麻豆传媒

Everyone who studies infectious disease knows Donald Ainslie Henderson as 鈥淒A鈥�. He studied medicine at the University of Rochester in the 1950s but found his niche in epidemiology when he took a job at the Communicable Disease Center in Atlanta, Georgia, now the Centers for Disease Control, to fulfil his mandatory military service. After fighting smallpox at the WHO, he became a major voice in public health, a dean at Johns Hopkins University in Baltimore, Maryland, and is now a chief architect of the US biodefence programme.

So鈥�how does it feel being the man who eradicated smallpox?

It feels pretty good. I think people realised the enormity of it later as they tried to set up other immunisation programmes. People say smallpox was easy. Well, it was easier than polio but it wasn鈥檛 easy. We had a lot of battles and a lot of people who worked very hard and who lived and died in the field. Terrific people. If I hadn鈥檛 gone out in the field a third of the time I might not have continued. But you go out and find these people living in the worst conditions, working day and night. You鈥檙e fed up with the bloody bureaucracy but go back and say: I鈥檝e got to fight for these people.

I have read that you feel those people did not get enough credit after smallpox was eradicated, so you had an award made for them 鈥� one of the bifurcated needles you used to vaccinate people, bent into a zero. But that鈥檚 not the pin you are wearing鈥�

No, this is the Presidential Medal of Freedom. But there have been those who thought the order of the bifurcated needle was pretty important too.

When did you know you had finally got rid of smallpox?

There was a moment in late January 1974 when I knew we were going to be able to eradicate smallpox. All of Africa was clear except for Ethiopia, the Americas were free, and only India and Bangladesh remained in Asia. But India had seemed insoluble. There was even talk that it was the natural home of smallpox, and eradication was impossible. We had changed strategy in the summer of 1973 and started national searches every month to find and contain outbreaks. The number of reported cases skyrocketed. But gradually the outbreaks decreased in size and, by January 1974, I felt we really had a chance. The last case in India was contained 5 months later, but from that summer of 1973 I had started spending two-thirds of my time outside Geneva, the staff stopped taking vacations, and we all sprinted for the finish line.

How did you end up as an epidemiologist?

It was assumed in the family that I would be a doctor 鈥� with a mother who was a nurse and her eldest brother a doctor. When I finished internship, I had to serve two years in the military, and someone turned up asking if anyone was interested in serving in the Epidemic Intelligence Service. It seemed to me that this might not be a bad way to spend two years. Then I stayed on, and in 1960 I became head of surveillance and set up a small unit to deal with smallpox. It was gone in the US by then, but we were expecting imported cases. The main federal aid agency, the Agency for International Development, asked me to send staff to Africa to launch a 4-year measles vaccination programme. It seemed unwise to me. If they couldn鈥檛 afford yellow fever vaccine at 10 cents a dose, they could never continue with measles vaccination at $1.75 per dose, and so I suggested smallpox eradication in 18 African countries, plus measles vaccine if the countries wished. Smallpox vaccine cost 1 cent per dose and was affordable.

What happened?

They rejected the idea. But President Johnson picked it up, and a year later, that turned into a global eradication programme which WHO member states agreed to support by a margin of only two votes. In November 1966, we went to Geneva for an 18-month assignment that finally ended 11 years later.

If you had to, could you eradicate smallpox again?

Yes, I think so, I think so. There鈥檚 a lot of bureaucracy, especially in the US, that would make it hard to act decisively but smallpox would scare people into action. Some people say with all the turmoil today it would be different. They assume we didn鈥檛 have turmoil. Good lord, we had the Nigerian civil war, Somalia invaded Ethiopia, East Pakistan seceded and India marched in. And there was the cold war, but that was actually helpful because the Russians joined with the US in the effort and provided valuable help in the socialist countries and large quantities of vaccine.

There has been a lot of talk about the threat of smallpox returning. Why worry about one disease that has gone?

We thought we could stop worrying about smallpox when we made it extinct outside the lab. We didn鈥檛 realise until the mid-90s that the Soviet Union had developed methods for producing large quantities of smallpox virus as a biological weapon. Even today there are former production centres in Russia that are still secret and neither foreigners nor some Russian scientists are allowed in. And there are a lot of unemployed scientist who have the expertise to produce smallpox. That鈥檚 why we have been holding conferences like this one in Geneva. It鈥檚 called 鈥淪mallpox Bioterrorism: Thinking the unthinkable鈥� because that is now what has become necessary.

Do you think we should have inspections under the Biological Weapons Convention, like the ones the US rejected in 2002?

I wish we could make something like that work. But frankly I see real difficulties. What would happen would be that those who play by the rules generally will, and those who don鈥檛, won鈥檛. The only possible answer is we have to do a lot more international networking in science, a lot more exchanging of people working in labs. We have had a programme for that in the US, and I don鈥檛 believe we have made the effort we should have to get people into Russian labs. Apart from that, we are just going to have to accept that we will always have to be prepared for the possibility of smallpox returning. And that means stocking the vaccine and having plans for containing the disease if it recurs.

Does it also mean we need to keep the virus and carry out animal experiments to find new drugs and vaccines?

I think my, um, good friends who are doing the animal experiments and I have somewhat different views on this. I don鈥檛 think the experiments look at all encouraging. You have to put a lot of virus into the monkeys, and even then it doesn鈥檛 look like human smallpox. How are you going to test anything with such an artificial system? And is someone going to spend the $800 million needed to take a smallpox drug from discovery to licensing?

Yet the US government has stockpiled the antiviral drug cidofovir in case of smallpox attack鈥�

My candid view is that there has been a lot of very fuzzy thinking about cidofovir. I do not see the science that supports its use either in treatment of clinical smallpox or vaccinia complications. We鈥檝e got the live vaccinia virus vaccine as a preventative for smallpox, and we鈥檝e got anti-vaccinia antibodies as a treatment for the undesirable effects of vaccinia. Fortunately we have very little cidofovir in the stockpile.

Could other diseases be eradicated?

Guinea-worm disease is the one possibility, but that is three years past its target. I see no other disease that is now a certain candidate for eradication. We should devote time and effort toward developing better control measures and implementing them.

How about polio?

Those who run the polio eradication programme have argued that eradication is eventually going to save money because once there is no more transmission among people we will be able to stop vaccinating. They are making an analogy with smallpox, but polio isn鈥檛 smallpox. By all means interrupt human transmission, but to stop vaccinating we have to know it will stay interrupted. Do we know that? We know that the live virus in the vaccine can revert to virulence and may be able to persist in nature for several years. And now it seems there are people with a genetic abnormality who can excrete the vaccine virus for years, and it could always revert. Polio is the easiest and cheapest vaccine to give of the many we give every year. So what鈥檚 the problem? Why don鈥檛 we just keep giving it?

Biologists in the US have to obey strict new biosecurity rules, with criminal penalties. Is this really necessary?

I think we have reacted very strongly on the homeland security side in the US, much more so than in Europe. After a while people will begin to ease off a little, but then there are many people selling services who are highlighting various risks for which they think they have products. I can identify lots of areas where we are so vulnerable it鈥檚 unbelievable I鈥檇 rather not go into the details, but at airports for example, we are still screening people鈥檚 bare feet when there are very large, very obvious risks out there that have essentially been ignored. We are in panic mode: security people are doing things we don鈥檛 need to do and omitting things we do need. There is a real need for mature, balanced judgement