By Michael Laris
Washington Post Staff Writer
Thursday, December 3, 2009
Two swine flu patients in Maryland and one in Virginia were hospitalized with a form of the virus resistant to a commonly used medicine, prompting infectious disease specialists to call for renewed caution even as the intensity of the pandemic has declined nationwide.
Tamiflu is one of the drugs used on the sickest patients, and it is not effective against the H1N1 virus in only a few cases. But epidemiologists said experience with other flu strains shows that resistance can spread quickly, making monitoring and prevention crucial.
"I don't want to scare the public, but I do want people to be responsible in what they need to be doing, not only for their patients but also for public health," said Trish Perl, a professor at Johns Hopkins University Hospital.
"It's been reported in Seattle. It's been reported at Duke. It's been reported in our place. All of a sudden, we're starting to see . . . more resistance than we saw earlier this spring," she said. "What it calls for is increased vigilance."
Diane Helentjaris, head of Virginia's office of H1N1 response, said two state residents have been treated for Tamiflu-resistant swine flu, one at a hospital in Virginia and one in another state.
"It's not unexpected at all, when you have many, many people taking an antiviral medication," she said.
Extended treatment of those with immune problems also contributes to drug resistance. "The longer you're on something the more likely you might develop some resistance," she said.
The two Hopkins patients, who have since been discharged, had weakened immune systems, and their treatment was consistent with that provided to leukemia patients. Staff members had been vaccinated and wore masks, hospital officials said.
Perl said initial virus samples responded to Tamiflu, but that changed during treatment, leading to a mutated, resistant form. "Under the pressure it can emerge," she said.
Doctors can try a different drug in such cases.
Perl said Tamiflu should not be over-prescribed because that gives the virus more chances to mutate. She also said people should avoid complacency and should be vaccinated.
In the District, officials confirmed the city's first swine flu-related death. The patient was an adult male with a preexisting condition, Health Department spokeswoman Dena Iverson said.