Aug. 29, 2012 -- A new virus, dubbed "Heartland virus," is being spread to people by ticks common in the Southeast, the CDC reports.
The only known cases are two northwestern Missouri men who fell ill in 2009. Ticks had bitten both men, but they did not get better after treatment with antibiotics. Tests later showed that the men did not have any tick-borne bacterial diseases.
But CDC researcher Laura K. McMullan, PhD, and colleagues did find something else: a previously unknown virus in the patients' blood.
"This virus could be a more common cause of human illness than is currently recognized," they suggest in the New England Journal of Medicine.
The two men, one age 57 and the other age 67, lived on different farms. The first had only a single tick bite. The second said that over a two-week period he'd received some 20 tick bites a day.
Both men had fever, fatigue, diarrhea, and low levels of blood platelets and white blood cells. The symptoms are similar to those of ehrlichiosis, a relatively common tick-borne disease that is caused by bacteria.
The first patient spent 10 days in the hospital. Two years later, he's still feeling tired and often has headaches. At first he had memory problems and loss of appetite, both of which slowly got better.
The second patient was in the hospital for 12 days. Over the next four to six weeks he had memory problems, fatigue, and loss of appetite. All of these symptoms went away and did not come back over the next two years.
The new virus is related to a tick-borne virus recently discovered in central and northeastern China. That virus, called SFTSV, causes fever and loss of blood platelets.
The most common ticks in northwestern Missouri, where the two men were infected with Heartland virus, are lone star ticks. These ticks are found throughout the Southeast and up the Atlantic coast to Maine.
No ticks carrying Heartland virus have been found. It's not clear whether a person infected with the new virus can spread it to another person, or whether a tick bite is necessary.
"Although these two patients had severe disease, the incidence of infection with the novel virus and range of disease severity are currently unknown," McMullan and colleagues write.
They warn health professionals to be on the lookout for people who fall ill after getting tick bites and who do not get better after antibiotic treatment.