BACTERIA

Cutaneous manifestations of Lyme borreliosis

Lyme disease is one of the least known infectious diseases. It is transmitted to humans through the bite of an infected tick, and can affect both children and adults. However, this disease is more prevalent in North America. And some people are more exposed than others. Indeed, wooded and humid areas are particularly conducive to the proliferation of ticks responsible for this disease. As a result, farmers, ranchers, hikers, hunters, forest rangers and those who live near wooded areas are most exposed to this disease. Although Lyme borreliosis has several stages, the following paragraphs will focus on the skin manifestations of Lyme borreliosis.

What is meant by "Lyme disease"?

Before getting to the heart of the matter, it is worthwhile to remind ourselves what Lyme disease is. Lyme borreliosis is an infectious disease caused by a bacterium, as was pointed out later. More specifically, the bacterium in question is Borrelia burgdorferi. This bacterium, it should be remembered, is transmitted to humans through tick bites. However, not all ticks can transmit the disease. In fact, the tick in question must be infected with the bacteria. It should be noted that Lyme disease is not new; it has been well known in the medical field since the 19th century. However, it has only been "rediscovered" in recent decades, particularly in Canada and North America. It should be noted, however, that all continents are home to tick species that can transmit this pathology. However, the species varies from one continent to another.

Where do we find the tick responsible for this disease?

As mentioned above, Lyme disease is currently most prevalent in North America. But anywhere in the world, a tick carrying the bacteria responsible for Lyme borreliosis can still be found, even in cities. However, it is mainly wet and wooded areas, areas full of shrubs and tall grasses that are most infected by this type of tick. These ticks can also have a variety of hosts such as mammals and small rodents, as well as certain species of birds and other animals that live in forests. In Canada, white-legged mice are the main host for the larvae  and pupae of ticks that carry the Lyme disease bacteria.

In addition, it should also be noted that the tick in question develops in several stages: larva, pupa and adult stage. The infected tick does not infect in the same way depending on its stage of development. It has been found that it is the nymphs that contaminate the most. In other words, the infected tick is most dangerous during the intermediate stage of its development. However, for the bacteria to be transmitted to humans, the nymphs must cling to the skin for several hours. In concrete terms, the risk of contamination is an increasing function of the length of time the tick remains attached to the skin. It is therefore essential that the tick is removed at the latest within 24 hours of the bite.

Skin signs of Lyme disease

The special thing about Lyme disease is that it can take years before symptoms are noticeable and worsen. Moreover, during its development, the most characteristic signs of this disease remain the cutaneous manifestations. Indeed, the other symptoms of Lyme borreliosis can sometimes mislead doctors into thinking that they may signify other conditions. Indeed, this disease can affect various other organs such as the heart, the eye, the nervous system or the joints.

Usually, it is the cutaneous manifestations that the disease causes that push patients to go see  a doctor. The evolution of these skin signs is as follows: