RT Journal Article SR Electronic T1 Central nervous system involvement of anaplasmosis JF BMJ Case Reports JO BMJ Case Reports FD BMJ Publishing Group Ltd SP e243665 DO 10.1136/bcr-2021-243665 VO 14 IS 12 A1 Jon Brandon Mullholand A1 Nathanial Tolman A1 Anna De Obaldia A1 Eileen Hennrikus YR 2021 UL http://casereports.bmj.com/content/14/12/e243665.abstract AB A 64-year-old woman presented with 24 hours of lethargy, confusion, headache, nausea and vomiting. Examination revealed expressive aphasia, conjunctival suffusion and a tick embedded in her popliteal fossa. Labs revealed hyponatraemia, transaminitis, leucopenia, thrombocytopenia and an elevated C reactive protein. Peripheral blood smear was unremarkable. MRI/magnetic resonance angiogram revealed bilateral frontoparietal subarachnoid haemorrhage which was further confirmed by lumbar puncture which revealed six nucleated cells, 92% lymphocytes, 1460 red blood cells, normal glucose and protein and negative cryptococcal antigen, herpes simplex PCR and Lyme PCR. Serum Lyme IgG/IgM antibodies and PCR, Erlichia chaffeensis serum IgG/IgM antibodies and PCR and anaplasma serum IgG/IgM antibodies were negative. Anaplasmosis serum PCR was positive. The tick was identified as Ixodes scapularis. The patient was diagnosed with anaplasmosis and treated with 21 days of doxycycline resulting in improvement of symptoms, but lingering headaches and word finding difficulties.