A mysterious illness that seems to have killed a farmer in Kansas has led to the discovery of a new virus last week: the Bourbon virus.
The farmer had been working on his field last spring when he got several tick bites, including one that appeared to be attached to his shoulder. A few days later, he got sick. First, there was nausea, weakness, and diarrhea. Then came the flu-like symptoms: loss of appetite, chills, fever, a headache.
The man went to get help from his doctor, who presumed his patient had another tick-borne illness, Ehrlichiosis. But even with medication, the farmer's condition rapidly deteriorated. One morning, when his wife could barely rouse him in his bed, the farmer was rushed to hospital, and from there, got even worse: his kidneys and lungs failed, he went into shock, and within 11 days, he was dead.
All the tests to look for tick-borne illnesses and a range of other disease-causing viruses and bacteria turned up negative. Even scarier, until this bout, the man had been perfectly healthy.
Now, public health officials think a new tick-borne bug is to blame. The virus, described in a report from the Centers for Disease Control and Prevention last week, has been named "Bourbon" after Bourbon County, Kansas, where the man lived.
There's still a lot to learn about this new pathogen, and scientists only seldom find new viruses that cause illnesses in humans. So we called Dr. Erin Staples, a medical epidemiologist located in Fort Collins, Colorado who co-published the report, to find out what we know and don't know about Bourbon.
Julia Belluz: The farmer who is believed to be the first man to die from Bourbon virus had pretty non-specific symptoms: fever, chills, etc. How did you figure out it was a novel virus causing this?
Erin Staples: He was put on treatment which is correct treatment for [the tick-borne illness] Ehrlichiosis. But he didn't get better. And he had tested for a number of infectious diseases, and all the tests came back negative. First we thought he may have Heartland virus disease, a condition we believe is caused by a virus transmitted by ticks, and has been found in the region. We were actually doing an active study to test people for that. But that tested negative, too. And in that testing, we discovered this new virus.
JB: How do we know Bourbon is also spread through ticks?
ES: The other viruses in the same family have been associated with hard and soft ticks as well as mosquitoes. Because of that, we do think that people are likely going to be infected through the bite of an infected tick or mosquito. This gentleman himself reported several tick bites prior to becoming unwell and got sick at a time of year when mosquitoes aren't as active but ticks are.
Given what we know, we think this virus may be transmitted by ticks but we do have fieldwork plans: CDC researchers will go in the field with Kansas researchers to look at and capture ticks and mosquitoes where the patient got unwell to find out where the virus might be living.
JB: What does this new discovery mean for public health?
ES: We're just reporting the discovery, and part of that is to get out the information to to clinicians. We also plan on working with the state health department in Kansas, as well as the Missouri health department, to set up prospective studies to try to identify additional cases.
JB: Are there other suspected cases?
ES: There are no reported illnesses in the farmer's family but we're going to be looking more closely at that. Right now, we're not getting reports of individuals that might fit the clinical signs and symptoms of this disease.
JB: What should doctors and patients do with this new information?
ES: The signs and symptoms from Bourbon are relatively non-specific: fever, muscle aches, gastrointestinal issues. These can happen with a lot of illnesses. But the low platelet and white-blood cell counts tend to suggest tick-borne illnesses. If a person has those signs and symptoms, a doctor should treat them. But if a person fails to improve on treatment and additional testing is coming back negative, we suggest they get tested for Bourbon and Heartland viruses.
JB: Can you say how deadly Bourbon might be?
ES: From one case, it's hard to say what the spectrum of illness might be, and it might be that this case is somewhat unusual in the fact that we were able to recover the virus from his blood. Maybe there are many other people infected and they might have gotten their blood samples through but we didn't see the same finding. If you expect that there was really a new virus out there causing a lot of people to die for no known reason that are otherwise healthy, we might have heard about it at this point.
So we made this discovery but now we have a lot more work to do in order to understand what role this is playing in human disease.
It's nice to be able to identify something new that's causing human disease but more importantly for me is providing answers to this family who had a relatively healthy family member who was doing quite well die suddenly after a short illness. Not knowing what caused that can cause a lot of issues.