West Nile virus may be three times more deadly than previously thought, because many deaths associated with the mosquito-borne virus occur years after the initial infection, researchers said Monday.
The findings were based on a study of 4,144 people in Texas, and were presented at the 2016 Meeting of the American Society of Tropical Medicine and Hygiene (ASTMH) in Atlanta, Georgia.
Among this group of people who became ill with West Nile virus between 2002 and 2012, 286 people died in the first three months. Another 268 people who survived the initial infection died over the next decade due to complications associated with the virus, researchers found.
"While we understand the current focus on Zika virus, for many people in the United States today, West Nile virus is the much more serious mosquito-borne threat and that threat may persist even for patients who appear to have survived the infection unscathed," said lead author Kristy Murray of Baylor College of Medicine and Texas Children's Hospital.
The Texas study showed a 13 percent fatality rate.
Nationwide, about four percent of people are believed to die of West Nile in the acute phase of the illness, or in the first three months, according to the US Centers for Disease Control and Prevention. The virus causes no symptoms at all in up to 80 percent of people. Some people report fever, rash, body pain, headache, vomiting or diarrhea.
WATCH VIDEO: What's the Best and Safest Way to Fight Mosquitoes?