April 29, 2009

experts comment on swine flu

The WHO has raised the pandemic threat level from 4 to 5, one short of the maximum, meaning that, according to this scale, a pandemic is imminent.

Dr Ben Adams, Lecturer in Mathematical Biology, University of Bath, said:

“It’s very difficult to tell in these early stages whether there will be a widespread outbreak in the UK this spring. Usually the pattern of spread for human influenza viruses is different depending on which part of the world you are in. In the northern and southern hemispheres, flu epidemics usually occur in the winter months. In tropical regions outbreaks can occur throughout the year. We don’t know why this difference arises.

“We are now nearing the end of the normal influenza season in the northern hemisphere. It remains to be seen whether or not this swine flu virus will defy the usual seasonal trend and continue to circulate in the UK through the summer, or migrate elsewhere until the autumn.

“It appears this strain of swine flu is a combination of human, pig and avian forms of the influenza virus. Normally bird flu infects the digestive tract and is passed on by contact with faeces. In contrast, human flu infects the lungs and is passed on by coughing and sneezing.

“Human infections with avian flu strains are rare and sustained human to human transmission has not been recorded. Pigs can be infected by avian, human and specific swine forms of the influenza virus. Therefore, they may act as mixing vessels.

“The genome of the influenza virus has eight segments. If an individual is infected with two or more different strains of the virus, they may swap whole segments of their genome. This process of reassortment can rapidly create new forms of the virus with radically different genetic codes and characteristics. The Mexican swine flu appears to be just such a reassortant virus.

“Work is continuing to determine exactly where the different genetic components came from and what the implications are for transmission and virulence in the human population. Clearly this virus is capable of sustained human to human transmission but this has not yet been reported in the UK.”

Keith Plumb, Fellow of the Institute of Chemical Engineers, Chair of the Institution’s Pharmaceutical specialist subject group, said:

“The UK is better placed than many other countries to cope with swine flu because of tested emergency procedures set up by the government and the high stocks of anti-viral medicines. The lessons already learnt from examining how to tackle Avian flu in terms of containment, rapid vaccine development, manufacture and distribution, will help with a potential swine flu pandemic. Any work on swine flu will allow us to learn more and increase the public’s understanding in ways that can be applied to the handling of future pandemics.

“Chemical engineers and scientists have developed methods for mass producing new vaccines (the figure of 3 million in 3 months was discussed at our recent conference on BioSafety) but pharmaceutical regulatory rules that surround new products could stop them being made available so quickly. The outbreak has exposed the inadequate working relationship between Government and the commercial vaccine suppliers. Relevant contracts are not in place to ensure the Government can stockpile the necessary quantity of vaccines.

“The manufacture of swine flu vaccine will likely take priority over the development of seasonal flu vaccines. This could leave us extra susceptible to seasonal flu outbreaks in the next 1-2 years.”

Dr Andrew Watts, Lecturer in Medicinal Chemistry, University of Bath, said:

“This outbreak of swine flu is already a global problem, but the number of cases is low. It appears the main reason there have been deaths in Mexico is that the symptoms are very similar to those of seasonal flu, and so it took some time for them to identify that they were dealing with a new strain.

“However, as soon as the new strain was identified, the necessary measures were put in place to combat it.

“People who have been confirmed as having swine flu are all responding well to treatment, which is encouraging. I’m confident that the UK has enough antiviral drugs to deal with this outbreak, and Government measures to limit the spread of infection are being put into effect.

“Here at the University of Bath we are developing the next generation of anti-viral drugs to treat the virus if in the future it evolves further resistance to current drugs.

“There is really no reason that people should be alarmed at the moment, although those who are at higher risk, such as people who’ve recently got back from Mexico and those who’ve been in contact with them, should contact their GP immediately if they get flu-like symptoms.”

Jeff Evans, Senior Lecturer in Disaster Healthcare, University of Glamorgan, said:

“FFP3 standard face masks are required to filter the airborne droplet nuclei responsible for transmission of the influenza virus. Not only is the mask needed, but proper training in the donning is required to make the mask effective.

“Over the counter & surgical masks are not designed as barriers to prevent inhalation of droplet nuclei. Surgical masks are designed to stop the surgeon spreading diseases outwards from themselves to the operative site, not to stop the inhalation of particulate contamination. Wandering the streets with a face mask on looks dramatic but will probably do little good.

“Effective means of self-protection include:
o,Excellent hand hygiene to prevent self-inoculation from contact with contaminated surfaces.
o,Dispose of tissues promptly
o,Observe good cough & sneeze hygiene
o,Social distancing can be effective, carefully consider attendance at large crowded social gatherings.”

Prof Sally Bloomfield, Chair of the International Scientific Forum on Home Hygiene (IFH), has posted the following on home hygiene: http://www.ifh-homehygiene.org/IntegratedCRD.nsf/IFH_Disease_Flu?OpenForm.