SENIOR Medical Officer Brenda Davidson, aware that senior epidemiologists at the US Centres for Disease Control and Prevention (CDC) are concerned about the prospect of a flu epidemic this winter, said flu "could spread like wildfire".

But she was confident Bermuda had been properly protected by Government's Epidemiology and Surveillance Unit before the onset of the traditional flu season.

"We haven't been seeing many cases so far this year," said Dr. Davidson, "but we don't expect to see any until January or February, our flu season. We can only tell you about the number of cases that have been reported to us by doctors, and so far none have been.

'We have a reporting system in place, and we actively canvass each physician on a weekly basis to find out what infections they are seeing. There's a list of diseases that are notifiable by law, conditions that the GPs have to tell us about even if we don't call them, like tubercolosis, Aids, and gonorrhoea.

"There's another list of what we call 'diseases of interest', like 'flu, or dengue fever, the types of diseases we would report to the Pan American Health Organisation (PAHO), based in New York and the Caribbean."

Dr. Davidson, in Government health service for some 25 years, was properly respectful of a recent article in the New York Times which reported that two of the most senior epidemiologists at the CDC were alarmed by the prospect of a serious outbreak of flu this year, and even more concerned by the possibility of an avian flu pandemic.

"Doctors Keiji Fukuda and Tim Uyeki have been preoccupied with broader and more haunting questions than the shortage of flu vaccine," reported Gretchen Reynolds. "They live with the spectre of the 1918 flu pandemic, which killed somewhere between 20 and 50 million people around the world and around 500,000 in the US, and with the assumption that another pandemic is inevitable."

"Flu epidemics and pandemics have a habit of starting out small and getting very big," said Dr. Davidson, who arrived in Bermuda from Ireland in 1969 to work at the hospital.

"There's not a lot you can do about them until you get a vaccine, and that can take a few years to make. The CDC concerns are nothing new, but they are very real. A new strain like the avian flu is a different kettle of fish. No one has an inbuilt response to that."

Bermuda's health service maintains close contact with the Epidemiological Centre in Trinidad, where there is a large laboratory, and with the CDC.

"We have a lot of links with the Caribbean, and a lot of information goes back and forth, and PAHO, a branch office of the World Health Organisation, has a base there. We know what the CDC are looking for, because they send us updates. We feed information to them, as do all of the other islands."

It was recently reported that Government was able to bring in an adequate supply of vaccine from the US before the Americans realised that they were short of flu vaccine there. The 4,000 vaccines received have been distributed to the hospital, clinics and doctors' offices.

"We think we have reached the majority of our target population," said Dr. Davidson, "and we have only a few doses of the vaccine left. We concentrated on the elderly and those considered most at risk."

Asked how many fatalities Bermuda suffered each year from the flu, Dr. Davidson said: "It's hard to say, because people do not die of flu so much as from complications. It's very hard to quantify, but probably a very small number here, one or two.

"We are as well prepared as we ever are, and numbers have actually been going down over the last few years, but we don't know if that's because of the flu vaccine."

Asked what Bermuda could do in the event of a flu or avian flu epidemic or pandemic, Dr. Davidson did not equivocate.

"There is actually not a lot you can do to prevent the spread of the disease," she advised, "but there are things we can all do to help avoid getting it ourselves or spreading it to others: simple things like avoiding crowded places, and washing your hands.

"Keep washing your hands! And cover any cough, and don't spread your germs to telephones, and bathroom taps, and door handles. That can help reduce the spread of any disease, and if you get it, there are anti-viral drugs available.

"If you get it in the early course of the infection you can reduce the number and severity of cases. But these drugs are not widely available and would be expensive. If someone is at risk of getting some complication that could be fatal, there are some anti-viral drugs that would help.

"There would not be enough medication to deal with a widespread outbreak, nor would it be indicated. Flu is generally a 'self-limiting' disease. Most people may feel terrible, but they don't die of it! The chances of a pandemic still exist, but I think that we could deal with it better, and people would be less likely to develop complications, because they are healthier, and because of public health interventions. It might not spread as fast."

CDC is considered the global "clearing house" for information, advice and assistance on epidemiological outbreaks world-wide.

The New York Times reported that Dr. Fukuda is, by nature, composed. He rarely employs exclamations, and never swears. Gretchen Reynolds wrote that he and his colleague Tim Uyeki find stalking the flu bug to be riveting, if disconcerting, work.

"But what keeps them up at night is the idea that global politics may prevent them from knowing until it's too late that a pandemic is brewing. At 49, Fukuda, the top influenza epidemiologist at the CDC, looks distinguished in a scruffy, academic way and reassuring. He smiles often and gently. So when Keiji Fukuda admits to being as concerned as 'I have ever been', people who know him start really worrying.

"In the past year, Fukuda has watched from his office in Atlanta as events overseas have seemed poised to spiral out of control. Between January and the end of October, 32 people have died from avian influenza in Vietnam and Thailand.

"Tens of millions of chickens have succumbed. Millions of others have been slaughtered. More people have admitted to outbreaks among birds in more provinces than would have been conceivable even 18 months ago. All of this, Fukuda says, 'certainly increases the possibility' of a much larger outbreak of avian flu among people."

His colleague Dr. Uyeki is more blunt than his boss, and is concerned that a world-wide flu pandemic may be brewing in the Far East.

"You have the ingredients in Asia right now for a public health disaster," he said. "It's a mess. It would be nice to be in the field in Asia, to see first hand what is going on."

Their concern is that some governments in the region are remaining close-mouthed, for political and economic reasons, about what is happening within their borders. This reticence exponentially increases the difficulty of the CDC's work. They fear that they might not learn of a big outbreak until it is too advanced to stop.

Flu viruses are divided into three types: A, B, or C, depending on the virus structure. Influenza A is the monster, in both animals and people, causing the most virulent illness. Type A influenzas (unlike Bs or Cs) have multiple sub-types with cryptic identifiers: H1N1, H2N2, H3N2. The 'H' is for hemagglutin, a spiky protein on the surface of the influenza molecule. In human flu viruses, the 'spikes' of hemagglutin connect with matching receptors on the outside of healthy respiratory cells. The virus then melds with the healthy cell and starts replicating.

Neuraminidase, the 'N' in the flu type, another protein, uncouples the virus from its host, tearing the cell membrane and allowing the progeny to escape, killing the cell. Loosed, they start repeating the process deeper and deeper into the respiratory tract.

SEVEN years ago, in Hong Kong, a three-year-old boy tested positive for a type A influenza, H5N1, a bird flu. It wasn't unfamiliar to flu investigators, having been isolated in wild birds in the early '60s, but this avian flu had never been known to infect a human being. An avian flu can occasionally jump from a bird to a person, but an isolated case is not a serious threat to people.

To cause a pandemic, an entirely new human influenza sub-type must emerge, to which people would not have been exposed or have built up immunities. In recent history, three main types of influenza A have circulated freely in humans, each of which caused a pandemic when they were introduced to the human race: the catastrophic 1918 Spanish flu pandemic, caused by H1N1; the 1957 Asian flu epidemic, which killed some 70,000 in the US, was brought about by H2N2, and the 1968 Hong Kong flu, responsible for 34,000 deaths in the US, was introduced by H3N2.

Science doesn't really understand how an avian flu becomes a human flu, but it suspects a process of gene swapping. The worst-case scenarios are what worry Fukuda and his colleagues, because there's so much reluctance in Asia to look for avian flu, that the particular moment when an epidemic becomes a pandemic may go unnoticed.

"In the beginning of a pandemic," he said, "we would have no way of knowing if it were going to be mild or severe. There would be panic."

The first sustained human-to-human transmissions of H5N1, the avian flu, might start insidiously, perhaps within one family whose infections aren't immediately identified as H5N1. It could spread though a village, travel to the nearest city, and race around the world before science had a chance to catch up.

Fukuda would like to be setting up studies in Asia, but he has to be asked. "I am," he said, "more anxious than I would like to be."

In a globalised world where the free flow of medical information can be impeded by politics and economics, and where peripatetic germs can hitch rides in the lungs or luggage of airline passengers, an avian flu virus in Asia yesterday can be in Bermuda today.

Bermuda's Dr. Davidson fully understands the concerns of her CDC colleagues.

"A real pandemic? It could happen and it could spread like wildfire," she advised. "That's what the doctors at CDC are worried about. It's their job to think about worst-case scenarios, and how we would cope with them."