Detection of <i>Neoehrlichia mikurensis</i> DNA in blood donors in southeastern Sweden

Sandelin, Lisa Labbé; Olofsson, Jenny; Tolf, Conny; Rohlén, Louise; Brudin, Lars; Tjernberg, Ivar; Lindgren, Per-Eric; Olsén, Björn; Waldenström, Jonas

doi:10.1080/23744235.2022.2087732

Cited by 5 publications

(5 citation statements)

References 38 publications

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“…N. mikurensis has been detected in ticks from more than 18 countries in Europe with a prevalence varying from 0.3% in Poland to 25.5% in Norway [ 1 , 24 – 27 ]. The prevalence of N. mikurensis in blood from immunocompromised patients and healthy blood donors found in this study is comparable to or slightly lower compared to our neighboring Scandinavian countries [ 12 , 28 ]. This agrees with a lower prevalence of N. mikurensis in ticks collected in Denmark compared to Norway [ 7 ].…”

Section: Discussionsupporting

confidence: 67%

“…A study from southern Norway found the prevalence of N. mikurensis in a cohort of immunocompromised patients living in a tick endemic area to be 7.4% (12/163), collected in 2018 (September–December) and 2019 (March–May), and 1.2% (1/85) in a cohort of immunocompetent controls, collected in 2013/2014 [ 12 ]. A recent study from southeastern Sweden found a prevalence of 0.7% among 1006 blood donors, collected in 2019 (June–August) and 2021 (February–November) [ 28 ]. The samples from our cohort of immunocompromised patients were collected all year round, and the blood donor samples were collected from March to October.…”

Section: Discussionmentioning

confidence: 99%

“…Hence, our findings may have been influenced by sampling outside “tick-season”. However, N. mikurensis has been found to persist in the bloodstream for longer periods among immunocompromised as well as in immunocompetent individuals [ 12 , 28 ], although re-infection is also possible. Considerably higher prevalence was found among symptomatic individuals, with recent tick-bite exposure in Norway (10%) and Sweden (1.9%) [ 18 , 19 ].…”

Section: Discussionmentioning

confidence: 99%

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Neoehrlichia mikurensis in Danish immunocompromised patients: a retrospective cohort study

Gynthersen

Hansen

Ocias

et al. 2023

Ann Clin Microbiol Antimicrob

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Background The tick-borne bacterium, Neoehrlichia mikurensis (N. mikurensis) can cause severe febrile illness and thromboembolic complications in immunocompromised individuals. We investigated the presence of N. mikurensis DNA in retrospectively collected plasma from a well-characterized cohort of Danish immunocompromised patients. Methods Plasma samples from 239 patients with immune dysfunction related to hematological or rheumatological disease or due to immunosuppressive therapy, were retrieved from a transdisciplinary biobank (PERSIMUNE) at Rigshospitalet, Copenhagen, Denmark. Serving as immunocompetent controls, plasma samples from 192 blood donors were included. All samples were collected between 2015 and 2019. Real-time PCR targeting the groEL gene was used to detect N. mikurensis DNA. Sequencing was used for confirmation. Borrelia burgdorferi sensu lato IgG antibodies were detected by ELISA as a proxy of tick exposure. Prevalence was compared using Fisher’s exact test. Results Neoehrlichia mikurensis DNA was detected in 3/239 (1.3%, 95% confidence interval (CI): 0.3 – 3.6%) patients, all of whom primarily had a hematological disease. Follow-up samples of these patients were negative. N. mikurensis DNA was not detected in any of the blood donor samples. IgG antibodies against B. burgdorferi s.l. were detected with similar prevalence in immunocompromised patients and blood donors, i.e., 18/239 (7.5%, 95% CI: 4.8–11.5%) and 11/192 (5.7%, 95%: CI 3.2–10.0%). Conclusion In this study, patients with N. mikurensis were not identified by clinical indication and N. mikurensis may therefore be underdiagnosed in Danish patients. Further investigations are needed to explore the clinical significance and implications of this infection.

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Section: Discussionsupporting

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Neoehrlichia mikurensis in Danish immunocompromised patients: a retrospective cohort study

Gynthersen

Hansen

Ocias

et al. 2023

Ann Clin Microbiol Antimicrob

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“…A Swedish study estimated the prevalence to be 0.7% (7/1006) of blood donors with N. mikurensis . 32 Here, the PCR analysis was based on whole blood, which has been reported to be less sensitive than plasma. 36 We increased the volume of plasma used for DNA extraction to account for a lower bacterial load among healthy individuals than immunocompromised.…”

Section: Discussionmentioning

confidence: 99%

“…5 17 40 Due to the overlap with symptoms often experienced in patients with inflammatory diseases combined with rheumatological patients' tolerance of their regular symptoms may increase the risk of missing or delaying a diagnosis of neoehrlichiosis. 13 17 The fact that N. mikurensis can persist in blood for extended periods of time 32 and the limited awareness of the infection among physicians, added to our concern that the infection could go unnoticed in this population. However, our results indicate that the infection is rare among rheumatological patients receiving TNFi in Denmark, and, therefore, routine screening of N. mikurensis is not recommended.…”

Section: Discussionmentioning

confidence: 99%

Neoehrlichia mikurensisis uncommon in rheumatological patients receiving tumour necrosis factor inhibitors and in blood donors: a retrospective cohort study

Gynthersen,

Ørbæk,

Høgdall

et al. 2024

RMD Open

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IntroductionNeoehrlichia mikurensisis a tick-borne bacterium that primarily causes disease in immunocompromised patients. The bacterium has been detected in ticks throughout Europe, with a 0%–25% prevalence.N. mikurensisinfection presents unspecific symptoms, which can easily be mistaken for inflammatory disease activity. We aimed to determine the prevalence ofN. mikurensisin rheumatological patients receiving tumour necrosis factor inhibitors (TNFi) and a cohort of healthy individuals.Materials and methodsThis retrospective cohort study included 400 rheumatological patients treated with TNFi and 400 healthy blood donors. Plasma samples were retrieved from the Danish Rheumatological Biobank and the Danish Blood Donor Study between 2015 and 2022. Age, sex, diagnosis and duration of TNFi treatment were recovered from the Danish Rheumatological Database, DANBIO. Data on age and sex were available for the blood donors. One plasma sample per individual was tested forN. mikurensisDNA-specific real-time PCR targeting thegroELgene.ResultsIn the rheumatological patients, the median age was 61 years (IQR 55–68 years), 62% were women, and 44% had a diagnosis of seropositive rheumatoid arthritis. In total, 54% of the patients were treated with infliximab. The median time from TNFi initiation to blood sampling was 20 months (IQR, 5–60 months).N. mikurensisDNA was not detected in any samples from patients or blood donors.ConclusionN. mikurensisinfection does not appear to represent a prevalent risk in Danish rheumatological patients receiving TNFi or in blood donors.

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Ten years of detecting Neoehrlichia mikurensis infections in Sweden: demographic, clinical and inflammatory parameters

Wennerås,

Wass,

Bergström

et al. 2024

Eur J Clin Microbiol Infect Dis

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Purpose To increase knowledge about the varied clinical manifestations of human infection with the emerging tick-borne pathogen Neoehrlichia mikurensis. Methods All patients diagnosed in Sweden with N. mikurensis infection during a 10-year period (2013–2023) were investigated regarding their demographic factors, risk factors, comorbidities, clinical signs and symptoms, and laboratory results. Multivariate models were generated using “Orthogonal Projections to Latent Structures-Discriminant Analysis” to identify clinical and immune parameters associated with N. mikurensis infection. Results During the 10-year period, 134 patients were diagnosed with N. mikurensis infection, 102 of whom were included in this study. Most of the patients (79%) were immunosuppressed. The main comorbidities were malignant B-cell lymphomas, multiple sclerosis, and rheumatoid arthritis. Rituximab therapy (59%) and splenectomy (14%) featured prominently. All patients resided in the southern tick-endemic part of Sweden, yet one-third of them were diagnosed in wintertime when ticks are inactive. Two asymptomatically infected blood donors were identified but transfusion-transmitted infection was not confirmed. Increased levels of C-reactive protein, orosomucoid, and total IgM in serum were associated with neoehrlichiosis. Previously unreported symptoms such as ankle edema, neck pain, numbness, and sudden deafness were detected in some patients. One case of aplastic anemia partially improved after eradication of the infection. Conclusions Neoehrlichiosis is a multi-faceted emerging infectious disease.

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Detection of Neoehrlichia mikurensis DNA in blood donors in southeastern Sweden

Cited by 5 publications

References 38 publications

Neoehrlichia mikurensis in Danish immunocompromised patients: a retrospective cohort study

Neoehrlichia mikurensis in Danish immunocompromised patients: a retrospective cohort study

Neoehrlichia mikurensisis uncommon in rheumatological patients receiving tumour necrosis factor inhibitors and in blood donors: a retrospective cohort study

Ten years of detecting Neoehrlichia mikurensis infections in Sweden: demographic, clinical and inflammatory parameters

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