A newly-discovered virus has led to the death of a man in Kansas, according to media reports.
The victim became ill last spring after he was bitten by ticks, USA Today reported, citing federal health officials Friday.
Following the tick bite, the 50-year-old patient complained of nausea, weakness and diarrhoea and became progressively sicker, eventually developing fever and chills.
He was initially treated with antibiotics, a standard therapy for illness related to tick bites, which can transmit bacteria. However, he became so sick that doctors reportedly transferred him to the University of Kansas Medical Centre in Kansas City.
Doctors tested him for a variety of well-known viruses, but found nothing they recognised. Eventually, they sent his blood sample to the US Centres for Disease Control and Prevention (CDC), where advanced tests found that the patient was infected by a virus hitherto unknown in the US.
CDC scientists have named the new virus the "Bourbon virus" after Bourbon county in Kansas, where the patient lived.
The Bourbon virus belongs to the family of thogotoviruses and its closest relatives have only been found in Europe, Asia and Africa, the USA Today report said.
The case was, however, perplexing for several reasons, health experts said.
Thogotoviruses usually make people sick by causing meningitis, an inflammation of the lining of the brain, or a brain inflammation called encephalitis. They are not known for causing problems with blood cells, according to the CDC.
However, early blood tests on the Kansas man showed that he suffered a decline in his white blood cells, which fight infections, as well as a decline in his platelets, which help the blood to clot.
Those symptoms were similar to those of ehrlichiosis, a bacterial illness caused by ticks that had been diagnosed in the US, said J. Erin Staples, a medical epidemiologist at the CDC.
Staples said that it might be possible that the Bourbon virus had been around for years, but had not been noticed because it never made anyone so sick before.
Experts felt that it could also be a possibility that the virus normally caused illness too mild for people to go to the doctor and the Kansas man's death could be a rare case in which a common virus proved deadly. Experts also conjectured that the virus could have evolved to become more dangerous.
Sophisticated tests have allowed scientists to discover a variety of new pathogens in recent years, from tick-borne illnesses to new strains of influenza.
"As diagnostic techniques have improved and surveillance of unexplained illnesses have increased, it is not surprising to find novel pathogens," said Amesh Adalja, senior associate at the Centre for Health Security of the University of Pittsburgh Medical Centre.
"It will be important to determine how widespread the Bourbon virus is in both ticks, insects, animals and humans and to grasp the spectrum of illness it is capable of causing," Adalja added.
