22 December 2005
Public Might Confuse Avian and Pandemic Flu, Expert Says
Spread of avian flu from Asia to Europe raises fears about the Americas
Officials at the Pan American Health Organization (PAHO) said December 20 that the spread of avian influenza from Asia to Europe has raised public concern that the H5N1 virus could reach the Americas.
According to a PAHO press release, such concern is justified but in some cases reflects confusion about the differences between bird flu and pandemic flu.
"Bird flu and pandemic flu are two different things," said Otavio Oliva, PAHO’s top expert on viral diseases.
"Both are a threat,” he added, “but the threats they pose to human and animal health are distinct. The danger is that people might think wrongly that the chicken in the supermarket or in their neighbor’s backyard is going to give them pandemic flu. Fortunately for everyone, that’s very unlikely.”
PAHO experts say that even health officials contribute to public confusion by using a single term – bird flu – to refer to three different phenomena: avian flu in birds, avian flu in people and pandemic flu.
An avian flu virus could mutate into a form that has acquired the ability to spread easily among humans, creating pandemic flu. Although health officials say the likelihood is growing that pandemic could arise, no pandemic has started yet.
Highly pathogenic H5N1, the cause of current concern, is an avian virus that has caused the death or destruction of tens of millions of birds in Asia and cost that region’s poultry industry billions of dollars.
In five countries where the virus is now endemic in birds – Cambodia, China, Indonesia, Thailand and Vietnam – H5N1 in rare instances has jumped to humans, causing almost 140 cases of illness including more than 70 deaths.
Fear of H5N1 has grown in recent weeks as the virus spreads from Asia to Greece, Romania, Turkey and Ukraine, apparently carried by wild birds. No human cases have been reported in those countries.
PAHO Assistant Director Carissa Etienne has warned that the H5N1 virus poses a significant threat to the poultry industry in the Americas, and a major threat to human health if it evolves into a strain that is easily transmissible between humans.
International efforts have focused mainly on fighting the virus among animals in Asia. The World Health Organization (WHO) is working with the U.N. Food and Agriculture Organization and the World Organisation for Animal Health to help Asian countries fight the virus in birds to reduce the likelihood that the disease could mutate to become contagious among humans.
WHO also has developed a contingency plan to contain a human pandemic virus where it emerges, using anti-viral drugs to treat people near the outbreak origin. Such a strategy has never been tried, and no one knows if it will succeed.
A growing number of countries outside Asia are now engaged in preventive efforts and in preparing for a potential human pandemic.
For additional information on avian influenza and efforts to combat it, see Bird Flu.
Flu information from PAHO is available on that organization’s Web site.
Text of the PAHO press release follows:
(begin text)
Pan American Health Organization
Press release, December 20, 2005
Avian vs. Pandemic Flu: Understanding the Threat
Washington, D.C., December 20, 2005 (PAHO)—Officials at the Pan American Health Organization (PAHO) acknowledged today that the spread of avian influenza from Asia to Europe has raised public concerns that the H5N1 virus could reach the countries of the Americas. While such concern is justified, in some cases it reflects confusion about the differences between bird flu and pandemic flu.
"Bird flu and pandemic flu are two different things," said Otavio Oliva, PAHO’s top expert on viral diseases. "Both are a threat, but the threats they pose to human and animal health are distinct. The danger is that people might think wrongly that the chicken in the supermarket or in their neighbor’s backyard is going to give them pandemic flu. Fortunately for everyone, that’s very unlikely.
But it’s also wrong to assume that we’ll be safe as long as the pandemic virus emerges in Asia and not in the Western Hemisphere."
PAHO experts note that even health officials contribute to public confusion by using a single term—"bird flu"—to refer to three different phenomena: (1) avian influenza in birds, (2) avian influenza in people, and (3) pandemic influenza, that is, a mutated form of an avian flu virus that has acquired the ability to spread easily between humans.
Highly pathogenic H5N1, the cause of the current concern, is an avian virus that has caused the death or destruction of tens of millions of birds in Asia and has cost that region’s poultry industry billions of dollars. In five countries—Cambodia, China, Indonesia, Thailand and Vietnam—where the virus is now endemic in birds, it has also, in rare instances, jumped to humans, causing more than 100 human cases and more than 70 deaths.
In recent weeks, fear of H5N1 has grown as the virus has spread from Asia to Greece, Romania, Turkey, and Ukraine, apparently carried by wild birds. However, no human cases have been reported in those countries.
PAHO Assistant Director Carissa Etienne warned in a presentation to the Organization of American States (OAS) last week that the H5N1 virus poses a significant threat to the poultry industry in the Americas, as well as a major threat to human health, should it evolve into a strain that is easily transmissible between humans.
One way the virus could enter the Americas is via migratory birds, she noted. "While our region is not covered by the world’s main flyways, there are some flyways that link Asia with Alaska, and we know there are birds that have crossed the Pacific from Asia to the Americas," said Etienne, citing data from the Food and Agriculture Organization (FAO).
If wild birds brought the virus to the Americas, and if the virus managed to infect domestic poultry, it could cause major losses to the poultry industry, Etienne explained. Moreover, since "poultry is the major source of protein in the region," H5N1 is also a threat to food security, she said.
Nevertheless, if H5N1 entered the Americas via migratory birds, "it would still be bird flu," Oliva explained. "It could cause isolated infections in humans, but it would still have to mutate to become easily transmissible between humans. This is a process that could take time."
Experts have noted that the farther H5N1 spreads geographically, the more chances it has to interact with new human and animal hosts and to develop the ability to spread easily between humans. But some experts think a pandemic strain of H5N1 is more likely to emerge in Asia, where the virus is already firmly established in birds, than in places where the virus has only recently arrived.
This could change over time, as the virus becomes established elsewhere. But "wherever a pandemic strain emerges, it is likely to spread quickly around the world from human to human, entering the Americas not by way of birds, but via humans," notes Oliva.
International efforts so far have focused primarily on combating the virus in Asia. The World Health Organization (WHO) is working with FAO and the World Organization for Animal Health (OIE) to help Asian countries fight the virus in birds. In addition, WHO has developed a contingency plan that would attempt to contain a human pandemic virus where it emerges, using antiviral drugs to treat people at the locus of the outbreak. Such a strategy has never been tried before, and no one knows if it will succeed.
A growing number of countries outside Asia are now engaged in preventive efforts and in preparing for a potential human pandemic. PAHO officials say it is essential to take preventive and preparatory steps in the Americas, and the organization is actively working with public health and veterinary officials throughout Latin America and the Caribbean.
"PAHO is urging its member countries to improve surveillance systems that can detect the disease in both wild birds and in poultry, and to develop preparedness plans for a potential human pandemic," said Etienne. "These threats are related, but different. An epizootic [an epidemic in birds] could be devastating to the region’s poultry industry and could threaten food security.
But a human pandemic would be on a whole other level. Depending on the lethality of the pandemic strain, it could cause millions of deaths and serious economic and social disruption. But it would not just be in the Americas; it would be throughout the world."
PAHO was established in 1902 and is the world’s oldest public health organization. It works with all the countries of the Americas to improve the health and the quality of life of the people of the Americas.
Additional reading: PAHO web page on influenza
"Bird Flu: Communicating the Risk,” article in Perspectives in Health magazine.
(end text)
(Distributed by the Bureau of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)
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