Cases Of Tamiflu Resistant Swine Flu In Md

Wednesday, December 02, 2009
Scott Wykoff

The Maryland Department of Health and Mental Hygiene has reported the first two cases of Tamiflu resistant Swine Flu in Maryland to the Centers for Disease Control and Prevention.

Molecular testing by the DHMH Laboratory confirmed that each case had the Tamiflu resistant virus strain.

Notification is underway to the state's acute-care hospitals, physicians and other health care providers to remain on the lookout for other possible cases.

The resistant strain is presumed preventable by the Swine Flu vaccine and can be treated by alternative antiviral medication. "This kind of mutation of the flu virus has been expected and that is why we've tested over 500 H1N1 samples from across the state for resistance to Tamiflu as a part of our flu monitoring and surveillance effort," said John M. Colmers, DHMH Secretary. "These two resistant cases are of concern because although infections such as this can be prevented with vaccine, we also want to retain all of our options for treating those with serious influenza complications."

Routine testing at the state Public Health Laboratory discovered the first Maryland case. Astute clinicians suspected and reported the second case after a patient continued to test positive for flu despite antiviral treatment.

Tamiflu (oseltamivir) is the most frequently prescribed flu medicine for flu treatment of adults and children aged 1 year and older. When properly prescribed, antivirals such as Tamiflu can slow the rate at which a flu virus infects cells in the body, thus reducing the spread and the severity of the illness. A Tamiflu resistant strain of Swine Flu makes it more difficult for physicians to treat patients. "There is no indication that any Tamiflu resistant strain of the Swine Flu virus has spread broadly through the general population," said Frances Phillips, DHMH Deputy Secretary for Public Health Services. "Both of these patients have recovered from influenza. However, DHMH is working closely with local hospitals and health departments to be sure the virus has not spread to others."

These cases were diagnosed with flu during October and November hospitalizations at The Johns Hopkins Hospital and both have recovered from influenza. While there does not appear to be any link between the two cases, both had immunosuppression, which is an identified risk factor for the development of antiviral resistance.

Worldwide, there have been a small number of Tamiflu resistant H1N1 influenza cases identified by public health authorities. The majority of these cases have occurred among immunosuppressed patients undergoing treatment for influenza. Nationally, there are several cases of these resistant viruses transmitted in the healthcare environment or in group settings. It is common for strains of seasonal influenza to become resistant to antiviral medications as well, which is another reason why seasonal influenza vaccination is highly recommended among those at high risk for influenza complications. "Vaccination remains the best protection against the flu," added Secretary Colmers. "While we continue to see flu activity on a downward slope in Maryland for now, more H1N1 vaccine arrives each day and we urge everyone, especially members of the five target populations, to contact their doctors, health care providers or local health departments to get vaccinated."
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