Published 3.10.2024
Text: Elisa Kortela
Image: Shutterstock
Editing: Viestintätoimisto Jokiranta Oy

 

Lyme borreliosis and tick-borne encephalitis (TBE) are the most common tick-borne diseases in Finland. The number of diagnosed Lyme borreliosis cases exceeds 7,000 annually, and TBE was diagnosed in 194 persons in 2023. Ticks living in Finland have been found to carry other potential pathogens as well, such as Neoehrlichia mikurensis, Anaplasma phagocytophilum, Rickettsia helvetica and Borrelia miyamotoi bacteria as well as protozoa of the Babesia species. Very little is known about the pathogenic potential of these rare microbes or the incidence and clinical picture of the infections caused by them. The diagnostics of new tick-borne diseases is difficult because these microbes do not grow in standard clinical bacterial cultures.

 

Different diseases with specific characteristics

Bacterial infections in humans caused by Neoehrlichia mikurensis were first reported in 2010. Since then, more than 100 cases of neoehrlichiosis have been diagnosed in Sweden. In Finland, the first case of human neoehrlichiosis was diagnosed in autumn 2023. Neoehrlichiosis may display recurrent fever, venous thromboses and muscle pain. Immunocompromised patients, in particular, are in the risk group for a symptomatic disease. Other tick-borne infections caused by the above-mentioned bacteria have been found in humans very rarely in Europe. These diseases have specific characteristics, for example, Rickettsia helvetica and Borrelia miyamotoi may cause meningitis. Elevated liver values, muscle pain and fever have been reported in relation with bacterial infections caused by Anaplasma phagocytophilum. Symptoms of the disease caused by Babesia protozoa include prolonged or recurrent fever and anaemia. In Finland, one case of an endemic babesiosis that led to death was reported in the early 2000s.

 

Weakened immune system is a risk factor

The FINtick study team is comprised of around 20 researchers. From left: Asko Järvinen (HUS), Jessica Tikkala (Varha), Marjaana Pitkäpaasi (ÅHS), Elisa Kortela (HUS), Jukka Hytönen (Varha) and Marika Nordberg (ÅHS).

The aim of the FINtick study, starting in autumn 2024, is to provide new information about the incidence and clinical picture of tick-borne diseases and to advance their diagnostics. We will collaborate with the SWEtick study carried out in Sweden, which has been recruiting patients since autumn 2023.

The FINtick study will be carried out within Varha (The wellbeing services county of Southwest Finland), HUS (Helsinki University Hospital) and ÅHS (Åland’s health and medical care). Individuals with a suspicion of a tick-borne disease are invited to participate in the study. Potential participants include children and adolescents aged 1–17 years as well as adults who have sought medical attention because of symptoms suggesting a tick-borne disease. Symptoms leading to the suspicion of a tick-borne disease include, for example, rash, arthritis, fever of unknown origin, myocarditis, blood count changes or neurological symptoms.

A weakened immune system of the body (immunodeficiency) has been found to be a significant risk factor for many tick-borne diseases. For this reason, we try to recruit, in particular, patients with an absent or dysfunctional spleen, patients who receive biological medication (such as CD20 antibody therapy) due to a chronic health condition, or patients whose immune system is weakened due to cancer or its treatment.

The aim is to recruit 500 subjects from the regions of Uusimaa, Southwest Finland and Åland. For each subject, the maximum period of participation will be six months. During the study, blood samples will be collected from the subjects and their health will be monitored by means of questionnaires.

 

Aiming at a treatment recommendation

Nucleic acid amplification tests and immunoassays are used as methods to identify tick-borne pathogens in the samples collected from the subjects. We are interested in finding out how many of the subjects actually have a tick-borne disease, what kind of symptoms the patients have and how they recover from the disease. The intention is to develop new methods for the diagnostics and monitoring of diseases by examining the samples collected from the subjects. The aim is to draw up a Finnish treatment recommendation for the diagnostics, treatment and monitoring of new tick-borne diseases.

 

 

 

 

 

Elisa Kortela, M.D., Ph.D., Specialist in internal medicine and infectious diseases, earned her doctoral degree from the University of Turku in 2021 with a dissertation on Lyme borreliosis: diagnostics, treatment and the role of healthcare services. Kortela is currently working as a specialist in infectious diseases at Jorvi Hospital, HUS, Helsinki. In addition to tick-borne diseases, she is interested in central nervous system infections and gastrosurgical infections.