Lutwick, Larry I.

Abstract Background Jamestown Canyon virus (JCV) is an emerging arboviral pathogen transmitted by mosquitoes in the United States and Canada. It is associated with neuroinvasive diseases and a wide spectrum of clinical presentations. Methods A retrospective chart review was conducted at the Mayo Clinic Health System in Northwest Wisconsin from January 2018 to December 2024, analyzing data from 12 hospitalized patients diagnosed with JCV infection. This study aimed to characterize the clinical, laboratory, imaging, and outcome profiles of the disease. The cohort included individuals aged 19 to 75 years, predominantly male (75%), with all patients reporting outdoor activity and 75% being pet owners. Results Only 27% of the patients recalled a mosquito bite. Among the cohort, 2 patients acquired an infection during the first trimester of pregnancy and subsequently delivered healthy infants. Coinfections with Borrelia burgdorferi were found in 33% of cases, while 16.7% of cases were seropositive to La Crosse virus. Magnetic resonance imaging of the brain was obtained in 5 patients and was nonspecific. Cerebrospinal fluid analysis demonstrated lymphocytic or monocytic pleocytosis in all cases where the test was performed. Conclusions All patients experienced clinical improvement, with only 1 developing lingering neurological symptoms in the form of brain fog. This study highlights the clinical heterogeneity of JCV infections and underscores the importance of including JCV in the differential diagnosis for patients residing in or traveling from endemic areas.

Anaplasma phagocytophilum is an obligate intracellular, Gram-negative pathogen, causative agent of Human Granulocytic Anaplasmosis (HGA). HGA usually manifests as a non-specific febrile illness, accompanied by evidence of leucopenia, thrombocytopenia, and an alteration in liver enzymes. Neurologic manifestations of anaplasmosis are rare and rarely reported. We describe a 62-year-old man who developed encephalitis due to an Anaplasma phagocytophilum infection. The patient favorably responded to intravenous doxycycline and recovered without neurological sequela. In the tick endemic area, clinicians should have a high index of suspicion for tick-borne diseases in patients presenting with neurological deficits. A prompt diagnosis and treatment lead to improvements in morbidity and mortality.