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A sensitive one-step immunocapture EIA for rapid diagnosis of influenza A.

Tkacova M, Vareckova E.

Institute of Virology, Slovak Academy of Sciences, Bratislava, Slovak Republic.

A highly sensitive one-step immunocapture EIA for the detection of influenza A virus antigen directly in a clinical specimen was developed. The sensitivity was achieved by using two high-affinity cross-reactive influenza type A-specific monoclonal antibodies, recognizing independent nonoverlapping epitopes on the influenza A nucleoprotein. One of the two MAbs was used as a capture antibody, while the other was coupled with enzyme peroxidase and served as a detector. Sensitivity to detection of highly purified recombinant influenza A virus nucleoprotein by EIA reached approximately 10 pg. Fifteen purified human influenza A virus strains of H1, H2 and H3 subtypes, isolated during the period 1934-1992, were tested by this system. All the influenza A viruses tested positive, whereas two influenza B viruses used as a control were negative. The efficiency of the system for detection of influenza A viral antigen directly in clinical specimens was confirmed by testing nasal and nasopharyngeal washes and aspirates, tested previously by time-resolved fluoroimmunoassay and by virus culture confirmation assay.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8795007&dopt=Abstract flu, influenza



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Equine influenza.

Timoney PJ.

Department of Veterinary Science, Gluck Equine Research Center, University of Kentucky, Lexington 40546-0099, USA.

A highly contagious virus infection of horses, influenza is the single most important equine respiratory disease in many countries. Two subtypes of equine influenza virus have been identified, A/equine-1 and A/equine-2, neither of which immunologically cross-reacts. In the case of A/equine-2 virus, two lineages exist, American and European, which appear to have evolved independently of one another. The acute febrile respiratory disease characteristic of influenza is frequently complicated by secondary bacterial infection, especially in unvaccinated horses. Primarily a respiratory-borne infection, influenza has been spread to a significant number of countries through the international movement of horses. Strains of A/equine-2 virus have been responsible for all known outbreaks of the disease since 1980. Simple rapid procedures are now available for the diagnosis of equine influenza. Prevention and control of influenza is based on frequent use of inactivated, adjuvanted vaccines, which confer only incomplete and short-term protection against this disease. To be maximally effective, vaccines need to be periodically updated and include influenza virus strains closely related to those in current circulation.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8800546&dopt=Abstract flu, influenza



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Study of influenza-associated encephalitis/encephalopathy in children during the 1997 to 2001 influenza seasons.

Yoshikawa H, Yamazaki S, Watanabe T, Abe T.

Department of Pediatrics, Niigata City General Hospital, Niigata, Japan. hideto hosp.niigata.niigata.jp

The 1997 to 2001 influenza A epidemics in Japan were markedly neurovirulent, and many children died of influenza-associated encephalitis/encephalopathy. We studied 20 patients with influenza-associated encephalitis/encephalopathy during the last four influenza seasons. No patients had been previously inoculated with influenza vaccine. Antipyretics were used in 16 patients before the onset of encephalopathy. Although all patients were treated intensively, 5 patients died and 8 had neurologic sequelae. Patients with coagulopathy, hepatic dysfunction, and computed tomographic abnormalities had a poor prognosis. The plasma concentrations of inflammatory cytokines were variable. The neuroradiologic findings could be divided into four categories. These findings indicated that the pathogenesis of the brain damage induced by influenza infection was variable. Further investigation is necessary to determine whether insufficient influenza vaccination or the use of antipyretics is one of the reasons for these epidemics of encephalopathy in Japanese children.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11785501&dopt=Abstract flu, influenza



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Genetic reassortment in pandemic and interpandemic influenza viruses. A study of 122 viruses infecting humans.

Shu LP, Sharp GB, Lin YP, Claas EC, Krauss SL, Shortridge KF, Webster RG.

Department of Virology & Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.

The human influenza pandemics of 1957 and 1968 were caused by reassortant viruses that possessed internal gene segments from avian and human strains. Whether genetic reassortment of human and avian influenza viruses occurs during interpandemic periods and how often humans are infected with such reassortants is not known. To provide this information, we used dot-blot hybridization, partial nucleotide sequencing and subsequent phylogenetic analysis to examine the 6 internal genes of 122 viruses isolated in humans between 1933 and 1992 primarily from Asia, Europe, and the Americas. The internal genes of A/New Jersey/11/76 isolated from a human fatality at Fort Dix, New Jersey in 1976 were found to be of porcine origin. Although none of the geographically and temporally diverse collection of 122 viruses was an avian-human or other reassortant, cognizance was made of the fact that there were two isolates from children from amongst 546 influenza A isolates obtained from The Netherlands from 1989-1994 which were influenza A reassortants containing genes of avian origin, viruses which have infected European pigs since 1983-1985. Thus, genetic reassortment between avian and human influenza strains does occur in the emergence of pandemic and interpandemic influenza A viruses. However, in the interpandemic periods the reassortants have no survival advantage, and the circulating interpandemic influenza viruses in humans do not appear to accumulate avian influenza virus genes.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8817180&dopt=Abstract flu, influenza



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Diagnostic testing or empirical neuraminidase inhibitor therapy for patients with influenza-like illness: what a difference a day makes.

Blitz SG, Cram P, Chernew ME, Monto AS, Fendrick AM.

Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, USA.

OBJECTIVE: To determine the clinical and economic trade-offs of available diagnostic and treatment options for patients with suspected influenza infection. DESIGN: Decision analytic model. PATIENTS: A simulated cohort of adults with influenza-like illness of less than 48 hours' duration. INTERVENTIONS: Patients received (1) no testing or treatment; (2) rapid testing for influenza, with neuraminidase inhibitors (NIs) prescribed for individuals who test positive; or (3) empirical NI therapy. A validated prediction rule to determine the probability of influenza infection based on patient signs and symptoms is available. The monetary value attributable to the incremental benefits of NI therapy must be quantified during the clinician visit. OUTCOME: Incremental cost per case of influenza treated with NIs. RESULTS: The decision whether to treat, test, or prescribe NIs empirically for patients presenting with influenza-like illness of less than 48 hours' duration depends on the probability of influenza and the value of the benefits of NI therapy. If the incremental value of NI therapy exceeds $200 and the probability of influenza is greater than 35%, empiric NI therapy is the preferred option. The test option has a very narrow band of preference due to suboptimal test characteristics and cost. CONCLUSION: The decision whether to prescribe NIs based on clinical criteria or restrict NI use to patients with a confirmed laboratory diagnosis of influenza depends on the likelihood of infection, the accuracy and cost of the diagnostic test, and the benefits attributable to NI therapy. Clinicians must consider these factors when determining cost-effective use of NIs.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11915972&dopt=Abstract flu, influenza



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Gene analysis of reassortant influenza virus by RT-PCR followed by restriction enzyme digestion.

Sakamoto S, Kino Y, Oka T, Herlocher ML, Maassab F.

Chemo-Sero-Therapeutic Research Institute, Shimizu Laboratory 668, Kumamoto, Japan.

An amplification system for nearly full length cDNA coding the eight influenza virus segments of A type (H1N1, H2N2, H3N2) and B type influenza viruses is described. Each of the segments of PB1, PB2, PA, NP, M, and NS can be amplified using one 5' primer and one 3' primer for A-type influenza viruses. The RT-PCR amplification system was applied to define the gene composition of three subtype cold-recombinant, live attenuated influenza viruses. Each segment of the attenuated influenza virus could be identified as deriving from segments of the Ca donor or wild virus by comparing the representative restriction enzyme digestion patterns of the three PCR products obtained from the Ca donor, the cold-live attenuated influenza viruses and the wild virus. This RT-PCR method, using RT-PCR followed by digestion of PCR products with restriction enzymes, was very beneficial for analyzing the genome of reassortant influenza viruses.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8882646&dopt=Abstract flu, influenza



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[A clinical study of chronic lower respiratory infection with Haemophilus influenza by transtracheal aspiration]

[Article in Japanese]

Tsujimoto M, Sawaki M, Mikasa K, Konishi M, Maeda K, Sakamoto M, Hamada K, Mori K, Teramoto S, Ueda K, Hirai T, Kita E, Narita N.

Second Department of Internal Medicine, Nara Medical University.

We have performed a clinical study on chronic lower respiratory tract infection (CLRTI) with Haemophilus influenzae (H. influenzae) by transtracheal aspiration (TTA) and analyzed clinical factors of the acute exacerbation. In 40 episodes (38 cases) of H. influenzae isolated from CLRTI, monobacterial infection with H. influenzae were 21 episodes and polymicrobial infection were 19 episodes. We classified the disease into acute exacerbated (27 episodes) and stable (13 episodes) phase and the former episodes were divided into bronchitis type (7 episodes) and pneumonia type (20 episodes). Polymicrobial infections were seen more in the pneumonia type (13 episodes) than in the bronchitis type (2 episodes). The principal organism detected with H. influenzae were alpha-Streptococcus and Neisseria sp. in the bronchitis type and S. pneumoniae in the pneumonia type. The acute exacerbated cases were divided into the following 4 patterns; 1. polymicrobial infection with continuous infection of P. aeruginosa, 2. monomicrobial infection after acute upper respiratory tract infection, 3. polymicrobial infection with S. pneumoniae after continuous infection of H. influenzae, 4. bacterial replacement by P. aeruginosa after acute exacerbation. The results of the study suggests that polymicrobial infection is an important chronic lower respiratory tract infection when caused H. influenzae.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8921678&dopt=Abstract flu, influenza



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Monitoring mortality as an indicator of influenza in Catalonia, Spain.

Dominguez A, Munoz P, Martinez A, Orcau A.

Department of Public Health and Health Regulations, Universitat de Barcelona, Spain.

STUDY OBJECTIVE: This study aimed to investigate the behaviour of two indicators of influenza activity in the area of Barcelona and to evaluate the usefulness of modelling them to improve the detection of influenza epidemics. DESIGN: Descriptive time series study using the number of deaths due to all causes registered by funeral services and reported cases of influenza-like illness. The study concentrated on five influenza seasons, from week 45 of 1988 to week 44 of 1993. The weekly number of deaths and cases of influenza-like illness registered were processed using identification of a time series ARIMA model. SETTING: Six large towns in the Barcelona province which have more than 60,000 inhabitants and funeral services in all of them. MAIN RESULTS: For mortality, the proposed model was an autoregressive one of order 2 (ARIMA (2,0,0)) and for morbidity it was one of order 3 (ARIMA (3,0,0)). Finally, the two time series were analysed together to facilitate the detection of possible implications between them. The joint study of the two series shows that the mortality series can be modelled separately from the reported morbidity series, but the morbidity series is influenced as much by the number of previous cases of influenza reported as by the previous mortality registered. CONCLUSIONS: The model based on general mortality is useful for detecting epidemic activity of influenza. However, because there is not an absolute gold standard that allows definition of the beginning of the epidemic, the final decision of when it is considered an epidemic and control measures recommended should be taken after evaluating all the indicators included in the influenza surveillance programme.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8935461&dopt=Abstract flu, influenza



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Influenza surveillance during winter 1997-1998 in Israel.

Peled T, Weingarten M, Varsano N, Matalon A, Fuchs A, Hoffman RD, Zeltcer C, Kahan E, Mendelson E, Swartz TA.

Israel Center for Disease Control, Gertner Institute for Health Policy Research, Tel Hashomer, Israel. tamar.p icdc.health.gov.il

BACKGROUND: Each winter influenza activity is a major cause of morbidity and mortality both in Israel and worldwide. OBJECTIVES: To identify the influenza viruses active in Israel during the winter season and to assess the extent of influenza morbidity. METHODS: Information was collected on a population of 18,684 individuals enrolled in two community clinics in central Israel. It included the total number of visits for acute respiratory infection--including influenza and influenza-like illness (ARI/flu-like)--during a 20 week surveillance period (23 November 1997 to 27 March 1998) and the percent of influenza virus isolates in nasopharyngeal specimens from a sample of patients with ARI/flu-like collected on a weekly basis during the same period. RESULTS: A total of 5,947 visits for ARI/flu-like were recorded among 18,684 enrolled patients in two community clinics (18.1%). The progressive increase in the number of visits for ARI/flu-like reached a peak on week 2/98 with 597 visits and a rate of 31.95 visits per 1,000 population. After this, a decrease to the initial values was evident by week 12/98. Most affected patients were in the age groups 5-14 and 65 years and over, with a rate of 733.5 and 605.3 visits per 1,000 population, respectively. Influenza virus was isolated from 92 of the 426 nasopharyngeal specimens (21.6%). The most commonly detected strain was A/Sydney/5/97 (H3N2) like (77.2%). The peak rate of isolates was recorded at the beginning of January (01/98). CONCLUSIONS: A/Sydney/5/97 (H3N2) like-strain was the dominant influenza virus. Its presence did not prevent the simultaneous activity of influenza A/H1N1 virus. The dynamic of the clinical disease as expressed by the weekly visit rate for ARI/flu-like was similar to the temporal pattern of the virological findings. The extent of morbidity suggests moderate epidemic activity.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11794913&dopt=Abstract flu, influenza



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Health impact of influenza in the United States.

Sullivan KM.

School of Medicine, Department of Pedirics, Emory University, Atlanta, Georgia, USA.

Influenza infection is associated with significant morbidity and mortality. The purpose of this investigation was to describe the health effects of influenza in the US. Although a number of different data sources have been used to provide estimates of the health impact of influenza in the US, estimates provided in this article are primarily based upon the experiences reported in community-based studies performed in Houston, Texas, and Tecumseh, Michigan. Estimates of the annual average are provided for the following: (1) infection rate; (2) number of influenza-associated respiratory illnesses; (3) number of ill days with influenza; (4) number of bed and activity restriction days due to influenza illness; (5) physician visits; (6) hospitalisations and days hospitalised; and (7) mortality. Large differences were found between estimates from Houston and Tecumseh, and possible explanations for these are provided. However, all estimates find that influenza is an important cause of morbidity and mortality in the US.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10160483&dopt=Abstract flu, influenza



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[Influenza in the 1994/95 season; composition of vaccine for the 1995/96 season]

[Article in Dutch]

Claas EC, de Jong JC, Bartelds AI, Rimmelzwaan GF, van Wijngaarden JK, Osterhaus AD.

National Influenza Centrum van de WHO, Erasmus Universiteit, afd. Virologie, Rotterdam.

The 1994/'95 season in the Netherlands was marked by a limited influenza activity which only emerged in late February. The influenza activity remained elevated until the end of April, which is unusually late, and epidemic activity was only reported in the south of the country. Both influenza A/H3N2 and B viruses were isolated in this period. In addition, influenza A/HINI viruses were isolated for the first time since March 1993, from two patients. The majority of the influenza A strains that circulated in the Netherlands in 1994/'95 reacted well with ferret antiserum raised against the strains of the 1994/'95 influenza vaccine, which therefore probably offered good protection. The reactivity of the B strains to antiserum raised against the vaccine strain, B/Panama/45/90, was only moderate, which implies that the protection against the Dutch influenza B strains was not optimal. Based on the results of the worldwide influenza surveillance, the World Health Organization (WHO) has recommended an alteration in both the A/H3N2 and the B component for the vaccine of 1995/1996.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7477582&dopt=Abstract flu, influenza