Central nervous system involvement of anaplasmosis

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.