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Avian Influenza - The Public Health Significance

by 5m Editor
5 September 2006, at 1:09pm

UK - Avian influenza or “bird flu” is an infectious disease of animals caused by viruses that normally infect only birds, and less commonly pigs. On rare occasions avian influenza viruses have crossed the species barrier to infect humans.

The current outbreak in poultry which started in mid 2003 is unprecedented in scale and severity despite over 150 million birds being destroyed.

However, despite the scale of the poultry outbreaks and the very many people exposed to dead and dying birds, by 23 August 2006 only 241 human cases of Influenza A H5N1 had been reported to the World Health Organisation (WHO). Most were in healthy children and young adults. 141 (59%) have died with fatality rates highest in the 10-19 year age group and lowest in those aged over 50 years. The main route of human infection is through direct contact with infected poultry, or surfaces and objects contaminated by bird faeces. There have been NO reports to date of H5N1 infection among laboratory workers handling H5N1 specimens or those involved in culling infected flocks.

The risks of H5N1 to human health are twofold. Of the few avian influenza viruses to cross the species barrier to infect man, the H5N1 subtype has caused the largest number of severe infections and death. The virus could, if given sufficient opportunities, change to a form that is highly infectious for humans and spreads easily from person to person. This could mark the start of a global outbreak or pandemic.

With the widespread distribution of H5N1 in poultry in some countries and continued exposure of humans more sporadic human cases are expected particularly over the winter months.

Extensive preparations have been made nationally, and within Northern Ireland, to respond to an avian influenza poultry incident. Joint arrangements are in place between DARD and the health sector to ensure that those potentially exposed to infected birds are quickly identified, assessed and offered antiviral therapy and seasonal influenza vaccine, if necessary.

Extensive planning is also underway to prepare for an influenza pandemic. While the timing nor the severity of the next pandemic can be predicted, the probability that a pandemic will occur has increased. For UK planning purposes it is assumed up to 25% of the population (approximately 400,000 people in NI) could become ill over a 6-8 week period with 10-35% workplace absenteeism. This will place unprecedented pressures on the health service, other essential services and industry. Few will escape being caught up, one way or another, in the pandemic. It is too late to start planning once the pandemic starts, therefore the more that can be undertaken now the better prepared the country will be to mitigate the consequences of a pandemic and facilitate subsequent recovery.

ThePoultrySite News Desk

5m Editor