Medical Blogs

March 3, 2007

Unveiling The Nature Of Human And Avian Influenza - Launch Of Influenza Photographic Exhibition Emphasises The Seriousness Of Influenza

Intriguing new photographic images and film footage released today to the public reveal the viruses responsible for seasonal influenza and the currently circulating H5N1 avian influenza 'bird flu' strain.

With contributions from world renowned photomicrographers Lennart Nilsson (Sweden) and Dennis Kunkel (USA), the public exhibition presents the whole influenza 'family tree', from seasonal to avian, epidemic to pandemic. The images have been released as part of a wider influenza exhibition launched this week, entitled Influenza through a Lens. Produced by a leading virology research centre, the images include time-lapse photography of how the strains replicate over time.

Professor John Oxford, Professor of Virology at St Bartholomew's and the Royal London Hospital, and Scientific Director of Retroscreen Virology, UK, the organisation responsible for producing the new time-lapse images, says, "There is so much talk of bird flu and fear of the pandemic, but every year we are subject to the serious threat of an outbreak of influenza which can result in severe illness and loss of life. These images show the different strains of the influenza virus and remind us to take influenza seriously in all its various guises."

H5N1 influenza, the much talked about 'bird flu', is one particular strain of the influenza virus, and is only transmitted to humans through close contact with infected birds. As of 16 February 2007, 273 people have been infected with the virus, of whom 167 have died[i][1]. Experts believe the next influenza pandemic is inevitable and possibly imminent[ii][2] and preparations are underway to try and minimise its impact.

Nonetheless, seasonal influenza remains a severe and debilitating disease and the annual onset presents a significant global threat, affecting 500 million people and claiming half a million lives each year. Regardless of the type of influenza strain which is most dominant each year, influenza's annual impact on society and the economy accounts for one in 10 of all absences from the workplace[iii][3] and costs 12 billion dollars in lost productivity annually in the US alone[iv][4].

Professor Ab Osterhaus, Professor of Virology, Medical Faculty, Erasmus Medical Center, Rotterdam, the Netherlands, states, "People can be complacent about seasonal influenza, but there is much that can be done. Current tools, such as vaccines and antivirals, are still under-used despite being both medically and economically justified. It's important for people to take seasonal influenza seriously and to take precautions to prevent and treat it whilst minimising its spread."

The findings of a recent survey[v][5] reveal some of the barriers to influenza management. Conducted in the US and Europe, the survey quizzed 132 doctors on the key reasons that limit their prescribing of influenza medication to their otherwise healthy patients. The perception of influenza as a self-limiting disease was ranked as a major factor by almost a quarter (23%), whilst a third (33%) considered over-the-counter symptomatic remedies as sufficient and almost half (46%) stated that their patients simply do not seek help in time to benefit from medical treatment for influenza.

About influenza

Influenza, commonly called "flu", is an acute respiratory illness that affects the upper and/or lower parts of the respiratory tract and is caused by an influenza virus. Flu is highly contagious and spreads rapidly by coughs and sneezes from people who are already carrying the virus. Patients become ill between 18 and 72 hours after being infected. The most common symptoms of uncomplicated influenza are an abrupt onset of fever, shivering, headache, muscle ache and a dry cough[vi][6].

There are three types of influenza viruses: A, B, and C. Influenza A subtypes and B viruses are classified by 'strains', variations of the virus caused by ongoing mutation. When a new strain of human influenza virus emerges, antibody protection that may have developed after infection or vaccination with an older strain may not provide protection against the new strain6.

The influenza 'family tree'

Influenza A viruses are divided into subtypes based on the molecules which are on their surface, called haemagglutinin (H) and neuraminidase (N). Haemagglutinin is involved in the attachment of the virus to cells in the respiratory system and neuraminidase is involved in the release of new virus particles from infected cells to uninfected cells in the body and allows the virus to spread. There are 16 types of H (H1 to H16) and 9 types of N (N1 to N9) and these combine in several ways to give the very large number of influenza sub-types e.g. H1N1, H5N1, H9N2, H7N7.

Key pandemic and seasonal strains of note include:

-- H1N1 was the first strain of influenza to be identified and labelled in 1933

-- H1N1 'Spanish flu' A in 1918 caused in excess of 40 million deaths worldwide (although, since influenza was only 'discovered' in 1933, the pandemic was at the time a mystery)

-- H2N2 'Asian flu' A in 1957 caused 1 million deaths worldwide

-- H3N2 'Hong Kong flu' A in 1968 caused 800,000 deaths worldwide in six weeks

-- H5N1 is the currently circulating avian influenza strain in birds that experts predict will mutate, becoming capable of human-to-human transmission, in the next pandemic

-- H3N2 was most dominant seasonal strain in the United States 2005/2006[vii][7]

About 'Influenza through a Lens'

'Influenza through a Lens' is sponsored by F. Hoffmann-La Roche Ltd for the advancement and support of medical, scientific, and patient initiatives.

The exhibition is open to the public from 22 February 2007, staged at Brussels Event Brewery, Rue Delaunoystraat 58 b/1, 1080 Brussels, Belgium. The exhibition unveils newly commissioned footage and photographic stills showing replication of the currently circulating H5N1 avian influenza virus and an epidemic influenza virus, and how the presence of an antiviral affects the replication of these viruses. The public will also learn about the different influenza virus strains, from human to avian, epidemic to pandemic, over the years.

About Retroscreen

Retroscreen Virology, London, UK, is one of Europe's leading contract virology research companies. The work it conducts is dedicated to creating the next generation of antivirals and vaccines in the field of biomedical research.

About the physician survey

The physician survey was conducted by an independent market research agency, Adelphi International Research, commissioned by Roche. 330 physicians were surveyed on current influenza perceptions and management across the United States and Europe (France, Germany and the United Kingdom), 132 of whom cited barriers to the prescription of influenza medication, such as antivirals, in otherwise healthy patients. This subset was asked to rank their key reasons for not prescribing such medication to patients. The overview of the results is as follows.

Base = 132

-- Influenza is as self-limiting disease
No. respondents who ranked this as 1st - 3rd reason - 30
Percentage of total respondents - 23%

-- Symptomatic remedies are effective enough for the treatment of influenza
No. respondents who ranked this as 1st - 3rd reason - 44
Percentage of total respondents - 33%

-- Patient(s) present too late
No. respondents who ranked this as 1st - 3rd reason - 60
Percentage of total respondents - 46%

About Roche

Headquartered in Basel, Switzerland, Roche is one of the world's leading research-focused healthcare groups in the fields of pharmaceuticals and diagnostics. As a supplier of innovative products and services for the early detection, prevention, diagnosis and treatment of disease, the Group contributes on a broad range of fronts to improving people's health and quality of life. Roche is a world leader in diagnostics, the leading supplier of medicines for cancer and transplantation and a market leader in virology.
Roche Influenza


[i][1] Cumulative Number of Confirmed Human Cases of Avian Influenza A/(H5N1) Reported to WHO, last updated 16 February 2007
[ii][2] WHO Avian Influenza Factsheet. Accessed 19 February 2007.
[iii][3] Smith A. The socioeconomic aspects and behavioural effects of influenza. In: Wood C, editor. Influenza: strategies for prevention. London UK: Royal Society of Medicine, 1988:46-52.
[iv][4] Nichol K et al. The efficacy and cost effectiveness of vaccination against influenza amongst elderly persons living in the community. N Eng J Med 1994; 331:778-84.
[v][5] Physician survey conducted by Adelphi International Research, commissioned by F. Hoffmann-La Roche Ltd, July 2006
[vi][6] European Influenza Surveillance Scheme, Influenza Factsheet. Accessed 19 February 2007.
[vii][7] Centers for Disease Control, 2005-6 US Influenza Season Summary. Accessed 19 February 2007.

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