Q&A: Bird Flu in Humans

Following are questions regarding bird flu in humans, along with responses from Drs. William Schaffner and Pascal James Imperato. Schaffner is chair of the Department of Preventive Medicine, Vanderbilt University School of Medicine, and an infectious-disease consultant for the World Health Organization. Imperato is chair of Preventive Medicine and Community Health, SUNY Downstate Medical Center, and former New York City health commissioner.

Q: Why have so many people died from bird flu in the past few weeks? H5N1 seems now to be exploding in many countries at once -- Sharon, Beckenham, Kent London

A: There are likely several contributing reasons: 1) Public health authorities around the world are looking harder for bird flu -- and, the harder you look, the more you will find. 2) Bird flu has spread to more countries both by migratory birds [mostly water fowl] as well as human activities [smuggling contaminated poultry, selling contaminated manure for fertilizer, etc.].

Please recall that most of the reports have been of infected birds and poultry, not humans. Even though transmission to humans is quite unusual, the more infected birds there are, the greater the chance of an occasional transmission event to a person. -- answered by Schaffner

Q: My doctors tell me bird flu is nothing to worry about, but clearly the experts are concerned. … People look for sound advice from their doctors and I am afraid the wrong message is being sent out. What is being done to help doctors spread the correct message about H5N1 and a possible pandemic? -- T.R., Tennessee

A: As one of the concerned experts, I hope that clear messages are getting out. Actually, your doctors were right on target -- they were trying to convey that bird flu is NOT here in the U.S. and still is NOT capable of being transmitted easily from person to person. Thus, please keep things in perspective. Indeed, the annual visitation of "regular" influenza actually causes, on average, the death of 36,000 persons in the U.S. each year, not to mention 200,000 hospitalizations. My strong recommendation, therefore, is for all to take advantage of the protection provided by yearly influenza vaccination. Please make sure that you -- and all in your family -- are protected each winter/spring influenza season. -- answered by Schaffner

Why do so many people fear it will lead to millions of deaths in healthy young people if this pandemic hits? -- Carone Sturm, Fairbanks, Alaska

A: This fear is based on comparisons to the mortality rates observed in the 1918 pandemic of influenza and the expressed opinions of some medical scientists. However, there is currently no firm scientific evidence to support this assumption. The disease is currently one of animals, primarily birds, and is not transmitted from person to person. Our ability to treat patients with influenza and its complications are far superior to any medical interventions available in 1918. Many people who died in 1918 developed secondary bacterial pneumonias for which we now have highly effective antibiotics. -- answered by Imperato

Q: Vietnam has not had a death this year from bird flu. Does this mean that they are effectively dealing with this problem either in their bird flocks or medical treatment of human cases? -- David, Elyria, Ohio

A: There are two principal factors that have reduced the level of transmission among birds and other animals in Southeast Asia and China at the present time. One is the mass vaccination campaigns in domestic fowl that have been undertaken in some areas. The other is that a large number of surviving wild birds now have protective antibodies to the virus and thus do not transmit it. Both these factors serve to interrupt transmission. That said, however, because the life spans of both wild and domestic birds are relatively short, younger wild birds will not have natural immunity and would be susceptible to the virus and could spread it once infected. -- answered by Imperato

Q: Since the regular flu season is coming to an end this spring, are the chances of the bird flu mutating into a pandemic less likely this year?" -- Lisa, Worcester, Mass.

A: Influenza viruses of all types regularly undergo varying degrees of either mutation or "re-assortment" [changes in their genes]. These changes take place throughout the year and are independent of the yearly flu season. Newly mutated or re-assorted viruses generally cause outbreaks during the regular flu season in the Northern Hemisphere between the months of October and March.

It is not likely that the bird flu virus, H5N1, will cause a pandemic this flu season. However, the virus is being closely monitored in order to determine if it mutates or re-assorts and in doing so if it acquires the ability to be easily transmitted from human to human. The possibility still exists that this bird flu virus could cause scattered human cases, local epidemics or even a pandemic in the future. -- answered by Imperato