In rare instances, biting flies such as horseflies or deerflies may be able to transmit Lyme disease to humans, a doctor said Wednesday, but other researchers disputed the report.
Dr. Steven Luger, a family physician in Old Lyme, Conn., said one of his patients developed the disease after being bitten by a fly while jogging in an area where the disorder was first identified and remains common.To date, scientists have found no evidence the disease is spread by anything other than several species of tiny deer ticks, which attach themselves to a person's skin and inject an infection-causing bacterium into the bloodstream.
Nevertheless, on the basis of the jogger's experience, Luger concluded that Lyme disease "may rarely be transmitted by biting flies," he said in a letter published in The New England Journal of Medicine.
But Lyme disease expert Andrew Spielman of the Harvard University School of Public Health in Boston challenged the report.
"It may not be impossible, but it comes as close to being impossible as anything I've heard," said Spielman, who discovered that the disease is transmitted by ticks that feed on mice and white-tailed deer.
Luger's letter "doesn't convince me at all that there is anything but ticks that people ought to be paying attention to," he said.
Research has shown that ticks generally need to be attached to a person for more than a day to transmit the disease, Spielman said. A fly bite occurs in "just a few seconds," he said.
The jogger more likely was infected through an unnoticed tick bite, Spielman said. It may also be possible that the fly bite triggered a reaction by the jogger's immune system linked to a previous episode of Lyme disease, he said.
More than 14,000 cases of Lyme disease have been reported in 43 states nationwide since 1980. Most cases have been reported in the Northeast and Mid-Atlantic coastal states from Massachusetts to Maryland, Wisconsin and Minnesota and California and Oregon.