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H1N1 virus may mutate in immunocompromised patients
The case of a 5-year patient with leukemia who died of H1N1 after the virus mutated into his body showed that people with weakened immune systems may be at increased risk for dangerous infections resistant to drugs, and illustrated the risks using current remedies to treat these patients, experts said.
EL UNIVERSAL
Wednesday September 29, 2010 07:55 PM
Boston .- Patients with depressed immune systems can develop rapid H1N1 flu infections that are resistant to all known drugs, doctors reported Wednesday in the Netherlands.
The case of a 5-year patient with leukemia who died of H1N1 after the virus mutated into his body showed that people with weakened immune systems may be at increased risk for dangerous infections resistant to drugs, and illustrated the risks using current remedies to treat these patients, experts said, Reuters reported.
The H1N1 virus that infected the child mutated to resist the three approved drugs for treatment, said Dr. Charles Boucher Medical Center of Erasmus University in Rotterdam in a letter to the New England Journal of Medicine.
"The current formula of the two drugs that we have an intrinsic problem with the resistance. A single mutation is sufficient for the virus to become resistant," Boucher said in a telephone interview.
It is a complicated issue for doctors, who have been advised to use drugs quickly in patients with cancer who are considered particularly vulnerable to influenza.
The child was being prepared for a transplant of bone marrow stem cells, a rigorous treatment requires first destroy the patient's immune system.
When he became ill with H1N1, was given antibiotics and Tamiflu, known generically as oseltamivir. The drug is manufactured and distributed by Roche and Gilead Sciences.
When it seemed that Tamiflu had eliminated the virus, we performed bone marrow transplantation. After influenza reappeared, said Boucher, and colleagues.
Doctors then tried to intravenous treatment with zanamivir, the generic name Relenza, made by GlaxoSmithKline and Biota. The child recovered and again, the virus seemed to disappear so he was sent home.
After 19 days, returned to hospital with flu symptoms. On this occasion, Relenza did not work. The child died three months later, in March.
Laboratory tests showed the virus that infected the child was resistant to BioCryst peramivir, an experimental drug in the same class as Tamiflu and Relenza was approved for intravenous treatment during a pandemic emergency.
This month, researchers reported that a woman in Singapore has developed resistance to Tamiflu within 48 hours.
In March, U.S. doctors reported on two cases that developed resistance to Tamiflu. Both patients had weakened immune systems, like the child in the Netherlands. One also has become resistant to peramivir. In such cases, Relenza work.
"In a typical scenario, the immune system helps prevent the growth of drug-resistant virus," said Boucher. "In the absence of an immune system might be a slight increased risk" of more resistant viruses, said.
Most influenza strains are already resistant to two older drugs, amantadine and rimantadine