Uveitis Secondary to Systemic/Ocular Zoonosis

This 63-year-old male was referred by his primary care provider for evaluation of ocular discomfort, blurring, and injection of two months’ duration. He also complained of photophobia. Past systemic health history included recent exposure to methicillin-resistant Staphylococcus aureus (MRSA). The patient travelled extensively, often for months at a time, in his position as a veterinarian who worked as a consultant to feed yards in multiple states. His current medications included systemic over-the counter antihistamines and an eye wash.

Presenting visual acuities with correction were 20/50 OD and OS. Pupils were irregular in shape, unequal in size, and reacted poorly to light. Biomicroscopy revealed bilateral grade 2+ endothelial cells and grade 2+ injection, but minimal anterior chamber cells and flare. Large areas of posterior synechiae were present OD and OS but were more significant OD. Applanation tensions were OD 28 mmHg and OS 21 mmHg. Grade 2+ nuclear sclerosis was noted in both eyes.

Our initial diagnosis was chronic bilateral uveitis, which apparently peaked in severity sometime before his evaluation. Additional diagnoses included posterior synechiae, elevated intraocular pressure (IOP) that was worse in the right eye, dense endothelial keratic precipitates (KP) on the visual axis, and nuclear sclerosis cataract. Our treatment plan included homatropine 5% solution OD and OS in office, prednisolone acetate 1% ophthalmic suspension q4h, and re-evaluation in 24 hours.

The following day, visual acuities were OD 20/50 and OS 20/25. Other findings were essentially unchanged except for the IOPs, which were OD 25 mmHg and OS 15 mmHg. Gonioscopy revealed extensive posterior synechiae and anterior synechiae involving the angles, OD greater than OS. We continued the prednisolone acetate in both eyes and added timolol maleate ophthalmic solution 0.5% q12h OD. We referred the patient to an infectious disease specialist to rule out systemic disease, specifically zoonosis. The reports came back positive for Q fever and brucellosis.

A Rare Cause of Uveitis

Zoonoses are infections that can be transmitted from animals to humans; the Centers for Disease Control and Prevention (CDC) estimates that three out of four new human sicknesses are zoonotic diseases.¹ Q fever is a zoonosis caused by infection with Coxiella burnetii, an intracellular organism. Common reservoirs include cattle, sheep, and goats, although other species may be infected. Transmission to humans typically occurs through inhalation of aerosols from contaminated soil or animal waste. It typically presents as flu-like symptoms including fever with chills, retrobulbar headache, myalgia, and fatigue. Pneumonia is a less common but potentially serious complication. The therapy of choice for acute Q fever is oral doxycycline for two weeks.

Uveitis associated with Q fever is an uncommon finding. Evidence suggests that uveitis may not result from direct injury to the ocular structure by C. burnetii, but rather from inflammatory injury triggered by C. burnetii.

Brucellosis is caused by Brucella abortus and other Brucella species. Like C. burnetii, Brucella is an intracellular organism; it is most commonly contracted by consuming unpasteurized milk products. It may also be acquired by inhalation of the live bacteria. The presenting signs are virtually identical to those of Q fever. Arthritis may be found in chronic cases. Typical therapy is a combination of oral doxycycline and rifampin for a minimum of six to eight weeks.

Ocular involvement in brucellosis is very uncommon, especially in acute cases, but tends to occur more frequently in patients who have chronic disease. Management of Brucella uveitis consists of conventional antibiotic therapy for the systemic disease plus typical therapy for anterior segment inflammation.

Reference

1. CDC. Zoonotic Diseases. 2017 Jul 14. Available at https://www.cdc.gov/onehealth/basics/zoonotic-diseases.html . Accessed on Feb. 21, 2018.