Tuesday, 3 March 2015

A new species of Tick-borne Virus from Bourbon County, Kansas.

In late spring 2014 a previously healthy man in his 50s was admitted to a hospital in Bourbon County, Kansas, suffering from Tick bites and a fever. Despite intensive care and treatment with broad-spectrum anti-microbial drugs he died of cardiopulmonary arrest brought on by multiple organ failure eleven days after the onset of the illness. Tests for a wide variety of wide variety of pathogens during treatment failed to identify the cause of the fever, but a previously unknown species of Thogotovirus was later isolated from his blood serum.

In a forthcoming paper in the journal Emerging Infectious Disease, Olga Kosoy and Amy Lambert of the Centers for Disease Control and Prevention at Fort Collins, Colorado, Dana Hawkinson of the University of Kansas Medical Center, Daniel Pastula of the Centers for Disease Control and Prevention at Fort Collins, Colorado, Cynthia Goldsmith of the Centers for Disease Control and Prevention at Atlanta, Georgia, Charles Hunt of the Kansas Department of Health and Environment and Erin Staples, also of the Centers for Disease Control and Prevention at Fort Collins, Colorado, formerly describe the new Thogotovirus as Bourbon County Virus.

The genus Thogotovirus is a member of the family Orthomyxoviridae, which also includes Influenza Viruses. At least seven species of Thogotovirus have previously been described; Araguari Virus, Aransas Bay Virus, Batken Virus, Dhori Virus, Jos Virus, Thogoto Virus, and Upolu Virus, all of which appear to be carried by Ticks. Of these only one has previously been isolated in North America, Aransas Bay Virus, which was isolated from Soft Ticks (Ornithodoros spp.) from seabird nests off the Texas coast. Two members of the genus have previously been shown capable of infecting and producing illnesses in humans. 

Thogoto Virus was found in two patients in Nigeria in 1966, an adult male with a febrile illness who later developed neuromyelitis optica (expand) and a fourteen-year-old boy who developed meningitis and died of complications of Sickle Cell Anemia. Antibodies to this Virus have been isolated from humans from other parts of Africa, Asia and Europe, suggesting that it may be more widespread. Dhori Virus has infected five workers at a Russian lab after accidental exposure in 1987, two of these patients went on to develop encephalitis. Antibodies to this Virus have also been found in human populations in Europe, Asia and Africa, suggesting that it too may be a more widespread cause of infections than is currently appreciated.

The viral particles isolated from the Bourbon County patient clearly belonged to a Thogotovirus, and appeared to be closely related to Batken Virus and Dhori Virus, neither of which has ever been isolated in the Western Hemisphere. The precise method of transmission for this Virus is unknown; all previously described species of Thogotovirus have been transmitted by Ticks and the patient was suffering from Tick bites when admitted to hospital making this the most likely cause of infection, but Batken Virus is known to also be carried by Mosquitoes, so a non-Tick vector cannot be ruled out for Bourbon County Virus.

Electron microscopic images of novel Thogotovirus isolate. Filamentous (A) and spherical (B) virus particles with distinct surface projection are visible in culture supernatant that was fixed in 2.5% paraformaldehyde. Kosoy et al. (2015).

See also…

Ixodid Ticks of the genus Amblyomma are parasites of Mammals found on all continents except Europe and Antarctica, but at their most diverse in South America, with 31 species described from Brazil alone (46% of all known Tick species from Brazil). These Ticks are...

In December 2013 cases of the haemorrhagic Virus Ebola began to be reported from the village of...

At least 467 people have died in an outbreak of  Ebola Hemorrhagic Fever in West Africa that began in February this year. The disease initially appeared in the remote border area between Guinea, Sierra Leone...

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