Unraveling a Complex Case: Brucellosis Manifesting as Fever of Unknown Origin, Septic Ankle Arthritis, and Iliacus Abscess

Brucellosis is an infectious disease caused by bacteria of the genus <i>Brucella</i>, predominantly affecting livestock and humans through contact or consumption. It is a major public health challenge, particularly in developing countries. Symptoms can be mild to severe, making diagnosis difficult and often resulting in more chronic problems if those issues are not addressed. Our case report is about a patient with brucellosis who ended up having multiple organ involvement and focusing on the benefits of early diagnosis and management. Our case report discusses a 61-year-old Jordanian male patient with a significant medical history, including heart failure, diabetes, and hypertension, who was admitted for left ankle pain, redness, and swelling after a recent travel to Italy. His symptoms began four months prior with abdominal pain, fever, anemia, and persistent gastrointestinal issues, worsening despite oral antibiotics. He developed progressive thigh pain and was ultimately diagnosed with septic arthritis, experiencing ongoing fever and new anemia. Blood tests indicated elevated erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and leukocytosis levels, while cultures were negative. Imaging revealed fluid collections around the right iliac and gluteus minimus muscles. A diagnosis of brucellosis was confirmed through lab tests. Management included doxycycline 100 mg and rifampicin 600 mg as part of the treatment protocol, hydration support, pain relief, and imaging-guided drainage to address the infection and its complications. In conclusion, this case highlights the diverse manifestations of brucellosis, including atypical symptoms such as fever of unknown origin (FUO), septic arthritis, and iliacus abscess. Studies underscore the need to consider brucellosis in the differential diagnosis of FUO, especially in endemic regions. A multidisciplinary management approach and a high level of clinical suspicion are crucial for achieving optimal outcomes in patients with this complex infection.