The current issue of The Archives of Neurology reports that organ transplant recipients who become infected with West Nile virus develop more severe neurological illness caused by the virus.
West Nile virus is an infection which in the last three years has had a significant impact in the United States. The virus is spread from birds to humans via mosquito bites. Symptoms include headache, fever and disorientation, and the disease can cause serious illness in a small percentage of infected people.
Until recently, human infection with West Nile virus, was limited to Africa, Asia and the Middle East. Since its arrival in the New York City area in 1999, human WNV infection has increased in scope and severity in the United States each year. In 2003, the U.S. Centers for Disease Control and Prevention reported more than 9,860 cases of WNV disease, which included 264 deaths. The article states that approximately 25,000 patients receive organ transplants in the United States each year. Transplant recipients are treated with long-term immune system-suppressing drugs that put them at greater risk for infections, including WNV.
B.K. Kleinschmidt-DeMasters, M.D., of the University of Colorado Health Sciences Center, Denver, and colleagues describe eleven transplant recipients (four kidney, two stem cell, two liver, one lung, and two kidney/pancreas) hospitalized with WNV encephalitis. All cases of WNV occurred between July 2003 and October 2003 and patients were seen in Colorado hospitals. All 11 patients received their organ five months to 15 years before being infected with WNV.
The researchers found that all but one patient had the usual early symptoms of WNV as documented in non-immunosuppressed patients. Ten patients developed meningoencephalitis (inflammation of the brain and membrane surrounding the brain and spinal cord), and three of the ten also developed acute flaccid paralysis (paralysis associated with loss of muscle tone). One patient developed acute flaccid paralysis without encephalitis. Six patients had significant movement disorders, including tremor.
Magnetic resonance imaging (MRI) of the brain revealed abnormalities in seven of eight tested patients. Nine of the 11 patients studied survived their infections, but three of them had significant problems caused by their infections and two patients died of complications of WNV.
"Naturally acquired WNV encephalitis in transplant recipients shows diagnostic, clinical, and laboratory features similar to those reported in nonimmunocompromised individuals, but neuroimaging, electroencephalography, and autopsy results verify that these patients develop neurological damage at the severe end of the spectrum," the authors write.