Report details drug-resistant H1N1 cases found at Duke in October

Four patients in a hematology-oncology ward at Duke became symptomatic of fever and respiratory symptoms during a six-day period from Oct. 6-11. They were subsequently diagnosed with a strain of the virus that was resistant to the drug Tamiflu, one of two medicines used to fight H1N1.

The patients were ill with underlying severely compromised immune systems and other complex medical conditions.

The U.S. Centers for Disease Control and Prevention and the state Division of Public Health worked with Duke to investigate the nature of the cases. Their findings were presented Saturday at the Fifth Decennial International Conference on Healthcare-Associated Infections in Atlanta, Ga.

“We found that the oseltamivir-resistant H1N1 influenza were isolated to the four patients. There was no evidence of spread to additional patients or caregivers on the affected ward,” said Luke Chen, M.D., an infectious diseases specialist at Duke University Medical Center.

The team carried out an epidemiologic investigation and reviewed patients’ medical records, infection control measures, and interviewed visitors and health care personnel.

“We were not able to establish that health care workers or visitors had a role in the transmission," Chen said.

Among hospitalized patients, influenza can often be hidden under other conditions and the suspicion for influenza might be low because many patients have other medical problems that could be causing their fever or respiratory symptoms, according to Chen.

“One key thing we can learn from this outbreak is that all clinicians and health care workers should suspect the diagnosis of influenza even among very ill patients, who have multiple medical problems,” Chen said.

Tamiflu is still the most effective treatment for the H1N1 virus, and a vaccination is the best prevention for contracting the virus, health officials said.