People who have recurring symptoms of Lyme disease after taking a full course of antibiotics most likely have a new infection, according to research that undercuts the theory that the illness can relapse.
The Lyme disease bacterium is spread by the tick bite that appears in the form of a “bull’s-eye rash,” according to the U.S. Centers for Disease Control and Prevention. If untreated, patients may develop fatigue, fever and muscle aches, palsy and eventually arthritis, nerve and heart disease.
A small number of patients have reported symptoms years after their initial treatment, raising concern that an incurable form of the disease exists, said Robert Nadelman, a researcher at New York Medical College in Valhalla. He analyzed bacteria from 17 people with consecutive episodes of the rash starting in 1991, and found the infections were caused by genetically distinct bacteria. There’s less than a 1 in 5 million chance that happened by chance, he said.
“Our data provide compelling evidence that courses of antibiotics that are recommended by Infectious Disease Society of America regularly cure early Lyme disease,” said Nadelman, a professor of medicine in the division of infectious diseases at New York Medical College in Valhalla, in a telephone interview. “When people have early Lyme disease again, it’s likely due to a new infection due to a new tick bite.”
The National Institutes of Health and the William and Sylvia Silberstein Foundation funded the study, which appears in Thursday’s New England Journal of Medicine.
There were 24,364 confirmed cases of Lyme disease reported in the United States last year, according to the CDC, including 3,118 in New York, 3,398 in New Jersey and 4,739 in Pennsylvania, states with the largest number of cases.
The controversy aboutrelapses versus the risk of repeat infection has broad implications for treatment and prevention, the researchers said. Chronic Lyme disease is showing up as a common diagnosis in people with unexplained pain, mental defects or fatigue, even if there is no evidence of infection with the bacteria that causes the disease, wrote Allen Steere, from Massachusetts General Hospital and Harvard Medical School.
“These patients are said to have persistent infection, which can be suppressed only with months or years of antibiotic therapy, and the therapy must be restarted when symptoms recur,” he wrote in an editorial that accompanied the study. “The weight of evidence is strongly against persistent infection as the explanation for persistent symptoms in antibiotic-treated patients with Lyme disease.”
The findings are “absolutely reassuring,” showing that people who have been bitten by tick that may harbor Lyme disease have an excellent chance of a cure, Nadelman said. Because it takes several days for a tick to transmit the infection, people who live in areas where the ticks are endemic should check themselves from head to toe each night, he said.