Lyme disease remains confusing to many

Infection not detected for weeks after bite

NEW HAVEN — People are still confused and misinformed about Lyme disease, despite its being documented and studied since at least 1977, when it was called Lyme arthritis.

Partly because the blood test for Lyme disease is not useful for at least three weeks after infection, by which time the bull’s- eye rash ( which is often simply red) has appeared, people may believe they have Lyme simply because they have aches in their joints or feel tired, according to Dr. Eugene Shapiro, a professor of pediatrics and epidemiology at the Yale School of Public Health, who recently wrote a viewpoint article for the JAMA Network, “Lyme Disease in 2018: What is New ( and What is Not).”

One problem, Shapiro said, is that “people misuse the tests. ... There’s a myth that a lot of people have Lyme disease, but the test will be negative.” That’s not true, he said. It’s just that the test is not effective shortly after infection.

“But that same test is supergood. It’s very sensitive four, five, six weeks after you get infected,” Shapiro said.

The inaccurate information extends to how quickly the disease, carried by the black- legged, or deer tick, is spreading, Shapiro said.

“Every year, we see all these publications about the stratospheric increase in Lyme disease,” he said. “In fact, for the last four years for which data are available, there are no significant increases” in reported cases. “There are small, incremental increases over time.

“Some of it is due to its spread to new areas that are next door” to where the disease is well estab- lished, such as western Pennsylvania and northern New England, he said.

There are two types of tests used to determine the presence of Lyme. One, an enzyme- linked immunosorbent assay, or ELISA, tests for the presence of antibodies, but “the rash develops before antibodies develop that you can detect,” Shapiro said.

The second test, called the Western blot test, is “specific for the bacteria that cause Lyme disease, he said. That bacterium is Borrelia burgdorferi, which the tick picks up from birds and transmits to humans.

If you see a rash that looks like Lyme, see your doctor, who will prescribe an oral antibiotic such as doxycycline, Shapiro said. In that case, “There’s no need to test,” he said. The risk is “not false positives, it’s false negatives,” he said. “If you have a typical rash … you have Lyme disease and the result of the test doesn’t matter.”

Once on the antibiotics, the test may show a negative result because “the treatment is very effective,” he said.

“People who have early Lyme disease, almost all of them will have a rash. If it’s early on, you should be carefully examined for the rash,” Shapiro said. But many people believe they have Lyme when they have a virus or are simply overtired for a long period of time.

“If you’ve had arthralgia — or pain in your muscles — or fatigue for long periods of time, weeks or months, but not other objective physical findings, it’s very unlikely you have Lyme disease,” he said.

Shapiro distinguished between such symptoms and the objective signs of Lyme disease, which include the rash ( which disappears over time), facial palsy or “frank arthritis,” such as a swollen knee joint. Arthritis can range in the degree of pain, but “when it’s caused by bacteria, including Lyme disease, there’s swelling, fluid in the joint,” Shapiro said.

However, “about 10 percent of people with Lyme disease don’t have the typical rash, but they have objective findings,” he said. “They have signs. It’s not just nonspecific symptoms.”

Shapiro’s JAMA Network article also mentions a second bacterial infection spread by the deer tick: Borrelia miyamotoi, which was first reported in the United States in 2013. The ELISA test can misdiagnose this disease as Lyme, Shapiro writes, but it usually is not accompanied by a rash. It can cause fever, headache, arthralgia and fatigue and can lead to meningitis in those with weak immune systems. There is no test for B. miyamotoi, but the same antibiotics, doxycycline and amoxicillin, will cure the patient.