This Rabbit-Borne Disease Is On The Rise This Year

© Shawn Nystrand, CC BY-SA 2.0 A rare disease spread by ticks and rabbits alike is on the rise this year in Colorado, South Dakota, Wyoming, and Nebraska, the CDC reports. A rare disease spread by ticks and rabbits alike is on the rise this year in Colorado, South Dakota, Wyoming, and Nebraska, the CDC reports.
It might sound like a gelato flavor, but the rare bacterial disease tularemia is no treat for its sufferers.
According to a report released Thursday by the Centers for Disease Control and Prevention (CDC), it’s only become more unpleasant this year due to an unexpected rise in cases throughout the bordering states of Colorado, South Dakota, Wyoming, and Nebraska — a total of 100 as of Sept. 30. Of these 100, 48 ended up hospitalized and one died. The tally is a sharp step up from the average 20 cases reported annually between the four states from 2004 to 2014.
“Health care providers should be aware of the elevated risk for tularemia within these states and consider a diagnosis of tularemia in any person nationwide with compatible signs and symptoms,” the authors cautioned.

The Bug That Can Be Anything

Tularemia is a particularly adaptable disease. The bacteria responsible for it, Francisella tularensis, is spread by a wide variety of means, whether it’s a tick bite, direct contact with animal hosts like the rabbit, inhaling it through the air, or ingesting contaminated food, water, and soil (thankfully, human-to-human transmission is off the table). Similarly, much like the plague, it manifests in its human victims differently, depending on how it enters the body.
These forms include, but aren’t limited to: pneumonic tularemia, which involves respiratory symptoms like bronchitis; glandular tularemia, which causes swollen, even rupturing, lymph nodes (a related form, ulceroglandular tularemia, adds skin lesions to the mix as well); and typhoidal tularemia, the result of an infection that wreaks havoc across the entire body, causing fever, muscle pain, and even sepsis in the worst cases.
In the cases reported to the CDC, sufferers ranged in age from 10 months to 89 years — the sole death involved an 85-year-old man. Fifty-one patients could have been exposed via animal contact, 49 through inhaling aerosolized tularemia particles, and 39 through tick or deer fly bites. At least 41 were possibly exposed through two or more avenues of transmission. And about one-quarter of cases each came down with its pneumonic, ulceroglandular, and typhoidal forms, respectively.
Since it’s caused by bacteria, tularemia is treatable with antibiotics, but as of yet, efforts to create a vaccine against it are still in the preliminary stages of research, though they are encouraging.
Given the disease’s ubiquity, its apparent increase this year is difficult to trace down to any one factor. “Although the cause for the increases in tularemia cases in Colorado, Nebraska, South Dakota, and Wyoming is unclear, possible explanations might be contributing factors, including increased rainfall promoting vegetation growth, pathogen survival, and increased rodent and rabbit populations,” the authors wrote. “Increased awareness and testing since tularemia was reinstated as a nationally notifiable disease in January 2000 is also a possible explanation for the increase in the number of cases in these four states.”
The annual total of tularemia cases in the U.S. has averaged 125 throughout the two past decades, with the disease far more prevalent in the early 20th century. 2013 and 2014 saw higher tallies of 203 and 180, respectively. While it will take time to determine the annual count this year, the researchers did find that cases of tularemia bordering those four states haven’t noticeably increased compared to last year.   
Whether this increase is a blip in the radar or signs of a genuine rise, though, there are prudent steps that everyone can take to avoid exposure, particularly within the four aforementioned states. “Residents and visitors to these areas should regularly use insect repellent, wear gloves when handling animals, and avoid mowing in areas where sick or dead animals have been reported,” the authors explained.
Source: Pedati C, House J, Hancock-Allen J, et al. Notes from the Field: Increase in Human Cases of Tularemia — Colorado, Nebraska, South Dakota, and Wyoming, January–September 2015. MMWR. 2015