Having pets is common, but getting a fatal infection from pet animals is rather uncommon.
A 68-year-old man presented to the clinic with a 2-month history of progressive painful swelling on the right side of his neck. At the start of swelling, two months back, the patient had a fever for one week.
Upon taking a thorough history, the patient revealed that he was administering prednisone to his outdoor cat, which was prescribed by a veterinarian to the cat for feline leukemia. The diagnosis was not confirmed by lab investigations. However, the cat died around two days before the patient’s symptoms began.
On physical examination, three erythematous lymph nodes were seen, which were painful to touch. The rest of the physical examination was unremarkable, and no other lymph nodes were palpable.
Laboratory investigation revealed positive IgM antibodies for Francisella tularensis (titer, 1:1280), the aerobic, gram-negative bacillus.
A diagnosis of glandular tularemia was made.
Tularemia is a rare but acute granulomatous infection caused by the bacillus Francisella tularensis, capable of infecting both humans and animals (small mammals).
Humans get infected by handling infected rodents, tick bite, ingestion, and inhalation of the bacteria. However, human-to-human transmission of this bacterium has not been seen yet.
The signs and symptoms of tularemia vary considerably from person to person, depending upon several factors, including the mode of transmission and the patient’s immune responses. The patient may be completely asymptomatic or may get a life-threatening infection. A high-grade fever of up to 104 oF is a common factor in the different clinical presentations.
The most common presentation is ulceroglandular, in which a skin ulcer develops, followed by lymphadenopathy. The second most common manifestation is Glandular tularemia, which is similar to ulceroglanduar except that the patient does not develop skin ulcers. Other manifestations include oculoglandular, oropharyngeal, typhoidal, and the most serious but rare form, pneumonic.
The diagnosis of tularemia is not straightforward because of the nonspecific and overlapping symptoms. Moreover, it is difficult to culture F. tularensis, and also it requires biosafety level 3 laboratory conditions due to a significantly high risk of spread to the lab personnel. Therefore, blood tests are usually done to confirm the diagnosis.
There isn’t a licensed vaccine yet, so the mainstay of treatment is antibiotics. Mostly aminoglycosides are given for 10 to 21 days, determined by the severity of the disease.
The patient in the discussion here was treated for four weeks with doxycycline. The lesions substantially improved within five days and completely resolved within three weeks
It’s a disease that can be transmitted easily from domestic cats.
If the cat consumes an infected prey, the bacteria can be fatal for the cat and can also be transmitted to any human in contact.
Pedati C, House J, Hancock-Allen J, Colton L, Bryan K, Ortbahn D, et al. Notes from the Field: Increase in Human Cases of Tularemia – Colorado, Nebraska, South Dakota, and Wyoming, January-September 2015. MMWR Morb Mortal Wkly Rep. 2015 Dec 4. 64 (47):1317-8
Ellis J, O. P. (n.d.). Tularemia. Retrieved from Pubmed: https://www.ncbi.nlm.nih.gov/pubmed/12364373
Laura Marks, M. P. (2018, September 06). Glandular Tularemia. Retrieved from The New England Journal of Medicine: https://www.nejm.org/doi/full/10.1056/NEJMicm1801531
Tularemia. (2018, December 13). Retrieved from Centers for Disease Control and Prevention: https://www.cdc.gov/tularemia/index.html