Lyme disease is on the increase everywhere in the world. This bacterial infection transmitted by the bite of ticks, can cause joint pain, fatigue, neurological damage and even facial paralysis temporary. Detected early, it is treatable. However, some people report that symptoms persist after treatment. And as Lyme disease is extremely difficult to diagnose, and how to be sure that she is the real culprit?
In the United States, approximately 15 000 cases were reported each year in the late 1990s. Today, it is about 30,000 cases, and recent estimates from the Centers for Disease Control (CDC) suggest that 10 times more people could contract the infection. In Europe, cases have been rising steadily for more than 30 years, and the world health Organization estimates that at least 65 000 people have the disease each year.
A disease that comes from a bacterium, the Borrelia burgdorferi, transmitted to humans through a tick bite. It is present today in most of North America and in some parts of Europe and Asia. According to a study in 2008, it would have “migrated” in America there are about 15 000 years before the arrival of humans, colonizing birds, small rodents and deer.
If the mechanisms behind the symptoms of Lyme are still misunderstood, in part, this is because the detection of the disease is difficult: on the one hand, it is possible to ignore for two days that a tick is clinging to us: most infections are caused by a nymph, a tick immature as little as 2 millimeters wide.
On the other hand, blood tests are not very effective when researchers are able to trace back to the bacteria: they are almost impossible to grow in culture. Instead, the researchers are monitoring the skin rashes in the form of a ring that 70% to 80 % people develop between a few days and a month after a tick bite. But this is not a surefire method of screening because “the ring” may be a less visible place of the body, or less noticeable on dark skin. African-Americans are the group who note the least this rash.
There are several types of tests looking for the antibodies produced by the immune system to fight the infection, but these tests can also present many false positives.
For all these reasons, the very existence of ” chronic Lyme disease “, the definition of which, moreover, is nebula, makes some doctors very sceptical: it may be, summarizes the New Scientist“almost impossible to determine if someone who seems to have chronic Lyme disease was actually infected, or had a disease completely different.”
This conflict is aggravated by the bad use of antibiotics : some activist groups, such as theInternational Lyme and Associated Diseases Society, advocate a course of antibiotic treatment long-term for chronic disease. However, several clinical trials demonstrate that this approach does not work better than placebo, in addition to involve significant risk, such as to contribute to the increase of antibiotic-resistant bacteria.
This also fits, complements the magazine, in a long history of the medical community to reject the chronic diseases that are difficult to define —as the chronic fatigue syndrome or fibromyalgia— putting the symptoms on the back of mental health issues poorly identified.
On the other hand, researchers such as John Aucott of Johns Hopkins University, Maryland, lead studies on participants with skin rash so characteristic, and having recently contracted Lyme disease without diagnosis past history of chronic pain or fatigue. “They are treated with an antibiotic standard and most of the people improve, but approximately 10 % are resistant to treatment,” he explains.
The researcher concludes that there is now enough evidence of the existence of the “syndrome of post-treatment Lyme disease” —even if the cause is still controversial.
Due to the overlap of symptoms with fatigue and chronic pain are common, there are no reliable statistics. Some estimates suggest that up to 20% of those who contract Lyme disease may experience these symptoms post-treatment.
As to what might explain this condition, there are a number of assumptions. Aucott and his team, for example, suggest that infection may trigger an autoimmune response, in which the body would turn against its own healthy cells, which would explain the fatigue and the pain continued after the antibiotic treatment.
Another possibility is that antibiotics do not kill all the bacteria, leaving a few organizations damaged. In animal studies, these “bacteria zombies” are slow to develop and cause arthritis symptoms more serious, while resistant to standard antibiotic treatment.
It could also be that there are no bacteria but the disease alters the neuronal networks by reframing how a person perceives the pain and the fatigue. The repetition of the pain over several months or years can indeed change a person’s attention, or even the anticipation of pain, creating a sort of feedback loop —as can be seen in people with fibromyalgia.
The other hypothesis, the syndrome may be a condition entirely different caused by other bacteria, it is also transmitted by ticks. Because ticks can be carriers of many bacteria and cause co-infections, which complicates research when setting out to identify the source of the symptoms of a poorly specific, very real, but still mysterious.
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