Reappearance of influenza B/Victoria/2/87-lineage viruses: epidemic activity, genetic diversity and vaccination efficacy in the Finnish Defence Forces.

A new B/Shangdong/7/97-like influenza virus (Victoria/2/87 lineage) predominated during the 2002/2003 epidemic season in Finland and was estimated to account for 2246 of the 13,496 feverish upper respiratory tract infections (URIs) occurring among conscripts in the Finnish army. The incidence (1716/10,000 conscripts) was indicative of moderate epidemic activity at most. Analysis of the cross-reactive antibodies induced in 1988 suggests that the basis of the protection was probably established during the childhood of the conscripts. Vaccination in autumn 2002 prevented 42% of the URIs during the influenza B outbreak and 71% (95% CI 42-85) of infections interpreted as influenza B. Despite the low genetic variability of the Shangdong/7/97-like viruses, breakages of a potential glycosylation site in haemagglutinin (HA1, position 197) were frequent; their biological significance is discussed. The Shangdong/7/97-like strains were HA1/NA reassortants, as were also the less abundant strains that for HA1 belonged to the B/Yamagata/16/88 lineage. A further reassortment, which probably emerged during the outbreak in one of the garrisons, supports our hypothesis that circumstances in these settings may especially favour the emergence of diversity by reassortment.

Virological and serological analysis of rhinovirus infections during the first two years of life in a cohort of children.

The occurrence of rhinovirus infections in a cohort of 329 children during the first 2 years of life was determined by virus detection and serological methods. Rhinovirus detection on nasopharyngeal aspirates and middle ear fluids comprised a combination of virus isolation in HeLa Ohio cells and a reverse transcription-polymerase chain reaction (RT-PCR)-hybridization assay on the inoculated cell cultures. Nasopharyngeal aspirates were collected when the child was referred to the study clinic because of respiratory symptoms. Nasopharyngeal aspirates and middle ear fluids were collected after clinical diagnosis of an acute otitis media. Complement-fixing antibodies to rhinovirus were determined from scheduled serum specimens collected at 6, 12, 18, and 24 months of age and from paired sera taken in the cases of acute otitis media. Rhinovirus infections were shown to be common in infants, 24% of the children had complement-fixing antibodies at the age of 6 months and 22% had had at least one rhinovirus episode indicated by virus detection. At the age of 2 years, 91.3% of the children had rhinovirus-specific antibodies, while 79% of the children had experienced rhinovirus infection as judged by the virus detection tests. However, the complement-fixation assay was poor as a diagnostic test. Of 458 acute otitis media episodes studied, 41% were shown to be associated with a rhinovirus by RT-PCR-hybridization, while significant fourfold rise in rhinoviral antibodies was detected only in 7% of the cases.

Enterovirus, mycoplasma and other infections as predictors for myocardial infarction.

OBJECTIVES: To study antibodies against five infectious agents for their prediction of major coronary events in men with and without evidence of coronary heart disease at baseline. DESIGN: A case-control study nested within a prospective population study. SUBJECTS: The study cases included 441 men 45-64 years old with nonfatal myocardial infarction or coronary death within a mean follow-up time of 10 years. A total of 165 men had already signs of heart disease at baseline, whilst 276 were apparently healthy at the beginning of the study. Two controls for each case were matched for age, heart disease status and place of residence. Antibodies against enterovirus, Mycoplasma pneumoniae, Chlamydia pneumoniae, cytomegalovirus and adenovirus were determined. RESULTS: Men without reported baseline heart disease, but not those with heart disease, showing the highest quartile of antibodies to enterovirus and mycoplasma or increased levels of immune complex-bound antibodies to chlamydia had a significantly higher risk of coronary events than men with lower level of antibodies. The increased risk demonstrated in men with high levels of antibodies to enterovirus and mycoplasma remained significant after adjustment for other antibodies, acute-phase reactant and conventional risk factors. Serological evidence of infection by multiple agents was also significantly associated with coronary events. CONCLUSIONS: Serological evidence for several infectious agents is associated with the risk of coronary heart disease, but only in men without baseline history of heart disease.

Epidemiology of documented viral respiratory infections and acute otitis media in a cohort of children followed from two to twenty-four months of age.

BACKGROUND: Viral upper respiratory infections (URIs) are considered major risk factors for acute otitis media (AOM) in young children. We studied the epidemiology and relative roles of different viruses in respiratory infections in a cohort of 329 Finnish children followed from 2 months to 2 years of age. METHODS: A nasopharyngeal aspirate (NPA) was collected whenever the child had signs and/or symptoms of URI and tested for the presence of common respiratory virus antigens or infectivity/nucleic acid (only rhinoviruses). Possible repeated detections of a given virus during a 30-day period were considered to represent a single designated virus-specific episode. AOM and URI episodes were defined in a similar way. RESULTS: At least one virus was detected in 837 (41.7%) of the 2005 NPA specimens examined. Rates of URI and virus-specific episodes showed expected seasonal variation with major peak occurrences coinciding with or preceding those of AOM. The proportions of rhinoviruses, respiratory syncytial (RS) virus, parainfluenza virus (PIV) type 3, influenza virus A and adenoviruses were 63.1, 14.7, 6.7, 6.7 and 6.2% of the total of 761 virus-specific episodes. Influenza virus B, PIV1 and PIV2 were each responsible for approximately 1% of the episodes. AOM was diagnosed in 870 URI cases (43.4%) and in 43.3% of cases associated with a virus-positive NPA. The latter figure was clearly higher (57.7%) for RS virus-positive specimens. CONCLUSIONS: The seasonal coincidence of URI and AOM demonstrated the obvious role of URI in the pathogenesis of AOM. The occurrence of rhinoviruses and RS virus in URI was strikingly more common than that of any other virus tested. Although rhinoviruses were definitely the most frequently found viruses in NPA specimens, the association of RS virus with concurrent AOM was relatively higher than that of any other virus.

Acceptable protective efficacy of influenza vaccination in young military conscripts under circumstances of incomplete antigenic and genetic match.

Commercial inactivated parenteral influenza vaccines reduced febrile (> or = 38 degrees C) respiratory illness by 53% (95% CL: 41-63%) during a 3 week outbreak in 1998 when A/Sydney/5/97(H3N2)-like influenza viruses were shown to be the predominant etiological agents and an older antigenic variant, A/Nanchang/933/95, served as the vaccine virus. The calculatory efficacy for preventing virologically diagnosed influenza infections was 57% (95% CL: 40-68%). The study population consisted of 1374 young male military conscripts. Vaccination coverage on a voluntary basis was 67%. Vaccination was ineffective in preventing febrile illness during a second epidemic wave lasting 2 weeks when mainly adenoviruses were shown to have been circulating in the garrison. Out of the 36 nasopharyngeal aspirates positive for influenza A by antigen detection, 18 A/Sydney/5/97-like strains (10 from non-vaccinated and eight from vaccinated subjects) and two A/Nanchang/933/95-like strains (both from non-vaccinated subjects) were isolated in MDCK cell cultures. Intraepidemic variation was detected among the A/Sydney/5/97-like field strains in their HA1 sequences and reactivity in HI tests, but no evidence was obtained that this variation would have been of significance to the virus in breaking through the vaccination-induced immunity.

Microbial etiology of community-acquired pneumonia in the adult population of 4 municipalities in eastern Finland.

To determine the etiology of community-acquired pneumonia in the adult population of a defined area, specific antibody responses in paired serum samples, levels of circulating pneumococcal immune complexes in serum samples, and pneumococcal antigen in urine were measured. Samples (304 paired serum samples and 300 acute urine samples) were obtained from 345 patients > or =15 years old with community-acquired, radiologically confirmed pneumonia, which comprised all cases in the population of 4 municipalities in eastern Finland during 1 year. Specific infecting organisms were identified in 183 patients (including 49 with mixed infection), as follows: Streptococcus pneumoniae, 125 patients; Haemophilus influenzae, 12; Moraxella catarrhalis, 8; chlamydiae, 37 (of which, Chlamydia pneumoniae, 30); Mycoplasma pneumoniae, 30; and virus species, 27. The proportion of patients with pneumococcal infections increased and of those with Mycoplasma infections decreased with age, but for each age group, the etiologic profile was similar among inpatients and among outpatients. S. pneumoniae was the most important etiologic agent. The annual incidence of pneumococcal pneumonia per 1000 inhabitants aged > or =60 years was 8.0.

Improved sensitivity and specificity of enzyme immunoassays with P1-adhesin enriched antigen to detect acute Mycoplasma pneumoniae infection.

An in-house P1-enriched (168-kDA protein) Mycoplasma pneumoniae antigen preparation was compared in IgG, IgA and IgM enzyme immunoassays (EIAs) to the respective EIAs employing crude antigen lysate, antigen prepared by Triton X-114 partition and two commercial antigens, one of which was an ether-extracted antigen and the other a P1-enriched antigen. In addition, three commercial kits from Sanofi Pasteur, Novum Diagnostica and Savyon Diagnostics were also assessed for comparison. Diagnostic sensitivity was studied with paired samples from adults (n=37) with acute respiratory illness interpreted as acute, recent or past infection to M. pneumoniae on the basis of the results of complement fixation test (CFT). If the consensus of at least two methods is taken as the true positive for acute infection, the diagnostic sensitivities of combined IgG and IgM EIAs were 100% for the Platelia(R), Sero MP and in-house EIAs whereas for the Novum EIAs and CFT- 97% and 74%, respectively. Moreover, the sensitivity of the P1-enriched antigen was proven superior on the basis of systematically highest OD(405 nm) ratios between convalescent and acute serum samples. Analytical specificity was studied by screening serum samples from 92 Finnish blood donors and 111 serum samples from cord blood. Diagnostic specificity was studied in a blind testing of 30 paired serum samples from infants with pneumonia of variable etiology. No single misinterpretation of acute infection from the group of samples with other respiratory diseases did occur. The present study confirmed and extended the earlier observations of the usefulness of P1-enriched antigen for reliable serologic diagnosis of acute M. pneumoniae infection.

Chlamydia pneumoniae is an important cause of community-acquired pneumonia in school-aged children: serological results of a prospective, population-based study.

The aetiology of community-acquired pneumonia in childhood was studied in the total population of 8851 children in the area of 4 municipalities in eastern Finland. All cases of community-acquired pneumonia (n = 201) were registered during a surveillance period of 12 months between September 1, 1981 and August 31, 1982. The diagnosis of pneumonia was verified radiologically in all identified cases. The diagnosis of chlamydial infection was based on an antibody response measured by complement fixation (CF), by enzyme immunoassay (EIA; IgG or IgM) or by microimmunofluorescence (MIF; IgG or IgM), and the diagnosis of mycoplasmal infection on CF alone. In total, 29 cases of Chlamydia sp. infection were diagnosed; 20 were caused by Chlamydia pneumoniae. Thus, C. pneumoniae was an aetiological agent in 10%, of the 201 pneumonia cases: the proportion was 9% for children aged 5-9 y and 31% for those aged 10 y or more. In the study population, the total incidence of C. pneumoniae pneumonia was 2.3/1000/y. Mycoplasma pneumoniae serology (CF) was positive in 44 patients (22%); the total incidence of M. pneumoniae pneumonia was 5.0/1000/y. Serological evidence of both Chlamydiae and M. pneumoniae was detected in 9 (41%) patients. Our results indicate that C. pneumoniae is an important cause of community-acquired pneumonia in school-aged children. Diagnostic serological response to Chlamydia species or M. pneumoniae was found in 42% of pneumonia patients between 5 and 9 y of age and in 67% of patients aged 10 y or more. Thus, we suggest that macrolides should be considered as an empirical antimicrobial treatment for community-acquired pneumonia, especially in school-aged outpatients.

Efficacy of PCR and other diagnostic methods for the detection of respiratory adenoviral infections.

Five methods were evaluated for the detection of adenovirus directly from nasopharyngeal aspirates (NPA), including conventional and rapid virus culture, two antigen detection tests, and the polymerase chain reaction (PCR). NPA specimens were obtained from 269 military conscripts suffering from an acute respiratory infection during an adenovirus outbreak. In 133 cases, paired blood specimens were also available. Virus culture followed by a hexon-specific immunofluorescence revealed 159 (59%) adenovirus-positive specimens and it was used as a reference method. In comparison to conventional culture, a rapid 2-day culture method had a sensitivity of 71%. The sensitivities of an enzyme immunoassay and time-resolved fluoroimmunoassay were 53% and 46%, respectively. The PCR method employing Ad7 hexon-specific primers showed a high sensitivity of 94%, and revealed an additional 15 (6%) specimens that could not be confirmed by virus culture. Serology based on significant adenovirus antibody rises had a diagnostic efficacy nearly equal to the virus culture and PCR methods, but a relatively high number of discordant results was found. The present study demonstrates that PCR is a very sensitive rapid diagnostic method for detecting adenovirus specific DNA in NPA specimens of adults.

Etiology of childhood pneumonia: serologic results of a prospective, population-based study.

BACKGROUND: To investigate the etiology of pediatric community-acquired pneumonia, we conducted a prospective, population-based study covering the total population <15 years of age (n = 8851) in 4 municipalities in eastern Finland. MATERIALS AND METHODS: The number of patients was 201; chest radiographs were available for all cases and paired sera for serologic assays were available for >90% of cases. The methods included assays for antibody response to 3 pneumococcal antigens, specific pneumococcal immune complex assays and conventional antibody tests for mycoplasmal, chlamydial and viral infections. RESULTS: Serologic evidence of specific microbial etiology was obtained in 133 (66%) of the pneumonia patients. Bacterial infection was diagnosed in 102 cases (51%) and viral infection in 51 cases (25%). Streptococcus pneumoniae was the most common agent (57 cases; 28%), followed by Mycoplasma pneumoniae (44; 22%), respiratory syncytial virus (43; 21%) and Chlamydia spp. (29; 14%). Haemophilus influenzae was identified in only 6% and Moraxella catarrhalis in only 3% of the children. More than one specific infection was found in 51 patients (25%). The proportion of pneumococcal cases varied from 24 to 36% by age. Mycoplasma infections were seen mostly in patients > or =5 years and Chlamydia infections in patients > or =10 years of age. CONCLUSIONS: The results of our prospective, strictly population-based study confirm the importance of S. pneumoniae in the etiology of community-acquired pneumonia in children of all ages. M. pneumoniae and Chlamydia pneumoniae are important from the age of 5 years onwards.

Nasopharyngeal eosinophil cationic protein in bronchiolitis: relation to viral findings and subsequent wheezing.

A prospective 4-month follow-up of children hospitalized with bronchiolitis revealed that high concentrations of eosinophil cationic protein (ECP) in nasopharyngeal aspirates (NPA) are predictive of wheezing after bronchiolitis. In the 29 patients who received no anti-inflammatory therapy the median concentration of NPA ECP was 882 ng/g in those with physician-diagnosed wheezing (P = 0.02). The NPA ECP concentration of the whole study group of 88 children with and without subsequent hospital admissions for wheezing were 531 and 299 ng/g, respectively (P = 0.02). At entry the children with negative viral findings had significantly higher concentrations of respiratory tract ECP than those with positive viral findings (515 vs. 240 ng/g; P = 0.01). The concentration of ECP in respiratory secretions decreased significantly after bronchiolitis (P = 0.01) provided that no new viral or mycoplasmal infection occurred. NPA ECP values decreased in relation to time regardless of whether anti-inflammatory therapy was used or not. Children with high concentrations of respiratory tract ECP seemed to benefit from anti-inflammatory therapy with nebulized cromolyn sodium or budesonide; both drugs significantly decreased the number of subsequent physician-diagnosed bronchial obstruction (P = 0.0006), and they tended to decrease the number of hospital admissions for wheezing (P = 0.08). Our results suggest that high concentrations of ECP in respiratory tract secretions in children with bronchiolitis reflect the presence of eosinophilic inflammation also seen in asthma.

Serum eosinophil cationic protein as a predictor of wheezing after bronchiolitis.

We have evaluated the role of eosinophil cationic protein (ECP) concentrations in serum in predicting wheezing after bronchiolitis, during infancy and early childhood. A prospective study at a university hospital serving all pediatric patients in a defined area was designed. Serum ECP concentrations were measured in 92 infants under the age of 2 years on admission for acute bronchiolitis, and 6 and 16 weeks after hospitalization. Nebulized anti-inflammatory therapy was initiated during hospitalization: 32 patients received cromolyn sodium and 32 patients received budesonide for 16 weeks; 30 control patients received no maintenance therapy. The numbers of subsequent physician-diagnosed wheezing episodes and hospital admissions for obstructive airway disease were recorded during 16 weeks of follow-up. At entry, 14 of 92 (15%) children had high (> or = 16 micrograms/L) levels of ECP in their serum. During the 16-week follow-up period, this group of patients had significantly more physician-diagnosed episodes of wheezing (86% vs. 43%, P < 0.01) and hospital admissions for wheezing (64% vs. 19%, P = 0.001) than those with serum levels of ECP < 16 micrograms/L. The number of patients with serum ECP > or = 8 micrograms/L was 25 (27%); 76% of this group developed physician-diagnosed wheezing (P < 0.01), and 48% had hospital admissions for wheezing (P < 0.01). Serum ECP levels decreased significantly with respect to time after bronchiolitis and did not differ among the three intervention groups. We conclude that a high serum ECP concentration during the acute phase of bronchiolitis is a specific but insensitive predictor of wheezing after bronchiolitis.

Detection of antibodies to Mycoplasma pneumoniae adhesion P1 in serum specimens from infected and non-infected subjects by immunoblotting.

Paired serum specimens from 17 patients with Mycoplasma pneumoniae infection, as demonstrated by a rise in complement fixation (CF) antibody titer and 14 single sera, negative in the CF test, were tested for the presence of Ig A, Ig G, and Ig M antibodies to a polypeptide with a molecular weight of 170 KDa (P1) in an immunoblot assay. In acute phase sera, collected in the 1st week of the disease, frequency of occurrence of the antibodies against P1 protein did not exceed 18%. Two to three weeks later, Ig A antibodies were detectable in 82.4%, Ig M in 76.5%, and Ig G antibodies in all convalescent phase sera. No sera negative in the CF test (titer < 4) had antibodies against M. pneumoniae adhesin P1.

Bacterial antibody assays in the diagnosis of acute lower respiratory tract infection in children.

Bacterial antibodies were studied in acute, intermediate and convalescent phase sera (mean duration from first to last sample 36 days) of 121 children hospitalized for acute lower respiratory tract infection. Antibody responses were observed in 45% of all cases and in 29% of the 21 children < 1 year old. A total of 15 responses to Streptococcus pneumoniae (pneumolysin), 20 to Haemophilus influenzae, 9 to Moraxella catarrhalis, 3 to chlamydiae and 8 to Mycoplasma pneumoniae were found. In 79 patients with 4 consecutive samples available, 52% of the 31 responses were measurable within 5 days from admission. Overall the responses were not associated with upper respiratory tract bacterial findings or acute otitis media. Significantly more responses were found in the 121 children with acute lower respiratory tract infection than in healthy controls (P < 0.007). We conclude that bacterial antibody assays provide a useful tool in the study of the etiology of acute lower respiratory tract infection in young children, even if the interval between paired serum samples is short.

Comparison of three serological methods for diagnosing Mycoplasma pneumoniae infection.

AIMS: To compare the novel Serofast latex agglutination test (International Mycoplasma, Toulon-Cedex, France) with the complement fixation test and enzyme immunoassay (EIA) for diagnosing acute Mycoplasma pneumoniae infection. METHODS: Paired sera from 60 patients with respiratory infection who had tested positive for M pneumoniae by complement fixation test were analysed with Serofast and indirect EIA for specific IgG and IgM antibodies. RESULTS: Serofast was less sensitive than the two other tests. Only 30 (50%) out of 60 paired sera which showed a diagnostic seroconversion or had high positive, unchanged antibody titres by complement fixation test or EIA, or both, tested positive with Serofast. Positive test results with Serofast were associated with the presence of a complement fixation test titre of > or = 512 and high positive IgM antibody titres measurable by EIA; virtually all patients with a complement fixation test titre of < 256 or those responding primarily in the IgG class tested negative with Serofast. Based on analysis of sera taken at the acute phase of infection, 10 (17%) of the 60 patients tested positive by complement fixation test, 10 (17%) by EIA, and only four (7%) by Serofast. CONCLUSIONS: Serofast was less sensitive than complement fixation test and EIA and it cannot be recommended as a replacement for either test in routine diagnostic use. It might prove useful in laboratories where non-specific tests, such as the determination of cold agglutinins, are still used for the diagnosis of M pneumoniae infection. Testing paired sera is, however, a prerequisite for obtaining acceptable sensitivity by Serofast as well as other serological methods currently available.

Evaluation of an antigen-capture enzyme immunoassay for rapid diagnosis of Mycoplasma pneumoniae infection.

A new enzyme immunoassay (EIA; Enzygost) for rapid detection of Mycoplasma pneumoniae antigen was evaluated in 51 young adults with acute respiratory infection. The EIA results using sputa and nasopharyngeal aspirates were compared with those of serological antibody tests, culture and a DNA probe. In sputum the sensitivity of the EIA ranged from 40% to 81% and the specificity from 64% to 100%, depending on the reference method. In nasopharyngeal aspirates the sensitivity was well below 20%, but the test was nearly 100% specific.

An epidemic of infections due to Chlamydia pneumoniae in military conscripts.

A prospective observational study of an epidemic of infection due to Chlamydia pneumoniae strain TWAR in Finnish military trainees provided new information on immunity following infection, the range of clinical syndromes and complications, and cell culture isolation. One-half of the trainees studied (43 of 86) had laboratory evidence of C. pneumoniae infection. The etiologic association of C. pneumoniae with disease was strengthened by the sharp increase in cases of pneumonia and in outpatient visits for acute respiratory disease along with the laboratory evidence of infection. The pattern of serological response suggested that 23 of the trainees had a primary TWAR infection and 20 had a reinfection. Evidence that prior infection modified the illness included the frequency of hospitalization (12 with primary infections vs. 1 with reinfection), the development of pneumonia (10 vs. 0), and the requirement for repeated courses of antibiotic therapy (13 courses vs. 0). Isolation was more frequent in HL cells (n = 25) than in HeLa 229 cells (n = 10).

Mycoplasma pneumoniae and Chlamydia trachomatis in acute lower respiratory infections in Filipino children.

The role of Mycoplasma pneumoniae and Chlamydia trachomatis in acute lower respiratory infection (ALRI) was studied by serologic analysis of 216 Filipino children less than five years old living in periurban slums and middle-class neighborhoods. Diagnostic antibody responses to M. pneumoniae and C. trachomatis were observed in 18 (8.3%) and five (4.3%), respectively, of the cases with ALRI. These bacteria are not susceptible to the antimicrobial treatments currently recommended for the treatment of ALRI in developing countries.