Influenza and influenza-like illnesses in Poland in the epidemic season 2010/2011 according to the SENTINEL influenza surveillance system.

The aim of this study was to analyze data collected by the SENTINEL influenza surveillance system in Poland in the first post-pandemic season 2010/2011. The results include weeks 35/2010-17/2011. Physicians registered weekly number of influenza-like illnesses and collected specimens. Laboratory tests were done using PCR and/or real-time PCR or immunofluorescence. Laboratories also isolated the influenza virus. Influenza-like illness incidence amounted to 2802.7/100000. Weekly incidence ranged from 11.3/100000 to 232/100000. The most affected group was children 0-4 years. Influenza-like illness peak occurred between weeks 02/2011 and 11/2011. Influenza infections were confirmed in 34.9% of specimens. More cases were caused by influenza A, including A(H1N1)pdm09 than influenza B (59.9% vs. 40.1%). The isolated strains were similar to A/California/7/2009 or B/Brisbane/60/2008. Season 2010/2011 in Poland did not differ from the rest of Europe. Further improvement is necessary, especially in the area of specimen collection at the beginning of an epidemic season and carrying out the isolation of the influenza virus.

Application of three duplex real-time PCR assays for simultaneous detection of human seasonal and avian influenza viruses.

This study was performed to develop real-time PCR (qPCR) for detection of human seasonal and avian influenza viruses in duplex format. First duplex qPCR detects haemagglutinin (HA) gene of influenza virus A(H1N1)pdm09 and HA gene of influenza virus A(H3N2), the second reaction detects neuraminidase (NA) gene of influenza virus A(H3N2) and NA gene of influenza virus A(H1N1)pdm09 and A(H5N1), and the third reaction detects HA gene of influenza A(H5N1) and nonstructural protein gene of influenza B virus. Primers and probes were designed using multiple alignments of target gene sequences of different reference strains. Assays were optimised for identical thermocycling conditions. Their specificity was confirmed by conventional PCR and monoplex qPCR with nucleic acids isolated from different influenza viruses and other respiratory pathogens. Plasmid constructs with a fragment of specific gene were used to assess sensitivity of the assay. The limit of detection ranged from 27 to 96 cDNA copies/reaction. Clinical specimens (n = 107) have been tested using new assays, immunofluorescence and monoplex qRT-PCR. It has been shown that developed assays have been capable of rapid and accurate simultaneous detection and differentiation of influenza viruses. They are more sensitive than immunofluorescence and at least as sensitive as monoplex qRT-PCR.

[Development of duplex real-time PCR assay for identification of influenza viruses of subtype A(H1)pdm09 and A(H3)]. / Zastosowanie reakcji duplex real-time PCR do identyfikacji wirusów grypy podtypu A(H1)pdm09 i A(H3).

INTRODUCTION: Among different laboratory techniques used in influenza surveillance, methods based on molecular biology, such as real-time PCR, play increasingly important role. They allow detection and identification of viruses currently circulating in human population and responsible for infections and diseases. The aim of the study was to develop duplex real-time PCR assay for detection and differentiation of influenza virus subtype A(H1N1) pdm09 and A(H3N2). METHODS: Specific primers targeting a highly conservative region ofhaemagglutinin gene and a dual-color TaqMan probes, labeled with fluorophore JOE (560 nm) and quencher BHQ-1 or CalFluor Red 610 (610 nm) and BHQ-2 were designed. The specificity of duplex reaction was evaluated using RNA isolated from reference strains of influenza virus A(H1N1)pdm09, A(H3N2), A(H1N1) and A(H5N1), B and other respiratory pathogens. Sensitivity of the assay was tested using serial dilutions ofplasmid constructs carrying fragment of specific viral HA gene, in range between 10 and 10(5) copies/sample. A number of 116 clinical samples were tested using developed duplex qPCR assay in comparison with the CDC monoplex assay, RESULTS: Positive duplex qPCR results were obtained only in samples containing RNA of influenza viruses of a specific subtype. The limit of detection (LOD) of developed method amounted up to 27 copies/sample for A(H1N1)pdm09 and up to 37 copies/sample for A(H3N2). CONCLUSIONS: The results show that developed TaqMan-based duplex qPCR assay is a valuable diagnostic tool in influenza virus surveillance for using in direct study of clinical specimens as well as identification of isolated strains of influenza virus.

[Methods of detection of selected respiratory viruses]. / Metody wykrywania wybranych wirusów wywolujacych zakazenia ukladu oddechowego.

Respiratory viruses contribute to significant morbidity and mortality in healthy and immunocompromised individuals and are considered as a significant economic burden in the healthcare system. The similar clinical symptoms in the course of different viral and bacterial respiratory infections make the proper diagnosis difficult. An accurate and prompt diagnostics is crucial for infection control and patient management decisions, especially regarding the use of antibacterial or antiviral therapy and hospitalization. Moreover, the identification of the causative agent eliminates inappropriate use of antibiotics and may reduce the cost of healthcare. A wide variety of diagnostic procedures is applied for the detection of viral agents responsible for respiratory tract infections. For many years, the viral antigen detection and standard isolation technique in cell culture was the main method used in routine diagnostics. However, in recent years the nucleic acid amplification techniques have become widely used and have significantly improved the sensitivity of viral detection in clinical specimens. Molecular diagnostic assays have contributed to revealing high rates of co-infection (multiplex reactions) and allow identification of agents that are difficult to culture. This paper discusses a number of technical aspects of the current most commonly used techniques, their general principles, main benefits and diagnostic value, but also some of their limitations.

[Influenza in Poland in 2009]. / Grypa w Polsce w 2009 roku.

A total number of 1,081,974 cases of influenza and influenza-like illness were registered in Poland in 2009 (incidence 2,835.9 per 100,000 population). It was nearly 5 times more than in 2008. The impact on increase of the number of reported cases have had two factors: the pandemic of influenza caused by virus A(H1N1)v, and increasing of the surveillance sensitivity. 3,177 (0.29%) cases was laboratory confirmed. In the area of particular regions incidence ranged from 805.2 in swietokrzyskie voivodeship to 5,257.9 in warmifisko-mazurskie voivodeship. Nearly 37% of cases were children under 15 years. The incidence in this age group was 6,851.2 (from 2,010.1 in Swietokrzyskie voivodeship, to 13,291.6 in warminsko-mazurskie voivodeship). The highest reported incidence was observed in age group 5-14 years (7,135.2). To hospitals, mainly for epidemiological reasons, 8,944 people were sent (0.83% all cases). According to Central Statistical Office data, there were 87 death cases, including 8 (9.2%) children in the age of 15. 70.1% of deaths were registered as cases caused by identified influenza virus.

Rapid differentiation of mixed influenza A/H1N1 virus infections with seasonal and pandemic variants by multitemperature single-stranded conformational polymorphism analysis.

Mixed infections of a single host with different variants of influenza A virus are the main source of reassortants which may have unpredictable properties when they establish themselves in the human population. In this report we describe a method for rapid detection of mixed influenza virus infections with the seasonal A/H1N1 human strain and the pandemic A/H1N1/v strain which emerged in 2009 in Mexico and the United States. The influenza virus A/H1N1 variants were characterized by the multitemperature single-stranded conformational polymorphism (MSSCP) method. The MSSCP gel patterns of hemagglutinin gene fragments of pandemic A/H1N1/v and different seasonal A/H1N1 strains were easily distinguishable 2 h after completion of reverse transcription-PCR (RT-PCR). Using the MSSCP-based genotyping approach, coinfections with seasonal and pandemic variants of the A/H1N1 subtype were identified in 4 out of 23 primary samples obtained from patients that presented with influenza-like symptoms to hospitals across Poland during the 2009-2010 epidemic season. Pandemic influenza virus strain presence was confirmed in all these primary samples by real-time RT-PCR. The sensitivity level of the MSSCP-based minor genetic variant detection was 0.1%, as determined on a mixture of DNA fragments obtained from amplification of the hemagglutinin gene of seasonal and pandemic strains. The high sensitivity of the method suggests its applicability for characterization of new viral variants long before they become dominant.

[Influenza in Poland in 2008]. / Grypa w Polsce w 2008 roku.

A total number of 227,346 cases of influenza and influenza-like illness were registered in Poland in 2008 (incidence 596.5 per 100,000 population). Compared to 2007 on 39.2% incidence decrease was observed. Regionally the incidence varied from 142.3 in swietokrzyskie voivodeship to 1,830.6 in opolskie. Children and adolescents under 15 years of age accounted for 36% of all cases (age group incidence 1,415.6). In this age group the incidence varied regionally from 342.9 in swietokrzyskie voivodeship to 4,083.6 in opolskie. The highest reported incidence was observed in age group 0-4 years (1,545.6). 153 patients (0.07% of all cases) required hospital admission. There were 16 deaths due to influenza, of which 11 (68.8%) were among persons over 70 years of age. In the epidemic season 2007/08 infections with influenza virus registered in Poland were caused by type A (60% of laboratory confirmed influenza cases) as well as by type B (40% of laboratory confirmed influenza cases), similarly to other parts of Europe. Forty-four influenza strains were isolated, including 24 strains of subtype A/H1 and 20 strains of type B. All of them were antigenically similar to the vaccine strains recommended for the epidemic season 2007/2008.

Immunization against influenza during the 2005/2006 epidemic season and the humoral response in children with diagnosed inflammatory bowel disease (IBD).

BACKGROUND: Patients with inflammatory bowel disease (IBD) who are treated long-term with immunosuppressive drugs can experience a decrease in their overall resistance to infections, including influenza. The purpose of this study was to evaluate the humoral response in children with IBD after being vaccinated against influenza. MATERIAL/METHODS: Children with IBD were vaccinated with split inactivated vaccine. They were divided into 2 groups: children treated with anti-inflammatory medications and children treated with 5-acetylsalicylic acid along with immunomodulatory therapy. Antihemagglutinin (anti-HA) and antineuraminidase (anti-NA) antibodies were assessed before vaccination and 1 and 6 months after vaccination. RESULTS: Anti-HA and anti-NA antibodies 1 and 6 months after vaccination were higher than before vaccination. In the patients treated with anti-inflammatory medications, the protection rate (PR) attained the highest level for antigens A/H1N1 and B 6 months after vaccination. However, for A/H3N2 the result was 88.9% at 1 and 6 months after vaccination. In the patients who received immunomodulatory medications, the highest PR was noted 6 months after vaccination (47.6-90.5%). The response rate (RR) in patients who were treated with the anti-inflammatory medications alone remained the same 1 and 6 months after vaccination. In patients who received the immunomodulatory regimen, the highest RR was recorded 6 months after vaccination (47.6-76.2%). CONCLUSIONS: Response to vaccination was satisfactory, although not for all vaccine antigens, especially in patients treated with immunomodulatory medications. The higher levels of RP and RR 6 months after vaccination compared with 1 month after vaccination lends support to the argument that IBD patients should be vaccinated as soon as vaccine is available in a season.

Anti-influenza vaccination in systemic lupus erythematosus patients: an analysis of specific humoral response and vaccination safety.

The objective of this study is to evaluate efficacy and safety of influenza vaccine in systemic lupus erythematosus (SLE) patients. We studied SLE patients and healthy subjects immunised with inactivated influenza vaccine. Efficacy was measured by comparing humoral response to vaccine antigens between groups. Safety was monitored by SLEDAI and serological markers. Subjects attended visits at baseline and on post-vaccination weeks 4 and 12. We enrolled 62 SLE patients and 47 healthy subjects. In post-immunisation week 4, anti-haemagglutinin antibody titres rose in the patient group at least 6.23-fold, compared to 11.90-fold among controls (P < or = 0.05). The seroconversion rate range was 53-56% among patients and 72-85% among controls (P < 0.05 for strains H1N1 and H3N2, NS for strain type B). The seroprotection rate ranged between 62% and 73% and between 90% and 98% in the patient and control group, respectively (P < 0.05). In post-vaccination week 12, the antibody titre was higher at least 3.86-fold in the patient group and 7.65-fold among controls. The seroconversion rate range was 32-40% among patients and 64-70% among controls, while the seroprotection rate ranged between 43% and 50% and between 79% and 94%, respectively (P < 0.005 for three strains). We identified one severe and six mild to moderate SLE exacerbations by week 12. The anti-nuclear antibodies and anti-double-stranded DNA titres grew by post-immunisation week 4 (P < 0.05). The post-vaccination response was weaker in SLE patients compared to healthy subjects. Immunisation did not change underlying disease activity.

[Influenza in Poland in 2007]. / Grypa w Polsce w 2007 roku.

A total number of 374,042 cases of influenza and influenza-like illness were registered in Poland in 2007 (incidence 981.3 per 100,000 population). Compared to 2006 on 48.6% incidence increase was observed. Despite this increase influenza activity in 2007 was among the lowest during the last four decades. Regionally the incidence varied from 182.2 in pomorskie voivodeship to 2,957.1 in opolskie. Children and adolescents under 15 years of age accounted for 33% of all cases (age specific incidence 2,098.3). In this age group the incidence varied regionally from 398.8 in pomorskie voivodeship to 5,908.3 in opolskie. The highest reported incidence was observed in age group 0-4 years (2,240.7). 763 patients (0.20% of all cases) required hospital admission. There were 18 deaths due to influenza, of which 17 (94.4%) were among persons over 70 years of age. In the epidemic season 2006/07 infections with influenza virus registered in Poland were mainly caused by type A, similarly to other parts of Europe. Seventeen influenza strains were isolated, including 12 strains of subtype A/H1 and 5 strains of subtype A/H3. All of them were antigenically similar to the vaccine strains recommended for the epidemic season 2006/07.

Antibody response to influenza vaccine in coronary artery disease: a substudy of the FLUCAD study.

BACKGROUND: Influenza vaccination is recommended for patients with cardiovascular diseases. The main reason for the low vaccination rates in such patients is insufficient knowledge about vaccination efficacy, including immune response to the vaccine. The aim of this study was to assess humoral response to influenza vaccination in patients with coronary artery disease. MATERIAL/METHODS: This was a substudy of the randomized prospective double-blind placebo-controlled FLUCAD study on influenza vaccination in the secondary prevention of ischemic coronary events in patients with coronary artery disease. Patients received inactivated subunit vaccine (n=325) or placebo (n=333). Anti-hemagglutinin and anti-neuraminidase antibody levels to the vaccine strains as well as IgM and IgG levels against influenza A and B were measured before administration of vaccine/placebo and after 8-10 weeks in 78 vaccinated and 97 placebo patients. RESULTS: Post-vaccination antibody titers were significantly higher than before vaccination, with mean increases of 4.9- to 5.7-fold for anti-hemagglutinin and 3.5- to 4.2-fold for neuraminidase antibodies. Post-vaccination protection rates ranged from 56.4 to 60.3% and response rates from 62.8 to 68%. The percentage of patients with significant post-vaccination concentrations of IgG and IgM was higher than before vaccination and amounted to 100% and 88.1% in the case of IgG and 14.3% and 5.2% in the case of IgM in response to influenza A and B, respectively. CONCLUSIONS: At least 60% of the patients achieved high post-vaccination antibody levels sufficient to prevent influenza.

Testing of human specimens for the presence of highly pathogenic zoonotic avian influenza virus A(H5N1) in Poland in 2006-2008 - justified or unnecessary steps?

Since 1997, human infections with highly pathogenic zoonotic avian influenza viruses have shown that the risk of influenza pandemic is significant. In Europe, infections caused by the highly pathogenic avian influenza A(H7N7) virus were confirmed in the human population in 2003 in the Netherlands. Moreover, outbreaks of A(H5N1) infections were observed in wild and farm birds in different European regions, including Poland in 2006-2008. This study presents 16 patients in Poland from whom clinical specimens were collected and tested for A(H5N1) highly pathogenic avian influenza. This article shows the results of laboratory tests and discusses the legitimacy of the collection and testing of the specimens. All patients were negative for A(H5N1) infection. Nevertheless, only two patients met clinical and epidemiological criteria from the avian influenza case definition. The conclusion is that there is still a strong necessity for increasing the awareness of medical and laboratory staff, as well as the awareness of some occupational groups about human infections with avian influenza viruses, including the importance of seasonal influenza vaccination. It should also be emphasized that in the case of patients suspected of being infected with avian influenza, the information about clinical symptoms is insufficient and must be accompanied by a wide epidemiological investigation.

[Influenza in Poland in 2006]. / Grypa w 2006 roku.

A total number of 251,815 cases of influenza and influenza-like illness registered in Poland in 2006 (incidence 660.4 per 100,000 population). Regionally the incidence varied from 75.6 per 100,000 in swietokrzyskie voivodeship to 1,690.4 in mazowieckie. The highest reported incidence was observed in age group 0-4 years (1,543.1 per 100,000). Children and adolescents under 15 years of age accounted for 34.3% of all cases (age specific incidence 1,434.8 per 100,000). In this age group the incidence varied regionally from 190.2 in lubuskie voivodeship to 3,582.5 in lódzkie. 284 patients (0.11% of all cases) required hospital admission. There were 14 deaths due to influenza, in 71.4% these were persons over 70 years of age. In the epidemic season 2005/06 infections with influenza virus registered in Poland were mainly caused by type B similarly to other parts of Europe. Thirty five influenza strains were isolated, including 6 strains of subtype A/H1, 2 strains of subtype A/H3 and 27 strains of type B. All of these isolates with the exception of one strain of influenza B were antigenically similar to the vaccine strains recommended for the epidemic season 2005/06.

Influenza vaccination in secondary prevention from coronary ischaemic events in coronary artery disease: FLUCAD study.

AIMS: To evaluate the effect of influenza vaccination on the coronary events in patients with confirmed coronary artery disease (CAD). METHODS AND RESULTS: Randomized, double-blind, placebo controlled study. We included 658 optimally treated CAD patients; 477 men, mean age 59.9+/-10.3 years. Three hundred and twenty-five patients received the influenza vaccine, and 333 patients placebo. Median follow-up was 298 (interquartile range 263-317) days. Primary endpoint was the cardiovascular death. Its estimated 12-month cumulative event rate was 0.63% in the vaccine vs. 0.76% in controls (HR 1.06 95% CI: 0.15-7.56, P = 0.95). There were two secondary composite endpoints: (i) the MACE (cardiovascular death, myocardial infarction, coronary revascularization) tended to occur less frequently in the vaccine group vs. placebo with the event rate 3.00 and 5.87%, respectively (HR 0.54;95% CI: 0.24-1.21, P = 0.13). (ii) Coronary ischaemic event (MACE or hospitalization for myocardial ischaemia) estimated 12-month event rate was significantly lower in the vaccine group 6.02 vs. 9.97% in controls (HR 0.54; 95% CI: 0.29-0.99, P = 0.047). CONCLUSION: In optimally treated CAD patients influenza vaccination improves the clinical course of CAD and reduces the frequency of coronary ischaemic events. Large-scale studies are warranted to evaluate the effect of influenza vaccination on cardiovascular mortality. (ClinicalTrials.gov: NCT 00371098).

[Influenza in Poland in 2005]. / Grypa w 2005 roku.

A total number of 773,234 cases of influenza and influenza-like illness registered in Poland in 2004 (incidence 1921.4 per 100,000 population). Regionally the incidence ranged from 3391.8 per 100,000 population in Mazowieckie to 364.0 in Swietokrzyskie. Children and adolescents under 15 years of age accounted for 34.5% of all cases (age specific incidence 4045.3 per 100,000). In this age group the incidence varied regionally from 6381.1 in Mazowieckie to 797.6 in Swietokrzyskie. 1469 patients (0.20% of all cases) required hospital admission. There were 52 deaths due to influenza, in 82.7% these were persons over 70 years of age. In the epidemic season 2004/05 forty nine strains of influenza virus were isolated in Poland, including 2 strains of subtype A/H1, 23 strains of subtype A/H3 and 24 strains of type B. Antigenic analysis showed that they were similar to A/New Caledonia/20/99 (H1N1), A/Wyoming/3/2003 (H3N2), B/Hong Kong/330/2001 and B/Jiangsu/10/2003. Besides, RT-PCR method and immunofluorescence test allowed to confirm influenza in other 26 cases and infections with respiratory viruses as RSV, parainfluenza or adenovirus in other 25 cases.