Stopping Spread Among Poultry

Dr. Alex Thiermann has been president of the standard setting committee for the World Animal Health Organization (OIE) in Paris, France since 1994. He has been seconded to the OIE by the U.S. Department of Agriculture to devote most of his time to the work of the OIE serving as a special advisor to the Director General. He served previously as senior trade coordinator and regional director for U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS) in Brussels. From 1997 to 1999, he was twice elected chairman of the World Trade Organization's Committee on Sanitary and Phytosanitary Measures (dealing with food safety and animal and plant health measures). A native of Chile, Dr. Thiermann attended the University of Chile at Santiago, where he received his doctorate of veterinary medicine. He also attended the School of Medicine at Wayne State University in Michigan, where he received a PhD degree in microbiology and immunology.

Multinational Monitor: How does avian flu affect bird populations and does it affect them all the same way?

Dr. Alex Thiermann: Avian flu in general is a disease that has been known for centuries. There are a variety of strains, just like we find with the human flu.

We are dealing currently with a very pathogenic and very aggressive strain, called H5N1. This kills poultry almost 100 percent - you will see a mortality rate of 70 to 80 percent in the first three days - so it is extremely pathogenic. It will affect most domestic poultry, whether it is turkeys or chickens. It also affects ducks, but ducks do not always show signs of disease and do not always die - they appear to be a little bit more resistant. Some of the wildlife species are not as sensitive. What we have encountered recently with swans in Europe is that they are very resistant carriers, as are some of the water foul that we saw in migrating the disease from Asia. Some species are less likely to be infected, such as domestic pigeons. We cannot say that they cannot be infected, but they at least are much less likely to be infected, and we do not have any information that they have been infected by this virus.

MM: Do you have any explanations for those different susceptibilities?

Thiermann: No, not at all. It is quite common in the animal world that the pathogenicity of viruses varies between species. Even within species, we have certain lines that are more susceptible than others.

MM: Is there any chance at this point of the disease not spreading to every region of the world?

Thiermann: Potentially, it can spread to any region of the world. The two main ways of transmission are by the movement of infected animals and products - so we continue to put a lot of emphasis on preventing any illegal trade - and through migratory water foul.

So while I said in theory it could come to the areas that have not been affected, such as the case of the Americas, it would either have to come in through illegal trade or through infected migratory wildlife.

There are a lot of conditions that would have to take place before that would happen. First, the migratory water foul that carry the disease through Europe must still be infected, and we don't know if that is the case. Second, this population would have to come in direct contact with and manage to infect birds in the North American flyways. Once those birds are infected, they would have to be able to carry the virus through the migration and then come in contact with domestic birds in the American continents. So it is possible, but I would call it unlikely.

MM: In retrospect, could the disease have been contained if proper measures had been taken at the initial outbreak?

Thiermann: It probably could have been contained. We could be doing a lot better now, and we would be witnessing many fewer areas affected if the right things were done at the right time.

More specifically, I mean that in 2003-2004, the disease could have been contained if the necessary resources had been mobilized for countries in Southeast Asia to control infection in domestic poultry.

The controls that we recommend to fight the disease in poultry do work. We keep talking about early detection, stamping out the infection, and in cases where it is spreading, combining the stamping out procedure with controlled vaccination.

Unfortunately, while there has been a lot of coverage on the pandemic potential, and about what we are going to do for pandemic preparedness, in my opinion, too much attention and resources went in to taking the measures for the fifth and sixth step for the pandemic evolution. Very little to no resources were deployed to fighting the first step of the potential pandemic evolution, which is preventing the spread through poultry in Vietnam, Thailand and other countries in Southeast Asia.

MM: Is vaccination an effective option, and if it is, why not do it more widely?

Thiermann: Vaccination is a useful tool for very specific purposes. We do not recommend preventative, across-the-board vaccination.

In France recently, they were monitoring wildlife, because it was suspected that if H5N1 came to France, it would be through wildlife. They detected the first dead duck, and they took the measures of raising the awareness and separating the domestic population. But they concluded that it would have been very difficult to isolate large numbers of domestic ducks through biocontainment, to put them indoors. So, under those conditions, the French government decided to vaccinate that particular duck population. They were isolated from the rest of the domestic population in case things didn't go well. There, vaccination was just an additional measure to complement what they were doing.

And then the vaccine must meet the efficacy standards set out by the OIE [the World Organization for Animal Health]. It has to be administered as recommended and with revaccination, and it has to be followed by surveillance. In other words, you need to monitor that vaccinated population through various mechanisms to determine whether they have antibodies because of the vaccine or whether they have antibodies because they have been infected. You have to accompany that total procedure by using sentinel animals - we recommend unvaccinated chickens - so if there is some virus circulation, it almost certainly will affect those sentinel birds, and you will know of the virus' presence.

Lastly, you have to have an exit strategy before you start. You have to know when and where you want to do it and how soon you will stop. It is not recommended to continue "just in case."

MM: Is the core concern with vaccination that because it is not wholly efficacious it will obscure the actual spread of the disease?

Thiermann: There are a number of factors.

One of them is that there is no need to expose animals to vaccines because we need the capability to respond when it is needed.

The second is that vaccination in most cases could prevent the animal from dying, but it certainly cannot give us a guarantee that the animals will not get infected. So especially when we are dealing with very large numbers of animals, one or another of them is going to get infected; and if we don't monitor it, it will give a false sense of security and allow the fire to smolder on the ground.

MM: How cooperative are farmers in eradication programs, if they know their birds will be culled?

Thiermann: It is very important that a compensation mechanism accompany early detection efforts, particularly when you are dealing with a backyard approach. And we have good examples, including Vietnam.

You have to move in quickly and work with industry and locals to make sure that you pay sufficiently but not too much. After all, these people don't want to get rid of the chickens. Having a program quite often coupled with other assistance - replacement birds, better diets and heating lamps to raise the day-old chickens, things like that - is more conducive to encouraging people to turn the chickens in and not to have a significant loss on their part.

I understand that the same is being done in Nigeria to make sure that there is a good compensation program there.

MM: What is the capability of veterinary services in developing countries, speaking generally and also specifically about sub-Saharan Africa?

Thiermann: The concern we have is that all of these things will work, provided you have a veterinary service that is able to apply the tools and do this early detection.

Any infection in any country poses a risk to the rest of us, so we need to help those countries that don't have the sufficient infrastructure for early detection and taking action. Importantly, such assistance is also going to put these countries in a better position to early report any future event of an emerging disease.

If we look back in history, we know that it is only a matter of years before we are faced with serious disease. We need to raise the ability of all countries to detect and respond. We need to strengthen veterinary services and we need to view them as a public good.

MM: Are you able to offer some general characterization of how robust those services are?

Thiermann: They vary immensely.

We have a plan that begins with an initial assessment of the strengths and weaknesses of veterinary services in accordance to the standards that the OIE has for veterinary service. We have developed an assessment tool and are preparing veterinary experts to use the tool. Basically, you approach all stakeholders - in both government and the private sector - and they have to respond to questions related to their legislation, their laboratory capabilities, the field force, ability to report, etc. Then you go section by section identifying the strengths and weaknesses of each of these systems.

We have a commitment from the World Bank that they will not support any veterinary service-related program, any grant, or loan to any country before the assessment has been done, so as to ensure that the money is devoted to addressing weaknesses that have been found.

MM: If the money has been made available from the Bank or from donors, how quickly can countries build out their services to fill the gap between what they have and what they should have?

Thiermann: Resources have been slow in coming, but I think things are beginning to move now.

It's difficult to make a general statement, but it's true that money alone is not going to solve the problem. Some problems - like bringing up laboratory capabilities or training laboratory personnel - can be addressed relatively quickly. By contrast, improving the field workforce and setting up a network for reporting - and, more importantly, setting up a culture of transparent reporting - may take a little longer.

We feel that it will take two to three years to really bring up to speed a fairly deficient veterinary services - provided that everyone wants to do it right.

MM: Has there been any deterioration in veterinary services over time in developing countries or has it been a chronically underinvested-in area?

Thiermann: Even in developed countries such as the UK or the U.S., there has been deterioration for a number of reasons.

In the case of the U.S., one reason is that veterinary services are funded on the basis of control and eradication programs for specific diseases - the big ones in livestock were tuberculosis and screw worm. As the eradication efforts succeeded, the money started drying up. While the systems are still adequate, we tend to trend down on expenditures.

In the case of the United Kingdom, when foot-and-mouth disease came in, it was evident that there was an insufficient field force to detect and report - it was more than three to four weeks before they detected it. So, in general, there are not too many countries that could claim to have fully functional veterinary services.

MM: The countries in Southeast Asia where the outbreaks started seem to be on their way to recovering reasonably well. What has happened to make this possible?

Thiermann: It was a combination of awareness in the field and vaccination, which in the beginning was not working very well but now is working extremely well.

While there are still cases in backyard flocks here and there, there are no human cases and the more industrial part of the poultry industry is not affected. This was achieved by a combination of detecting, stamping out and disinfecting, followed by a vaccination campaign.

In Thailand, it was an awareness in a key population and disinfection without vaccination.

In Cambodia, they deployed some 900,000 of what they called "barefoot veterinarians" -villagers that were given mobile phones to report any unusual case in poultry and in humans.

So there are different, very clever and at times inexpensive ways that raise awareness and allow quick reporting.

By contrast, we are not seeing the same in Indonesia, for example - that is one place where something is not working right.

MM: What would you say the role is or has been industrial farming operations in the spread of the disease?

Thiermann: In general, it has been very minor.

If we look even in Thailand, a major poultry exporter from the very beginning of the outbreak, extremely few industrial poultry operations were affected with the disease. It is not a disease that affected the commercial industry and certainly not a disease that was spread through commercial operations. It was primarily in the backyard chickens, and the Thais learned very quickly that they had to separate the industrial operations.

And it is a question of who gave it to who: it is very possible that backyard chickens may have infected certain wildlife that had started migrating, because the disease was not transmitted to the rest of the world until this year, while it festered in Asia for a while.

The illegal movement of poultry and poultry products may have played a bigger role in transmission to Egypt and Nigeria and other parts of Africa.

But the industrial part of the poultry in Southeast Asia was rarely affected.

MM: How has the international poultry trade been affected by H5N1?

Thiermann: When the disease was reported in Thailand, the entire market was shut down. After awhile, it reopened, but primarily it was restricted to cooked poultry meat. But the industry has not had the virus, and the virus has really negatively affected the industries as importing countries have made requests that go far beyond what is recommended through international standards.

MM: Do you expect the H5N1 virus to play itself out and die down in the near or medium term, or is this going to be with us for the foreseeable future?

Thiermann: It is very difficult to completely eradicate the virus, but my expectation is that if we do everything right, the effect will be significantly minimized. I think we will live with avian influenza in pockets here and there, particularly in those areas where backyard and wildlife come together, but hopefully through raising awareness we will keep a bigger part of the industry out of it and we will keep humans from being exposed and increasing the risk of a human pandemic.