- The bull’s eye rash is usually the most prominent symptom of Lyme disease.
- The bull's eye rash is not always visible.
- Serological tests are the most commonly used indicators to determine whether there is Lyme infection.
Lyme disease is primarily diagnosed through an analysis of the symptoms, although blood tests are also sometimes used.
What to keep in mind when diagnosing Lyme disease
The bull’s eye rash is usually the most prominent symptom of Lyme’s disease, and a visualization of this rash is usually indicative of an infection. Nevertheless, the rash is not always visible, there are some people who may get infected by the Borrelia bacteria but don’t have the rash. The rash does not always appear as a bull’s eye either, sometimes it can remain solid red, and that is also indicative of an infection. In the cases when no rash appears, the diagnosis is a little bit harder, until other signs and symptoms appear when the bacteria gets disseminated through the bloodstream to other body parts.
Most people will not recall a tick bite because the tick, along with its saliva, injects some chemicals that cause numbness. The bite is, therefore, painless and most people won’t feel the bite or recall such an experience.
It’s easier to inquire about whether they had been in endemic Lyme disease areas, where infected deer ticks are common. The north-eastern region of the US has the most concentration of Lyme disease cases, although other areas, like Canada, Minnesota, and Maine have had an increased number of cases reported.
Even though Lyme disease is concentrated in certain areas, anyone who spends time in the woods would be at risk of an infection. If someone presents the signs and symptoms of the disease and also spent time outdoors, it can be a safe bet that they’ve got Lyme disease. Of course, it would be more definitive if there were other symptoms too.
When blood tests are done, there is a possibility that the results may be negative, even though the person is infected. If the bull’s eye rash is present, even though the tests are negative, the individual should be treated for Lyme disease.
Tests for Lyme disease
A number of lab tests, as well as neuroimaging examinations, may be used to diagnose Lyme disease.
Serological tests are the most commonly used indicators to determine whether there is a Lyme infection. However, these tests are most effective during the late stages when the body has produced sufficient antibodies in the blood. In the early stages of the disease, these antibodies can’t be detected in serological tests, and this leads to false positive results. Because of this, as well as the cost of the tests, they are not often used, except in addition to other symptoms.
Polymerase chain reaction test detects the DNA of the Lyme disease spirochete but it also often gives false negative results. However, it is most effective for detecting Lyme’s arthritis, when the Lyme disease affects the bones.
Some laboratories have also started to use urine antigen tests, PCR tests on urine as well as new technologies like LTT-MELISA. However, the CDC discourages these tests because their effectiveness hasn’t been verified yet.
MRI’s and SPECT images have been shown to be useful in diagnosing Lyme disease in certain situations. However, these methods are still not reliable.