Bird flu: your questions answered...

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On Wednesday, Europeans learned they should avoid eating raw eggs and cook chicken carefully to cut down any risk of contracting bird flu. Clive Cookson, the FT's science editor, will be answering your questions online about the disease. You can email him now at: ask@ft.com


Is there certainty as to how long the present H5N1 virus can survive in bird faeces? Could it perhaps take a ‘spore’ form that might pose a threat for days, weeks or months in the right conditions?
Bernard O’Donnell

Clive Cookson: There has not been enough testing in the field to answer your question reliably. A virus is not a living cell and, unlike some microbes, it does not have anything like a “spore”. How long the virus can survive in bird droppings will depend critically on temperature and humidity. The period could range from a few hours in hot dry conditions to weeks in a large mass of faeces that remains wet.


How is bird flu transmitted to people? I hear it’s safe to eat cooked chicken - does that mean that it’s transmittable through raw poultry? I live in China where they serve some dishes with chicken bone-marrow, should I avoid those too?
Isabelle Dérobert, China

Although the evidence is far from complete, it seems that bird flu has been transmitted to people mainly by breathing in dust, feathers and tiny droplets of body fluids from infected birds. The virus could in principle spread through raw meat through the digestive route is much less important than respiratory transmission. The important thing is to make sure the chicken is cooked so that no pink meat is left. I’m afraid I don’t know how chicken bone marrow is used in Chinese cuisine but if it is raw then you should avoid it - if cooked you can eat it.


Do the eggs present the same threat as the meat of infected chickens?
Salah Aourra

Clive Cookson: Yes, eggs can carry bird flu virus on their shells and inside in the white and yolk. The World Health Organization says that, to be absolutely safe, stick to hard boiled eggs that have been boiled at least 5 minutes.


I booked a private tour of Vietnam and Cambodia for next December well before the explosion of bird flu news. We are to be travelling by plane or private car and staying in 4 star hotels. Should we cancel the trip?. Is the risk associated only with people in contact with infected birds? Your advice is appreciated.
Carlos and Diana Glandt, The Netherlands

Clive Cookson: I myself would not cancel the trip, unless evidence emerges before then that the avian strain has “gone human”. At present the risk is limited to people in contact with infected birds.


Given that flu is more prevalent in cold climates would it be correct to say that a flu pandemic, should one occur, be more likely to spread rapidly in colder climates?
John Arvanitis

Clive Cookson: No, pandemic strains do not follow the rules of normal “seasonal” flu. In the past pandemics have erupted in the summer as well as the winter, and they have spread through the tropics as well as temperate regions.


My wife feeds and waters 20 or so free range doves daily. What are your views on the action she should take?
John Airey

Clive Cookson: If she is in the UK, then carry on as normal until avian flu has reached wild birds here. Then, continue to give the doves food and water but keep her distance from them.


What is bird flu doing to birds? Are all bird species susceptible to it? What is the mortality rate among birds? Could H5N1 wipe out any species?
Pete Maclean

Clive Cookson: Species vary enormously in their susceptibility to H5N1, in ways that ornithologists do not yet understand. Some wild ducks seem to carry the infection without disease, while geese and swans have succumbed. I doubt whether H5N1 will wipe out any entire species.


The assumed inevitability of a mutated avian flu virus resulting in a human pandemic is based on the preceding historical pandemics. Could it not be that the high awareness and high level of monitoring that are present now in combination with rapid response in cases of detection may prevent the outbreak of a pandemic for as long as these conditions are met?
Rens de Groot

Clive Cookson: A pandemic is not absolutely inevitable, I agree.


Does heat destroy a virus such as this, and at what level? (Would roasting make a diseased chicken safe, boiling adequately deal with Indonesian coffee beans hit by droppings, etc.? And are reports of an effective vaccine having been produced (Hungary) true; if so, is it currently being tested in humans?
Neal Ball, Chicago

Clive Cookson: Any temperature about 70 deg C for a few minutes would kill the virus, so a thoroughly roasted chicken without any remaining pink flesh should be safe.

A vaccine against H5N1 is indeed being developed in Hungary but there is not enough clinical evidence to show that it is more effective than other vaccines in development.


Emphasis is being given to the role played by poultry flocks - particularly outdoor, free-range systems - but isn’t there a greater potential role/threat in the UK from pigeons, ducks etc in urban environment. Can they contract this flu? If so do they not pose a greater threat to humans than free-range poultry due to closer proximity and contact if the virus mutates?
Lawrence Woodward

Clive Cookson: Urban birds could contract avian flu. But I don’t think contact with them is as close as that of a chicken farmer with his or her flock.


Everyone seems to have got into a flap about bird flu this week. Is there any reason to panic?

Clive Cookson: No. It is disappointing but not surprising that autumnal migrations have spread the deadly H5N1 flu strain from Asia to birds in south-east Europe (certainly in Romania and Turkey and probably Greece and Macedonia too). There is no evidence the virus has made the genetic mutation everyone dreads: changing to a form that would spread between people.


Is it inevitable that, sooner or later, the avian flu virus will “go human” and start a pandemic?

Clive Cookson: Virologists say there will eventually be another pandemic, though there is no way of predicting whether it will be relatively mild like Asian flu in 1957 and Hong Kong flu in 1968, which killed an estimated 1m people each, or catastrophic like the 1918 Spanish flu that killed 50m. A pandemic starts when an avian flu strain mutates or mixes with human virus and transmits through a population that has no immunity to it.

The H5N1 strain, responsible for more than 100m bird deaths in Asia, is the most likely candidate because it is so widespread and, on the rare occasions when it infects a human, so virulent. If we are lucky H5N1 may never undergo the random genetic changes required to go human. But another avian virus will, sooner or later.


When and where is a pandemic most likely to begin?

Clive Cookson: The timing of its start is completely unpredictable, though some experts say on the basis of limited genetic surveillance data that H5N1 is unlikely to go human over the next few months. Asia remains the most likely location because it has so many birds and people living in close proximity.


If H5N1 does go human, how fast will the pandemic spread?

Clive Cookson: Mathematical modelling shows there is a small but realistic chance of snuffing out a newly humanised strain of avian flu before it even starts a pandemic. Excellent surveillance and rapid administration of Tamiflu antiflu tablets could stop a local outbreak.

Otherwise the virus could spread around the world within a few weeks. An international travel ban would make little difference, because there would have to be some exceptions and flu is so infectious.


Will there be enough time to develop, manufacture and administer a vaccine against the pandemic strain before it spreads around the world?

Clive Cookson: Certainly not. Even using the best new technology and huge resources, it would take four to six months to isolate and characterise the new viral strain, grow seed stock, start manufacturing, prove the vaccine works in clinical trials, license it and deliver to the field. By then millions might have died. But past pandemics have occurred in two or three waves, over about a year, so a crash programme to develop a vaccine would still be worthwhile.

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