A team of Baylor College of Medicine has followed a large group of patients who had been at one time diagnosed with West Nile virus.
The article goes on (I separate the paragraphs of the quotation to draw your attention to this):The Baylor team studied 4,144 Texas residents who were infected with West Nile virus from 2002 to 2012. "Out of this population, we identified 554 deaths (13 percent)," they said in a written summary of their findings presented at a meeting of the American Society of Tropical Medicine and Hygiene.
West Nile virus typically causes mild flu-like symptoms, so doctors usually only see the severe cases. "We found a substantial number of reported West Nile virus cases died within the first 90 days of infection," the team said. About 7 percent of the really sick patients, 286 in all, died within three months, they said.
But another 210 patients who had severe symptoms died after they seemed to have recovered, the team reported — mostly from other infections or kidney failure.
"We also found increased risk for all-cause mortality in those who were under 60 years of age at the time of infection," they said.
But it's not clear why [they have earlier mortality]. Doctors are starting to find mysterious and long-term effects from all sorts of viruses, including Zika and Ebola viruses. Those two have been found to stay in certain parts of the body of some patients for months, sometimes causing a recurrence of symptoms.