A research paper in Proceedings of the National Academy of Sciences, published online on February 10th, shows that the H5N1 virus has persisted in its birthplace, southern China, for almost ten years and has been introduced into Vietnam on at least three occasions, and to Indonesia. The authors suggest that such transmissions are perpetuated mainly by the movement of poultry and poultry products, rather than by migrating birds.
This is significant because it strongly supports bird conservationists, who have been arguing that most outbreaks in South-East Asia can be linked to movements of poultry and poultry products, or infected material from poultry farms, such as mud on vehicles or people's shoes. Conservationists also argue that live animal markets have played an important role in the H5N1's spread. Such markets were the source of the first known outbreak in Hong Kong in 1997 when 20% of the chickens in live poultry markets were infected.
BirdLife International, a conservation group, reckons there are three likely transmission routes for H5N1: commercial trade and the movement of poultry; trade in wild birds; and the use of infected poultry manure as agricultural fertiliser. Bird conservationists add that although migratory birds can carry and transmit the virus, it is often not clear whether they picked up the infection from poultry.
The U.S. Department of Agriculture has a website on Avian Influenze. Its factsheet informs us:
Historically, there have been three HPAI (highly pathogenic avian influenza) outbreaks in poultry in this country--in 1924, 1983 and 2004. No significant human illness resulted from these outbreaks.
The 1924 H7 HPAI outbreak was detected in and eradicated in East Coast live bird markets.
The 1983-84 H5N2 HPAI bird outbreak resulted in the destruction of approximately 17 million chickens, turkeys, and guinea fowl in the northeastern United States to contain and eradicate the disease.
In 2004, USDA confirmed an H5N2 HPAI outbreak in chickens in the southern United States. The disease was quickly eradicated thanks to close coordination and cooperation between USDA, state, local, and industry leaders. Because of the quick response, the disease was limited to one flock.
USDA classifies avian Influenza as of high (HPAI) or low (LPAI) pathegenicity. It reports that "there are 144 different characterizations of the virus based on two groups of proteins found on the surface of the virus. One group is the hemagglutinin proteins (H), of which there are 16 different types (H1-H16); the other group is the neuraminidase proteins (N), of which there are 9 different types (N1-N9). The virus detected (in birds) in several Asian and European countries is an H5N1 type of highly pathogenic (HPAI) virus."
LPAI poses no known serious threat to human health, however some strains of HPAI viruses can be infectious to people. Since December 2003, a growing number of Asian countries have reported outbreaks of HPAI in chickens and ducks. Humans also have been affected, most of who had direct contact with infected birds. The rapid spread of HPAI in 2004 and 2005 is historically unprecedented and of growing concern for human health as well as for animal health.
The Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota, in its excellent technical summary of the agricultural and wildlife threat from bird flu, provides information on international epidemics.
* In Mexico, an H5N2 strain transformed from LPAI to HPAI and caused an outbreak in 1994-95; the virus continued to circulate until 2003, and "nearly a billion birds have been affected."
* In the Netherlands a strain of H7N7 caused an epidemic in 2003. 30 million birds out of 100 million birds in country were killed; 255 flocks were infected. Disease spread to Belgium but was quite rapidly contained. Over 80 human cases were reported, and one veterinarian died.
* in British Columbia (Canada), an H7N3 strain broke out in 2004; over 19 million birds were culled.
CIDRAP reports that the H5N1 pandemic that started in 2003 and continues, having spread from Asia to Europe and Africa is "by far the most severe outbreak of avian influenza ever recognized. As of December 2005, over 140 million birds have died or been culled. WHO has officially recognized more than 170 human cases, with about half of them fatal, in Vietnam, Thailand, Cambodia, Indonesia, China, Turkey, and Iraq."
Some Implications for Food Security:
The poultry industry has been globalized and industrialized. I recall when I lived in Chile, 40 years ago, a friend was amazed that in Valparaiso he could buy frozen chicken from the United States cheaper than fresh chicken from Chile. U.S. producers had industrialized the production of poultry, increased productivity enormously, and changed chicken from a luxury food to a staple.
For example, this projection from the International Food Policy Research Institute:
Meat Prices, Production and Demand: 1997- 2020
* The price of poultry is expected to go down a slight 4%.
* Demand will rise by 9.4 million metric tons or 33.5% in the developed world and 38.2 million metric tons or 131.0% in the developing world by 2020.
* Developing countries will increase production by 122.8% and developed countries by 37.4%.
* Developed countries will increase net exports by 3.2 million metric tons.
* Total world production will equal 105.0 million metric tons in 2020.
Now one can find huge chicken houses all over the world, producing poultry in an industrialized process. The development of the industry has made meat and eggs more affordable for billions of people. It has also created conditions in which avian flu epidemics can reach pandemic proportions.
Nigeria imports more than a million chicks a year, and, as the Economist article indicates, there is some reason to believe that the international trade in poultry is more responsible for the spread of the disease than is the flight of wild birds.
Bird flu does not easily transmute into human flu, and no one knows whether the current bird pandemic flu will do so. As I have written, this situation seems to be one in which there is a small probability of a catastrophic event. We should certainly prepare, but we probably should not panic!
On the other hand, a pandemic of flu in poultry seems very likely. The costs of destroying poultry have already been in the billions of dollars in Asia, and the disease has spread to Africa and Europe. Fortunately agricultural experts are taking the disease very seriously.
I would point out that the disease may have nutritional effects on human populations. Of course, poor people eat less if their income goes down, and killing tens of millions of chickens will reduce income for many people. The eggs and meat produced by the poultry industry are important sources of protein, and if the supply goes down, protein nutrition will suffer somewhere.
As vegetarians demonstrate, people can get all the protein they need without meat and eggs. Perhaps one thing that should be done now is to develop nutrition education materials and train educators on how to substitute vegetable protein for poultry and eggs. We might also consider agricultural extension programs promoting legumes and other high protein crops. And we might consider other micro-livestock, such as rabbits to provide an alternative source of meat in the absence of foul.