On May 28th, the CDC confirmed the second case of Bourbon Virus, this time in a patient in Payne County, Oklahoma.  In a previous article in February 2015, this novel disease was diagnosed in a >50 year old man in Kansas, who died from multi-organ failure (ultimately cardiovascular arrest).

Payne County, Oklahoma/David Benbennick
Payne County, Oklahoma/David Benbennick

Disease from the virus in this second case self-resolved after appropriate rehydration treatment; there is no cure for Bourbon Virus, and antibiotics will have no effect.  Symptoms of disease with Bourbon Virus include nausea, fever, chills, weakness, diarrhea, headache, myalgia and joint pain.  The fatal case in Kansas also developed leukopenia, thrombocytopenia, lymphadenopathy, impaired renal function and pleural effusions.

Bourbon Virus was isolated and sequenced by the CDC as a novel virus in the genus Thogotovirus in the Orthomyxoviridae family.  Two closely related viruses in this genus, Thogoto and Dhori, have only yet been found in the eastern hemisphere and cause neurological diseases such as meningitis and encephalitis, which were absent in the two cases of Bourbon Virus.  Respiratory symptoms associated with influenza, another virus in the Orthomyxoviridae family, were also absent in both cases.

The other Thogotoviruses are known to be transmitted via arthropods, such as ticks and mosquitoes, taking blood meals from humans.  In the fatal first case of Bourbon Virus, the patient had sustained bites from ticks and was found with a high level of viremia from the virus, although the vector involved in its transmission has not yet been definitively identified.  Coincidentally, another tick-borne virus, Heartland virus, first discovered in Missouri and Tennessee in 2012, presents with similar symptoms followed by immune cell and clotting deficiency.  Health officials at the CDC are advising citizens in the Midwestern United States to take steps to avoid coming into contact with ticks.

Steven Smith, M.Sc. is an Infectious diseases epidemiologist