When two Missouri farmers wound up hospitalized with fever, fatigue, low blood cell counts and elevated liver enzymes in 2009, doctors suspected ticks were to blame.
Both men recently had reported tick bites, including a 57-year-old whose wife plucked a single critter off his abdomen with tweezers and a 67-year-old man who figured he was bitten 20 times a day for two weeks while rebuilding fences on his 40-acre farm.
"I was getting worse and worse," recalled Robert Wonderly, now 60, of Sheridan, Mo., the victim with the single bite.
The men had all the symptoms of ehrlichiosis, a potentially dangerous bacterial infection spread by, yes, ticks. But when scientists cultured samples of the farmers� blood, the bacteria were nowhere to be found.
�We placed it into the culture and then we didn�t get anything,� recalled Dr. William L. Nicholson, a research microbiologist who specializes in emerging and zoonotic infectious with the Centers for Disease Control and Prevention. �And that, to us, indicated that we had something else in there that we weren�t testing for.�
That something turned out to be an entirely new virus discovered only through sophisticated genetic analysis conducted by Nicholson�s colleagues at the CDC�s Viral Special Pathogens branch. The scientists reported their findings in this week's issue of the New England Journal of Medicine.
�This particular virus has never been detected before,� said Nicholson. �This is unique to the world.�
So far, the Missouri men are the only known victims of the new germ, which has been identified as a phlebovirus, part of the Bunyaviridae family of potentially serious bugs. Hantavirus, spread by deer mice, comes from that group. So does the deadly Crimean-Congo hemorrhagic fever.
But Nicholson, along with state and local health officials, has been scouring the region where the men were infected. They�re looking for additional signs of what has been dubbed �the Heartland virus,� after Heartland Regional Medical Center in St. Joseph, Mo., where the men were treated -- and because it was discovered in the nation�s heartland.
The new virus appears to be very rare. Although there are plenty of phleboviruses around -- more than 70 -- they are divided by the ways that they�re spread. Some are carried by sand flies, for instance. Others, like the Rift Valley fever virus, are spread by mosquitoes.
The only other tick-borne phlebovirus known to cause disease in humans is called SFTSV -- severe fever with thrombocytopenia syndrome virus -- which was recently identified in central and northeastern China.