Abstract & Commentary

Human Jamestown Canyon Virus

By Dean L. Winslow, MD, FACP, FIDSA, Chief, Division of AIDS Medicine, Santa Clara Valley Medical Center; Clinical Professor, Stanford University School of Medicine, is Associate Editor for Infectious Disease Alert.

Dr. Winslow is a speaker for Cubist Pharmaceuticals and GSK, and is a consultant for Siemens Diagnostics.

Synopsis: Human infection with the mosquito-borne bunyavirus Jamestown Canyon Virus (JCV) is rare. A case of encephalitis in a 51-year-old man from Montana is reported. Diagnosis was made by detection of JCV-specific IgM ELISA results and a four-fold rise in JCV plaque reduction neutralization test (PRNT) titers.

Sources: Centers for Disease Control and Prevention. Human jamestown canyon virus infection — Montana, 2009. MMWR Morb Mortal Wkly Rep 2011;60:652-655.

A previously healthy 51-year-old man with no history of travel outside of Montana presented to a local emergency department in May 2009 with fever, frontal headache, dizziness, numbness, and tingling. Initial evaluation, including CT scan of the brain, was negative and he was given symptomatic treatment. One week later he presented to his primary care physician (PCP) with continued fever, headache, and new onset of myalgias and weakness. A lumbar puncture yielded normal CSF. He was later referred to a neurologist who treated him for migraine. An acute phase serum drawn at the time of his visit to his PCP tested positive for West Nile Virus (WNV)-specific IgM and IgG by ELISA at the Montana Public Health Laboratory. The sample was sent to the CDC's arbovirus diagnostic laboratory at Fort Collins, CO, and convalescent samples were obtained 16 days and 189 days after symptom onset. Analysis of these three samples demonstrated stable WNV titers suggestive of remote infection with this virus and equivocal results for La Crosse Virus (LACV), but an increase in JCV titers.


JCV is a mosquito-borne zoonotic pathogen belonging to the California serogroup of bunyaviruses. The natural vertebrate host for JCV is the white-tailed deer. While JCV is widely distributed throughout North America, human infection is rare, with only 15 cases reported in the United States since 2004. This is the first case reported from Montana. The patient experienced a relatively mild, but prolonged encephalitis illness and seemingly recovered completely with supportive treatment. JCV should be considered by clinicians in the differential diagnosis of suspected arboviral infections. The MMWR report of this case emphasizes the extensive antibody cross-reactivity between JCV, WNV, and other arboviruses associated with neurologic disease in humans. The two-year interval between initial presentation of this case, submission of serologic specimens, and final report of this case in MMWR also suggests that clinicians should not expect prompt confirmation of the diagnosis of this infection.