Flu Virus resistance
Jan. 15th, 2006 09:54 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
brdgtThis Season's Flu Virus Is Resistant to 2 Standard Drugs
By LAWRENCE K. ALTMAN, The New York Times, January 15, 2006
WASHINGTON, Jan. 14 - Doctors should stop prescribing two standard antiviral drugs to treat or prevent this season's influenza because the predominant strain has quickly become resistant to them, federal health officials said Saturday.
The standard drugs are amantadine and rimantadine.
Instead, the Centers for Disease Control and Prevention recommended that doctors prescribe two newer antiviral drugs, oseltamivir (Tamiflu) and zanamivir (Relenza), and said ample supplies were available. The agency also urged the public to get flu shots.
The new findings concern only the strain of influenza causing regular seasonal influenza, and not avian influenza or pandemic influenza, said the centers' director, Dr. Julie L. Gerberding.
She said 91 percent of the human influenza A (H3N2) virus samples isolated in her agency's laboratories this flu season were resistant to both amantadine and rimantadine. A (H3N2) is this season's dominant strain. The agency's influenza surveillance program studies samples from state health departments.
"We feel that this represents a sample of A (H3N2) influenza virus that is broad enough and comes from a wide enough geographic area to have broad population implications, and so we are issuing this recommendation for the entire United States," Dr. Gerberding said.
Scientists have been alarmed about a rising incidence of drug resistance among influenza viruses isolated from patients around the world over the last decade and their ability to be transmitted from person to person.
Globally, the incidence rose to 12.3 percent in the 2003-2004 season from 0.4 percent in the 1994-1995 season, the C.D.C. and other scientists reported in The Lancet on Oct. 1, 2005. In the United States, the incidence of such resistance has soared to 91 percent from 1 percent.
Despite the earlier findings, "we were not expecting it to be quite as dramatic so soon, this year," Dr. Gerberding said.
"We do not know what accounts for the unexpected increase in resistance," she told reporters in a hastily arranged news conference.
The findings were made Friday and confirmed today. They needed to be conveyed quickly, she said, to alert doctors to switch medications for those patients on amantadine and rimantadine and not to start treating others with them. The drugs are thought to be most effective when given in the first 48 hours of illness.
Influenza viruses constantly mutate. One theory is that the A (H3N2) influenza strain suddenly developed a mutation against amantadine and rimantadine. Another theory is that the resistance developed from inappropriate use of the two drugs, which are widely available over the counter in many countries. In the United States, all marketed antiviral drugs effective against influenza require a prescription.
Drugs are far less important in preventing influenza than keeping one's hands clean, covering one's nose and mouth when sneezing and coughing, staying home from school and work during respiratory illness; and vaccines, Dr. Gerberding said.
So far, influenza has gotten off to a slow start in the United States and Europe. It is widespread in Arizona, California, Colorado, Nevada, New Mexico, Oregon and Texas. New York City has reported sporadic influenza activity.
The disease centers' sudden warning comes at a time when historians, health officials and policy groups have focused attention on how deadly influenza has been in recent decades. The so-called Spanish flu of 1918 and 1919 is considered one of the worst, if not the worst, pandemics in history.
The World Health Organization, a United Nations agency based in Geneva, has repeatedly said that the world is not prepared for the next pandemic. Concern exists that an avian strain of influenza, A (H5N1), could cause the next pandemic if it develops the ability to spread from person to person. So far only 148 human A (H5N1) cases, 79 of them fatal, have been reported to the agency, which says that nearly all have been from direct contact with infected birds. The strain was first detected in Hong Kong in 1997 and has spread through Southeast Asia and recently in Russia and Turkey.
Governments around the world have been ordering large stockpiles of Tamiflu in case a pandemic develops. One strain of A(H5N1) is resistant to amantadine and rimantadine, but sensitive to Tamiflu and Relenza. So far, another strain seems sensitive to all four drugs.
Health officials are just as concerned about the regular seasonal influenza, which kills an estimated 36,000 people in the United States each year.
By LAWRENCE K. ALTMAN, The New York Times, January 15, 2006
WASHINGTON, Jan. 14 - Doctors should stop prescribing two standard antiviral drugs to treat or prevent this season's influenza because the predominant strain has quickly become resistant to them, federal health officials said Saturday.
The standard drugs are amantadine and rimantadine.
Instead, the Centers for Disease Control and Prevention recommended that doctors prescribe two newer antiviral drugs, oseltamivir (Tamiflu) and zanamivir (Relenza), and said ample supplies were available. The agency also urged the public to get flu shots.
The new findings concern only the strain of influenza causing regular seasonal influenza, and not avian influenza or pandemic influenza, said the centers' director, Dr. Julie L. Gerberding.
She said 91 percent of the human influenza A (H3N2) virus samples isolated in her agency's laboratories this flu season were resistant to both amantadine and rimantadine. A (H3N2) is this season's dominant strain. The agency's influenza surveillance program studies samples from state health departments.
"We feel that this represents a sample of A (H3N2) influenza virus that is broad enough and comes from a wide enough geographic area to have broad population implications, and so we are issuing this recommendation for the entire United States," Dr. Gerberding said.
Scientists have been alarmed about a rising incidence of drug resistance among influenza viruses isolated from patients around the world over the last decade and their ability to be transmitted from person to person.
Globally, the incidence rose to 12.3 percent in the 2003-2004 season from 0.4 percent in the 1994-1995 season, the C.D.C. and other scientists reported in The Lancet on Oct. 1, 2005. In the United States, the incidence of such resistance has soared to 91 percent from 1 percent.
Despite the earlier findings, "we were not expecting it to be quite as dramatic so soon, this year," Dr. Gerberding said.
"We do not know what accounts for the unexpected increase in resistance," she told reporters in a hastily arranged news conference.
The findings were made Friday and confirmed today. They needed to be conveyed quickly, she said, to alert doctors to switch medications for those patients on amantadine and rimantadine and not to start treating others with them. The drugs are thought to be most effective when given in the first 48 hours of illness.
Influenza viruses constantly mutate. One theory is that the A (H3N2) influenza strain suddenly developed a mutation against amantadine and rimantadine. Another theory is that the resistance developed from inappropriate use of the two drugs, which are widely available over the counter in many countries. In the United States, all marketed antiviral drugs effective against influenza require a prescription.
Drugs are far less important in preventing influenza than keeping one's hands clean, covering one's nose and mouth when sneezing and coughing, staying home from school and work during respiratory illness; and vaccines, Dr. Gerberding said.
So far, influenza has gotten off to a slow start in the United States and Europe. It is widespread in Arizona, California, Colorado, Nevada, New Mexico, Oregon and Texas. New York City has reported sporadic influenza activity.
The disease centers' sudden warning comes at a time when historians, health officials and policy groups have focused attention on how deadly influenza has been in recent decades. The so-called Spanish flu of 1918 and 1919 is considered one of the worst, if not the worst, pandemics in history.
The World Health Organization, a United Nations agency based in Geneva, has repeatedly said that the world is not prepared for the next pandemic. Concern exists that an avian strain of influenza, A (H5N1), could cause the next pandemic if it develops the ability to spread from person to person. So far only 148 human A (H5N1) cases, 79 of them fatal, have been reported to the agency, which says that nearly all have been from direct contact with infected birds. The strain was first detected in Hong Kong in 1997 and has spread through Southeast Asia and recently in Russia and Turkey.
Governments around the world have been ordering large stockpiles of Tamiflu in case a pandemic develops. One strain of A(H5N1) is resistant to amantadine and rimantadine, but sensitive to Tamiflu and Relenza. So far, another strain seems sensitive to all four drugs.
Health officials are just as concerned about the regular seasonal influenza, which kills an estimated 36,000 people in the United States each year.
