Yale researchers have discovered a tick-borne illness so new to people in the United States that it doesn't have a common name.
The new bacterial infection is spread by the same deer tick that causes Lyme disease and causes a recurring fever, muscle aches, fatigue and, sometimes, a rash and neurological problems.
Using blood tests, researchers have found evidence of infection in 18 cases in southern Connecticut and Westchester County, N.Y. They estimate that the infection can found in 1 percent of the population in areas where Lyme disease is found.
The actual size of the adult tick is only the size of an apple seed. The young deer tick is the size of a poppy seed. Photo by Geoffrey Attardo
There are currently no tests available for the illness. So far, patients have responded well to a short course of doxycycline, the antibiotic used to treat Lyme disease, said Peter Krause, a senior research scientist at Yale School of Public Health who worked on the study.
"People shouldn't panic about it but should be aware of it," Krause said.
The infection, caused by the Borrelia miyamotoi bacterium, is far less prevalent than Lyme disease. Only about 2 percent of the deer ticks transmit the new infection compared to the 20 percent that transmit Lyme disease, Fish said.
The adult deer tick is the size of an apple seed and is relatively easy to spot. But when it's younger -- and more likely to transmit Lyme disease -- it is only the size of a poppy seed.
The best prevention is to avoid tick-infested areas, if possible, and take fairly stringent precautions when in those areas, said Durland Fish, an epidemiology professor at the Yale School of Public Health and senior author of the study.
He suggested tucking the bottom of your pants into your socks and using insect repellent. Besides this new infection, deer ticks can carry five other pathogens, including a malaria-like organism called babesiosis and the Powassan virus, which causes brain damage and can be fatal.
"It's not just Lyme disease anymore," Fish said. "People should take ticks bites seriously and try to avoid them."
Fish first discovered the corkscrew-shaped bacterium in ticks in Connecticut and 12 other states about 10 years ago. The bacterium is carried by the kind of ticks that carry Lyme disease -- the deer tick in Connecticut, the western blacklegged tick out west, the sheep tick in Europe and the tiaga tick in Russia.
After discovering the bacterium, Fish applied unsuccessfully for grants from the National Institutes of Health and the Centers for Disease Control for 10 years to look for the infection in people.
Then, at a conference three years ago in Cyprus, he heard about research being done by a Russian scientist who had found the infection in humans. They decided to collaborate and applied for and won funding from the National Institutes of Health to study the infection in people. They studied symptoms in 46 Russian patients. In about 10 percent of the Russian cases, the fever disappeared and then returned in a couple of weeks several times.
The Yale scientists do not know if the disease causes long-term damage if left untreated and plan to apply for more funding from the NIH to further study symptoms.
There is some concern that it can cause neurological problems. In the New England Journal, another scientist, Joseph L. Gugliotta, reported a case involving an 80-year-old New Jersey woman who developed a high fever and became withdrawn and progressively confused, developed a wobbling gait and had difficulty hearing.
Physicians, fearing a recurrence of her cancer, did a spinal tap and found evidence of the bacterium. They treated her with antibiotics and the woman recovered. However, it is hard to draw conclusions from the case because the woman's immune system was compromised due to the cancer, Krause said.