<i>Anaplasma bovis</i>–Like Infections in Humans, United States, 2015–2017

T he genus Anaplasma includes several species of tickborne, zoonotic pathogens of global importance.Three recognized species (Anaplasma phagocytophilum, Anaplasma ovis, and Anaplasma bovis) and one provisionally named species (Anaplasma capra) are associated with moderately severe to severe disease in humans (1).Human infections with A. bovis, a pathogen first identified in monocytes of cattle in Algeria in 1936 and subsequently detected in other countries in Africa, Asia, and the Americas, were reported from China in 2017 (1-3).In 2015, a targeted metagenomic approach designed to amplify the V1-V2 region of the bacterial 16S rRNA (rrs) gene identified DNA of an A. bovis-like agent in blood specimens from 2 US patients with suspected tickborne illnesses (4).The agent demonstrated 100% identity across a 357bp region of rrs to A. bovis-like sequences amplified from several human-biting Dermacentor tick species in North America ( 4).An additional 2 US patients positive for this same Anaplasma species were identified in 2017 (L.Kingry et al., unpub.data), although the genetic identity of this pathogen remained limited to the same 357-bp sequence of rrs (5-7).To further characterize the phylogenetic position of this novel agent, we evaluated additional sequences to determine the uniqueness of this strain among the expanding global complex of A. bovis-like bacteria. The StudyWe extracted DNA from 100 µL of EDTA-treated whole blood obtained from 4 patients from whom partial rrs sequences of an A. bovis-like agent were identified from a targeted metagenomics assessment of whole blood specimens collected from US patients with suspected tickborne disease (4; L. Kingry et al., unpub.data).DNA extracts containing A. bovis DNA were also available from an adult Dermacentor andersoni tick collected in Saskatchewan Landing Provincial Park in Saskatchewan, Canada, and from 5 adult Dermacentor variabilis ticks collected in Washita County, Oklahoma; Floyd County, Iowa; and Sarpy and Cass Counties, Nebraska, from which partial rrs sequences most similar with A. bovis were amplified previously (5,6).We amplified segments of the rrs, citrate synthase (gltA), and heat shock chaperon (groEL) genes using Taq PCR Master Mix Kit (QIAGEN, https://www.qiagen.com)(Table 1).Each 20-µL primary reaction consisted of 1 µM of each primer, 10 µL Taq Master Mix, 2 µL DNA, and 6 µL molecular-grade water.Secondary reactions (groEL only) consisted of 1 µM of each primer, 10 µL Taq Master Mix, 1 µL primary PCR product, and 7 µL molecular-grade water.We resolved PCR amplicons on a 1% agarose gel in Tris-acetate-EDTA buffer and cut amplicons from the gel and purified using a Wizard SV Gel and PCR Clean-up kit (Promega, https://www.promega.com).We sequenced each purified amplicon (1 µL) bidirectionally Anaplasma bovis-Like Infections in Humans, United States, 2015-2017

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