Texas health officials are downplaying any current health risk from a little-known mosquito-borne virus found for the first time to have infected and caused symptoms in a person.
University of Florida researchers reported this month that based on their analysis, a teenager tested for Zika two years ago actually had the Keystone virus, which can be found in some animal populations along coastal regions stretching from Texas to the Chesapeake Bay. His symptoms were a mild fever and a rash.
“Although the virus has never previously been found in humans, the infection may actually be fairly common in (some areas),” Dr. J. Glenn Morris, director of the Emerging Pathogens Institute at the University of Florida, said in a statement. “It’s one of those instances where if you don’t know to look for something, you don’t find it.”
The findings, published in the journal Clinical Infectious Diseases, are another indicator of the disease potential caused by mosquitoes. A recent study by the U.S. Centers for Disease Control and Prevention showed an almost doubling of mosquito-borne disease cases in the United States since the early 2000s.
There is no diagnostic test for the virus, which is carried by a species of mosquito — Aedes atlanticus, a cousin of Aedes aegypti — found mostly near water and wooded areas. Officials said hunters and campers are most likely to come in contact with such mosquitoes.
A spokesman for the Texas department of health said the virus already is detected sporadically through public mosquito surveillance efforts in the state. He said it was identified in a mosquito sample from Orange County (which is east of Beaumont) in 2017 and in two samples from Galveston County in 2015.
“To this point, we haven’t seen it as a significant threat to public health,” said Chris Van Eusen, director of media relations for the Texas Department of State Health Services. “But we’ll continue to look for Keystone and other viruses that may emerge as causes of human disease.”
James LeDuc, director of the Galveston National Laboratory at the University of Texas Medical Branch, agreed that the virus “probably won’t cause much human disease” and “absolutely isn’t on the order of, say, West Nile or Zika.”
Keystone is “unlikely to become a public health issue — unless the virus mutates,” LeDuc said.
LeDuc studied Keystone in the 1970s in Texas and developed immune system antibodies to the virus, typically a sign one has been infected. He never developed any symptoms.
Still, the virus is part of a group found to cause encephalitis in several species, including humans, said the Florida researchers. Because of that, Morris, a corresponding author of the report, emphasized the need for additional research on Keystone.
The Florida teen was taken to an urgent care clinic in Florida in 2016 out of caution about the then circulating Zika virus. Tests at the time ruled out Zika, but the Florida researchers determined after all manner of testing that Keystone was present in cultures taken from the boy.
The Keystone virus was named after the Tampa Bay area where it was initially identified in 1964.