Avian flu experts are concerned that springtime migratory birds and infected poultry shipments could bring the deadly avian flu virus into the United States, which is currently free of the disease. In response, U.S. public health officials have launched a program to detect and contain potential outbreaks of the deadly virus.
Hon Ip, an avian flu expert with the U.S. Department of the Interior, says the new national surveillance program is an ambitious and unprecedented effort to monitor the movement of wild birds, which might be carrying the deadly H5N1 avian flu virus. "The United States is a huge country. There are millions of birds on the move -- but we're going to work smart."
Ip says scientists will be monitoring specific species of wild birds. They'll be focusing on bird flocks coming from Asia, where there's been an epidemic of H5N1, and paying less attention to birds from Europe, where there have been only isolated reports of infected wild-birds.
"We looked at the species of migratory birds on both coasts, both the west and east coasts," he says. "We looked at the situation in terms of how many different species of North American birds actually fly over the Pacific or Atlantic Ocean to Europe or Asia. We looked at the number of species and number of birds in each species that does so. It looks like Alaska has way more birds in terms of sheer number -- we're talking millions -- and species, at least 30 -- that have a portion of the population that fly over into Asia. That's a significantly higher number than the birds on the east coast that will have contact and mingle with birds in Europe."
Hon Ip says surveillance teams will be stationed in as many as 40 different locations in Alaska alone. There will also be teams up and down the U.S. Pacific coast and even scattered among the islands of the west and south Pacific.
"We're going to spread out in some of the [migratory] flyways in the lower 48 states and some of the islands in Oceania. It's going to be a lot of people and a lot of field team efforts," he says. "Don't forget, the Pacific Ocean is a huge ocean. There are birds that fly across the middle of the Pacific. They don't necessarily fly up the coast of Asia. There are other birds that take two different migratory paths that go through the U.S. trust territories in the Pacific. So we also have projects in Oceania, centered around Hawaii and some of the U.S. trust territories to look at those birds that are going to take the mid-ocean route possibly up to the west coast and up to Alaska as well.
What are the American scientists looking for?
"Collecting droppings is one way of collecting samples. We're going to actively trap the targeted species we choose -- having the bird in hand, as it were. We will also look for die-offs of wild birds," Ip says.
"If HN51 does kill birds along the migratory route, we will have people on the lookout for unusual die-offs of birds and those will be sent in for us to investigate. We will try to figure out the cause of death for the birds. We don't want to sample every single Canada goose under the sun. We want to sample bird species that are likely to come over from Asia."
Hon Ip says scientists are also using satellites to track the wild birds, some of which have been implanted with radio transmitters. "Transmitters now allow us to get this incredible information about where birds are migrating, how far they fly between times. You can correlate that with satellite maps from NOAA [National Oceanographic and Atmospheric Administration] so you can see how they're reacting in terms of weather conditions: Are they being put off by them? Do they fly right through it? Do they take advantage of cold fronts that come through? All sorts of stuff. It's just incredible."
That's only one part of the national surveillance program, which is run jointly by the U.S. Department of the Interior and the Department of Agriculture. Agriculture official Ron DeHaven says his agency's role is monitoring imports of poultry products on ships and airplanes, and at the borders.
"We have -- through our customs and border protection, in fact -- sent numerous alerts to be on the lookout for international passengers who might be bringing those products unknowingly," DeHaven says, adding they are also "focusing on high-risk commodity shipments that would be coming from affected countries that might be accidentally or intentionally mislabeled as something else. We're putting a lot of increased resources toward that effort."
Since 2001, about 90 people worldwide have died from close contact with birds infected with the H5N1 virus. A total of about 170 human cases have been reported. The current virus appears unable to jump from person-to-person. But experts warn that could change if the virus mutates.
Murray Trostle, with the U.S. Agency for International Development, says the small number of human victims to date is the result of worldwide vigilance. "The fact that we've only seen 170 cases globally in the last five years is really quite remarkable. The countries have done a very good job of detecting these cases early and reporting them and controlling them.
Officials say the United States is gearing up to do likewise -- as Trostle puts it - "to do a good job, stop the outbreak soon, and prevent it from becoming a human pandemic."