RFE/RL: What is avian influenza?
Cheng: Avian influenza -- also known as bird flu -- is a contagious disease that we normally only see in birds and sometimes in pigs. And the concern for us is that when it affects wild birds, that can, in turn, affect domestic poultry like chickens and ducks that people keep for food. And, in turn, there may be interactions between those birds and humans and -- in very, very care cases -- it's possible for this disease to jump into humans.
RFE/RL: The current outbreak is caused by a strain known as H5N1, which can be transmitted to humans. Could you explain why this strain is of particular concern?
Cheng: We've seen that this strain is capable of infecting humans from time to time. It has jumped the species barrier. And also since 2004 we've seen it become essentially established in the Asian poultry populations. So we know that this is a strain that is quite hardy. It can survive in the environment, and it has the capability to infect humans. So that it essentially is meeting two other conditions that we need for a pandemic. This is a new subtype of influenza that has never circulated before in humans, and we know it's capable of causing human infection. So what we're worried about is that if this strain somehow changes to acquire the ability to be transmitted among humans. And if that happens, it's possible that we could have a pandemic.
RFE/RL: How is it transmitted to humans?
Cheng: We don't know exactly how it is transmitted to humans. It is still a very rare occurrence when the strain infects humans, but we believe that it's somehow airborne and that humans will get this disease if they come into very close contact with diseased birds. So if they are handling chickens who have died of H5N1, [if] they're preparing it for food maybe, if they inhale some of the dust in which these chickens have been, then it's possible that they could acquire this disease. But we don't know exactly how.
RFE/RL: Can you catch it by eating chicken or eggs?
Cheng: No, we haven't had any cases that have been linked to consumption of food. Well-cooked chicken and eggs are not a risk factor for contracting H5N1. But the reason that we talk about it is that in these parts of rural Asia, the people who are eating the chicken are also involved in its preparation -- so they are de-feathering the chicken and slaughtering the chicken -- and that can be a risk factor for contracting H5N1.
RFE/RL: What are the symptoms in humans?
Cheng: It's very similar to influenza, so it will be respiratory symptoms, fever and coughing, body aches, and things like that.
RFE/RL: Can it be treated?
Cheng: There is one known treatment so far that has been shown to be effective for treating people with avian influenza -- but only if it's given in the very early courses of illness -- and that's called oseltamivir or Tamiflu.
RFE/RL: Is there a vaccine to protect humans against H5N1?
Cheng: There is not yet. There are several initiatives that are working on a H5N1 vaccine. The most advanced is one in the United States. They are basically working with an H5N1 strain from Vietnam to produce a vaccine. This is still in the very early stages, and WHO encourages countries that have the resources to invest in this kind of vaccine development so that we might be better prepared if a pandemic does emerge from this particular strain.
RFE/RL: Would a flu shot protect humans from catching bird flu?
Cheng: No, it would not. The regular flu shots you get, those take into account the seasonal influenza strains that are going around, and this does not offer any protection against avian influenza.
RFE/RL: So far, some 60 people have died from the H5N1 avian-flu virus in several Asian countries, such as Vietnam. What is being done in the affected countries to contain the virus and prevent its spread?
Cheng: We have WHO offices there, in the countries that are most affected. We are working very closely with the ministries of health to identify cases as they become apparent, and we are also working with the countries to strengthen their surveillance systems. There is ongoing research into vaccines in several countries. I think the most important thing WHO is doing is encouraging all countries worldwide to work on a pandemic preparedness plan so that they consider some of the issues that will come up during a pandemic now, before it happens.
International Conference Aims For Coordinated Response To Bird Flu