Tick-borne Pathogens Detected in the Blood of Immunosuppressed Norwegian Patients Living in a Tick-endemic Area

Abstract

Background The knowledge regarding the occurrence and the clinical implications of tick-borne infections in immunosuppressed patients living in tick-endemic areas is limited. Methods Adult patients with autoimmune conditions requiring immunosuppressive treatment such as infliximab and rituximab, were invited to participate in the study when they attended the hospital for treatment and/or control of the disease. Whole blood samples were analysed by real-time PCR for Borrelia burgdorferi s.l., Borrelia miyamotoi, Anaplasma phagocytophilum, Rickettsia spp., Candidatus Neoehrlichia mikurensis and Babesia spp. Results The occurrence of tick-borne pathogens in the blood of patients (n=163) with autoimmune conditions requiring immunosuppressive treatment were evaluated. Pathogen DNA was detected in 8.6% (14/163) of the patients. The predominant pathogen was Candidatus Neoehrlichia mikurensis (12/14), which was carried in the blood of infected patients for 10-59 days until treatment with doxycycline. Borrelia burgdorferi sensu lato and Rickettsia spp. were detected in one patient each. The B. burgdorferi-infected patient presented with fever, whereas the remaining patients were judged to have subclinical infections. Borrelia miyamotoi, Anaplasma phagocytophilum, and Babesia spp. were not detected in any patient. Conclusions Patients treated with biologicals and living in a tick-endemic area seem to have a high risk of contracting Ca. Neoehrlichia mikurensis infection which if left untreated could result in thromboembolic complications.

The emerging tick-borne pathogen Neoehrlichia mikurensis: first French case series and vector epidemiology

“…Another interesting observation is the duration of bacteremia, notably in patient C, who remained bacteremic for more than two months (77 days). This fact is corroborated by several studies on N. mikurensis in immunocompromised and immunocompetent patients [13,33,34]. This long-lasting bloodstream infection allows the late diagnosis of neoehrlichiosis using molecular tools such as PCR because thus far, there is no reliable serological assay allowing the retrospective diagnosis of N. mikurensis infection [41].…”

“…Although this bacterium has been observed in the eastern part of France in ticks [ 24 , 25 ], no studies have been carried out on patients in France. To date, cases of neoehrlichiosis have been reported in northern and central Europe, especially in Sweden [ 10 , 33 ], Norway [ 34 ], Germany [ 35 ], Switzerland [ 36 ], and the Czech Republic [ 37 ] and more recently in Austria [ 38 ]. Cases have also been reported in China [ 8 ].…”

“…We cannot be certain that neoehrlichiosis was the cause of this thrombosis; nevertheless, thrombosis should be highly monitored in patients with neoehrlichiosis. Indeed, several reports emphasize the fact that thromboembolic events, including deep vein thrombosis, could occur during the course of N. mikurensis infection, especially in immunocompromised patients [ 10 , 34 ]. N. mikurensis tropism for endothelial cells [ 12 ] is probably responsible for the development of thrombosis.…”

No molecular detection of tick-borne pathogens in the blood of patients with erythema migrans in Belgium

“…The positive patients were asymptomatic or had non-characteristic symptoms, such as fever, headache, arthralgia, myalgia and malaise. In addition, N. mikurensis has been detected in two of 102 persons bitten by ticks in a study in Sweden [ 43 , 50 ], in five asymptomatic foresters in Poland [ 51 ] and in 12 subclinical/asymptomatic immunosuppressed patients in Norway [ 52 ]. Clinical cases have been reported in Europe, originating from Germany, Czech Republic, Sweden and Switzerland [ 4 , 14 , 53 , 54 ].…”

Neoehrlichia mikurensis Causing Thrombosis and Relapsing Fever in a Lymphoma Patient Receiving Rituximab

“…Since then, several case reports from Europe have been published [10]. Severe infection primarily affects immunocompromised individuals, and splenectomised, rituximabtreated patients with haematological malignancies or autoimmune diseases in particular [3,11,12]. Impaired ability to generate a specific antibody response to N. mikurensis in asplenic and B-cell deficient patients likely plays an important role in the pathogenesis of severe illness [13].…”