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.

"Our report seeks to increase provider awareness about the increase of tularemia, especially in these four states, in order to ensure that it is being recognized, reported and treated appropriately," lead researcher Dr. Caitlin Pedati told Medical Daily.

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. For all the trouble it can cause, however, our interactions with the germ are simply an unhappy accident. "Tularemia is fundamentally a disease of animals, and has been found in hundreds of different types of animals," Pedati explained.

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. According to Pedati, the majority were infected with the less virulent of tularemia's two major disease-causing strains, type B.

As of yet, efforts to create a vaccine against it are still in the preliminary stages of research, though they are encouraging. Thankfully, it is treatable. "Tularemia infections generally respond well to appropriate antibiotic therapy and mortality is usually quite low," Pedati said.

Given the disease’s ubiquity, its apparent increase this year is difficult to trace down to any one factor. "The specific reasons for the rise in tularemia in these four states is still unclear. It is possible that increased rainfall has promoted vegetation growth allowing for the propagation of the animals and vectors that carry tularemia," Pedati offered, "Additionally, when observing increases in case reports it is always important to consider increased awareness and testing are simply identifying more of these cases than in the past."

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. "Although somewhat speculative, this decrease is thought to be due to changes in game hunting and consumption practices," said Pedati. "Specifically, rabbit hunting and consumption was much more common 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 or elsewhere haven’t noticeably increased compared to last year. Pedati and her team do expect the toll to reach over 200.

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. "The public should be aware of preventive practices which include use of insect repellent, wearing gloves when handling dead animals, and avoiding mowing in areas with sick or dead animals," said Pedati, "The state health departments are continuing to work in conjunction with our experts from the CDC’s National Center for Emerging and Zoonotic Infectious Diseases in order to gather more information and gain a better understanding of this trend."

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.