Faculty Bibliography

''The tests clearly indicate that the viruses from Vietnam and South Korea are very closely related,'' said Dr. Klaus Stohr, a W.H.O. influenza expert. But he said they were distinct from the strain found in Hong Kong last year. That strain infected 18 people in Hong Kong in 1997, killing 6, and was found in duck meat in South Korea in 2001. In a new development, the birds have been found to be producing large amounts of type A virus, of the H5N1 strain, in respiratory secretions and saliva. In the past they usually excreted the virus only in feces, Dr. Stohr said. Developing a vaccine is a complex process. Because the H5N1 strain kills chickens, scientists cannot use chicken eggs in the initial stage of making the vaccine, as they do for human strains of influenza virus. Instead, scientists working with the health agency -- in London, at the Centers for Disease Control and Prevention in Atlanta, and elsewhere -- are using a newer laboratory technique known as reverse genetics

The worry is that the avian influenza strain, A(H5N1), could combine with a human influenza virus to create a new strain. That strain, in turn, could cause a large epidemic in people. It might even become the seeds of an influenza pandemic that many experts agree is inevitable and possibly imminent. Italian scientists are credited with identifying avian influenza (often called bird flu) more than a century ago. There are now about 15 avian influenza strains that usually infect birds exclusively, particularly migratory waterfowl. The strains produce a range of illness from mild to lethal. Birds that survive infection excrete the virus and can spread it widely in flight patterns. Influenza experts still fear the exchange of genetic material between the bird A(H5N1) strain and a human influenza virus. The swap occurs in a process called reassortment, which occurs when people are concurrently infected with human and avian influenza strains. In effect, humans serve as a virus mixing bowl

Nigeria has exported polio to at least six West African countries in recent months, [David Heymann] said. His team is awaiting molecular tests to determine whether the viruses isolated from the Benin and Cameroon cases came from Nigeria or one of the seven neighboring countries that have reported cases. They are: Benin, Burkina Faso, Cameroon, Chad, Ghana, Niger and Togo. Cameroon and Benin are now conducting such campaigns in an effort to prevent the imported cases from spreading further. But the immunization campaigns are costly and put an added burden on countries that had previously eradicated polio because they take money from other important health programs, Heymann said. In a second move, the WHO has invited the health ministers from affected countries to discuss polio eradication at the agency's headquarters in Geneva on Thursday. Nigeria's national health minister has made a commitment to attend the meeting, as has a representative of the state of Kano, where the opposition to polio vaccination programs is centered, Heymann said

The agency monitors influenza activity in a number of ways. One is a statistical calculation based on the number of deaths from pneumonia and influenza in 122 cities. By that measure, influenza exceeded the statistical threshold for a seasonal epidemic, for the first time, the week that ended Dec. 27. The calculation shows that the number of deaths from pneumonia and influenza have exceeded the usual number for recent weeks. But it will take a few more weeks to determine how many there will be. This season, the vast majority of influenza has been caused by a new variant of the virus known as the Fujian strain, which this year's vaccine was not developed to combat. Officials believe, however, that there is some cross-protection. The strain seems to have hit young children hard. The C.D.C. earlier reported 42 deaths in children from influenza this season. According to one statistical model, about 92 deaths in children occur a year on average in this country. Aventis, which is owned by Aventis S.A., said it would team with Crucell, a Dutch biotechnology company, to produce flu vaccine in cultures of human cells, rather than in hen's eggs, as is done now. But the new vaccine will not even begin to be tested in people until 2005 and will not be approved for use for several years after that

The number of children's deaths has risen from the 42 reported late last month. Precise assessments of the severity of the flu epidemic for children are impossible because influenza is not nationally reported, said Dr. Julie L. Gerberding, director of the centers, in Atlanta. The percentage of deaths attributed to pneumonia and influenza rose slightly to exceed the epidemic threshold, a crucial determinant of the severity of an influenza season. The threshold is based on a statistical calculation that the centers derives from the number of deaths from pneumonia and influenza in 122 cities. The data usually reflects deaths three to four weeks earlier. In another step, the agency is asking state officials to consider making children's deaths from influenza routinely reportable. The sole estimate of children's influenza deaths is in an academic study that indicates that the total is 92 in an average year

The spread of polio to Benin and Cameroon, which the Geneva- based UN agency is expected to announce this week, is a discouraging setback in its $6 billion (Canadian) effort to have polio join smallpox as the only diseases to be eliminated from the human population. Nigeria has exported polio to at least six West African countries in recent months, [David L. Heymann] said. His team is awaiting molecular tests to determine whether the viruses isolated from the Benin and Cameroon cases came from Nigeria or one of the seven neighbouring countries that have reported cases. They are: Benin, Burkina Faso, Cameroon, Chad, Ghana, Niger and Togo. Nigeria's national health minister has agreed to attend the meeting, as has a representative of the state of Kano, where the opposition to polio vaccination programs is centred, Heymann said

The spread of polio to Benin and Cameroon, which the Geneva- based U.N. agency is expected to announce this week, is a discouraging setback in its $4.6 billion effort to have polio join smallpox as the only diseases to be eliminated from the human population. The chief obstacle is opposition to polio immunization by some Islamic leaders in the state of Kano, in the northern part of the country. These opponents contend that the vaccine contains hormones that sterilize girls, [David L. Heymann] said

''It is a setback, and the situation is really very concerning,'' Dr. David L. Heymann, the epidemiologist in charge of the W.H.O. polio eradication program, said in telephone interviews. ''But we cannot let the effort fail. We have no choice -- we have to stop transmission this year.'' Nigeria has exported polio to at least six West African countries in recent months, Dr. Heymann said. His team is awaiting molecular tests to determine whether the viruses isolated from the Benin and Cameroon cases came from Nigeria or one of the seven neighboring countries that have reported cases. They are: Benin, Burkina Faso, Cameroon, Chad, Ghana, Niger and Togo. Cameroon and Benin are now conducting such campaigns in an effort to prevent the imported cases from spreading further. But the immunization campaigns are costly and put an added burden on countries that had previously eradicated polio because they take money from other important health programs, Dr. Heymann said

The spread of polio to Benin and Cameroon, which the Geneva- based U.N. agency is expected to announce this week, is a discouraging setback in its $4.6 billion effort to have polio join smallpox as the only diseases to be eliminated from the human population. Nigeria has exported polio to at least six West African countries in recent months, [David L. Heymann] said. His team is awaiting molecular tests to determine whether the viruses isolated from the Benin and Cameroon cases came from Nigeria or one of the seven neighboring countries that have reported cases. They are: Benin, Burkina Faso, Cameroon, Chad, Ghana, Niger and Togo. Cameroon and Benin are now conducting such campaigns in an effort to prevent the imported cases from spreading further. But the immunization campaigns are costly and put an added burden on countries that had previously eradicated polio because they take money from other important health programs, Heymann said

Officials had warned that there was a mismatch between the current vaccine and the Fujian strain of influenza virus that was causing most illness this season. But they said the vaccine should still offer some protection to many people. At meetings last February and March where experts made educated guesses about what strains to use in preparing this season's vaccine, the panel members knew about the new Fujian strain. But it was too late to include it in the vaccine manufactured for the Northern Hemisphere. The vaccine being prepared for the Southern Hemisphere is formulated to protect against the Fujian strain. The effectiveness rates of influenza vaccine vary in part according to the age and health status of the individual. Influenza vaccine prevents illness in about 80 percent of children and young adults. The vaccine is less effective in preventing symptoms among those 65 and older, but prevents major complications like pneumonia in about 70 percent of those who receive it in the older population