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Pandemic influenza and pandemic planning
- Por Socinorte ..
- Publicado 14 Sep 07
- Reuniones Científicas
- S/V
Claude Hannoun, Professeur Honoraire , Institut Pasteur, Paris.
Influenza is one of these familiar plagues which are sometimes mild, sometimes very serious and which are generally underestimated. Clinical diagnosis is not easy since the disease is multiform and many other viruses can produce similar symptoms. A biological confirmation is possible, but delicate: it is necessary to take a nose or throat swab, to send it to a specialized laboratory, and it is not cheap. Actually, the familiar, seasonal epidemic influenza is now under control or we know how to control it. Vaccination of high risk subjects, including elderly patients is recommended in all industrialized countries, reducing morbidity, hospitalizations, costs, mortality and death. Only a few improvements remain to achieve, such as vaccination of children, of health professionals, and reduction of the age limit to 60 years or less.
But there is another face to the problem of influenza. Three pandemics occurred during the 20th century, one of them being one of the worse (if not the worse) health disaster of humanity. The so-called (wrongly) "Spanish Flu", killed between 30 and 100 millions people according to evaluations, in less than one year. There are reasons to think that birds are the reservoirs of viruses which can change their characteristics and specificity over time.
Influenza viruses can also infect birds. All serotypes of the virus surface proteins are present in the world of birds, but very often without causing any disease. On the other hand, humans are usually not susceptible to these avian viruses. As it already happened in the past, an epizootic of avian influenza appeared in China in 1997, with a strain capable of killing chicken and ducks,. But, that time, something new was observed: a panzootic developed, slowly first, and then faster, spreading over South East Asia, Central Asia and Europe. In Western Europe, several countries have experienced the finding of dead wild or domestic birds (Austria, Germany, Croatia, Italy, France, Denmark) and control measures have been implemented to interrupt the contagion chain between birds.
An additional degree of gravity was reached when, starting in 1997, but recently accelerating, human direct contagion has occurred. What was considered as practically impossible has now resulted in more than 100 human deaths in 8 countries (China, Vietnam, Cambodia, Thailand, Indonesia, Iraq, Turkey and Azerbaijan). What could change this situation of a severe but rare infection into a world catastrophe is simply the eventuality of an adaptation or humanization of this avian virus. No case of human to human transmission has been confirmed so far but surveillance has been reinforced.
Many governments, in collaboration with WHO and OIE have studied the possibility to develop, as a precaution, emergency plans which include non medical decisions, plans to design, manufacture, distribute and use a specific vaccine, and to stockpile antivirals.
But there is another face to the problem of influenza. Three pandemics occurred during the 20th century, one of them being one of the worse (if not the worse) health disaster of humanity. The so-called (wrongly) "Spanish Flu", killed between 30 and 100 millions people according to evaluations, in less than one year. There are reasons to think that birds are the reservoirs of viruses which can change their characteristics and specificity over time.
Influenza viruses can also infect birds. All serotypes of the virus surface proteins are present in the world of birds, but very often without causing any disease. On the other hand, humans are usually not susceptible to these avian viruses. As it already happened in the past, an epizootic of avian influenza appeared in China in 1997, with a strain capable of killing chicken and ducks,. But, that time, something new was observed: a panzootic developed, slowly first, and then faster, spreading over South East Asia, Central Asia and Europe. In Western Europe, several countries have experienced the finding of dead wild or domestic birds (Austria, Germany, Croatia, Italy, France, Denmark) and control measures have been implemented to interrupt the contagion chain between birds.
An additional degree of gravity was reached when, starting in 1997, but recently accelerating, human direct contagion has occurred. What was considered as practically impossible has now resulted in more than 100 human deaths in 8 countries (China, Vietnam, Cambodia, Thailand, Indonesia, Iraq, Turkey and Azerbaijan). What could change this situation of a severe but rare infection into a world catastrophe is simply the eventuality of an adaptation or humanization of this avian virus. No case of human to human transmission has been confirmed so far but surveillance has been reinforced.
Many governments, in collaboration with WHO and OIE have studied the possibility to develop, as a precaution, emergency plans which include non medical decisions, plans to design, manufacture, distribute and use a specific vaccine, and to stockpile antivirals.
