In 2024, five people and 27 animals in Minnesota contracted the rare bacterial disease tularemia in the seven-county Minneapolis-St. Paul metropolitan area, state health authorities and the Centers for Disease Control and Prevention (CDC) reported yesterday in Morbidity and Mortality Weekly Report.
Two of the infected people reported recently mowing over animal carcasses; all were hospitalized for a median of 6 days and released without complications.
Each year from 2000 to 2023, a median of one person and two animals in the state were diagnosed as having the potentially serious illness, usually transmitted via tick or deer-fly bites, inhalation of contaminated material, or contact with infected animals, the authors noted. Animal tularemia cases spiked in Minnesota in 2023, with 20 cases; no human cases were reported.
Tularemia cases have been rising in the United States, climbing by more than half from 2011 to 2022, the CDC reported in December 2024.
Caused by the bacterium Francisella tularensis, tularemia typically affects 200 to 300 people each year in the United States, most often in the central part of the country.
Symptoms depend on how the person was exposed and usually include fever and local signs such as swollen lymph nodes and skin ulcers. There is no Food and Drug Administration–approved vaccine against tularemia.
Four patients had pneumonic disease
Of the five people diagnosed in 2024, four had pneumonic tularemia, which is usually caused by inhaling bacteria-containing dust or aerosols. Three patients weren't diagnosed as having tularemia until after hospital release. After diagnosis, all patients were prescribed the antibiotics ciprofloxacin or doxycycline as postexposure prevention.
In comparison, 2 of 32 (6.3%) human tularemia cases in Minnesota identified from 2000 to 2023 were the pneumonic form.
Of the 27 tularemia-positive animals reported via lab reports or veterinarians in 2024, 21 (78%) were domestic cats, 5 (19%) were domestic dogs, and 1 (4%) was a wild rabbit. Most animals had a nonlocalized typhoidal infection or oropharyngeal manifestations characterized by fever, mouth ulcers, and swollen lymph glands.
Four animals (15%) died of their infections, and two (7%) were euthanized due to a poor prognosis or concern about costs. Three pet owners and one veterinary worker were exposed, and one owner took antibiotics after a scratch from an infected cat, but none developed tularemia.
No ticks were found during drag sampling for three human and two animal cases at the likely exposure site and nearby public spaces. In the case of the two patients who reported mowing over animal carcasses, rabbit and mouse remains found at the site were too decomposed for testing.
Health workers advised to consider tularemia
"Increased veterinary awareness after tularemia-related communications in 2023 likely contributed to the increase in animal tularemia case reporting, in addition to a true increase in cases," the authors wrote.
Veterinarians should consider tularemia in cats and dogs with compatible symptoms, including high fever, oral ulcers, and lymphadenopathy.
They urged healthcare providers to consider tularemia in patients with fever and history of tick or deer-fly bites, contact with sick animals, or mowing over a rabbit or rodent.
"When ordering testing for a patient in whom tularemia is suspected, providers should alert the laboratory to ensure that laboratorians take appropriate precautions such as working in a biosafety cabinet and wearing gloves, gowns, and eye protection," they concluded. "Veterinarians should consider tularemia in cats and dogs with compatible symptoms, including high fever, oral ulcers, and lymphadenopathy."
