Case of tularemia reported in Colorado

Photo: Dr_Microbe/Adobe Stock

Colorado public health officials recently announced the detection of the first human case of tularemia this year in a resident of Wheat Ridge, Colorado.¹ The disease mainly affects rural areas, but has been detected nationwide, save for Hawaii.²

Tularemia is caused by the bacterium Francisella tularensis and is commonly found in wildlife animals.² The infection is most frequent in rodents, rabbits, and hares, which often experience significant mortality during outbreaks.³ It is also found in insects like ticks and deer flies. Transmission to humans can occur through bites of infected insects, skin contact with infected animals, drinking or eating contaminated water or food, or by inhaling airborne bacteria through contaminated aerosols or agricultural and landscaping dust.^1,3

Approximately 200 human cases of tularemia are reported annually in the United States, with most cases being found in western and south-central states.² In 2023, 9 human cases were reported in Colorado.⁴

"While tularemia is rare, it is important for residents to be aware of the symptoms and take preventive measures," said Rachel Reichardt, environmental health specialist at Jefferson County Public Health, in a news release.¹ "Prompt treatment with antibiotics is effective, so early diagnosis and medical attention are crucial."

Symptoms of tularemia include fever, non-healing skin ulcers at the infection site, swollen and painful lymph glands, inflamed eyes, sore throat, mouth sores, diarrhea, or pneumonia. In cases where the infection is due to contaminated food or water ingestion, symptoms may consist of a sore throat, abdominal pain, and diarrhea. Inhalation of F tularensis can lead to pneumonia, which can cause symptoms such as fever, chills, headache, muscle aches, dry cough, and progressive weakness.¹

The incubation period for the disease is 3 to 5 days but can vary from 1 to 14 days.² Treatment consists of a course of antibiotics. In humans, tularemia can be effectively treated and cured. It is advised to seek medical attention if symptoms associated with tularemia after potential contact with wildlife are experienced.¹

Tularemia infection in pets

Cases of the disease have been reported in dogs, cats, pigs, and horses. However, sheep are most commonly infected.⁵ In dogs, tularemia infection is rare, but much like humans, canines can become infected through insect or arachnid bites, drinking contaminated water, or by eating an infected wildlife animal. Symptoms of an infection in canines include short periods of decreased appetite, lethargy, and mild fever. Dogs may also experience conjunctivitis, uveitis, draining abscesses, and enlarged lymph nodes, although these symptoms are uncommon. Infected dogs are treated with antibiotics.⁵

The disease is also uncommon in cats, but exposure and illness are still possible. Signs of a tularemia infection in felines depends on the route of infection and bacterial species, but it can consist of a high fever, large and painful lymph nodes in the neck and head, abdominal pain, a tick infestation, jaundice, and organ system failure.^6,7 Other symptoms include decreased appetite, stiffness, reduced mobility, coughing, diarrhea, frequent urination, open mouth and throat sores, and increased pulse and respiratory rates.⁷ A tularemia infection in cats requires antibiotics, as well as hospitalization with effective supportive care, including intravenous fluid therapy. The mortality rate for cats infected with tularemia is high, with collapse and death occurring within a few hours to days.⁷

Measures to take to prevent human and pet exposure include¹:

• Using insect repellent during all outdoor activity
• Avoiding all contact with wild rodents
• Avoiding feeding or enticing rodents and rabbits into the yard or patio
• Eliminating piles of lumber, trash and weeds around the home
• Avoiding touching sick or dead animals and wearing gloves if handling is necessary
• Avoiding drinking untreated surface water like lakes, ponds, and rivers
• Ensuring thorough cooking of meat before consumption
• Keeping pets on a leash while in areas where contact with wildlife is possible
• Consulting a veterinarian after any pet interaction with wildlife
• Providing immediate veterinary care for sick pets and avoiding handling sick pets without using hand and face protection

References

1. First 2024 human case of tularemia found in Jefferson County. News release. Jefferson County Colorado Public Health. July 3, 2024. Accessed July 9, 2024. https://www.jeffco.us/CivicAlerts.aspx?AID=2247
2. Frequently asked questions (FAQ) about tularemia. Centers for Disease Control and Prevention. April 4, 2018. Accessed July 9, 2024. https://emergency.cdc.gov/agent/tularemia/faq.asp#:~:text=Tularemia%2C%20also%20known%20as%20%E2%80%9Crabbit,Q.
3. About tularemia. Centers for Disease Control and Prevention. Accessed July 9, 2024. https://www.cdc.gov/tularemia/about/index.html
4. Zoonotic disease in Colorado, 2018-2023. Colorado Department of Public Health and Environment. Accessed July 9, 2024. https://docs.google.com/document/d/e/2PACX-1vQiHGHnuA3a1eItYaqFdusko0oPPOXTDqc84Vre5iVq1hPgTF7oafN5_lUNiDdsDvy-PmFFpPw0L6iV/pub
5. Weir M, Williams K, Downing R. Tularemia in dogs. VCA Animal Hospitals. Accessed July 10, 2024. https://vcahospitals.com/know-your-pet/tularemia-in-dogs
6. Weir M, Williams K, Downing R. Tularemia in cats. VCA Animal Hospitals. Accessed July 10, 2024. https://vcahospitals.com/know-your-pet/tularemia-in-cats
7. Foley JE. Tularemia in cats. Merck Veterinary Manual. August 2018. Accessed July 10, 2024. https://www.merckvetmanual.com/cat-owners/disorders-affecting-multiple-body-systems-of-cats/tularemia-in-cats