A DOCTOR WRITES:Moving to phase six of a six-point pandemic scale will make little difference to most of us
THE DECLARATION of the world’s first flu pandemic for 41 years by the World Health Organisation (WHO) has been well flagged; nonetheless it is the long overdue realisation of a prediction by experts in infectious diseases.
With the last global pandemic declared in 1968 and an approximate 30-year gap between influenza pandemics, the current outbreak is more than 10 years behind schedule. Scientists had expected the avian influenza virus to be the culprit; this H1N1 version of influenza A has instead emerged from pigs.
Influenza viruses affect humans, pigs, birds and other animals. Most are species specific, but as we have seen the virus can be transmitted from animals to humans.
Swine flu usually occurs in people who have contact with pigs; what is different in the case of the latest outbreak is the ready human-to-human transfer of this flu virus.
The WHO has confirmed that human cases are of a never before seen version of the H1N1 strain of influenza A. This latest version of the virus contains genetic material from humans, birds and swine, which suggests it has arisen from a mixing of different versions of the virus.
It is this type of genetic reassortment that scientists have warned would lead to the next flu pandemic.
Now that we have moved to phase six of a six-point pandemic scale, what does this mean? In epidemiological terms it means we are seeing human-to-human transmission in at least two regions in the world.
It does not mean the virus is in any way more deadly or more virulent.
The symptoms of swine flu in humans are the same as our regular seasonal flu. They are: muscle aches, high temperature, cough, sore throat, runny nose, headache and a general feeling of malaise. Diarrhoea and vomiting may also occur. Typically, the symptoms come on within hours, rather than the slower development of symptoms seen with the common cold and other viruses.
The Republic has sufficient stockpiles of effective antiviral drugs. Tamiflu, taken as a tablet, and Relenza, a spray, work if they are taken within 48 hours of the onset of flu symptoms.
Because this strain of swine flu is genetically distinct from previous flu strains, there are, as yet, no vaccines available to combat it. However, pharmaceutical companies are already working on a vaccine that matches the genetic make-up of the pandemic virus. This should be available in the autumn.
How worried should we be about the pandemic declaration? In practice, it will make little immediate difference to most of us. It does mean that the authorities will change their focus from containment to mitigation. This means the intense contact tracing we have seen in response to the 12 cases identified here to date will be relaxed for future cases. The aim of mitigation is to delay and “flatten” the peak of the epidemic; to try to spread out the impact on the healthcare system; and to buy time in the hope that the number of cases will be reduced.
The practical effects such as measures to implement social distancing (the suspension of school classes and other mass gatherings) may be seen in southern hemisphere countries such as Australia and Chile, which have experienced a sudden surge in cases in recent days. This is because it is winter south of the equator, a season that lends itself to the ready spread of respiratory viruses.
While it may be a reminder of what we may face later in the year, yesterday’s declaration should not trigger public alarm here.
The old and the young represent the classic at-risk groups from regular flu outbreaks. We know that when a new virus emerges, death may occur in healthy adults who mount the strongest immune response to infection. Such is the level of inflammation that fluid leaks from cells causing serious illness.
However, this is not the case with the present pandemic. In fact those aged over 60 appear to have some natural immunity to the H1N1 flu and are the least affected. People with pre-existing diseases such as diabetes are being hit hardest.
The situation here may worsen in the autumn, but for the present there is no need for alarm.