A is for air travel, the manner in which swine flu attacked the world from its outbreak point in Mexico. Research in the New England Journal of Medicine showed that in March and April last year more than two million people flew from Mexico to more than 1,000 cities worldwide. Researchers said patterns of departures from Mexico in those months varies little from year to year. Swine flu began its spread in March and April this year. Passengers travelled from Mexico to 164 countries. Four out of five of those went to the United States.

B is for bird flu, no relation. Last year the world braced itself for a bird flu pandemic that broke out in Asia and began spreading. The worst didn't come to pass, however, and when swine flu first appeared it was initially regarded as a case of the boy who cried wolf. That was soon revised when it was discovered that the wolf was really there, the swine was spreading, and that we should be grateful the bird's pandemic wings were broken.

C is for contagious. The H1N1 virus appears to be highly contagious and can spread quickly from person to person through tiny droplets in coughs and sneezes. If you are close to a person with flu you can breathe these droplets in and become infected. Droplets can also be passed from surfaces like door handles and hand rails.

D is for death. The HSE is now conceding that the spread of the flu is such that it is inevitable that deaths will occur, most likely later this year. The head of population health at the HSE, Pat Doorley, says we are likely to follow a pattern set in Britain.

"Looking at the pattern in the UK, it is clear we are going to have more cases and that the doubling time for those cases will shorten and, inevitably, there will be some deaths," he said. Over 700 people are now believed to have died worldwide from swine flu.

At the same time, he said there was no need for people to become alarmed because while it was a "fairly infectious" disease, the World Health Organisation (WHO) has described it as a moderate illness.

Last week, two patients were seriously ill with the flu, one of them reported to be in a critical condition. The latest estimates point to at least 1,500 in this country being infected.

E is for elderly. For once in matters flu-like, the elderly appear to be best placed to ride it out. Out of the 1,500 or so people already affected by the virus in this country (as of 23 July), only 3% of cases involve people over 65 years of age. One in 10 cases occurred in children aged up to four years, while three out of 10 cases affected five- to 19-year-olds.

The figures also show that 43% of cases are of people between 20 and 44, with 14% aged between 45 and 65.

F is for face masks. The face mask is now a worldwide symbol of the flu, most likely to be seen in international airports, worn by frequent flyers. All the expert evidence suggests that the masks provide only the minimum protection against catching the virus, but the high visibility of the masks means that they are the perfect tool with which to spread panic, and raise stress levels among all and sundry.

G is for Gawker.com, a US website which claims the reaction to swine flu has been entirely hysterical. It has compiled a video montage of news coverage on the issue, calling it "Aporkalypse Now".

H is for hygiene. A new sneeze etiquette is being encouraged, attempting to ensure that hands and hankies are used extensively in stopping the spread of germs through sneezes.

Hankies are now being deployed in all manner of workplaces.

I is for infection. Stopping the spread of infection involves high-grade hygiene again. Tips from health websites include: keep your fingernails clean and clipped short, avoid sharing personal items such as razors, face towels, deodorant and bar soap and disinfect gym equipment before use.

J is for John Hemming, British MP, who called for those suspected of having swine flu to be excluded from the country. He wanted airline travellers to be barred, but didn't specify how this might be done. The WHO said travel-exclusion orders such as those proposed would not be helpful.

K is keeping it among the pigs. Flu is common among swine, but what has now happened is it has transmitted to humans. The most likely manner in which the flu passed to humans was through those who work with poultry and swine, who are deemed to be at increased risk of contraction. Vaccination of these workers is a primary public-health matter, but inevitably some were not vaccinated and so we have a pandemic on our hands.

L is for lovers. Love stories may have to be rewritten at discos. One of the extreme measures that is so far only the subject of rumours is that some disc jockeys are considering banning the slow set in order to minimise chances of the virus traipsing down the same road as the birds and the bees.

In Britain, there has been advice to women to refrain from getting pregnant while the flu is raging, but the HSE's Pat Doorley says there are no plans to make such recommendations on this side of the Irish Sea.

In a similar vein, the Bishop of Cork and Ross John Buckley has written to priests in his diocese telling them to ask mass-goers not to shake hands. Since May, the traditional sign of peace at mass has been a no-go area in the Derry diocese.

Doorley says there is no need to resort to such measures as cutting out handshakes or banning the gathering of large groups of people.

M is for Mexico. For it was here that the flu mutated from swine to humans. The central American country is one of the worst affected so far and its tourism industry has taken a severe battering.

N is for noting the origins of swine flu. First spotted in 1918 during the flu pandemic of that year. It was noted that pigs were becoming sick at the same time as humans. It wasn't until 1930 that an influenza virus was identified as being the cause of disease in pigs.

O is for an outbreak, which begets an epidemic, which begets a pandemic.

P is for pork, meat of the swine. One of the great myths is that those at risk or hoping to escape infection should avoid eating pork. But the meat of the swine is just fine.

Q is for quantifying these flu pandemics. The only two pandemics in the latter half of the 20th century were the Asian flu of 1957 and the Hong Kong flu of 1968. The 1957 pandemic broke out in China and spread across to North America, where it was responsible for up to 70,000 deaths. Advances in medical technology meant it was identified early on and a vaccine developed by late 1957. However, a second wave hit the following year accounting for many of the deaths.

The Hong Kong flu of 1968 killed around 34,000 people. The lesser number of casualties was put down to greater awareness following the flu of 11 years earlier, and the fact that the earlier pandemic immunised many by the time the Hong Kong flu took flight.

R is for rates of admission to hospital and deaths. According to research in the US, the rate of admissions to hospitals and deaths of those infected is relatively low. For every 1,000 infections of the swine flu, there are 40 admissions to hospital and a single death. The same level of research in Europe is not yet available. These figures imply that the virus is no more deadly than other strains of flu which attack every winter. The difference is in the level of spread of infection.

S is for symptoms. They do not creep up over a number of days, but hit like a sledgehammer. The symptoms are quite similar to those of regular flu. It's the usual stuff: fever, headache, sore throat, nasal stuffiness and cough. And body aches are very common. The only thing is to go to bed, but that doesn't banish the miserable feeling. Doctors advise to stay between the sheets for up to a week, and with a bit of luck and a headwind, you'll be back in harness in no time.

T is for Tamiflu and treatment. In mid-July, the HSE accepted that it was no longer possible to contain the flu, so it switched to a policy of treatment. Tamiflu is now available in pharmacies throughout the country and those ill with flu and in high-risk groups will be prescribed the anti-viral treatment by GPs. The HSE is advising that Tamiflu only be dispensed to those at the greatest risk of a severe dose.

U is for UCD, the first third-level institute to confirm a swine flu case.

V is for vaccine. Expected to be ready by the autumn. There is currently much debate as to the value of a vaccine and whether or not efforts should be made to accelerate its availability.

W is for washing. Again and again, it's back to hygiene. Washing hands regularly is encouraged. One American health outlet poses the rhetorical question: "Not sure how long to scrub? Sing the Happy Birthday song in your head while rubbing your hands together with soap and rinse when done." Have a nice day.

X is for the X factor, that unforeseen side effect of swine flu. In 1975, a US soldier died of swine flu, fuelling fears of an outbreak. A vaccine was rushed out. No pandemic occurred but the vaccine had some bad side effects. The debacle helped sink the re-election chances of President Ford, who had pushed for the vaccination campaign. Since then, American politicians haven't liked talking about swine flu, lest they come down with a dose of Gerald Forditis.

Y is for Young, Neil. The aging rocker doesn't have the flu but he does have a nasal inflection. The main point of his inclusion in this A to Z is that he is a fine musician, whether rocking to beat the band in the free world, or plucking out some acoustic tunes. As such, he is the perfect antidote to a dose of the flu, and we would recommend taking him to bed for the duration. Of particular worth might be his Live at Massey Hall album from 1971, which was recorded only a few short years after the Hong Kong flu of 1968.

Z is for zoonotic. This is the technical name given to swine flu when it has transmitted from the swine into humans, causing human influenza.