Three Chilean patients had confirmed reinfection with the 2009 pandemic influenza A (H1N1) virus after successful treatment with oseltamivir, according to a letter published in the January 2010 issue of Emerging Infectious Diseases.
“Reinfection is rarely seen in nonpandemic influenza A,” said Dr. Carlos M. Perez of Pontificia Universidad Catolica de Chile (Santiago) and colleagues.
The first patient was a healthy 14-year-old girl who had a fever, sore throat, and nasal congestion when H1N1 infection was confirmed by polymerase chain reaction (PCR) testing. She was treated with oseltamivir, and her symptoms resolved after 2 days.
“Twenty days later, fever, muscle aches, and vomiting developed in the patient,” the researchers said. The patient was treated with amantadine, and she recovered. Subsequent PCR testing confirmed reinfection with pandemic influenza (EID 2010;16:156-7).
The second patient was a 62-year-old woman who developed a high fever, cough, and nasal congestion while she was hospitalized prior to surgery. PCR testing and viral culture confirmed infection with the pandemic H1N1 virus. She received oseltamivir starting 5 days after the onset of symptoms, and the symptoms resolved within the next 5 days.
Two weeks later, while she was still hospitalized, the patient again developed fever, bronchial obstruction, and productive cough; PCR testing again was positive for pandemic H1N1. “The patient was again treated with oseltamivir, and PCR results were negative for influenza after 48 hours of antiviral treatment,” the researchers said.
The third patient was a previously healthy 38-year-old man hospitalized for mitral and aortic valve replacement following acute endocarditis caused by Staphylococcus aureus. The patient developed a sore throat, nasal congestion, cough, and a low-grade fever 11 days after surgery, while he was still hospitalized.
PCR testing confirmed pandemic H1N1 infection, and the patient was treated with oseltamivir. His respiratory symptoms resolved after 5 days. “He was discharged from the hospital, but readmitted 18 days later with nasal congestion, cough, and high fever,” the researchers said. Repeat testing again was positive for pandemic flu; he was successfully retreated with oseltamivir.
H1N1 reinfection in these patients could be due to the high rate of infection in the community at the time, as well as the immunocompromised status of the second and third patients, the researchers noted. The occurrence of two reinfections in hospitalized patients raises the possibility of nosocomial transmission, they added, but more information is needed.
Disclosures: None was reported.