Prevalence Of H1N1 Research Articles

Epidemiology of Influenza-like Illness and Respiratory Viral Etiology in Adult Patients in Taiyuan City, Shanxi Province, China between 2018 and 2019.

To determine the epidemiological status of influenza and understand the distribution of common respiratory viruses in adult patients with influenza-like illness (ILI) cases in Taiyuan City, Shanxi Province, China, epidemiological data between 2018 and 2019 were retrieved from the China Influenza Surveillance Information System, and two sentinel ILI surveillance hospitals were selected for sample collection. All specimens were screened for influenza virus (IFV) and the other 14 common respiratory viruses using real-time polymerase chain reaction. The results of the 2-year ILI surveillance showed that 26,205 (1.37%) of the 1,907,869 outpatients and emergency patients presented with ILI, with an average annual incidence of 297.75 per 100,000 individuals, and ILI cases were predominant in children <15 years (21,348 patients, 81.47%). Of the 2713 specimens collected from adult patients with ILI, the overall detection rate of respiratory viruses was 20.13%, with IFV being the most frequently detected (11.79%) and at a relatively lower rate than other respiratory viruses. Further subtype analysis indicated an alternating or mixed prevalence of H1N1 (2009), H3N2, Victoria, and Yamagata subtypes. This study provides a baseline epidemiological characterization of ILI and highlights the need for a nationwide detection and surveillance system for multiple respiratory pathogens.

High Prevalence of Influenza A (H1N1 and H3N2) Infection in South Iran

Background: Influenza A is divided into a number of subtypes, the most common of which are circulating H3N2 and H1N1. Influenza A and B viruses, which normally circulate in humans (human influenza viruses), are responsible for seasonal influenza pandemics each year. This study evaluated the prevalence of influenza in Hormozgan province and determined the type and subtypes of influenza circulating in the community. Materials and Methods: The present study was conducted in a single center on 1237 patients with acute respiratory syndrome and flu-like symptoms in Hormozgan province, Iran from August 2022 to December 2022. Eventually, patients’ data such as the age, gender, and hospitalization rate of patients with influenza underwent investigation. Results: Out of a total of 1237 samples of patients, 349 (28.2%) cases were diagnosed with positive influenza and 888 (71.80%) cases were negative. Of 349 cases of positive influenza, 3 and 346 cases were diagnosed with influenza B and A, respectively. The results represented that out of a total of 349 positive cases of influenza, 216 (61.90%) and 133 (38.10%) people were hospitalized and visited as outpatients, respectively. Conclusion: From August 2022 to December 2022, Hormozgan province in the south of Iran witnessed an influenza peak with an increase in the prevalence of H1N1 and H3N2 subtypes. The dominant subtype of this peak was H3N2 influenza, but the prevalence of the H1N1 subtype also demonstrated a significant increase. Finally, the cases of hospitalization of patients with positive influenza represented an increase.

Clinical profile, morbidity and mortality among swine flu (H1N1) infected patients: 2015 Gwalior, Madhya Pradesh pandemic, India

Background: Influenza is known to cause annual seasonal epidemics in Asian subcontinent. Our study assessed the clinical profile, factors influencing the response, prognosis and outcome in H1N1 positive patients during February- March 2015. We aimed to understand the epidemiology and patterns of the disease so that the high risks groups could be identified.Methods: Medical records of the patients who were admitted during Feb-March 2015, as a suspected case to the swine flu ward of J A Hospital and G R Medical College, Gwalior, India were manually retrieved and retrospectively studied. H1N1 positive patients, who were diagnosed clinically and confirmed by RT-PCR method, were included for analysis.Results: Out of 208 patients were admitted for suspicion of swine flu influenza and underwent testing out of which 88 (42.30%) were found to be positive for H1N1. Most common (37.40%) affected age group was 20-30 years. Females were more involved (62.5%), out of which 20% were antenatal. The common presenting symptoms were cough, fever, breathlessness. Overall case fatality ratio was 4.45%.Conclusions: Patients with influenza like illness should not panic as many of them become negative for H1N1. In our area prevalence of H1N1 was high in young and females. Most of the patients recovered with symptomatic treatment and oseltamivir therapy. Proper prevention steps, personal hygiene and admission to designated swine flu ward can be helpful in preventing the spread in the community.

Prevalence of H1N1 in and around Hyderabad during pandemic and post pandemic period

Background &amp; Objectives: Pandemic H1N1 spread 74 countries and prompted World Health Organization to raise alarm label it as phase 6. The present study was conducted on throat and nasal swab samples received and tested at IPM Hyderabad, India during 2009-2011 to collect information on positive cases. Materials and Methods: Throat and nasopharyngeal swabs from influenza A H1N1 patients who were clinically diagnosed during august 2009-September 2011 along with their clinico-epidemiological details were collected from identified hospitals from Andhra Pradesh and other neighbouring States. Samples were tested by Real time reverse transcriptase PCR. Results: A total of 6805 samples, both throat and nasal swab samples from each patient were tested for H1N1 influenza virus, of which, 1329 (19.5%) were positive for pandemic influenza A H1N1, comprising 41.1% males and 44.13% females. 11.52% were below 5yrs age. Interpretation &amp; Conclusions: The study showed a peak of cases of pandemic influenza A H1N1 in august 2009 and indicated predominance of H1N1 positive cases (19.5%) in clinically suspected group. So prompt steps should be taken in case of pandemics to contain the spread of disease and lower the load of mortality and morbidity due to pandemics.

Inhibition of Neuraminidase Inhibitor-Resistant Influenza Virus by DAS181, a Novel Sialidase Fusion Protein

Antiviral drug resistance for influenza therapies remains a concern due to the high prevalence of H1N1 2009 seasonal influenza isolates which display H274Y associated oseltamivir-resistance. Furthermore, the emergence of novel H1N1 raises the potential that additional reassortments can occur, resulting in drug resistant virus. Thus, additional antiviral approaches are urgently needed. DAS181 (Fludase®), a sialidase fusion protein, has been shown to have inhibitory activity against a large number of seasonal influenza strains and a highly pathogenic avian influenza (HPAI) strain (H5N1). Here, we examine the in vitro activity of DAS181 against a panel of 2009 oseltamivir-resistant seasonal H1N1 clinical isolates. The activity of DAS181 against nine 2009, two 2007, and two 2004 clinical isolates of seasonal IFV H1N1 was examined using plaque number reduction assay on MDCK cells. DAS181 strongly inhibited all tested isolates. EC50 values remained constant against isolates from 2004, 2007, and 2009, suggesting that there was no change in DAS181 sensitivity over time. As expected, all 2007 and 2009 isolates were resistant to oseltamivir, consistent with the identification of the H274Y mutation in the NA gene of all these isolates. Interestingly, several of the 2007 and 2009 isolates also exhibited reduced sensitivity to zanamivir, and accompanying HA mutations near the sialic acid binding site were observed. DAS181 inhibits IFV that is resistant to NAIs. Thus, DAS181 may offer an alternative therapeutic option for seasonal or pandemic IFVs that become resistant to currently available antiviral drugs.

A new concept of the epidemic process of influenza A virus.

Influenza A virus was discovered in 1933, and since then four major variants have caused all the epidemics of human influenza A. Each had an era of solo world prevalence until 1977 as follows: H0N1 (old style) strains until 1946, H1N1 (old style) strains until 1957, H2N2 strains until 1968, then H3N2 strains, which were joined in 1977 by a renewed prevalence of H1N1 (old style) strains. Serological studies show that H2N2 strains probably had had a previous era of world prevalence during the last quarter of the nineteenth century, and had then been replaced by H3N2 strains from about 1900 to 1918. From about 1907 the H3N2 strains had been joined, as now, by H1N1 (old style) strains until both had been replaced in 1918 by a fifth major variant closely related to swine influenza virus A/Hswine1N1 (old style), which had then had an era of solo world prevalence in mankind until about 1929, when it had been replaced by the H0N1 strains that were first isolated in 1933. Eras of prevalence of a major variant have usually been initiated by a severe pandemic followed at intervals of a year or two by successive epidemics in each of which the nature of the virus is usually a little changed (antigenic drift), but not enough to permit frequent recurrent infections during the same era. Changes of major variant (antigenic shift) are large enough to permit reinfection. At both major and minor changes the strains of the previous variant tend to disappear and to be replaced within a single season, worldwide in the case of a major variant, or in the area of prevalence of a previous minor variant. Pandemics, epidemics and antigenic variations all occur seasonally, and influenza and its viruses virtually disappear from the population of any locality between epidemics, an interval of many consecutive months. A global view, however, shows influenza continually present in the world population, progressing each year south and then north, thus crossing the equator twice yearly around the equinoxes, the tropical monsoon periods. Influenza arrives in the temperate latitudes in the colder months, about 6 months separating its arrival in the two hemispheres. None of this behaviour is explained by the current concept that the virus is surviving like measles virus by direct spread from the sick providing endless chains of human influenza A.(ABSTRACT TRUNCATED AT 400 WORDS)