Publications
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Dahlberg, Audun Olav; Aase, Audun; Reiso, Harald; Thortveit, Erik Thomas; Eikeland, Randi & Engstrøm, Morten
[Show all 7 contributors for this article]
(2025).
Persistent self-reported health complaints in Norwegians who attribute their symptoms to tick bites or tick-borne disease– a cross-sectional controlled study.
BMC Infectious Diseases.
25.
doi:
10.1186/s12879-025-11104-0.
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Background: The frequency and mechanisms of persistent health complaints attributed to tick bites or tick-borne diseases are unknown. We evaluate such complaints in Norwegian cases and controls. Methods: People older than 18 years with persistent health complaints of six months or more attributed to tick bites or tick-borne diseases (cases) were recruited into a nationwide cross-sectional study between October 2016 and January 2021. Demographic data, tick bites, antibiotic use, and tick-borne pathogen serology were recorded. We evaluated somatic symptoms (PHQ-15), fatigue (Fatigue Severity Scale), mental and physical health (RAND-36), affective symptoms (HAD Scale) and modern health worries (MHW Scale) as outcome measures. Serological tests included IgG antibodies against B. burgdorferi (Bb) and other tick-borne pathogens. The control population (n = 2803) was recruited from a tick-endemic region in Søgne, southern Norway. Differences between cases and controls were evaluated. Results: A total of 500 responses were collected through general practitioners (n = 14), by invitation (n = 94), and by Short Message Service (SMS) (n = 392). The estimate of prevalence is based on 392 of 270.000 included by SMS (0.15%). The SMS cohort reported better physical health than those recruited by invitation. Cases had significantly more somatic and affective symptoms, fatigue, comorbidities, and reduced quality of life related to health than controls. The differences in fatigue and physical health between cases and controls were not related to previous tick exposures. Bb IgG and other antibodies against tick-borne pathogens were more prevalent in cases than controls. In multivariable analyses, cases that were never treated did not exhibit higher somatic symptom scores compared to those treated multiple times. Seropositive Bb cases had worse mental health (p < 0.001) and more depressive symptoms (p = 0.017) than seronegative cases. Conclusions: The crude prevalence of persistent health complaints in Norway attributed to tick bites or tick-borne diseases is 0.15%. The cases reported significantly poorer physical health, including increased fatigue, when compared to the controls. These relationships were not affected by tick exposures. However, poorer mental health in cases may be associated with Bb seropositivity, especially for the ones with comorbidities. In conclusion, no clear associations were found between tick bites, tick-borne diseases and persistent health complaints.
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Thortveit, Erik Thomas; Aase, Audun; Petersen, Lizette Balle; Lorentzen, Åslaug Rudjord; Mygland, Åse & Ljøstad, Unn
(2020).
Subjective health complaints and exposure to tick-borne infections in southern Norway.
Acta Neurologica Scandinavica.
ISSN 0001-6314.
142(3),
p. 260–266.
doi:
10.1111/ane.13263.
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Objectives: Whether tick‐borne infections can cause chronic subjective health complaints is heavily debated. If such a causal connection exists, one would expect to find more health complaints among individuals exposed to tick‐borne infections than among non‐exposed. In this study, we aimed to assess if exposure to tick‐borne infections earlier in life, evaluated by examination of serum for IgG antibodies to tick‐borne microbes, was associated with self‐reported somatic symptom load. Materials & Methods: All individuals with residential address in Søgne municipality in southern Norway, aged 18‐69 years, were invited to participate in the study. Blood samples were analyzed for IgG antibodies to different tick‐borne microbes, and somatic symptom load was charted by the Patient Health Questionnaire‐15 (PHQ‐15). Results: Out of 7424 invited individuals, 2968 (40.0%) were included in the study. We detected IgG antibodies to Borrelia burgdorferi sensu lato (Bb) in 22.9% (95% CI 21.4‐24.4). Bb seropositive individuals reported less frequently moderate to severe somatic symptom load (ie, PHQ‐15 sum score ≥ 10) than seronegative individuals (12.5% versus 17.7%, difference 5.2% [95% 2.1‐8.0]). However, when adjusting for several other variables in a multivariable linear regression model, presence of serum IgG antibodies to Bb was not associated with somatic symptom load. Presence of IgG antibodies to other tick‐borne microbes than Bb, or seropositivity to at least two microbes, was also not associated with somatic symptom load. Conclusion: Presence of serum IgG antibodies to tick‐borne microbes was not associated with self‐reported somatic symptom load.
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Thortveit, Erik Thomas; Aase, Audun; Petersen, Lizette Balle; Lorentzen, Åslaug Rudjord; Mygland, Åse & Ljøstad, Unn
(2020).
Human seroprevalence of antibodies to tick-borne microbes in southern Norway.
Ticks and Tick-borne Diseases.
ISSN 1877-959X.
11(4),
p. 1–6.
doi:
10.1016/j.ttbdis.2020.101410.
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The tick Ixodes ricinus is widespread along the coastline of southern Norway, but data on human exposure to tick-borne microbes are scarce. We aimed to assess the seroprevalence of IgG antibodies to various tick-borne microbes in the general adult population living in a Norwegian municipality where ticks are abundant. Søgne is a coastline municipality in the southernmost part of Norway, and has a high density of ticks. All individuals aged 18-69 years with residential address in Søgne municipality (n = 7424) were invited to give a blood sample and answer a questionnaire. Blood samples from 3568 individuals were available for analysis. All samples were analyzed for IgG antibodies to Borrelia burgdorferi sensu lato (Bbsl), and around 1500 samples for IgG antibodies to other tick-borne microbes. Serum IgG antibodies to Bbsl were present in 22.0% (785/3568) of the tested samples, tick-borne encephalitis virus (TBEV) in 3.1% (45/1453), Anaplasma phagocytophilum in 11.0% (159/1452), Babesia microti in 2.1% (33/1537), Bartonella henselae/B. quintana in 0.1% (2/1451) and Rickettsia helvetica/R. conorii in 4.2% (60/1445). Serum IgG antibodies to A. phagocytophilum and R. helvetica/R. conorii were significantly more prevalent (p = 0.010 and p = 0.016, respectively) among individuals with serum IgG antibodies to Bbsl than among individuals without. In conclusion, our study showed a high exposure to Bbsl in the general adult population living in a coastline municipality in the southernmost part of Norway. The population is also exposed to A. phagocytophilum, R. helvetica/R. conorii, B. microti and TBEV, but very rarely B. henselae/B. quintana.
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Thortveit, Erik Thomas; Lorentzen, Åslaug Rudjord; Ljøstad, Unn & Mygland, Åse
(2018).
Somatic symptoms and fatigue in a Norwegian population with high exposure to ticks.
Ticks and Tick-borne Diseases.
ISSN 1877-959X.
10(1),
p. 156–161.
doi:
10.1016/j.ttbdis.2018.09.012.
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Bøe, Magne Geir; Thortveit, Erik Thomas; Vatne, Anita & Mygland, Åse
(2016).
Chronic headache with medication overuse: Long-term prognosis after withdrawal therapy.
Cephalalgia.
ISSN 0333-1024.
37(13),
p. 1215–1221.
doi:
10.1177/0333102416672493.
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Thortveit, Erik Thomas; Bøe, Magne Geir; Ljøstad, Unn; Mygland, Åse & Tveiten, Arnstein
(2014).
Organizational changes aiming to reduce iv tPA door-to-needle time.
Acta Neurologica Scandinavica.
ISSN 0001-6314.
130(4),
p. 248–252.
doi:
10.1111/ane.12204.
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Published
Mar. 21, 2025 3:37 PM
- Last modified
Mar. 21, 2025 3:37 PM
