NEW YORK – Pope John Paul II (search) may have returned to the hospital to battle an infection that arose as a complication of his prior case of flu or flu-like illness, American doctors speculated Thursday.
The Vatican has not released details about the pope's condition, but experts said people don't get a relapse of influenza itself.
Rather, flu can lead to a bacterial infection such as pneumonia or bronchitis, which is an inflammation of the tubes that carry air into the lungs.
It's also possible that the pope's initial illness earlier this month was not literally influenza but a flu-like infection, said Dr. William Hall, a geriatrics specialist at the University of Rochester. Infection with respiratory syncytial virus (search) (pronounced "sin-SISH-ull") can produce a more prolonged flu-like illness in elderly people, he said.
The Vatican has referred to the 84-year-old pope's illnesses as a "syndrome of influenza." Experts noted that a variety of diseases are commonly called the flu even when not caused by an influenza virus.
Hall and Dr. William Schaffner, a Vanderbilt University influenza expert, both speculated that the pope may be suffering from congestive heart failure, a treatable condition in which the heart is unable to pump enough blood to meet the body's needs. That can appear after a case of the flu, Hall said.
It's also possible that the pope has caught a cold or genuine influenza if he didn't have it before or if he encountered a different strain of influenza virus, said Dr. Martin J. Blaser, chair of the department of medicine at the New York University School of Medicine.
But the pope's age, slumped posture and Parkinson's disease (search) would raise his risk of getting pneumonia as a complication of an infection, said Blaser, president-elect of the Infectious Diseases Society of America.
Experts say the Parkinson's and slumped posture would make it harder for the pope to keep pneumonia bacteria out of his lungs, in part by impairing his ability to cough.
A new round of illness after flu in an elderly person is "not a good sign," Hall said, because "each of these episodes takes its toll and it weakens many parts of the body," making it more susceptible to further problems. Schaffner agreed that the pope's reported symptoms are "noteworthy and serious."
But Hall noted the pope is getting top-notch medical care. "There's a reasonable chance of pulling through this," Hall said.
"We would hope and have every expectation that with appropriate care he can weather this .. and can recover from it," Schaffner said.