How to differentiate an acute borreliosis from a previous infection?Lyme borreliosis is a disease that is not always easy to diagnose. It is particularly hard to differentiate between an acute and previous infection. If left untreated, borreliosis may cause difficult symptoms that will limit the patient’s life in many ways and may lead, in the worst case, to an inability to work. New methods are needed for the diagnostics of Lyme borreliosis. Currently, the potential of imaging techniques is being explored.
Writer: Annukka Pietikäinen
The number of Lyme borreliosis cases has increased in recent years. The disease is caused by the Borrelia burgdorferi bacterium, which transmits through infected ticks when they attach to humans to feed on their blood. Fortunately, not all ticks carry Borrelia and the prevalence of bacteria in tick populations varies from one region to another. It takes hours for the bacteria to transmit from a tick to a human being. If you notice soon enough that a tick has attached to your skin and you manage to remove it, the risk of getting Lyme borreliosis is small. It is, thus, highly recommended to check for ticks on your clothes and skin whenever you have been out in nature.
If the Borrelia bacterium manages to transmit from the tick to a human, a red and expanding circular rash will typically appear on the site of the tick bite. In obvious cases, the doctor may prescribe the patient antibiotics without laboratory testing. However, a circular rash is not necessarily seen in all cases, or it may develop on your body in a place where it goes unnoticed. In these cases, the bacteria may disseminate from the skin to other parts of body, including joints, the nervous system and the heart. When the infection has spread, the symptoms are varying, depending on which organ is affected. Diagnostics at a progressed disease stage call for laboratory testing.
Borreliosis can be diagnosed through serological testing, that is, by determining antibodies that are specific to Borrelia. In most cases, serology-based diagnostics are functional but there are two major problems. First, at the very early stages of disease, the number of antibodies developed is not necessarily large enough for detection through laboratory testing. Another problem is that the antibodies remain in the body for a long period of times, up to years, after an infection. These antibodies do not, however, protect against re-infection, so it is possible that a person is infected with Lyme borreliosis several times. Thus, a positive antibody finding does not show whether the patient has an acute infection or has previously had Lyme borreliosis. Unfortunately, the PCR and cultivation methods are not suitable to borreliosis diagnostics because of their poor sensitivity.
So, how might we differentiate between a fresh infection and an earlier disease? The aim of our research team is to develop new methods for the diagnostics of Lyme borreliosis in order to solve this issue. We are investigating the possibility of using mass spectrometry to identify biomarkers, or metabolites, that would indicate an acute infection. Another approach is to apply imaging methods for the examination of Lyme borreliosis. We have shown that it is possible to image an acute infection caused by the Borrelia bacterium by means of positron emission tomography (PET). Our team is developing a tracer that would bind to the Borrelia bacterium in the body and could be detected by means of PET imaging. The grant received from the Sakari Alhopuro Foundation plays a key role in the achievement of these targets.
PhD Annukka Pietikäinen is working as Microbiologist in the Clinical Microbiology Unit of the TYKS (Turku University Hospital) Laboratories, and as a post-doc researcher at the Department of Biomedicine, University of Turku. She earned her doctoral degree in 2019 with a thesis on the pathogenesis and laboratory diagnostics of Lyme borreliosis. Her current research focuses on the development of the laboratory diagnostics of Lyme borreliosis.
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