title: Close geographic association of human neoehrlichiosis and tick populations carrying "Candidatus Neoehrlichia mikurensis" in eastern Switzerland.
abstract: Neoehrlichiosis caused by "Candidatus Neoehrlichia mikurensis" is an emerging zoonotic disease. In total, six patients have been described in Europe, with the first case detected in 2007. In addition, seven patients from China were described in a report published in October 2012. In 2009, we diagnosed the first human case of "Ca. Neoehrlichia mikurensis" infection in the Zurich area (Switzerland). Here, we report two additional human cases from the same region, which were identified by broad-range 16S rRNA gene PCR. Both patients were immunocompromised and presented with similar clinical syndromes, including fever, malaise, and weight loss. A diagnostic multiplex real-time PCR was developed for specific detection of "Ca. Neoehrlichia mikurensis" infections. The assay is based on the signature sequence of a 280-bp fragment of the "Ca. Neoehrlichia mikurensis" 16S rRNA gene and incorporates a "Ca. Neoehrlichia mikurensis" species, a "Ca. Neoehrlichia" genus, and an Anaplasmataceae family probe for simultaneous screening. The analytical sensitivity was determined to be below five copies of the "Ca. Neoehrlichia mikurensis" 16S rRNA gene. Our results show that the assay is suitable for the direct detection of "Ca. Neoehrlichia mikurensis" DNA in clinical samples from, for example, blood and bone marrow. In addition, it allows for monitoring treatment response during antibiotic therapy. Using the same assay, DNA extracts from 1,916 ticks collected in four forests in close proximity to the patients' residences (<3 km) were screened. At all sampling sites, the minimal prevalence of "Ca. Neoehrlichia mikurensis" was between 3.5 to 8% in pools of either nymphs, males, or females, showing a strong geographic association between the three patients and the assumed vector.
authors.affiliation: Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.
authors.forename: Florian P
authors.initials: FP
authors.lastname: Maurer
authors.forename: Peter M
authors.initials: PM
authors.lastname: Keller
authors.forename: Christian
authors.initials: C
authors.lastname: Beuret
authors.forename: Cornelia
authors.initials: C
authors.lastname: Joha
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Achermann
authors.forename: Jacques
authors.initials: J
authors.lastname: Gubler
authors.forename: Daniela
authors.initials: D
authors.lastname: Bircher
authors.forename: Urs
authors.initials: U
authors.lastname: Karrer
authors.forename: Jan
authors.initials: J
authors.lastname: Fehr
authors.forename: Lukas
authors.initials: L
authors.lastname: Zimmerli
authors.forename: Guido V
authors.initials: GV
authors.lastname: Bloemberg
mesh_terms: D000368:Aged; D000710:Anaplasmataceae / Q000302:isolation & purification*; D000711:Anaplasmataceae Infections / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology*; D000818:Animals; D001483:Base Sequence; D002681:China / Q000453:epidemiology; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D015995:Prevalence; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D016415:Sequence Alignment; D013987:Ticks / Q000382:microbiology*; D019371:Topography, Medical
chemical_list: D012336:RNA, Ribosomal, 16S