THURSDAY, Aug. 24, 2006 (HealthDay News) -- Half of people infected with the West Nile virus experience ongoing health problems such as fatigue, headaches, depression and tremors a year after diagnosis, U.S. researchers report.
And people diagnosed with "relatively benign" West Nile fever were just as likely to experience long-term health complaints as people who had been hospitalized with more severe West Nile virus-related illnesses, such as meningitis or encephalitis, the study found.
"We knew before that West Nile encephalitis was a serious health threat, but we didn't appreciate how much ongoing morbidity there is for West Nile fever, which is much more common," study lead author Dr. Paul Carson, University of North Dakota School of Medicine and Health Science, said in a prepared statement.
The study of 49 patients is published in the Sept. 15 issue of Clinical Infectious Diseases.
Most people infected with the West Nile virus have no symptoms. About 20 percent develop flu-like West Nile fever, and about one percent develops more serious diseases.
The patients in the study were tested about 13 months after they'd been diagnosed with West Nile fever or one of the more severe diseases.
"What we found is that there is a substantial amount of ongoing symptoms both among those patients diagnosed with West Nile fever as well as those with the more severe diseases, encephalitis and meningitis," Carson said.
Nearly half the patients in the study scored low on the physical component of a standardized test for overall general health, and a third of them scored low on the mental component of the test.
Other findings: 25 percent of patients had moderate to severe depression; 84 percent reported fatigue; 20 percent had tremors.
The findings suggest that West Nile fever is more serious than previously thought, Carson said.
"I hope this study will raise awareness that West Nile virus poses a substantial public health threat," he said. "Hopefully, this may give greater impetus to increase resources for prevention -- vector control and vaccine -- and treatment development."
As of Aug. 15, the U.S. Centers for Disease Control and Prevention have recorded 388 human cases this year of infection with West Nile virus, including 13 deaths. Cases have so far been reported in 25 of the 50 states.
The U.S. National Center for Infectious Diseases has more about West Nile virus.