Richard Lewis of Wayne State University in Detroit said his team has confirmed four of the paralysis cases thus far and is awaiting tests to confirm the diagnosis in three more limb paralysis patients.
"These cases all happened the last week of August. We had pathology by early September and immediately wrote up the findings," Lewis told United Press International. He presented the findings at the 127th annual meeting of the American Neurological Association.
The four patients, three men and a woman, ranged in age from 27 to 48 and were "fairly healthy before this," Lewis said. "One patient had a history of diabetes and two years ago he was treated for non-Hodgkins lymphoma."
Unlike West Nile cases hospitalized for treatment of life-threatening encephalitis, the paralysis patients have almost no classic flu symptoms, he said. "One patient had a headache and a little malaise about a week before, but no fever, muscle aches or vomiting," Lewis said. Two patients had transient diarrhea a day or two before the onset of paralysis.
The report from Michigan follows earlier reports of polio-like symptoms in West Nile virus three patients in Mississippi and one in Georgia. Lewis said he thinks it is important to publicize these cases so that physicians are aware that "paralysis can be the only symptom of infection."
Richard Johnson of Johns Hopkins University in Baltimore said there is a long history of paralysis associated with "tick-borne diseases as well as in Japanese encephalitis." Johnson was not associated with the study. He added, however, it is useful to "get out the news about these symptoms so that physicians who are not familiar with these symptoms are alerted."
The associated paralysis in those cases as in the West Nile cases is "flaccid limb paralysis," Johnson told UPI.
Lewis said his patients had paralysis of either an arm or leg as well as some facial muscle involvement, which causes the entire face to sag. Also, one of the Michigan patients had some "confusion about time and place, suggesting cognitive involvement." He added he was surprised by the speed of symptom onset.
"One man took a nap on his porch and when he woke up his leg felt a little funny. He hobbles across the porch and falls and an hour later he can't move. I'm just surprised that patients get so weak, so fast," Lewis said.
Johnson, who was in medical training during the last big polio outbreak in the 1950s, noted polio also has a fast onset of symptoms but "not that fast."
Lewis explained the newly reported paralysis cases suggest the West Nile virus might be mutating or it might "affect different populations in different ways. For example the initial cases reported in New York were all encephalitis cases. Now we are seeing these paralysis cases as the disease moves west and south."
Johnson said it is likely that the virus is changing and this evolution of tick- or mosquito-borne viruses is not unusual.