fully meets pandemic preparedness needs.

METHODS

We first developed a conceptual framework to help systematically identify strategies to improve the detection of an early case or cluster of novel human influenza disease during the pre-pandemic period. We then developed a process model (flow diagram) depicting nine major pathways through which a case in the community could be detected and confirmed, and mapped the improvement strategies onto this model. Finally, we developed an interactive decision tool by building quantitative measures of probability and time into each step of the process model and programming it to calculate the net probability and time required for case detection through each detection pathway. Input values for each step can be varied by users to assess the effects of different improvement strategies, alone or in combination. We illustrate application of the tool using hypothetical input data reflecting baseline and 12-month follow-up scenarios, following concurrent implementation of multiple improvement strategies.

RESULTS

We compared outputs from the tool across detection pathways and across time, at baseline and 12-month follow up. The process model and outputs from the tool suggest that traditional efforts to build epidemiology and laboratory capacity are efficient strategies, as are more focused strategies within these, such as targeted laboratory testing; expedited specimen transport; use of technologies to streamline data flow; and improved reporting compliance. Other promising strategies stem from community detection - better harnessing of electronic data mining and establishment of community-based monitoring.

CONCLUSION

Our practical tool allows policymakers to use their own realistic baseline values and program projections to assess the relative impact of different interventions to improve the probability and timeliness of detecting early human cases or clusters caused by a novel influenza virus, a possible harbinger of a new pandemic. Policymakers can use results to target investments to improve their surveillance infrastructure. Multi-national planners can also use the tool to help guide directions in surveillance system improvements more globally. Finally, our systematic approach can also be tailored to help improve surveillance for other diseases.

RespiFinder: a new multiparameter test to differentially identify fifteen respiratory viruses

Broad-spectrum analysis for pathogens in patients with respiratory tract infections is becoming more relevant as the number of potential infectious agents is still increasing. Here we describe the new multiparameter RespiFinder assay, which is based on the multiplex ligation-dependent probe amplification (MLPA) technology. This assay detects 15 respiratory viruses in one reaction. The MLPA reaction is preceded by a preamplification step which ensures the detection of both RNA and DNA viruses with the same specificity and sensitivity as individual monoplex real-time reverse transcription-PCRs. The RespiFinder assay was validated with 144 clinical samples, and the results of the assay were compared to those of cell culture and a respiratory syncytial virus (RSV)-specific immunochromatography assay (ICA). Compared to the cell culture results, the RespiFinder assay showed specificities and sensitivities of 98.2% and 100%, respectively, for adenovirus; 96.4% and 100%, respectively, for human metapneumovirus; 98.2% and 100%, respectively, for influenza A virus (InfA); 99.1% and 100%, respectively, for parainfluenza virus type 1 (PIV-1); 99.1% and 80%, respectively, for PIV-3; 90.1% and 100%, respectively, for rhinovirus; and 94.6% and 100%, respectively, for RSV. Compared to the results of the RSV-specific ICA, the RespiFinder assay gave a specificity and a sensitivity of 82.4% and 80%, respectively. PIV-2, PIV-4, influenza B virus, InfA H5N1, and coronavirus 229E were not detected in the clinical specimens tested. The use of the RespiFinder assay resulted in an increase in the diagnostic yield compared to that obtained by cell culture (diagnostic yields, 60% and 35.5%, respectively). In conclusion, the RespiFinder assay provides a user-friendly and high-throughput tool for the simultaneous detection of 15 respiratory viruses with excellent overall performance statistics.

Active influenza surveillance at the local level: a model for local health agencies

Laboratory-supported, community-based local surveillance systems for influenza can act as early warning systems in identifying the initial entry points of different influenza strains into the community. Unfortunately, local health departments often have limited resources to implement this type of surveillance. We developed and evaluated an active, local influenza surveillance system in 3 metropolitan Denver, Colo, counties that enabled timely case ascertainment and strain identification at little cost. When compared with Colorado's surveillance system, our system detected cases 7 to 8 weeks earlier than the state's electronic disease reporting system.

Potential for early warning of viral influenza activity in the community by monitoring clinical diagnoses of influenza in hospital emergency departments

BACKGROUND

Although syndromic surveillance systems are gaining acceptance as useful tools in public health, doubts remain about whether the anticipated early warning benefits exist. Many assessments of this question do not adequately account for the confounding effects of autocorrelation and trend when comparing surveillance time series and few compare the syndromic data stream against a continuous laboratory-based standard. We used time series methods to assess whether monitoring of daily counts of Emergency Department (ED) visits assigned a clinical diagnosis of influenza could offer earlier warning of increased incidence of viral influenza in the population compared with surveillance of daily counts of positive influenza test results from laboratories.

METHODS

For the five-year period 2001 to 2005, time series were assembled of ED visits assigned a provisional ED diagnosis of influenza and of laboratory-confirmed influenza cases in New South Wales (NSW), Australia. Poisson regression models were fitted to both time series to minimise the confounding effects of trend and autocorrelation and to control for other calendar influences. To assess the relative timeliness of the two series, cross-correlation analysis was performed on the model residuals. Modelling and cross-correlation analysis were repeated for each individual year.

RESULTS

Using the full five-year time series, short-term changes in the ED time series were estimated to precede changes in the laboratory series by three days. For individual years, the estimate was between three and 18 days. The time advantage estimated for the individual years 2003-2005 was consistently between three and four days.

CONCLUSION

Monitoring time series of ED visits clinically diagnosed with influenza could potentially provide three days early warning compared with surveillance of laboratory-confirmed influenza. When current laboratory processing and reporting delays are taken into account this time advantage is even greater.

FluSTAR, A Novel Influenza Surveillance System: Outcomes from the 2005–2006 Flu Season

BACKGROUND

The FluSTAR Surveillance System covers most of the United States, providing local and national information on influenza and influenza-like illness that is updated twice weekly.

METHODS

Descriptive statistical analyses were performed to explore demographic characteristics, symptoms, vaccination status, and treatment of patients tested for influenza, using a rapid test kit, in the FluSTAR program during the 2005 to 2006 influenza season (October 1, 2005-April 11, 2006).

RESULTS

Of 17,247 patients tested, the most common age groups were 35 to 49 (20%) or 19 to 34 years (18%). Overall, 22% of tests were positive. Patients testing positive were more likely to report influenza-associated symptoms such as cough and fever than those testing negative. Most patients testing positive were prescribed antiviral agents.

CONCLUSIONS

Surveillance systems such as FluSTAR can provide timely data on the circulation of influenza and influenza-like illness. This information could assist with accurate diagnosis and aid treatment decisions.

Clinical evaluation of the SD Bioline influenza virus antigen test for rapid detection of influenza viruses A and B in children and adults during the influenza season

The performance of the SD Bioline rapid antigen test kit for influenza virus detection was evaluated with 295 respiratory specimens during the influenza season. The overall sensitivity and specificity of the SD Bioline test were 61.9% and 96.8% for the influenza A virus antigen and 54.5% and 100% for the influenza B virus antigen, respectively. The results were consistent with peak influenza activities.

The influence of rapid influenza diagnostic testing on antibiotic prescribing patterns in rural Thailand

OBJECTIVES

Rapid influenza diagnostic testing is potentially a useful means to decrease inappropriate prescription of antibiotics. We studied the impact of access to rapid influenza test results on antibiotic prescribing and other patient management practices for outpatients with influenza-like illness (ILI) in a rural province in Eastern Thailand.

METHODS

A medical record review was performed for 300 patients of all ages selected from five outpatient departments using a 1:2 ratio of ILI cases with and without influenza infection identified by the QuickVue rapid test. Chi-square analysis or Fisher's exact test was used to compare patient management practices (antibiotic prescriptions, individual treatments administered, additional tests ordered, and related hospitalization) between rapid test positive and negative patients. Logistic regression was used to evaluate the effect of rapid test results on patient management practices for ILI.

RESULTS

Eighty-two percent of all patients with ILI were prescribed antibiotics. Patients with a positive rapid test were less likely to be prescribed antibiotics than those with a negative result (73% vs. 87%, respectively, p=0.003). The likelihood of antibiotic prescription for influenza positive patients was 0.41 times the likelihood for influenza negative patients (95% CI 0.23-0.74, p=0.003). There was no significant difference in the frequency of other patient management practices between influenza positive and negative patients.

CONCLUSIONS

Thai outpatients with ILI are prescribed antibiotics at a frequency approximately twice that reported in the USA. Having access to a rapid influenza test result was associated with a significant decrease in antibiotic prescription. Improved access to rapid influenza testing and expanded physician education may reduce inappropriate antibiotic use and improve patient care.

Simultaneous detection of five different DNA targets by real-time Taqman PCR using the Roche LightCycler480: Application in viral molecular diagnostics

One of the most interesting aspects of real-time PCR based on the detection of fluorophoric labeled oligonucleotides is the possibility of being able to detect conveniently multiple targets in the same PCR reaction. Recently, Roche Diagnostics launched a real-time PCR platform, the LightCycler480 (LC480), which should be well suited for multiplex real-time PCR analysis. In this paper the performance of the LC480 and accompanying software for the detection of five different targets was analyzed. Target DNAs mixed at equimolar concentrations were detected reproducibly and quantitatively. In addition, mixing different concentrations of the five targets demonstrated that the LC480 is capable of providing quantitative results for a mixture of DNA sequences without losing sensitivity. When applied to the practice of molecular diagnosis of four respiratory viral infections the multiplex assay showed almost complete concordance with corresponding single-target PCRs. The application of multiplex PCR for the detection of multiple pathogens within the same sample will provide a major contribution to the efficiency, logistics and cost-effectiveness of molecular diagnostics.

Rapid and highly informative diagnostic assay for H5N1 influenza viruses

A highly discriminative and information-rich diagnostic assay for H5N1 avian influenza would meet immediate patient care needs and provide valuable information for public health interventions, e.g., tracking of new and more dangerous variants by geographic area as well as avian-to-human or human-to-human transmission. In the present study, we have designed a rapid assay based on multilocus nucleic acid sequencing that focuses on the biologically significant regions of the H5N1 hemagglutinin gene. This allows the prediction of viral strain, clade, receptor binding properties, low- or high-pathogenicity cleavage site and glycosylation status. H5 HA genes were selected from nine known high-pathogenicity avian influenza subtype H5N1 viruses, based on their diversity in biologically significant regions of hemagglutinin and/or their ability to cause infection in humans. We devised a consensus pre-programmed pyrosequencing strategy, which may be used as a faster, more accurate alternative to de novo sequencing. The available data suggest that the assay described here is a reliable, rapid, information-rich and cost-effective approach for definitive diagnosis of H5N1 avian influenza. Knowledge of the predicted functional sequences of the HA will enhance H5N1 avian influenza surveillance efforts.

Symptomatic predictors of influenza virus positivity in children during the influenza season

BACKGROUND

Symptomatic predictors of the etiology of infectious diseases are necessary when quick action is required in treatment, as with cases of influenza or anthrax, or for when patient isolation is required, as with cases of severe acute respiratory syndrome (SARS). Predictors of influenza virus infection during the influenza season have previously been evaluated in adult studies of the antiviral agent zanamivir; cough and temperature > or =37.8 degrees C predicted influenza virus positivity in 79% of those evaluated.

METHODS

Fever and other respiratory symptoms were examined to determine their value in predicting influenza virus-positive status in children. Data analyzed were from a clinical trial of zanamivir in children 5-12 years of age and from a trial of oseltamivir in children 1-12 years of age.

RESULTS

In the pediatric study of zanamivir, as in the adult zanamivir study, cough and fever were the best predictors of influenza virus infection; a temperature > or =38.2 degrees C plus cough predicted 83% (95% CI, 79%-88%) of illnesses that were determined to be influenza virus positive. Cough (positive predictive value, 70%; 95% CI, 64%-75%), but not fever, was the best predictor of influenza virus-positive status in children aged 5-12 years in the oseltamivir trials, but neither cough nor fever were successful predictors in young children 1-4 years of age. The latter findings appeared to be the result of less symptomatic diversity among patients recruited for this trial, such that subjects who were determined to be influenza virus positive and subjects who were influenza virus negative had similar symptoms.

CONCLUSIONS

The results of these studies suggest that, during the influenza season, symptomatic predictors of influenza virus infection are applicable to identification of cases in children, although confirmation of predictive values in subjects 1-4 years of age may require further study of additional signs/symptoms.

Field performance and new uses of rapid influenza testing in Thailand

OBJECTIVES

Rapid influenza tests are increasingly used in surveillance systems and for clinical care in Southeast Asia. However, the performance and utility of rapid influenza tests under field conditions in rural Southeast Asia has not been evaluated.

METHODS

In the context of a larger study on the causes of respiratory illness in rural Thailand, we used a rapid test to collect data on influenza burden, seasonality, and cost of illness. We compared the performance of the QuickVue Influenza Test to tissue cell viral culture and reverse transcriptase-polymerase chain reaction (RT-PCR) among 1092 Thai patients meeting the World Health Organization case definition for influenza-like illness over a 12-month period.

RESULTS

The sensitivity and specificity of the QuickVue test compared to viral culture were 77% and 96%, respectively. Rapid influenza tests were useful to describe the seasonality of influenza, estimate the cost of illness, increase the sensitivity of surveillance, conduct outbreak responses, and guide evaluation of suspected avian influenza virus infections.

CONCLUSIONS

Despite their high cost, rapid influenza diagnostic tests are useful tools for influenza research, surveillance, and outbreak investigations in Southeast Asia.

Performance characteristics of a rapid immunochromatographic assay for detection of influenza virus in children during the 2003 to 2004 influenza season

STUDY OBJECTIVE

We evaluate the performance of a rapid assay (Binax NOW) for the detection of influenza A virus in children.

METHODS

The performance of an in vitro rapid immunochromatographic assay for detection of influenza A virus was compared to viral culture in 4,383 consecutive respiratory specimens received during the 2003 to 2004 season, which included an influenza A epidemic in October and November of 2003.

RESULTS

The overall test sensitivity was 61.6% (95% confidence interval [CI] 60.3% to 63.2%) and specificity was 95.8% (95% CI 95.1% to 96.3%). In preplanned subset analyses, we found the test more sensitive in infants aged 90 days or younger (sensitivity 70.3%; specificity 96.6%) and less specific during the epidemic (sensitivity 61.7%; specificity 90.4%).

CONCLUSION

This rapid assay was highly specific for detecting influenza A in children and thus appears useful for confirming this infection. Because of its limited sensitivity, however, a negative test cannot rule out influenza A.

The impact of influenza on the health and health care utilisation of elderly people

Despite intensive research, influenza viruses still present one of the major causes of respiratory disease throughout the world. The elderly population and those individuals considered "at risk" due to presenting co-morbidity are especially vulnerable to influenza infection; this is evident from increased rates of morbidity and mortality in these populations during winter epidemic periods. Successful vaccination campaigns have targeted these groups over the last few years, providing protection to an increasing number of susceptible individuals. However, during periods of influenza virus activity there are still seasonal pressures put on both primary and secondary health care services. In the event of a serious influenza epidemic or pandemic, these burdens could jeopardise health care provision to at risk populations. In this report we discuss current issues surrounding the impact of influenza on the health care utilisation of elderly people.

Rapid Tests for Influenza

A variety of antigen-capture assays are commercially available for the detection of influenza. In addition, real-time multiplex polymerase chain reaction (PCR) has been used to detect influenza A and B in clinical specimens. The commercial assays can be completed in less than 30 minutes and have a sensitivity of at least 70% and a specificity of 90%, compared with viral isolation. They are useful not only in the diagnosis and treatment of individual patients with influenza-like illness but also in surveillance for influenza, decreasing the time of nosocomial outbreaks, decreasing the use of laboratory tests, and decreasing antibiotic use in patients with influenza. Some of the rapid antigen assays, and PCR, can detect the H5N1 and H9N1 viruses. Real-time multiplex PCR also detects a variety of respiratory viruses within 6 hours, with only 1 hour of hands-on technician time. The widespread use of the rapid tests for influenza is changing the practice pattern of physicians who care for patients with influenza.

A 5-year experience with influenza prevention and containment in a program of all-inclusive care for elderly adults

BACKGROUND

Influenza causes mortality and morbidity in the frail elderly population. Influenza prevention and mitigation models need to be developed for this population.

METHODS

An observational study at a Program for All-Inclusive Care for the Elderly (PACE) during years 1999-2004. Participants were frail elderly adults who meet the state Medicaid requirements for nursing home placement.

RESULTS

Over 91% of participants have been immunized yearly since the beginning of the program. Employee immunization has increased yearly from 61% to 90%, and caregivers known to be immunized increased from 9% to 62% over the last 4-year period. During 2 influenza seasons, we placed all our participants on ramantidine prophylaxis within a 2-week period.

CONCLUSIONS

The incentives and flexibility offered by PACE have allowed our participants to enjoy much higher influenza immunization rates than experienced by other elderly adults while also prophylaxing employees and caregivers. Our systems have allowed us to prophylax all our participants within a short time during 2 influenza seasons. Nonetheless, many questions remain regarding the optimal way to decrease the burden of influenza in frail elderly adults. With adequate integration and supplementary financing, PACE programs throughout the United States could serve as laboratories to test candidate interventions.

Comparison of a new lateral-flow chromatographic membrane immunoassay to viral culture for rapid detection and differentiation of influenza A and B viruses in respiratory specimens

The performance of a new rapid lateral-flow chromatographic membrane immunoassay test kit for detection of influenza virus was evaluated and compared to that of viral culture in respiratory secretions collected from 400 adults and children seen at three large university hospitals during the recent 2003 influenza season. The rapid test provided results in 15 min, with excellent overall performance statistics (sensitivity, 94.4%; specificity, 100%; positive predictive value, 100%; negative predictive value, 97.5%). Both influenza A and B type viruses were reliably detected, with no significant difference in performance statistics noted by influenza virus type or by the center performing the test.

Comparison of the directigen flu A+B membrane enzyme immunoassay with viral culture for rapid detection of influenza A and B viruses in respiratory specimens

The performance of a commercially available, rapid membrane enzyme immunoassay for influenza A and B virus detection was compared to that of viral culture in 4,092 respiratory specimens collected from patients presenting with respiratory symptoms during the 2002-2003 influenza season. The test's overall sensitivity was 43.83%, lower than previously reported but similar for detection of both influenza A and B viruses (42.98 versus 44.76%). However, specificity, 99.74%, was excellent for both influenza A and B viruses (99.82 versus 99.92%). These values make this test a very good confirmatory test when clinical suspicion is high, but a less accurate screening test for large populations.

Rapid and sensitive method using multiplex real-time PCR for diagnosis of infections by influenza a and influenza B viruses, respiratory syncytial virus, and parainfluenza viruses 1, 2, 3, and 4

Laboratory diagnosis of viral respiratory infections is generally performed by virus isolation in cell culture and immunofluorescent assays. Reverse transcriptase PCR is now recognized as a sensitive and specific alternative for detection of respiratory RNA viruses. A rapid real-time multiplex PCR assay was developed for the detection of influenza A and influenza B viruses, human respiratory syncytial virus (RSV), parainfluenza virus 1 (PIV1), PIV2, PIV3, and PIV4 in a two-tube multiplex reaction which used molecular beacons to discriminate the pathogens. A total of 358 respiratory samples taken over a 1-year period were analyzed by the multiplex assay. The incidence of respiratory viruses detected in these samples was 67 of 358 (19%) and 87 of 358 (24%) by culture and real-time PCR, respectively. Culture detected 3 influenza A virus, 2 influenza B virus, 57 RSV, 2 PIV1, and 2 PIV3 infections. All of these culture-positive samples and an additional 5 influenza A virus, 6 RSV, 2 PIV1, 1 PIV2, 1 PIV3, and 3 PIV4 infections were detected by the multiplex real-time PCR. The application of real-time PCR to clinical samples increases the sensitivity for respiratory viral diagnosis. In addition, results can be obtained within 6 h, which increases clinical relevance. Therefore, use of this real-time PCR assay would improve patient management and infection control.

Influenza

Although most influenza infections are self-limited, few other diseases exert such a huge toll of suffering and economic loss. Despite the importance of influenza, there had been, until recently, little advance in its control since amantadine was licensed almost 40 years ago. During the past decade, evidence has accrued on the protection afforded by inactivated vaccines and the safety and efficacy in children of live influenza-virus vaccines. There have been many new developments in vaccine technology. Moreover, work on viral neuraminidase has led to the licensing of potent selective antiviral drugs, and economic decision modelling provides further justification for annual vaccination and a framework for the use of neuraminidase inhibitors. Progress has also been made on developing near-patient testing for influenza that may assist individual diagnosis or the recognition of widespread virus circulation, and so optimise clinical management. Despite these advances, the occurrence of avian H5N1, H9N2, and H7N7 influenza in human beings and the rapid global spread of severe acute respiratory syndrome are reminders of our vulnerability to an emerging pandemic. The contrast between recent cases of H5N1 infection, associated with high mortality, and the typically mild, self-limiting nature of human infections with avian H7N7 and H9N2 influenza shows the gaps in our understanding of molecular correlates of pathogenicity and underlines the need for continuing international research into pandemic influenza. Improvements in animal and human surveillance, new approaches to vaccination, and increasing use of vaccines and antiviral drugs to combat annual influenza outbreaks are essential to reduce the global toll of pandemic and interpandemic influenza.

Comparison of lateral-flow immunoassay and enzyme immunoassay with viral culture for rapid detection of influenza virus in nasal wash specimens from children

The performance of two commercially available rapid test kits for influenza virus detection was compared to that of viral culture by using 356 nasal wash specimens collected during the 2001 to 2002 influenza season. Overall, the two rapid tests were easy to perform and showed comparable sensitivities (70.4 and 72.2%) and specificities (97.7 and 98.3%); for both test kit groups, most of the specimens that yielded false-negative results were found to be growing influenza B virus.

Development of a predictive index for picornavirus infections

To create a clinical prediction index that aids in the diagnosis of picornavirus respiratory infections, we analyzed patients from 5 clinical trials designed to evaluate the efficacy of an antiviral treatment for respiratory infections. Logistic regression was used to determine which baseline symptoms and patient characteristics best predicted picornavirus infection. Parameter estimates were then used to create a predictive index for estimating the probability of picornavirus infection on the basis of cold symptoms. The presence at baseline of rhinorrhea (odds ratio [OR], 2.73), nasal congestion (OR, 1.63), and sore throat (OR, 1.37) increased the likelihood of picornavirus infection; the presence of myalgia (OR, 0.71) and fever (OR, 0.59) decreased the likelihood. The positive and negative predictive values of the model were 61.5% and 64.4%, respectively. The model was simplified for clinical use by creating a whole-number index: the lowest possible score (-3) indicates a 15% chance of picornavirus infection and the highest (7) indicates a 69% chance of picornavirus infection.