Tularemia, a rare bacterial infection that spreads between animals and human beings, has seen a large increase in case numbers over the past decade, according to the U.S. Centers for Disease Control and Prevention.
Tularemia is caused by the bacterium Francisella tularensis. People can become infected via multiple paths, including skin contact with infected animals, getting bitten by ticks and deer flies, consuming contaminated water, and inhaling contaminated aerosols. Among animals, hares, rabbits, and rodents are more susceptible to the bacterium.
Out of the 47 states that reported tularemia cases, four in the central region—Arkansas, Kansas, Missouri, and Oklahoma—made up 50 percent of all reported incidents.
White people accounted for the vast majority of cases at 84 percent, followed by American Indians or Alaska Natives at 9 percent, and 63 percent of cases occurred in men.
The CDC attributed the high incidence rates among Native Americans to the concentration of their reservations in central states as well as their engagement in certain activities that result in higher contact with infected creatures.
While tularemia can result in death, it is treatable with antibiotics, the agency said. Case fatality rates are typically less than 2 percent. However, rates could rise to 24 percent depending on factors such as the infecting phenotype.
“Reducing tularemia incidence will require tailored prevention education,” the report said. “Mitigating morbidity and mortality will require health care provider education, particularly among providers serving tribal populations, regarding early and accurate diagnosis and treatment.”
In the United States, tularemia is a “nationally notifiable disease,” with infections reported to the CDC by various state health agencies.
Symptoms, Precautions
According to the CDC, symptoms of tularemia infection vary depending on how the bacteria enters the human body.For instance, the most common form of tularemia is “ulceroglandular,” in which a skin ulcer forms at the entry point, accompanied by the swelling of regional lymph glands. This typically occurs after a person handles an infected animal or gets bitten by a tick or deer fly.
An “oculoglandular” type of tularemia is caused when bacteria enter the body via the eyes. People experience inflammation and irritation of the eyes, with lymph glands near the ear swelling.
The most serious form of the illness is “pneumonic.” Symptoms include cough, chest pain, and difficulty breathing.
“This form results from breathing dust or aerosols containing the organism. It can also occur when other forms of tularemia are left untreated and the bacteria spread through the bloodstream to the lungs,” the CDC says.
As a precautionary measure, the CDC advises people to use insect repellants registered by the U.S. Environmental Protection Agency when camping, hiking, or working outdoors.
People should ideally wear long pants and long sleeves to prevent deer flies and ticks from coming into contact with the skin, the agency said. If any ticks attach to the body, they must be removed immediately.
When mowing or landscaping, “don’t mow over sick or dead animals. When possible, check the area for carcasses prior to mowing,” the agency said. “Use of masks during mowing and other landscaping activities may reduce your risk of inhaling the bacteria, but this has not been studied.”
Infection through handling animals occurs when hunting or skinning creatures such as rabbits, prairie rats, muskrats, and other rodents.
The agency said outbreaks of tularemia have occurred among hamsters purchased from pet stores.
“At least one child in the U.S. has developed tularemia after being bitten by a pet hamster,” it said.
Domestic cats are “very susceptible to tularemia and have been known to transmit the bacteria to humans,” the CDC said.
