In The Days

• Source: Chicago Tribune
• Author: Jeremy Manier
• News Date: 2/16/08

Drug-resistant virus could limit treatment options, doctors say

“For nation shall rise against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes, in divers places.”
—Matthew 24:7

Ten Chicago-area patients have tested positive for an unusual type of drug-resistant influenza, prompting concern and increased surveillance by local and federal health officials.

The strain of flu can be treated successfully with some drugs, but it does not respond to Tamiflu, the most common anti-viral medication for flu. The Illinois Department of Public Health issued a health alert to doctors and hospitals Thursday, suggesting that flu patients who are in intensive care receive a combination of drugs until their virus can be analyzed.

Officials said eight of the Tamiflu-resistant infections came from an outbreak at a single Chicago health-care facility, the name of which has not been released.

Nationwide, 4.6 percent of flu samples tested have shown signs of drug resistance this season, said officials with the federal Centers for Disease Control and Prevention. In previous years, resistance to the drug hovered below 1 percent of all cases.

“We have seen this before, though not at this level,” said Dr. Joe Bresee, chief of epidemiology and prevention in the CDC’s influenza division.

The worry among some experts is that flu strains could develop resistance to more than one drug, leaving doctors with few options for treating severely ill patients. One way that could happen would be for patients to get infected with two flu strains at once, each with resistance to a different type of anti-viral medication.

“If you had two viruses in the same cell, they could recombine and generate a new virus,” said Dr. Steven Wolinsky, chief of infectious diseases at Northwestern University. “The fact that we’re seeing resistance to first-line medications is worrisome.”

Anti-viral drugs work by preventing viruses from making more copies of themselves inside human cells. They are different from antibiotics, which kill bacteria. Just as bacteria can evolve resistance to antibiotics, viruses can develop into strains that do not succumb to anti-viral medication.

In other news, the CDC reported Friday that this season, the flu has killed 10 U.S. children. Bresee said the deaths are “not totally unexpected,” given the rate of 44 to 73 child flu deaths the last few years; the agency continues to monitor the fatality rate.

Four of the young flu victims also had been infected with staph bacteria. Experts said patients who are weakened by flu often are more vulnerable to staph and other secondary infections.

Illinois officials said they have seen more flu cases occur in recent weeks, which is normal for this time of year. Although it’s too soon to judge whether this flu season is worse than normal, several factors could increase the toll.

For one thing, this season’s flu vaccine is not a perfect match with the viruses that are infecting people. Each season’s vaccine is formulated based on an educated guess about what flu variants will hit the U.S., and this year’s guess was a bit off.

“Slightly more than half of the viruses we’re looking at are somewhat different from the vaccine strains,” Bresee said. Although people who have been vaccinated should get some protection, it will be less than if the vaccine had matched this season’s virus.

This year’s form of flu virus also may be naturally more likely to cause disease. In most years, some form of the H1N1 variety is most common, but this time about 55 percent of cases belong to the H3N2 group, which can produce more severe cases of illness.

Bresee said no one can gauge how bad things are until more time has passed.

“I’ll tell you in May,” he said.