Even antibiotics can't always stop the bacterium

Borrelia can hide in the human body for years
from the Academy of Finland

Transmitted by tick bites, the Borrelia bacterium can hide in the human body for up to several years in spite of antibiotic treatment. The patient's symptoms may be so vague that it is extremely difficult to make the connection. The research team under Professor Matti Viljanen have now developed a mouse model that can be used to locate the hidden Borrelia bacterium and to target treatment more accurately. Professor Viljanen and his team are working in a joint Finnish-Swedish research consortium under the Microbes and Man research programme that is jointly funded by the Academy of Finland and the Swedish Foundation for Strategic Research.

The mouse model developed by Professor Viljanen and his team closely resembles chronic borreliosis in humans. Antibiotic treatment of infected mice means that the bacteria can no longer be detected in the animals by ordinary means. The symptoms, however, remain unchanged. When the mice then receive treatment that changes their immune defence system, the bacterium comes out of hiding, which may have continued for months. This result lends strong support to the theory that the Borrelia bacterium can withdraw into some unknown hiding place in the patient's body even after antibiotic treatment. The mouse model opens the door to locating these hiding places and the mechanisms with which the bacterium hides itself. This in turn may pave the way to developing methods for the treatment and prevention of borreliosis.

Ticks transmit several diseases, the most common in Scandinavia being Lyme borreliosis. A hidden Borrelia bacterium may spread from the skin to various organs, where it can hide and cause symptoms for years. Even at this stage it is usually possible to evict the bacterium from the patient's body by proper treatment. However, the symptoms persist in around one in ten patients in spite of all treatments. Sometimes the symptoms may be extremely severe and cause permanent disability.