Tularemia in the US: Increase in cases, different states hardest hit

During the last decade (2001-2010), their were a total of 1,208 human tularemia cases reported to the Centers for Disease Control and Prevention (an average of 120/year).

Public domain image/Jon Sullivan via Wikimedia commons

This has been the approximate average number of cases going back to the 1980s.

However, in recent years, and in particular in 2015, the number of human cases of the zoonotic bacterial infection has risen significantly.

During the first 11 months of 2015, federal health officials put the case tally in humans at 235, according to the most recent Notifiable Diseases and Mortality Table.  Colorado has seen the most (46) accounting for one-fifth of cases nationally. 

And the increases haven’t just been seen in 2015. During the first four years of this decade (2011-2014), 698 human tularemia cases were reported at an annual average of nearly 175.

Other states reporting high numbers of cases include Nebraska (21), South Dakota (20) and Wyoming (16).

Another difference is the states most affected between the 2001-2010 period and 2015. During the past decade, six states accounted for 59% of reported cases: Missouri (19%), Arkansas (13%), Oklahoma (9%), Massachusetts (7%), South Dakota (5%), and Kansas (5%)–Only South Dakota is on the top of the list in 2015.

Why the increase in cases?

This is hard to pinpoint according to experts.

Dr. Christina Nelson with CDC Division of Vector-Borne Diseases told The Global Dispatch sister-site, Outbreak News Today in September when the question was posed:

While the number of plague and tularemia cases are above average this year, the exact reasons are hard to pinpoint.  For both diseases, the number of cases tends to fluctuate from year-to-year, most likely due to the complicated relationship between arthropods (fleas in the case of plague and ticks or deer flies in the case of tularemia), rodents or rabbits, and human activity.

What is tularemia?

Tularemia is caused by infection with the bacterium, Francisella tularensis.

People can get tularemia, or Rabbit fever, if they handle infected animals, such as rabbits, rodents or hares, or are bitten by ticks or deer flies. They also can be exposed by touching contaminated soil, drinking contaminated water or inhaling bacteria.

Anyone who becomes ill after exposure to a sick or dead animal, or after spending time in areas where sick or dead wild animals have been seen, should talk to a health care provider about the possibility of tularemia. Tularemia is treatable with antibiotics.

Symptoms of tularemia include abrupt onset of fever, chills, headache, muscle aches, joint pain, vomiting, dry cough and difficulty breathing. Other symptoms are skin ulcers, swollen and painful lymph glands, inflamed eyes, sore throat, mouth sores, diarrhea or pneumonia. Tularemia often is overlooked as a diagnosis because it is rare, and the symptoms are similar to other diseases. The incubation period (from being exposed to becoming ill) for tularemia is typically 3 to 5 days, but can range from 1 to 14 days.

Robert Herriman is a microbiologist and the Editor-in-Chief of Outbreak News Today and the Executive Editor of The Global Dispatch

Follow @bactiman63

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